Aldo Sorniotti

Professor Aldo Sorniotti


Professor in Advanced Vehicle Engineering
+44 (0)1483 689688
13 AA 03

Academic and research departments

Department of Mechanical Engineering Sciences.

Research

Research interests

My teaching

My publications

Publications

Bottiglione F, De Pinto S, Mantriota G, Sorniotti A (2014) Energy consumption of a battery electric vehicle with infinitely variable transmission, Energies 7 (12) pp. 8317-8337
© 2014 by the authors.Battery electric vehicles (BEVs) represent a possible sustainable solution for personal urban transportation. Presently, the most limiting characteristic of BEVs is their short range, mainly because of battery technology limitations. A proper design and control of the drivetrain, aimed at reducing the power losses and thus increasing BEV range, can contribute to make the electrification of urban transportation a convenient choice. This paper presents a simulation-based comparison of the energy efficiency performance of six drivetrain architectures for BEVs. Although many different drivetrain and transmission architectures have been proposed for BEVs, no literature was found regarding BEVs equipped with infinitely variable transmissions (IVTs). The analyzed drivetrain configurations are: single- (1G) and two-speed (2G) gear drives, half toroidal (HT) and full toroidal (FT) continuously variable transmissions (CVTs), and infinitely variable transmissions (IVTs) with two different types of internal power flow (IVT-I and IVT-II). An off-line procedure for determining the most efficient control action for each drivetrain configuration is proposed, which allows selecting the optimal speed ratio for each operating condition. The energy consumption of the BEVs is simulated along the UDC (Urban Driving Cycle) and Japanese 10-15 driving cycle, with a backward facing approach. In order to achieve the lowest energy consumption, a trade-off between high transmission efficiency and flexibility in terms of allowed speed ratios is required.
de Novellis L, Sorniotti A, Gruber P, Shead L, Ivanov V, Hoepping K (2012) Torque vectoring for electric vehicles with individually controlled motors: State-of-the-art and future developments, World Electric Vehicle Journal 5 (2) pp. 617-628
© 2012 WEVA.This paper deals with the description of current and future vehicle technology related to yaw moment control, anti-lock braking and traction control through the employment of effective torque vectoring strategies for electric vehicles. In particular, the adoption of individually controlled electric powertrains with the aim of tuning the vehicle dynamic characteristics in steady-state and transient conditions is discussed. This subject is currently investigated within the European Union (EU) funded Seventh Framework Programme (FP7) consortium E-VECTOORC, focused on the development and experimental testing of novel control strategies. Through a comprehensive literature review, the article outlines the stateof- the-art of torque vectoring control for fully electric vehicles and presents the philosophy and the potential impact of the E-VECTOORC control structure from the viewpoint of torque vectoring for vehicle dynamics enhancement.
Sorniotti A, Sampo' E, Velardocchia M, Bonisoli E, Galvagno E (2008) Friction inside Wheel Hub Bearings: Evaluation through Analytical Models and Experimental Methodologies, SAE 2007 Transactions Journal of Engines SAE International
De Novellis L, Sorniotti A, Gruber P, Orus J, Rodriguez Fortun J-M, Theunissen J, De Smet J (2014) Direct yaw moment control actuated through electric drivetrains and friction brakes: Theoretical design and experimental assessment, Mechatronics 26 pp. 1-15 Elsevier
A significant challenge in electric vehicles with multiple motors is how to control the individual drivetrains in order to achieve measurable benefits in terms of vehicle cornering response, compared to conventional stability control systems actuating the friction brakes. This paper presents a direct yaw moment controller based on the combination of feedforward and feedback contributions for continuous yaw rate control. When the estimated sideslip exceeds a pre-defined threshold, a sideslip-based yaw moment contribution is activated. All yaw moment contributions are entirely tunable through model-based approaches, for reduced vehicle testing time. The purpose of the controller is to continuously modify the vehicle understeer characteristic in quasi-static conditions and increase yaw and sideslip damping during transients. Skid-pad, step-steer and sweep steer tests are carried out with a front-wheel-drive fully electric vehicle demonstrator with two independent drivetrains. The experimental test results of the electric motor-based actuation of the direct yaw moment controller are compared with those deriving from the friction brake-based actuation of the same algorithm, which is a major contribution of this paper. The novel results show that continuous direct yaw moment control allows significant "on-demand" changes of the vehicle response in cornering conditions and to enhance active vehicle safety during extreme driving maneuvers.
De Novellis, Sorniotti A, Gruber P (2013) Wheel Torque Distribution Criteria for Electric Vehicles With Torque-Vectoring Differentials, IEEE Transactions on Vehicular Technology
The continuous, precise modulation of the driving and braking torque of each wheel is considered to be the ultimate goal for controlling the performance of a vehicle in steady-state and transient conditions. To do so, dedicated torque-vectoring controllers which allow optimal wheel torque distribution under all possible driving conditions have to be developed. Commonly, vehicle torque-vectoring controllers are based on a hierarchical approach, consisting of a high-level supervisory controller which evaluates a corrective yaw moment, and a low-level controller which defines the individual wheel torque reference values. The problem of the optimal individual wheel torque distribution for a particular driving condition can be solved through an optimization-based control allocation algorithm, which must rely on the appropriate selection of the objective function. With a newly developed off-line optimization procedure, this article assesses the performance of alternative objective functions for the optimal wheel torque distribution of a four-wheel-drive fully electric vehicle. Results show that objective functions based on minimum tire slip criterion provide better control performance than functions based on energy efficiency.
Velardocchia M, D'Alfio N, Bonisoli E, Galvagno E, Amisano F, Sorniotti A (2008) Block-oriented models of torque gap filler devices for AMT transmissions, SAE Technical Papers
Vehicles equipped with Automated Manual Transmissions (AMT) for gear shift control show many advantages in terms of reduction of fuel consumption and improvement of driving comfort and shifting quality. In order to increase both performance and efficiency, an important target is focused on the minimization of the typical torque interruption during the gear shift, especially in front of the conventional automatic transmission. Recently, AMT are proposed to be connected with planetary gears and friction brakes, in order to reduce the torque gap during the gear change process. This paper is focused on a block-oriented simulation methodology developed in Matlab/Simulink/ Stateflow® environment, able to simulate the performance of a complete FWD powertrain and in particular to predict dynamic performance and overall efficiency of the AMT with innovative Torque Gap Filler devices (TGF). A comparison between traditional Manual Transmission (MT) system and AMT with TGF device is presented, focusing in particular on the gear shift control strategies able to improve the performance of these systems. Some dynamic simulations are discussed in order to validate the proposed model and to simulate performance and limitations of this mechanical solution. Copyright © 2008 SAE International.
Sorniotti A, Holdstock T, Pilone GL, Viotto F, Bertolotto S, Everitt M, Barnes RJ, Stubbs B, Westby M (2012) Analysis and simulation of the gearshift methodology for a novel two-speed transmission system for electric powertrains with a central motor, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING 226 (D7) pp. 915-929 SAGE PUBLICATIONS LTD
Pennycott A, De Novellis L, Gruber P, Sorniotti A (2014) Optimal braking force allocation for a four-wheel drive fully electric vehicle, Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering
Sampo' E, Sorniotti A, Crocombe AD (2010) Chassis Torsional Stiffness: Analysis of the Influence on Vehicle Dynamics, Tire and Wheel Technology and Vehicle Dynamics and Handling, 2010
Sorniotti A, Subramanyan S, Turner A, Cavallino C, Viotto F, Bertolotto S (2011) Selection of the Optimal Gearbox Layout for an Electric Vehicle, SAE International Journal of Engines 4 (1) pp. 1267-1280
The paper describes the advantages due to the adoption of multi-speed transmission systems within fully electric vehicles. In particular, the article compares a conventional single-speed transmission layout, a 2-speed layout based on a novel gearbox architecture capable of seamless gearshifts, and a Continuously Variable Transmission layout. The selection of the optimal gear ratios for the 2-speed system has been based on an optimization procedure, taking into account the efficiency characteristics of the components of the whole vehicle powertrain. The control system for the Continuously Variable Transmission system has been designed with the aim of maximizing the efficiency of the operating points of the electric motor. The results show that there is a significant advantage in adopting a 2-speed transmission system over the single-speed layout, and, despite a reduction in motor losses, the typically lower efficiency characteristics of Continuously Variable Transmissions do not result in lower energy consumption for the four case study vehicles.
Chatzikomis C, Sorniotti A, Gruber P, Shah M, Bastin M, Orlov Y (2017) Torque-vectoring control for an autonomous and driverless electric racing vehicle with multiple motors, SAE International Journal of Vehicle Dynamics, Stability and NVH 1 (2) SAE International
Electric vehicles with multiple motors permit continuous direct yaw moment control, also called torque-vectoring. This allows to significantly enhance the cornering response, e.g., by extending the linear region of the vehicle understeer characteristic, and by increasing the maximum achievable lateral acceleration. These benefits are well documented for human-driven cars, yet limited information is available for autonomous/driverless vehicles. In particular, over the last few years, steering controllers for automated driving at the cornering limit have considerably advanced, but it is unclear how these controllers should be integrated alongside a torque-vectoring system. This contribution discusses the integration of torque-vectoring control and automated driving, including the design and implementation of the torque-vectoring controller of an autonomous electric vehicle for a novel racing competition. The paper presents the main vehicle characteristics and control architecture. A quasi-static model is introduced to predict the understeer characteristics at different longitudinal accelerations. The model is coupled with an off-line optimization for the a-priori investigation of the potential benefits of torque-vectoring. The systematic computation of the achievable cornering limits is used to specify and design realistic maps of the reference yaw rate, and a non-linear feedforward yaw moment contribution providing the reference cornering response in quasi-static conditions. A gain scheduled proportional integral controller increases yaw damping, thus enhancing the transient response. Simulation results demonstrate the effectiveness of the proposed approach.
Lu Q, Gentile P, Tota A, Sorniotti A, Gruber P, Costamagna F, De Smet J (2016) Enhancing vehicle cornering limit through sideslip and yaw rate control, Mechanical Systems and Signal Processing 75 pp. 455-472
Fully electric vehicles with individually controlled drivetrains can provide a high degree of drivability and vehicle safety, all while increasing the cornering limit and the ?fun-to-drive? aspect. This paper investigates a new approach on how sideslip control can be integrated into a continuously active yaw rate controller to extend the limit of stable vehicle cornering and to allow sustained high values of sideslip angle. The controllability-related limitations of integrated yaw rate and sideslip control, together with its potential benefits, are discussed through the tools of multi-variable feedback control theory and non-linear phase-plane analysis. Two examples of integrated yaw rate and sideslip control systems are presented and their effectiveness is experimentally evaluated and demonstrated on a four-wheel-drive fully electric vehicle prototype. Results show that the integrated control system allows safe operation at the vehicle cornering limit at a specified sideslip angle independent of the tire-road friction conditions.
Sorniotti A, D'Alfio N, Morgando A (2008) Shock Absorber Modeling and Experimental Testing, SAE 2007 Transactions Journal of Passenger Cars: Mechanical Systems
Sorniotti A, Velardocchia M (2008) Enhanced Tire Brush Model for Vehicle Dynamics Simulation, Vehicle Dynamics and Simulation and Tire and Wheel Technology, 2008 SAE International
Pennycott A, de Novellis L, Sorniotti A, Gruber P (2014) The Application of Control and Wheel Torque Allocation Techniques to Driving Modes for Fully Electric Vehicles, SAE International Journal of Passenger Cars - Mechanical Systems 7 (2) pp. 488-496
The combination of continuously-acting high level controllers and control allocation techniques allows various driving modes to be made available to the driver. The driving modes modify the fundamental vehicle performance characteristics including the understeer characteristic and also enable varying emphasis to be placed on aspects such as tire slip and energy efficiency. In this study, control and wheel torque allocation techniques are used to produce three driving modes. Using simulation of an empirically validated model that incorporates the dynamics of the electric powertrains, the vehicle performance, longitudinal slip and power utilization during straight-ahead driving and cornering maneuvers under the different driving modes are compared. The three driving modes enable significant changes to the vehicle behavior to be induced, allowing the responsiveness of the car to the steering wheel inputs and the lateral acceleration limits to be varied according to the selected driving mode. Furthermore, the different driving modes have a significant impact on the longitudinal tire slip, the motor power losses and the total power utilization. The control and wheel torque allocation methods do not rely on complex and computationally demanding online optimization schemes and can thus be practically implemented on real fully electric vehicles. Copyright © 2014 SAE International.
Dizqah AM, Lenzo B, Sorniotti A, Gruber P, Fallah S, De Smet J (2016) A Fast and Parametric Torque Distribution Strategy for Four-Wheel-Drive Energy-Efficient Electric Vehicles, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 63 (7) pp. 4367-4376 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Holdstock T, Sorniotti A, Everitt M, Fracchia M, Bologna S, Bertolotto S (2012) Energy consumption analysis of a novel four-speed dual motor drivetrain for electric vehicles, 2012 IEEE Vehicle Power and Propulsion Conference, VPPC 2012 pp. 295-300 IEEE
The electric vehicle is becoming increasingly prevalent as a viable option to replace hydrocarbon fuelled vehicles, and as such the development of high efficiency fully electric drivetrains is a particularly relevant research topic. The drivetrain topology is one of the main focuses of research on fully electric drivetrains, because of the variety of available options. For example, the adoption of multiple-speed mechanical transmissions can improve both the performance and energy consumption when compared to a single-speed transmission. A four-speed, dual motor drivetrain design is presented in this article which works on the principle of two double-speed transmissions, each driven by a separate motor linked through a sole secondary shaft. This drivetrain architecture provides increased flexibility of the electric motor operating points, theoretically being beneficial to the overall efficiency of the system for any driving condition. This paper presents the design of the transmission, its governing equations and the method adopted to optimize the state selection map and electric motor torque distribution. A backward-facing energy consumption model is used to compare the results of the four-speed transmission with those of single- and double-speed transmissions for four case study vehicles. © 2012 IEEE.
Lekakou C, Lei C, Markoulidis F, Sorniotti A (2012) Nanomaterials and Nanocomposites for High Energy/High Power Supercapacitors, 2012 12TH IEEE CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO) IEEE
Sorniotti A (2013) Linear and non-linear methods to analyse the drivability of a through-the-road parallel hybrid electric vehicle, International Journal of Powertrains 2 (1) pp. 52-77
Individually-controlled powertrains of fully electric
vehicles present an opportunity to enhance the steady-state and
transient cornering response of a car via continuously-acting
controllers and enable various ?driving modes? to be available.
This study investigates the associated potential for energy savings
through the minimization of power losses from the motor units
via wheel torque allocation. Power losses in straight-ahead
driving and a ramp steer maneuver for different motor types and
under different wheel torque allocation schemes are analyzed in
an offline simulation approach. Significant reductions in motor
power losses are achieved for two motor types using an
optimization scheme based on look-up tables of motor loss data.
Energy loss minimization cannot be achieved through a direct
quadratic approximation of the power losses.
Sorniotti A (2008) Air Suspension and Damping: Technologies and Applications,
Sorniotti A, D'Alfio N, Morgando A, Velardocchia M, Amisano F (2007) An Objective Evaluation of the Comfort during the Gear Shift Process, Transmissions & Drivelines
Santucci A, Sorniotti A, Lekakou C (2013) Model predictive control for the power-split between supercapacitor and battery for automotive applications, 2013 IEEE International Electric Vehicle Conference, IEVC 2013
Research and development of energy storage systems are almost entirely dominated by the need for continuously increasing their performance, reducing weight, cost, and increasing efficiency. The combination of battery and supercapacitor within the hybrid energy storage system (HESS) involves the management of the power between the two devices. The objective of this study is to develop a novel model predictive controller for the HESS of a through-the- road-parallel hybrid electric vehicle, which aims to extend the battery life. Results in terms of battery life expectancy and HESS energy efficiency are presented and discussed. © 2013 IEEE.
Sorniotti A, D'Alfio N (2008) Vehicle Dynamics Simulation to Develop an Active Roll Control System, SAE 2007 Transactions Journal of Passenger Cars: Mechanical Systems SAE International
Sorniotti A (2008) Driveline Modeling, Experimental Validation and Evaluation of the Influence of the Different Parameters on the Overall System Dynamics, Transmission and Driveline, 2008
Sorniotti A (2009) Tire Thermal Model for Enhanced Vehicle Dynamics Simulation, Tire and Wheel Technology and Vehicle Dynamics and Simulation, 2009
Sorniotti A (2008) Shock Absorber Thermal Model: Basic Principles and Experimental Validation, Steering and Suspension Technology Symposium, 2008 SAE International
Sorniotti A, Velardocchia M (2008) Dual Rate Boosters: Analysis, Modeling and Experimental Evaluation of Their Performance, SAE 2007 Transactions Journal of Passenger Cars: Mechanical Systems
Sorniotti A, Curto M (2008) Racing Simulation of a Formula 1 Vehicle with Kinetic Energy Recovery System, SAE International
Laghari N, Sorniotti A, Parker GA (2010) Comparative linear analysis of alternative layouts of heavy goods vehicles, SAE International Journal of Commercial Vehicles 2 (2) pp. 85-100
This paper presents comparative analyses of steering wheel responses of various layouts for heavy goods vehicles, including rigid and articulated configurations. Newton and Lagrange techniques have been adopted to formulate and verify the generalized linear model for multi-axle rigid and articulated vehicles. The model is then used to simulate, analyze and compare steering angle response of a variety of commercially available vehicles. The study includes the analyses of steady state response and dynamic behavior for different layouts in terms of axle positions, number of axles and multiple steered axles.
Velardocchia M, Bonisoli E, Galvagno E, Vigliani A, Sorniotti A (2007) Efficiency of Epicyclic Gears in Automated Manual Transmission Systems,
De Novellis L, Sorniotti A, Gruber P, Pennycott A (2014) Comparison of feedback control techniques for torque-vectoring control of fully electric vehicles, IEEE Transactions on Vehicular Technology 63 (8) pp. 3612-3623
© 2014 IEEE.Fully electric vehicles (FEVs) with individually controlled powertrains can significantly enhance vehicle response to steering-wheel inputs in both steady-state and transient conditions, thereby improving vehicle handling and, thus, active safety and the fun-to-drive element. This paper presents a comparison between different torque-vectoring control structures for the yaw moment control of FEVs. Two second-order sliding-mode controllers are evaluated against a feedforward controller combined with either a conventional or an adaptive proportional-integral-derivative (PID) controller. Furthermore, the potential performance and robustness benefits arising from the integration of a body sideslip controller with the yaw rate feedback control system are assessed. The results show that all the evaluated controllers are able to significantly change the understeer behavior with respect to the baseline vehicle. The PID-based controllers achieve very good vehicle performance in steady-state and transient conditions, whereas the controllers based on the sliding-mode approach demonstrate a high level of robustness against variations in the vehicle parameters. The integrated sideslip controller effectively maintains the sideslip angle within acceptable limits in the case of an erroneous estimation of the tire-road friction coefficient.
D'Alfio N, Morgando A, Sorniotti A (2006) Electro-hydraulic brake systems: design and test through hardware-in-the-loop simulation, VEHICLE SYSTEM DYNAMICS 44 pp. 378-392 TAYLOR & FRANCIS INC
De Novellis L, Sorniotti A, Gruber P, Shead L, Ivanov V, Hoepping K Torque Vectoring for Electric Vehicles with Individually Controlled Motors: State-of-the-Art and Future Developments, 26th Electric Vehicle Symposium 2012 Curran Associates
Sorniotti A, Velardocchia M (2007) Multi-body Modelling of Hydraulic Brake Calipers,
Laghari N, Sorniotti A, Parker G (2010) Linear Analysis of the Effect of Tire Dynamics on the Overall Vehicle Performance, Tire and Wheel Technology and Vehicle Dynamics and Handling, 2010
Lekakou C, Markoulidis F, Lei C, Sorniotti A, Perry J, Hoy C, Martorana B, Cannavaro I, Gosso M (2012) Meso-nano and micro-nano ion transport in porous carbon composite electrodes for energy storage applications, ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials
In energy storage devices carbonaceous composite electrodes are a popular choice, consisting of activated carbon (ac), conductive additives and a polymeric binder matrix. The active electrode components are in the form of ac particles, ac fibres, or ac monolith combined with conductive additives such as carbon black. Activated carbon plays the most important role for storing a large amount of energy in the form of ions contained in the carbon nanopores. This study considers a modelling approach to the meso-nano and micro-nano infiltration of ions into the porous carbon structure during the operation of the energy storage device. Depending on the pore size, ion size and solvent molecule size, ions may be solvated or unsolvated as they move, where ions are solvated in meso-pores for most cases. Molecular model simulations have been performed to determine the values of the geometrical parameters of different ions, solvated and unsolvated in various solvents. A meso-nano and micro-nano ion infiltration model has been developed in this study under both steady state and dynamic conditions.
Lu Q, Sorniotti A, Gruber P, Theunissen J, De Smet J (2016) H-infinity loop shaping for the torque-vectoring control of electric vehicles: Theoretical design and experimental assessment, MECHATRONICS 35 pp. 32-43 PERGAMON-ELSEVIER SCIENCE LTD
Pennycott A, De Novellis L, Sabbatini A, Gruber P, Sorniotti A (2014) Reducing the motor power losses of a four-wheel drive, fully electric vehicle via wheel torque allocation, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 228 (7) pp. 830-839
Individually controlled electric motors provide opportunities for enhancing the handling characteristics and the energy efficiency of fully electric vehicles. Online power loss minimisation schemes based on the electric motor efficiency data may, however, be impractical for real-time implementation owing to the heavy computational demand. In this paper, the optimal wheel torque distribution for minimal power losses from the electric motor drives is evaluated in an offline optimisation procedure and then approximated using a simple function for online control allocation. The wheel torque allocation scheme is evaluated via a simulation approach incorporating straight-ahead driving at a constant speed, a ramp manoeuvre and a sequence of step steer manoeuvres. The energy-efficient wheel torque allocation scheme provides motor power loss reductions and yields savings in the total power utilisation compared with a simpler method in which the torques are evenly distributed across the four wheels. The method does not rely on complex online optimisation and can be applied on real electric vehicles in order to improve the efficiency and thus to reduce power consumption during different manoeuvres. © IMechE 2014.
Sorniotti A (2013) A novel clutchless multiple-speed transmission for electric axles, International Journal of Powertrains 2 (2/3) pp. 103-131 Inderscience
Fully electric vehicles and range-extended electric vehicles can be characterised by a multitude of possible powertrain layouts, many of them currently under investigation and comparison. This contribution presents a novel clutchless seamless four-speed transmission system which can be concurrently driven by two electric motor drives, for use in fully electric vehicles or electric axles for through-the-road parallel hybrid electric vehicles. The transmission system allows the electric motors to work in their high efficiency region for a longer period during a typical driving schedule. This paper describes the layout of the novel transmission system, the equations for modelling its dynamics and the criteria for the selection of the best gearshift maps for energy efficiency. Finally, an energy consumption and performance comparison between the novel drivetrain, a conventional single-speed electric drivetrain and a double-speed electric drivetrain is discussed in detail for two case study vehicles.
Santucci A, Sorniotti A, Lekakou C (2014) Power split strategies for hybrid energy storage systems for vehicular applications, Journal of Power Sources 258 pp. 395-407
This paper deals with the control system development for a hybrid energy storage system, consisting of a battery and a supercapacitor, for a through-the-road-parallel hybrid electric vehicle. One of the main advantages deriving from the coupling of a battery and a supercapacitor is the possibility of reducing battery ageing, in addition to energy efficiency improvements when the system operates in critical climate conditions. At the moment, no specific controller has been proposed with the aim of directly reducing battery wear. This paper presents a novel model predictive controller and a dynamic programming algorithm including a simplified battery ageing model in their formulations. The simulation results of the model predictive controller and dynamic programming algorithm are compared with the results deriving from a rule-based strategy. The rule-based controller achieves a 67% reduction of the root mean square values of battery current along a selection of driving cycles in comparison with the same vehicle equipped with battery only. In the same conditions the battery peak current is reduced by 38%. The model predictive controller and the dynamic programming algorithm further reduce the root mean square value by 6% and 10% respectively, whilst the peak values are additionally decreased by 17% and 45%. © 2014 The Authors. Published by Elsevier B.V.
Sorniotti A, Morgando A, Velardocchia M (2006) Active roll control: system design and hardware-in-the-loop test bench, VEHICLE SYSTEM DYNAMICS 44 pp. 489-505 TAYLOR & FRANCIS INC
Sorniotti A (2012) The effect of half-shaft torsion dynamics on the performance of a traction control system for electric vehicles, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 26 (9) pp. 1145-1159 Sage
This article deals with the dynamic properties of individual wheel electric powertrains for fully electric vehicles, characterised
by an in-board location of the motor and transmission, connected to the wheel through half-shafts. Such a layout
is applicable to vehicles characterised by significant power and torque requirements where the adoption of in-wheel
electric powertrains is not feasible because of packaging constraints. However, the dynamic performance of in-board
electric powertrains, especially if adopted for anti-lock braking or traction control, can be affected by the torsional
dynamics of the half-shafts. This article presents the dynamic analysis of in-board electric powertrains in both the time
domain and the frequency domain. A feedback control system, incorporating state estimation through an extended
Kalman filter, is implemented in order to compensate for the effect of the half-shaft dynamics. The effectiveness of the
new controller is demonstrated through analysis of the improvement in the performance of the traction control system.
Goggia T, Sorniotti A, De Novellis L, Ferrara A, Gruber P, Theunissen J, Steenbeke D, Knauder B, Zehetner J (2014) Integral Sliding Mode for the Torque-Vectoring Control of Fully Electric Vehicles: Theoretical Design and Experimental Assessment, IEEE Transactions on Vehicular Technology
Sorniotti A, Barber P, De Pinto S (2016) Path Tracking for Automated Driving: A Tutorial on Control System Formulations and Ongoing Research, In: Watzenig D, Horn M (eds.), Automated Driving - Safer and More Efficient Future Driving 5 pp. 71-140 Springer International Publishing
In automated driving system architectures (see the classification according to [1]),
three layers can be typically defined [2]:
(i) The perception layer, aimed at detecting the conditions of the environment
surrounding the vehicle, e.g., by identifying the appropriate lane and the
presence of obstacles on the track;
(ii) The reference generation layer, providing the reference signals, e.g., in the
form of the reference trajectory to be followed by the vehicle, based on the
inputs from the perception layer;
(iii) The control layer, defining the commands required for ensuring the tracking
performance of the reference trajectory. These commands are usually
expressed in terms of reference steering angles (usually on the front axle only)
and traction/braking torques.
This chapter focuses on the control layer and, in particular, the steering control
for autonomous driving, also defined as path tracking control. The foundations of
path tracking control for autonomous driving date back to well-known theoretical
and experimental studies on robotic systems and driver modeling, detailed in several
papers and textbooks (e.g., see the driver model descriptions in [3?9]). Moreover,
automated driving experiments with different controllers have been conducted since
the 1950s and 1960s, by using inductive cables or magnetic markers embedded in
roadways to indicate the reference path [10, 11].
This contribution presents a survey of the main control techniques and formulations
adopted to ensure that the automatically driven vehicles follow the reference
trajectory, including analysis of extreme maneuvering conditions. The discussion
will be based on a selection of different control structures, at increasing levels
of complexity and performance. The focus will be on whether complex steering
controllers are actually beneficial to autonomous driving. This is an important
point, considering that Stanley and Sandstorm, the vehicles that obtained the
first two places at the DARPA Grand Challenge (2004?2005), used very simple
steering control laws based on kinematic vehicle models. In contrast to this,
Boss, the autonomous vehicle winning the DARPA Urban Challenge (2007), was
characterized by a far more advanced model predictive control strategy [12?15].
The main formulas for the different steering control structures will be concisely
provided as a tutorial on the control system implementations, so that the reader can
actually appreciate the characteristics of each formulation, and
Mehdizadeh Gavgani A, Bingham T, Sorniotti A, Doherty J, Cavallino C, Fracchia M (2015) A Parallel Hybrid Electric Drivetrain Layout with Torque-Fill Capability, SAE International Journal of Passenger Cars - Mechanical Systems 8 (2) pp. 767-778
Copyright © 2015 SAE International.This paper discusses the torque-fill capability of a novel hybrid electric drivetrain for a high-performance passenger car, originally equipped with a dual-clutch transmission system, driven by an internal combustion engine. The paper presents the simulation models of the two drivetrains, including examples of experimental validation during upshifts. An important functionality of the electric motor drive within the novel drivetrain is to provide torque-fill during gearshifts when the vehicle is engine-driven. A gearshift performance indicator is introduced in the paper, and the two drivetrain layouts are assessed in terms of gearshift quality performance for a range of maneuvers.
Goggia T, Sorniotti A, De Novellis L, Ferrara A (2014) Torque-vectoring control in fully electric vehicles via integral sliding modes, Proceedings of the American Control Conference pp. 3918-3923
This paper discusses an integral sliding mode algorithm for yaw rate control of a torque-vectoring fully electric vehicle with individually controlled motor drives. The overall control structure is presented and the integral sliding mode formulation is derived starting from the yaw moment balance equation of the vehicle. The performance of the controller, continuously active in order to track a set of reference understeer characteristics, is evaluated against that of the baseline vehicle (i.e. The vehicle without yaw rate control) in ramp steer and step steer maneuvers. Simulation results show a good tracking of the reference yaw rate deriving from the adoption of the integral sliding mode controller. Moreover, ease of implementation and robustness against model uncertainties make this controller particularly suitable for this type of application. © 2014 American Automatic Control Council.
De Pinto S, Camocardi P, Sorniotti A, Gruber P, Perlo P, Viotto F (2016) Torque-fill control and energy management for a 4-wheel-drive electric vehicle layout with 2-speed transmissions, IEEE Transactions on Industry Applications
This paper presents a novel 4-wheel-drive electric vehicle layout consisting of one on-board electric drivetrain per axle. Each drivetrain includes a simplified clutch-less 2-speed transmission system and an open differential, to transmit the torque to the wheels. This drivetrain layout allows eight different gear state combinations at the vehicle level, thus increasing the possibility of running the vehicle in a more energy efficient state for the specific wheel torque demand and speed. Also, to compensate the torque gap during gearshifts, a ?torque-fill? controller was developed that varies the motor torque on the axle not involved in the gearshift. Experimental tests show the effectiveness of the developed gearshift strategy extended with the torque-fill capability. Energy efficiency benefits are discussed by comparing the energy consumptions of the case study vehicle controlled through a constant front-to-total wheel torque distribution and conventional gearshift maps, and the same vehicle with an energy management system based on an off-line optimization. Results demonstrate that the more advanced controller brings a significant reduction of the energy consumption at constant speed and along different driving cycles.
Lenzo B, De Filippis G, Dizqah A, Sorniotti A, Gruber P, Fallah S, De Nijs W (2017) Torque Distribution Strategies for Energy-Efficient Electric Vehicles with Multiple Drivetrains, Journal of Dynamic Systems Measurement and Control: Transactions of the ASME 139 (12) 121004 American Society of Mechanical Engineers
The paper discusses novel computationally efficient torque distribution strategies for electric vehicles with individually controlled drivetrains, aimed at minimizing the overall power losses while providing the required level of wheel torque and yaw moment. Analytical solutions of the torque control allocation problem are derived and effects of load transfers due to moderate driving/braking and cornering conditions are studied and discussed in detail. Influences of different drivetrain characteristics on the front and rear axles are described. The results of the analytically-derived algorithm are contrasted with those from two other control allocation strategies, based on the off-line numerical solution of more detailed formulations of the control allocation problem (i.e., a multi-parametric non-linear programming problem). The solutions of the control allocation problem are experimentally validated along multiple driving cycles and in steady-state cornering, on an electric vehicle with four identical drivetrains. The experiments show that the computationally efficient algorithms represent a very good compromise between low energy consumption and controller complexity.
Lenzo B, Sorniotti A, Gruber P, Sannen K (2017) On the experimental analysis of single input single output control of yaw rate and sideslip angle., International Journal of Automotive Technology 18 (5) pp. 799-811 Springer Verlag
Electric vehicles with individually controlled drivetrains allow torque-vectoring, which improves vehicle safety and drivability. This paper investigates a new approach to the concurrent control of yaw rate and sideslip angle. The proposed controller is a simple single input single output (SISO) yaw rate controller, in which the reference yaw rate depends on the vehicle handling requirements, and the actual sideslip angle. The sideslip contribution enhances safety, as it provides a corrective action in critical situations, e.g., in case of oversteer during extreme cornering on a low friction surface. The proposed controller is experimentally assessed on an electric vehicle demonstrator, along two maneuvers with quickly variable tire-road friction coefficient. Different longitudinal locations of the sideslip angle used as control variable are compared during the experiments. Results show that: i) the proposed SISO approach provides significant improvements with respect to the vehicle without torque-vectoring, and the controlled vehicle with a reference yaw rate solely based on the handling requirements for high-friction maneuvering; and ii) the control of the rear axle sideslip angle provides better performance than the control of the sideslip angle at the centre of gravity.
Di Nicola F, Sorniotti A, Holdstock T, Viotto F, Bertolotto S (2012) Optimization of a multiple-speed transmission for downsizing the motor of a fully electric vehicle, SAE International Journal of Alternative Powertrains 1 (1) pp. 134-143
The research presented in this paper focuses on the effects of downsizing the electric motor drive of a fully electric vehicle through the adoption of a multiple-speed transmission system. The activity is based on the implementation of a simulation framework in Matlab / Simulink. The paper considers a rear wheel drive case study vehicle, with a baseline drivetrain configuration consisting of a single-speed transmission, which is compared with drivetrains adopting motors with identical peak power but higher base speeds and lower peak torques coupled with multiple-speed transmissions (double and three-speed), to analyze the benefits in terms of energy efficiency and performance. The gear ratios and gearshift maps for each multiple-speed case study are optimized through a procedure developed by the authors consisting of cost functions considering energy efficiency and performance evaluation. The cost functions are explained in the paper along with the models adopted for the research. Copyright © 2012 SAE International.
Galvagno E, Morina D, Velardocchia M, Sorniotti A (2012) Drivability analysis of through-the-road-parallel hybrid vehicles, Meccanica pp. 1-16
In the last decade, Hybrid Electric Vehicles (HEVs) have spread worldwide due to their capability to reduce fuel consumption. Several studies focused on the optimisation of the energy management system of hybrid vehicles are available in literature, whilst there are few articles dealing with the drivability and the dynamics of these new powertrain systems. In this paper a 'Through-the-Road-Parallel HEV' is analysed. This architecture is composed of an internal combustion engine mounted on the front axle and an electric motor powering the rear one. These two powertrains are not directly connected to each other, as the parallel configuration is implemented through the road-tyre force interaction. The main purpose of this paper is the drivability analysis of this layout of HEVs, using linearised mathematical models in both time (i.e. vehicle response during tip-in tests) and frequency domain (i.e. frequency response functions), considering the effect of the engaged gear ratio. The differences from a traditional Front-Wheel-Drive (FWD) configuration are subsequently highlighted. Furthermore, the authors compare different linearised dynamic models, with an increasing number of degrees of freedom, in order to assess which model represents the best compromise between complexity and quality of the results. Finally, a sensitivity analysis of the influence of the torque distribution between the front (thermal) and rear (electric) axles on vehicle drivability is carried out and presented in detail. © 2012 Springer Science+Business Media Dordrecht.
Abuasaker S, Sorniotti A (2010) Drivability analysis of heavy goods vehicles, SAE International Journal of Commercial Vehicles 3 (1) pp. 195-215 SAE International
The paper presents linear and non-linear driveline models for Heavy Goods Vehicles (HGVs) in order to evaluate the main parameters for optimal tuning, when considering the drivability. The implemented models consider the linear and non-linear driveline dynamics, including the effect of the engine inertia, the clutch damper, the driveshaft, the half-shafts and the tires. Sensitivity analyses are carried out for each driveline component during tip-in maneuvers. The paper also analyses the overall frequency response using Bode diagrams and natural frequencies.
De Novellis L, Sorniotti A, Gruber P (2013) Design and comparison of the handling performance of different electric vehicle layouts, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING Sage
In contrast with conventional vehicles driven by an internal-combustion engine, the number of motors in fully electric cars is not fixed. A variety of architectural solutions, including from one to four individually controlled electric drive units, is possible and opens up new avenues in the design of vehicle characteristics. In particular, individual control of multiple electric powertrains promises to enhance the handling performance in steady-state and dynamic conditions. For the analysis and selection of the best electric powertrain layout based on the expected vehicle characteristics and performance, new analytical tools and metrics are required. This article presents and demonstrates a novel offline procedure for the design of the feedforward control action of the vehicle dynamics controller of a fully electric vehicle and three performance indicators for the objective comparison of the handling potential of alternative electric powertrain layouts. The results demonstrate that the proposed offline routine allows the desired understeer characteristics to be achieved with any of the investigated vehicle configurations, in traction and braking conditions. With respect to linear handling characteristics, the simulations indicate that the influence of torque-vectoring is independent of the location of the controlled axles (front or rear) and is considerably affected by the number of controlled axles.
Sorniotti A (2010) Torque Gap Filler for Automated Manual Transmissions: Principles for the Development of the Control Algorithm, SAE International Journal of Engines
Accelerated Pavement Testing (APT) facilities are nowadays considered
fundamental for the thorough understanding of the performance of pavements.
The amount of information that can be derived from APT investigations can serve
as the basis for a more performance-related pavement design but also for the
development of new pavement types and innovative materials.
In the design and use of such facilities, special care should be placed in the
modeling of the loading systems which are employed to produce accelerated
damage. Such an analysis is important both in the preliminary design phase, in
which technological solutions are found in order to simulate the effects of heavy
vehicles on the pavement, and in the various phases of investigation, when the
recorded damage has to be clearly related with effective loading conditions. In
this respect, modeling can be a valuable support to the evaluation of the data
which can be acquired by means of a proper instrumentation of the facility.
In order to address such issues, the Authors have developed a design
procedure which together with typical stationary calculations includes the
adoption of Multi-Body (MB) and Finite Elements (FE) models of the testing
system. As proven by the first implementation exercises of the design procedure,
the use of MB and FE models allows the evaluation of the dynamics of the system
in a wide variety of testing conditions. Thus, stresses and strains in the structure of
the APT facility can be estimated and the dynamic forces and torques which arise
during testing at the tire-pavement interface can be predicted.
Given the width of the design problem, this paper gives only a general
overview of the structure of the proposed procedure, with its application to a
specific case which has been studied in depth. Refinements are still under way and
will hopefully yield a set of modeling methods which in the future will be
available for the design of new APT facilities and for the assessment of the
performance of existing systems.
Grott M, Biral F, Sorniotti A, Oboe R, Vincenti E (2010) Vehicle simulation for the development of an active suspension system for an agricultural tractor, SAE International Journal of Commercial Vehicles 2 (2) pp. 12-25
The design of suspension systems for heavy-duty vehicles covers a specific field of automotive industry. The proposed work focuses on the design development of a front controllable suspension for an agricultural tractor capable to satisfy the system requirements under different operating conditions. The design of the control algorithms is based on the developed multibody model of the actual tractor, including the pitch motion of the sprung mass, the anti-dive effects during braking and forward-reverse maneuvers and the non-linear dynamics of the actuation system. For an advanced analysis, a novel thermo-hydraulic model of the hydraulic system has been implemented. Several semi-active damping controls are analyzed for the specific case study. Therefore, the most promising damping strategy is integrated with other control functions, namely a self-leveling control, an original control algorithm for the reduction of the pitch motion, an anti-impact system for the hydraulic actuator and an on-line adaptation scheme, which preserves an optimal damping ratio of the suspension, even against large variations in operating conditions.
Pennycott A, De Novellis L, Gruber P, Sorniotti A (2014) Sources of power loss during torque?vectoring for fully electric vehicles, International Journal of Vehicle Design pp. 157-177
De Novellis L, Sorniotti A, Gruber P (2014) Driving modes for designing the cornering response of fully electric vehicles with multiple motors, Mechanical Systems and Signal Processing
© 2015 The Authors. Fully electric vehicles with multiple drivetrains allow a significant variation of the steady-state and transient cornering responses through the individual control of the electric motor drives. As a consequence, alternative driving modes can be created that provide the driver the option to select the preferred dynamic vehicle behavior. This article presents a torque-vectoring control structure based on the combination of feedforward and feedback contributions for the continuous control of vehicle yaw rate. The controller is specifically developed to be easily implementable on real-world vehicles. A novel model-based procedure for the definition of the control objectives is described in detail, together with the automated tuning process of the algorithm. The implemented control functions are demonstrated with experimental vehicle tests. The results show the possibilities of torque-vectoring control in designing the vehicle understeer characteristic.
De Novellis L, Sorniotti A, Gruber P (2013) Optimal Wheel Torque Distribution for a Four-Wheel-Drive Fully Electric Vehicle, SAE International Journal of Passenger Cars: Mechanical Systems 6 (1) pp. 128-136
Vehicle handling in steady-state and transient conditions can be significantly enhanced with the continuous modulation of the driving and braking torques of each wheel via dedicated torque-vectoring controllers. For fully electric vehicles with multiple electric motor drives, the enhancements can be achieved through a control allocation algorithm for the determination of the wheel torque distribution. This article analyzes alternative cost functions developed for the allocation of the wheel torques for a four-wheel-driven fully electric vehicle with individually controlled motors. Results in terms of wheel torque and tire slip distributions among the four wheels, and of input power to the electric drivetrains as functions of lateral acceleration are presented and discussed in detail. The cost functions based on minimizing tire slip allow better control performance than the functions based on energy efficiency for the case-study vehicle.
Amisano F, Sorniotti A, Velardocchia M (2008) A method for controlling a power assisted propulsion system in a motor vehicle, EP20060425763 20061109
Sorniotti A, Damiani E, Moorin T (2011) Experimental validation of a heavy goods vehicle fuel consumption model, SAE Technical Papers
Over the last decade the simulation of driving cycles through longitudinal vehicle models has become an important stage in the design, analysis and selection of vehicle powertrains. This paper presents an overview of existing software packages, along with the development of a new multipurpose driving cycle simulator implemented in the Matlab/Simulink environment. In order to evaluate the performance of the simulator, a MAN TGL 12.240 multi-usage delivery vehicle was fitted with a CAN-bus data logger and used to create a series of 'real-life' drive cycles. These were inputted into the vehicle model and the simulated fuel mass flow-rate and engine rotational speed were compared to those experimentally obtained. Copyright © 2011 SAE International.
Lekakou C, Foderingham M, Abbas MK, Sorniotti A, Cosmas JP (2014) Photovoltaic energy source, Battery-supercapacitor energy storage/power system, electric vehicle charge station, in the grid, WIT Transactions on Engineering Sciences 88 pp. 305-310
A system of photovoltaic (PV)-supercapacitor battery is outlined in this study for the charging of a battery for a mid-power electric vehicle (EV) or hybrid vehicle, in conjunction with charging contributions from the grid. Computational models have been developed for each component of the system, namely the PV, supercapacitor, and battery. Model predictions are presented for each system component and validated with experimental data. The required PV area for the charging of the battery of a mid-range EV or hybrid vehicle has also been estimated. © 2014 WIT Press.
De Pinto S, Lu Q, Camocardi P, Chatzikomis C, Sorniotti A, Lekakou C (2016) Electric vehicle driving range extension using photovoltaic panels, VPPC Conference Proceedings
This paper investigates the potential benefits of photovoltaic (PV) panels on electric vehicles. In addition to the PV panels on the roof of the car, in this study a PV panel is installed below the windshield to increase energy capture when the car is parked. An electro-mechanical actuator makes the PV panel disappear under the roof when the passengers are in the vehicle. The paper presents the simulation model of the overall PV architecture, including the DC/DC converter and the energy storage system. Based on recorded temperature and solar irradiance profiles, the model calculates the energy input and the corresponding range extension. The resulting values are discussed for a prototype four-wheel-drive urban electric vehicle operating in five European locations.
De Pinto S, Chatzikomis C, Sorniotti A, Mantriota G (2017) Comparison of Traction Controllers for Electric Vehicles with On-Board Drivetrains, Transactions on Vehicular Technology 66 (8) pp. 6715-6727 IEEE Xplore
An extensive literature discusses traction control system designs for electric vehicles. In general, the proposed control structures do not include consideration of the actuation dynamics, which are especially important for vehicles with on-board drivetrains, usually characterized by significant torsional dynamics of the half-shafts. This paper compares the performance of a selection of traction controllers from the literature, with that of PID and ? control structures specifically designed for on-board electric drivetrains. The analysis in the frequency domain and the simulation results in the time domain show the significant performance improvement provided by the control system designs considering the actuation dynamics.
Sorniotti A, Pilone G, Viotto F, Bertolotto S, Everitt M, Barnes R, Morrish I (2011) A novel seamless 2-speed transmission system for electric vehicles: Principles and simulation results, SAE International Journal of Engines 4 (2) pp. 2671-2685 SAE International
This article deals with a novel 2-speed transmission system specifically designed for electric axle applications. The design of this transmission permits seamless gearshifts and is characterized by a simple mechanical layout. The equations governing the overall system dynamics are presented in the paper. The principles of the control system for the seamless gearshifts achievable by the novel transmission prototype - currently under experimental testing at the University of Surrey and on a prototype vehicle - are analytically demonstrated and detailed through advanced simulation tools. The simulation results and sensitivity analyses for the main parameters affecting the overall system dynamics are presented and discussed. © 2011 SAE International.
Bucchi F, Lenzo B, Frendo F, De Nijs W, Sorniotti Aldo (2018) The effect of the front-to-rear wheel torque distribution on vehicle
handling: an experimental assessment,
Proceedings of IAVSD 2017 (Dynamics of Vehicles on Roads and Tracks)
The front-to-rear wheel torque distribution influences vehicle handling and, ultimately,
affects key factors such as vehicle safety and performance. At a glance, as part of the
available tire-road friction is used for traction on the driven axle, a Front-Wheel-Drive (FWD)
vehicle would be expected to be more understeering than a Rear-Wheel-Drive (RWD) vehicle
with equivalent characteristics. However, in specific conditions such effect may be counterbalanced,
or even reversed, by the yaw moment caused by the lateral contribution, in the vehicle
reference system, of the traction forces at the front wheels. This paper discusses the experimental
assessment of the phenomenon in steady-state cornering, for a fully electric vehicle with
multiple motors, allowing different front-to-rear wheel torque distributions. The results confirm
that the yaw moment effect of the front traction forces is significant, especially at low vehicle
speeds and high lateral accelerations. In particular, in the case study maneuvers, the RWD configuration
of the vehicle resulted more understeering than the FWD one at the speed of 30 km/h.
Chatzikomis Christoforos, Sorniotti Aldo, Gruber Patrick, Shah M, Bastin M, Orlov Y (2017) Torque-vectoring control for an autonomous and driverless electric racing vehicle with multiple motors, SAE Int. J. Veh. Dyn., Stab., and NVH 1 (2) pp. 338-351
Electric vehicles with multiple motors permit continuous direct yaw moment control, also called torque-vectoring. This allows to significantly enhance the cornering response, e.g., by extending the linear region of the vehicle understeer characteristic, and by increasing the maximum achievable lateral acceleration. These benefits are well documented for human-driven cars, yet limited information is available for autonomous/driverless vehicles. In particular, over the last few years, steering controllers for automated driving at the cornering limit have considerably advanced, but it is unclear how these controllers should be integrated alongside a torque-vectoring system. This contribution discusses the integration of torque-vectoring control and automated driving, including the design and implementation of the torque-vectoring controller of an autonomous electric vehicle for a novel racing competition. The paper presents the main vehicle characteristics and control architecture. A quasi-static model is introduced to predict the understeer characteristics at different longitudinal accelerations. The model is coupled with an off-line optimization for the a-priori investigation of the potential benefits of torque-vectoring. The systematic computation of the achievable cornering limits is used to specify and design realistic maps of the reference yaw rate, and a non-linear feedforward yaw moment contribution providing the reference cornering response in quasi-static conditions. A gain scheduled proportional integral controller increases yaw damping, thus enhancing the transient response. Simulation results demonstrate the effectiveness of the proposed approach.
de Filippis G, Lenzo B, Sorniotti A, Gruber P, Sannen K, De Smet J (2016) On the energy efficiency of electric vehicles with multiple motors, IEEE Vehicle Power and Propulsion Conference (VPPC), 2016
Electric Vehicles (EVs) with multiple motors permit to design the steady-state cornering response by imposing reference understeer characteristics according to expected vehicle handling quality targets. To this aim a direct yaw moment is generated by assigning different torque demands to the left and right vehicle sides. The reference understeer characteristic has an impact on the drivetrain input power as well. In parallel, a Control Allocation (CA) strategy can be employed to achieve an energy-efficient wheel torque distribution generating the reference yaw moment and wheel torque. To the knowledge of the authors, for the first time this paper experimentally compares and critically analyses the potential energy efficiency benefits achievable through the appropriate set-up of the reference understeer characteristics and wheel torque CA. Interestingly, the experiments on a four wheel-drive EV demonstrator show that higher energy savings can be obtained through the appropriate tuning of the reference cornering response rather than with an energy efficient CA.
Gruber P, Sorniotti A, Lenzo B, De Filippis G, Fallah S (2016) Energy efficient torque vectoring control, Advanced Vehicle Control (Proceedings of AVEC'16) CRC Press (Taylor & Francis Group)
Tire forces are at the heart of the dynamic qualities of vehicles. With the advent of electric vehicles the precise and accurate control of the traction and braking forces at the individual wheel becomes a possibility and a reality outside test labs and virtual proving grounds. Benefits of individual wheel torque control, or torque-vectoring, in terms of vehicle dynamics behavior have been well documented in the literature. However, very few studies exist which analyze the individual wheel torque control integrated with vehicle efficiency considerations. This paper focuses on this aspect and discusses the possibilities and benefits of integrated, energy efficient torque vectoring control. Experiments with a four-wheel-drive electric vehicle show that considerable energy savings can be achieved by considering drivetrain and tire power losses through energy efficient torque vectoring control.
Sorniotti A, Gruber P, Lenzo B, De Filippis G, Fallah S (2017) Energy efficient torque vectoring for electric vehicles with multiple drivetrains,
The benefits of individual wheel torque control, or torque vectoring, in terms of vehicle dynamics behaviour have been well documented in the literature. However, few studies analyse individual wheel torque control integrated with electric vehicle efficiency considerations. The possibilities and benefits of energy efficient torque vectoring control for electric vehicles with multiple drivetrains are discussed. In particular, energy consumption reductions can be obtained through specific design of the wheel torque control allocation algorithm and the reference yaw rate characteristics. Experiments with a four-wheel-drive electric vehicle demonstrate considerable energy savings.
Lenzo B, De Filippis G, Sorniotti A, Gruber P, Sannen K (2016) Understeer characteristics for energy-efficient fully electric vehicles with multiple motors, EVS29 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium Proceedings
Electric vehicles with multiple motors allow torque-vectoring, which generates a yaw moment by assigning different motor torques at the left and right wheels. This permits designing the steady-state cornering response according to several vehicle handling quality targets. For example, as widely discussed in the literature, to make the vehicle more sports-oriented, it is possible to reduce the understeer gradient and increase the maximum lateral acceleration with respect to the same vehicle without torque-vectoring. This paper focuses on the novel experimentally-based design of a reference vehicle understeer characteristic providing energy efficiency enhancement over the whole range of achievable lateral accelerations. Experiments show that an appropriate tuning of the reference understeer characteristic, i.e., the reference yaw rate of the torque-vectoring controller, can bring energy savings of up to ~11% for a case study four-wheel-drive electric vehicle demonstrator. Moreover, during constant speed cornering, it is more efficient to significantly reduce the level of vehicle understeer, with respect to the same vehicle with even torque distribution on the left and right wheels.
Theunissen J, Sorniotti A, Gruber P, Fallah S, Dhaens M, Reybrouck K, Lauwerys C, Vandersmissen B, Sakka M, Motte K Explicit model predictive control of active suspension systems,
Vacca F, Pinto De S, Hartavi Karci A, Gruber P, Viotto F, Cavallino C, Rossi J, Sorniotti A (2017) On the Energy Efficiency of Dual Clutch
Transmissions and Automated Manual Transmissions,
Energies 10 (10) 1562 pp. 1-22 MDPI
The main benefits of dual clutch transmissions (DCTs) are: (i) a higher energy efficiency
than automatic transmission systems with torque converters; and (ii) the capability to fill the torque
gap during gear shifts to allow seamless longitudinal acceleration profiles. Therefore, DCTs are viable
alternatives to automated manual transmissions (AMTs). For vehicles equipped with engines that
can generate considerable torque, large clutch-slip energy losses occur during power-on gear shifts
and, as a result, DCTs need wet clutches for effective heat dissipation. This requirement substantially
reduces DCT efficiency because of the churning and ancillary power dissipations associated with
the wet clutch pack. To the knowledge of the authors, this study is the first to analyse the detailed
power loss contributions of a DCT with wet clutches, and their relative significance along a set of
driving cycles. Based on these results, a novel hybridised AMT (HAMT) with a single dry clutch
and an electric motor is proposed for the same vehicle. The HAMT architecture combines the high
mechanical efficiency typical of AMTs with a single dry clutch, with the torque-fill capability and
operational flexibility allowed by the electric motor. The measured efficiency maps of a case study
DCT and HAMT are compared. This is then complemented by the analysis of the respective fuel
consumption along the driving cycles, which is simulated with an experimentally validated vehicle
model. In its internal combustion engine mode, the HAMT reduces fuel consumption by >9% with
respect to the DCT.
Zanchetta Mattia, Tavernini Davide, Sorniotti Aldo, Gruber Patrick, Lenzo B., Ferrara A., De Nijs W., Sannen K., De Smet J. (2018) On the Feedback Control of Hitch Angle through Torque-Vectoring, 2018 IEEE 15th International Workshop on Advanced Motion Control (AMC) pp. 535-540 Institute of Electrical and Electronics Engineers (IEEE)
This paper describes a torque-vectoring (TV)
algorithm for the control of the hitch angle of an articulated
vehicle. The hitch angle control function prevents trailer
oscillations and instability during extreme cornering maneuvers.
The proposed control variable is a weighted combination of terms
accounting for the yaw rate, sideslip angle and hitch angle of the
articulated vehicle. The novel control variable formulation results
in a single-input single-output (SISO) feedback controller. In the
specific application a simple proportional integral (PI) controller
with gain scheduling on vehicle velocity is developed. The TV
system is implemented and experimentally tested on a fully electric
vehicle with four on-board drivetrains, towing a single-axle passive
trailer. Sinusoidal steer test results show that the proposed
algorithm significantly improves the behavior of the articulated
vehicle, and justify further research on the topic of hitch angle
control through TV.
Vacca F, Capilli G, Sorniotti A, Fracchia M, Remondin T, Cavallino C, Bottiglione F (2018) A Novel Hybridized Automated Manual
Transmission for High Performance Cars,
Proceedings of AMC 2018 IEEE
Because of the introduction of progressively more
restrictive regulations that aim to reduce fuel consumption and
CO2 emissions, the automotive industry is focusing its efforts on
environmentally friendly passenger cars. In particular, different
electrification roadmaps are pursued by the individual car
makers, and electrified drivetrain layouts are progressively
introduced into the market. This process involves all vehicle
segments, including high performance passenger cars. In this
context, this study presents a novel hybridized automated manual
transmission (HAMT) for cars with high power characteristics.
The HAMT includes six gear ratios associated with the internal
combustion engine, and two gear ratios associated with an
electric motor. The energy efficiency of the HAMT is measured
on a drivetrain test rig, and compared with that of an equivalent
dual clutch transmission (DCT). Simulation results based on the
experimentally measured efficiency maps show the significant
energy consumption reduction of the HAMT in its internal
combustion engine mode, with respect to the DCT.
Wang Zhengyuan, Montanaro Umberto, Fallah Saber, Sorniotti Aldo, Lenzo Basilio (2018) A Gain Scheduled Robust Linear Quadratic Regulator for Vehicle Direct Yaw Moment Control, Mechatronics 51 pp. 31-45 Elsevier
Direct yaw moment controllers improve vehicle stability and handling in severe manoeuvres. In direct yaw moment control implementations based on Linear Quadratic Regulators (LQRs), the control system performance is limited by the unmodelled dynamics and parameter uncertainties. To guarantee robustness with respect to uncertainties, this paper proposes a gain scheduled Robust Linear Quadratic Regulator (RLQR), in which an extra control term is added to the feedback contribution of a conventional LQR to limit the closed-loop tracking error in a neighbourhood of the origin of its state-space, despite the uncertainties and disturbances acting on the plant. In addition, the intrinsic parameter-varying nature of the vehicle dynamics model with respect to the longitudinal vehicle velocity can compromise the closed-loop performance of fixed-gain controllers in varying driving conditions. Therefore, in this study the control gains optimally vary with velocity to adapt the closed-loop system to the variations of this parameter. The effectiveness of the proposed RLQR in improving the robustness of a classical LQR against model uncertainties and parameter variations is proven analytically, numerically and experimentally. The simulation and vehicle test results are consistent with the formal analysis proving that the RLQR reduces the ultimate bound of the error dynamics.
De Filippis Giovanni, Lenzo Basilio, Sorniotti Aldo, Gruber Patrick, De Nijs Wouter (2018) Energy-Efficient Torque-Vectoring Control of Electric Vehicles with Multiple Drivetrains, Proceedings of the IEEE 67 (6) pp. 4702-4715 Institute of Electrical and Electronics Engineers (IEEE)
The safety benefits of torque-vectoring control of electric vehicles with multiple drivetrains are well known and extensively discussed in the literature. Also, several authors analyze wheel torque control allocation algorithms for reducing the energy consumption while obtaining the wheel torque demand and reference yaw moment specified by the higher layer of a torque-vectoring controller. Based on a set of novel experimental results, this study demonstrates that further significant energy consumption reductions can be achieved through the appropriate tuning of the reference understeer characteristics. The effects of drivetrain power losses and tire slip power losses are discussed for the case of identical drivetrains at the four vehicle corners. Easily implementable yet effective rule-based algorithms are presented for the set-up of the energy-efficient reference yaw rate, feedforward yaw moment and wheel torque distribution of the torque-vectoring controller.
Energy storage is a fundamental requirement for utilising clean but intermittent renewable resources, maintaining a resilient power grid and powering a multitude of portable electric devices and systems. The work presented in this thesis investigates methods of filling the performance gap between electrochemical capacitors (EC) (commonly known as supercapacitors) and batteries; the former often have high power capability but low energy density while the latter often have high energy density but low power capability. Three approaches towards this are taken during this work: first, capacitance balancing of a traditional electrical double-layer capacitor (EDLC) type EC device is attempted by electrode material asymmetry; this approach advances upon previous techniques in which cells have electrode material symmetry but electrode mass asymmetry. The benefits of capacitance balancing were found to be improved device energy density and reduced capacitance loss during long term operation. Second, a novel type of lithium ion capacitor (LIC) which uses a silicon based negative electrode is developed. Such a device was found to offer high power capability (23 kW kg-1) while demonstrating an energy density of over 97 W h kg-1, both values are per total electrode mass. Third, layer-targeted spray deposition was used to deposit multi-walled carbon nanotubes (MWCNTs) at specific locations within an electrode structure. It was found that spray depositing MWCNTs at the outer electrode surface may increase its power capability. A consequence of this targeted deposition may be a reduction in the current collector material alongside improvements in energy storage and power capabilities.
Tota Antonio, Lenzo Basilio, Lu Qian, Sorniotti Aldo, Gruber Patrick, Fallah Saber, Velardocchia Mauro, Galvagno Enrico, De Smet Jasper (2018) On the experimental analysis of integral sliding modes for yaw rate and sideslip control of an electric vehicle with multiple motors, International Journal of Automotive Technology 19 (5) pp. 811-823 Springer Verlag
With the advent of electric vehicles with multiple motors, the steady-state and transient cornering responses can be designed based on high-level reference targets, and implemented through the continuous torque control of the individual wheels, i.e., torque-vectoring or direct yaw moment control. The literature includes several papers describing the application of the sliding mode control theory to torque-vectoring. However, the experimental implementations of sliding mode controllers on real vehicle prototypes are very limited at the moment. More importantly, to the knowledge of the authors, there is lack of experimental assessments of the performance benefits of direct yaw moment control based on sliding modes, with respect to other controllers, such as the proportional integral derivative controllers or linear quadratic regulators currently used for stability control in production vehicles. This paper aims to reduce this gap by presenting an integral sliding mode controller for concurrent yaw rate and sideslip control. A new driving mode, the Enhanced Sport mode, is proposed, inducing sustained high values of sideslip angle, which can be safely limited to a specified threshold. The system is experimentally assessed on a four-wheel-drive electric vehicle along a wide range of maneuvers. The performance of the integral sliding mode controller is compared with that of a linear quadratic regulator during step steer tests. The results show that the integral sliding mode controller brings a significant enhancement of the tracking performance and yaw damping with respect to the more conventional linear quadratic regulator based on an augmented single-track vehicle model formulation.
Metzler Mathias, Tavernini Davide, Sorniotti Aldo, Gruber Patrick (2018) Explicit nonlinear model predictive control for vehicle stability control, Proceedings of 9th International Munich Chassis Symposium 2018, chassis.tech plus Springer Vieweg
Nonlinear model predictive control is proposed in multiple academic studies as an ad-vanced control system technology for vehicle operation at the limits of handling, allow-ing high tracking performance and formal consideration of system constraints. How-ever, the implementation of implicit nonlinear model predictive control (NMPC), in which the control problem is solved on-line, poses significant challenges in terms of computational load. This issue can be overcome through explicit NMPC, in which the optimization problem is solved off-line, and the resulting explicit solution, with guar-anteed level of sub-optimality, is evaluated on-line. Due to the simplicity of the explicit solution, the real-time execution of the controller is possible even on automotive control hardware platforms with low specifications. The explicit nature of the control law fa-cilitates feasibility checks and functional safety validation. This study presents a yaw and lateral stability controller based on explicit NMPC, actuated through the electro-hydraulically controlled friction brakes of the vehicle. The controller performance is demonstrated during sine-with-dwell tests simulated with a high-fidelity model. The analysis includes a comparison of implicit and explicit implementations of the control system.
Lenzo B, Sorniotti Aldo, Gruber Patrick (2018) A Single Input Single Output Formulation for Yaw Rate and Sideslip Angle Control via Torque-Vectoring, AVEC 2018 Proceedings
Many torque-vectoring controllers are based on the concurrent control of yaw rate and sideslip angle through complex multi-variable control structures. In general, the target is to continuously track a reference yaw rate, and constrain the sideslip angle to remain within thresholds that are critical for vehicle stability. To achieve this objective, this paper presents a single input single output (SISO) formulation, which varies the reference yaw rate to constrain sideslip angle. The performance of the controller is successfully validated through simulations and experimental tests on an electric vehicle prototype with four drivetrains
Tavernini Davide, Metzler Mathias, Gruber Patrick, Sorniotti Aldo (2018) Explicit non-linear model predictive control for electric vehicle traction control, IEEE Transactions on Control Systems Technology IEEE
This study presents a traction control system for electric vehicles with in-wheel motors, based on explicit non-linear model predictive control. The feedback law, available beforehand, is described in detail, together with its variation for different plant conditions. The explicit controller is implemented on a rapid control prototyping unit, which proves the real-time capability of the strategy, with computing times in the order of microseconds. These are significantly lower than the required sampling time for a traction control application. Hence, the explicit model predictive controller can run at the same frequency as a simple traction control system based on Proportional Integral (PI) technology. High-fidelity model simulations provide: i) a performance comparison of the proposed explicit non-linear model predictive controller with a benchmark PI-based traction controller with gain scheduling and anti-windup features; and ii) a performance comparison among two explicit and one implicit non-linear model predictive controllers based on different internal models, with and without consideration of transient tire behavior and load transfers. Experimental test results on an electric vehicle demonstrator are shown for one of the explicit non-linear model predictive controller formulations.
Theunissen Johan, Sorniotti Aldo, Gruber Patrick, Fallah Saber, Dhaens M, Reybrouck K, Lauwerys C, Vandersmissen B, Al Sakka M, Motte K (2018) Explicit model predictive control of an active suspension system, chassis.tech plus 2018 ? 9th International Munich Chassis Symposium pp. 201-214 Springer Fachmedien Wiesbaden GmbH
Model predictive control (MPC) is increasingly finding its way into industrial applications, due to its superior tracking performance and ability to formally handle system constraints. However, the real-time capability problems related to the conventional implicit model predictive control (i-MPC) framework are well known, especially when targeting low-cost electronic control units (ECUs) for high bandwidth systems, such as automotive active suspensions, which are the topic of this paper. In this context, to overcome the real-time implementation issues of i-MPC, this study proposes explicit model predictive control (e-MPC), which solves the optimization problem off-line, via multi-parametric quadratic programming (mp-QP). e-MPC reduces the on-line algorithm to a function evaluation, which replaces the computationally demanding on-line solution of the quadratic programming (QP) problem. An e-MPC based suspension controller is designed and experimentally validated for a case study Sport Utility Vehicle (SUV), equipped with the active ACOCAR suspension system from the Tenneco Monroe product family. The target is to improve ride comfort in the frequency range of primary ride ( 40% compared to the passive vehicle set-up for frequencies
Chatzikomis Christoforos, Sorniotti Aldo, Gruber Patrick, Zanchetta Mattia, Willans D, Balcombe B (2018) Comparison of Path Tracking and Torque-Vectoring Controllers for Autonomous Electric Vehicles, IEEE Transactions on Intelligent Vehicles IEEE
Steering control for path tracking in autonomous vehicles is well documented in the literature. Also, continuous direct yaw moment control, i.e., torque-vectoring, applied to human-driven electric vehicles with multiple motors is extensively researched. However, the combination of both controllers is not yet well understood. This paper analyzes the benefits of torque-vectoring in an autonomous electric vehicle, either by integrating the torque-vectoring system in the path tracking controller, or through its separate implementation alongside the steering controller for path tracking. A selection of path tracking controllers is compared in obstacle avoidance tests simulated with an experimentally validated vehicle dynamics model. A genetic optimization is used to select the controller parameters. Simulation results confirm that torque-vectoring is beneficial to autonomous vehicle response. The integrated controllers achieve the best performance if they are tuned for the specific tire-road friction condition. However, they can also cause unstable behavior when they operate in lower friction conditions without any re-tuning. On the other hand, separate torque-vectoring implementations provide consistently stable cornering response for a wide range of friction conditions. Controllers with preview formulations, or based on appropriate reference paths with respect to the middle line of the available lane, are beneficial to the path tracking performance.
Metzler Mathias, Tavernini Davide, Sorniotti Aldo, Gruber Patrick (2018) An Explicit Nonlinear MPC Approach to Vehicle Stability Control, Proceedings of The 14th International Symposium on Advanced Vehicle Control Tsinghua University
Nonlinear model predictive control (NMPC) is proposed in multiple academic studies as an advanced control system technology for vehicle operation at the limits of handling, allowing high tracking performance and formal consideration of system constraints. However, the implementation of implicit NMPC, in which the control problem is solved on-line, poses significant challenges in terms of computational load. This issue can be overcome through explicit NMPC, in which the optimization problem is solved off-line, and the resulting explicit solution, with guaranteed level of sub-optimality, is evaluated on-line. This study presents a yaw and lateral stability controller based on explicit NMPC, actuated through the friction brakes of the vehicle. The controller performance is demonstrated during sine-with-dwell tests simulated with a high-fidelity model. The analysis investigates the influence of the weights in the cost function formulation and includes a comparison of different settings of the optimal control problem.
Lenzo Basilio, Bucchi Francesco, Sorniotti Aldo, Frendo Francesco (2018) Handling performance of a vehicle with different front-to-rear wheel torque distribution, Vehicle System Dynamics Taylor & Francis
The handling characteristic is a classical topic of vehicle dynamics. Usually, vehicle handling
is studied through the analysis of the understeer coefficient in quasi-steady-state maneuvers. In
this paper, experimental tests are performed on an electric vehicle with four independent motors,
which is able to reproduce front-wheel-drive, rear-wheel-drive and all-wheel-drive (FWD,
RWD and AWD, respectively) architectures. The handling characteristics of each architecture
are inferred through classical and new concepts. More specifically, the study presents a procedure
to compute the longitudinal and lateral tire forces, which is based on a first estimate
and a subsequent correction of the tire forces that guarantee the equilibrium. A yaw moment
analysis is then performed to identify the contributions of the longitudinal and lateral forces.
The results show a good agreement between the classical and new formulations of the understeer
coefficient, and allow to infer a relationship between the understeer coefficient and
the yaw moment analysis. The handling characteristics for the considered maneuvers vary
with the vehicle speed and front-to-rear wheel torque distribution. In particular, an apparently
surprising result arises at low speed, where the RWD architecture is the most understeering
configuration. This outcome is discussed through the yaw moment analysis, highlighting the
yaw moment caused by the longitudinal forces of the front tires, which is significant for high
values of lateral acceleration and steering angle.
Gao Jianbing, Tian Guohong, Sorniotti Aldo, Karci Ahu Ece, Di Palo Raffaele (2019) Review of thermal management of catalytic converters to decrease engine emissions during cold start and warm up, Applied Thermal Engineering 147 pp. 177-187 Elsevier
Catalytic converters mitigate carbon monoxide, hydrocarbon, nitrogen oxides and particulate matter emissions from internal combustion engines, and allow meeting the increasingly stringent emission regulations. However, catalytic converters experience light-off issues during cold start and warm up. This paper reviews the literature on the thermal management of catalysts, which aims to significantly reduce the light-off time and emission concentrations through appropriate heating methods. In particular, methods based on the control of engine parameters are easily implementable, as they do not require extra heating devices. They present good performance in terms of catalyst light-off time reduction, but bring high fuel penalties, caused by the heat loss and unburnt fuel. Other thermal management methods, such as those based on burners, reformers and electrically heated catalysts, involve the installation of additional devices, but allow flexibility in the location and intensity of the heat injection, which can effectively reduce the heat loss in the tailpipe. Heat storage materials decrease catalyst light-off time, emission concentrations and fuel consumption, but they are not effective if the engine remains switched off for long periods of time. The main recommendation of this survey is that integrated and more advanced thermal management control strategies should be developed to reduce light-off time without significant energy penalty.
One of the major phenomena compromising the comfort of the passenger vehicles is jerk. Jerk occurs as a response to the transient in the driver torque demand. The transient provokes torsional oscillation of the drivetrain, which results in oscillations and jerk of the vehicle. These oscillations and jerk are transmitted to the driver and can cause discomfort to the driver and thus affecting the drivability of the vehicle.
The aim of this work is to develop an anti-jerk controller to achieve smooth response of the vehicle and enhance the drivability metrics. The drivability analysis in this thesis focused on the longitudinal dynamic response during the tip-in manoeuvre.
The anti-jerk controller introduced in this work is an optimisation-based controller. It is developed by using two models, i.e. a linear model and non-linear model. The developed models include detailed description of the drivetrain system such as clutch, primary shaft, secondary shaft, differential, half-shaft, tyres and the vehicle. The engine was modelled using the engine map. To achieve high confidence of the models fidelity, the models were verified by experimental data which ensures that the models are accurate and characterised by the required details.
The anti-jerk controller is an optimised controller and uses a gain scheduling where the gain scheduling optimisation was performed off-line to reduce the engineering time in the controller gain tuning.
The simulation results of the models with the controller show a significant improvement of the drivability, which is measured by the overshoot and the rise time on the acceleration profile.
Chatzikomis C., Zanchetta M., Gruber P., Sorniotti A., Modic B., Motaln T., Blagotinsek L., Gotovac G. (2019) An energy-efficient torque-vectoring algorithm for electric vehicles with multiple motors, Mechanical Systems and Signal Processing 128 pp. 655-673 Elsevier
In electric vehicles with multiple motors, the individual wheel torque control, i.e., the so-called torque-vectoring, significantly enhances the cornering response and active safety. Torque-vectoring can also increase energy efficiency, through the appropriate design of the reference understeer characteristic and the calculation of the wheel torque distribution providing the desired total wheel torque and direct yaw moment. To meet the industrial requirements for real vehicle implementation, the energy-efficiency benefits of torque-vectoring should be achieved via controllers characterised by predictable behaviour, ease of tuning and low computational requirements. This paper discusses a novel energy-efficient torque-vectoring algorithm for an electric vehicle with in-wheel motors, which is based on a set of rules deriving from the combined consideration of: i) the experimentally measured electric powertrain efficiency maps; ii) a set of optimisation results from a non-linear quasi-static vehicle model, including the computation of tyre slip power losses; and iii) drivability requirements for comfortable and safe cornering response. With respect to the same electric vehicle with even wheel torque distribution, the simulation results, based on an experimentally validated vehicle dynamics simulation model, show: a) up to 4% power consumption reduction during straight line operation at constant speed; b) >5% average input power saving in steady-state cornering at lateral accelerations >3.5/m/s2; and c) effective compensation of the yaw rate and sideslip angle oscillations during extreme transient tests.
Tavernini Davide, Vacca Fabio, Metzler Mathias, Savitski Dzmitry, Ivanov Valentin, Gruber Patrick, Hartavi Karci Ahu Ece, Dhaens Miguel, Sorniotti Aldo (2019) An explicit nonlinear model predictive ABS controller for electro-hydraulic braking systems, IEEE Transactions on Industrial Electronics pp. 1-1 Institute of Electrical and Electronics Engineers (IEEE)
This study addresses the development and Hardware-in-the-Loop (HiL) testing of an explicit nonlinear model predictive controller (eNMPC) for an anti-lock braking system (ABS) for passenger cars, actuated through an electro-hydraulic braking (EHB) unit. The control structure includes a compensation strategy to guard against performance degradation due to actuation dead times, identified through experimental tests. The eNMPC is run on an automotive rapid control prototyping unit, which shows its real-time capability with comfortable margin. A validated high-fidelity vehicle simulation model is used for the assessment of the ABS on a HiL rig equipped with the braking system hardware. The eNMPC is tested in 7 emergency braking scenarios, and its performance is benchmarked against a proportional integral derivative (PID) controller. The eNMPC results show: i) the control system robustness with respect to variations of tire-road friction condition and initial vehicle speed; and ii) a consistent and significant improvement of the stopping distance and wheel slip reference tracking, with respect to the vehicle with the PID ABS.

Modern vehicle safety control systems are critical to the enhancement of lateral vehicle stability and the reduction of fatal accidents. Safety control systems based on direct yaw moment control (DYC) enhance vehicle stability during cornering. In such systems, the yaw moment adjustment is obtained from the difference of the traction/braking forces between the left and right wheels. A DYC can be actuated through the friction brakes, mechanical devices, or individually controlled electric motors. The implementation of the DYC through the friction brakes is not desirable, as it reduces vehicle velocity and consequently degrades driving comfort. On the other hand, electrical differentials and DYC actuation through individually controlled motors are more effective and less intrusive.

The major contribution of this project is to propose novel high-level control algorithms for DYC systems that aim to improve vehicle lateral stability using individually controlled electric motors and a novel electrical differential system known as Twinster. The novelty is in the formulation of a control algorithm that improves vehicle stability and handling in severe driving manoeuvres while ensuring robustness against system uncertainties. To guarantee robustness of the control system against system uncertainties and disturbances, this thesis proposes a gain scheduled robust linear quadratic regulator (RLQR), in which an extra control term is added to the feedback term of a conventional LQR to limit the closed-loop tracking error in the neighbourhood of the origin of its state space. In addition, the gains of the proposed regulator optimally vary based on the actual longitudinal vehicle velocity to adapt the closed-loop system to the variations of this parameter. It is noted that the intrinsic parameter-varying nature of the vehicle dynamics model with respect to the longitudinal vehicle velocity can jeopardise the closed-loop performance of fixed-gain control algorithms in different driving conditions. Both numerical and experimental results show the superior performance of the proposed control system compared to conventional LQR control systems in terms of vehicle stability and handling improvement. In addition, the experimental results indicate that the controller is robust against unmodelled dynamics and uncertainties on both individually wheel-controlled and rear-wheel torque-vectoring axle vehicles.

This thesis is organised as follows. Chapter 1 introduces the motivation and scope for this thesis, while Chapter 2 includes the literature survey on DYC, the control algorithms, and torque differential devices. Chapter 3 is devoted to the vehicle model for control system design and to the formulation of the control algorithm. Chapter 4 represents the numerical and experimental results of the proposed controller on an electric vehicle with individually controlled wheels. Chapter 5 explains the design process of retrofitting a torque-vectoring device (GKN Twinster) on an electric Formula Student car, whereas Chapter 6 discusses the implementation of the controller on the retrofitted electric Formula Student car. Finally, the discussion and final remarks are included in Chapter 7.

Theunissen Johan, Sorniotti Aldo, Gruber Patrick, Fallah Saber, Ricco Marco, Kvasnica Michal, Dhaens Miguel (2019) Regionless Explicit Model Predictive Control of Active Suspension Systems with Preview, IEEE Transactions on Industrial Electronics Institute of Electrical and Electronics Engineers (IEEE)
Latest advances in road profile sensors make the implementation of pre-emptive suspension control a viable option for production vehicles. From the control side, model predictive control (MPC) in combination with preview is a powerful solution for this application. However, the significant computational load associated with conventional implicit model predictive controllers (i-MPCs) is one of the limiting factors to the widespread industrial adoption of MPC. As an alternative, this paper proposes an explicit model predictive controller (e-MPC) for an active suspension system with preview. The MPC optimization is run offline, and the online controller is reduced to a function evaluation. To overcome the increased memory requirements, the controller uses the recently developed regionless e-MPC approach. The controller was assessed through simulations and experiments on a sport utility vehicle demonstrator with controllable hydraulic suspension actuators. For frequencies
Gao Jianbing, Tian Guohong, Sorniotti Aldo (2019) On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle, Energy Science & Engineering Wiley Open Access
Metzler Mathias, Scamarcio Alessandro, Gruber Patrick, Sorniotti Aldo (2019) Real-time capable nonlinear model predictive wheel slip control for combined driving and cornering, Proceedings of the 26th IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks (IAVSD 2019) Springer
This paper presents a traction controller for combined driving and cornering
conditions, based on explicit nonlinear model predictive control. The prediction
model includes a nonlinear tire force model using a simplified version of
the Pacejka Magic Formula, incorporating the effect of combined longitudinal
and lateral slips. Simulations of a front-wheel-drive electric vehicle with multiple
motors highlight the benefits of the proposed formulation with respect to a controller
with a tire model for pure longitudinal slip. Objective performance indicators
provide a performance assessment in traction control scenarios.
Scamarcio Alessandro, Metzler Mathias, Gruber Patrick, Sorniotti Aldo (2019) Influence of the prediction model complexity on the performance of model predictive anti-jerk control for on-board electric powertrains, Proceedings of the 26th IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks (IAVSD 2019) CRC Press
Anti-jerk controllers compensate for the torsional oscillations of automotive
drivetrains, caused by swift variations of the traction torque. In the literature
model predictive control (MPC) technology has been applied to anti-jerk
control problems, by using a variety of prediction models. However, an analysis
of the influence of the prediction model complexity on anti-jerk control performance
is still missing. To cover the gap, this study proposes six anti-jerk MPC
formulations, which are based on different prediction models and are fine-tuned
through a unified optimization routine. Their performance is assessed over multiple
tip-in and tip-out maneuvers by means of an objective indicator. Results
show that: i) low number of prediction steps and short discretization time provide
the best performance in the considered nominal tip-in test; ii) the consideration
of the drivetrain backlash in the prediction model is beneficial in all test cases;
iii) the inclusion of tire slip formulations makes the system more robust with respect
to vehicle speed variations and enhances the vehicle behavior in tip-out
tests; however, it deteriorates performance in the other scenarios; and iv) the inclusion
of a simplified tire relaxation formulation does not bring any particular
benefit.

The research of this thesis focuses on the hardware-in-the-loop (HIL) assessment of proof-of-concept automotive systems. Two main applications are investigated: i) hybridised drivetrains; and ii) novel wheel slip controllers for anti-lock braking systems (ABS) applications.

The activities related to the assessment of proof-of-concept transmissions involve preliminary simulations and experimental evaluation of novel transmission prototypes for high performance passenger cars. A model-based approach is used to analyse the main power loss contributions of a baseline case study transmission. The newly developed hybridised transmission offers comparable performance (i.e. smooth acceleration profile during gearshift events), addressing comfort requirements. The experimental activity showed the efficiency improvements due to the mechanical layout of the new hybridised transmission. The benefits deriving by the hybridisation are also assessed through simulations carried out considering alternative proof-of-concept transmission layouts and an on-line implementable energy management strategy (A-ECMS). Other examples of hybridization layouts are also reported, i.e., the very recently developed hybrid rear axle module (HRAM). Furthermore, because of its ?modular? nature, the device can be equipped with advanced mechanical systems which allow a left-to-right torque distribution.

The wheel slip controller assessment on a HIL test rig setup involves an electro-hydraulic braking (EHB) unit. Because of their decoupled nature, EHBs offer independent and continuous modulation of the pressure levels at the four corners of the vehicle. For this test case, the HIL methodology is employed to quantify the performance benefits deriving from a PID-based wheel slip controller and a more advanced control strategy such as an explicit non-linear model predictive controller (eNMPC). The eNMPC performs better with respect the PID-based wheel slip controller on different test case scenarios. The results obtained during the development process have proven the effectiveness of the presented devices.

Lenzo B., Zanchetta M., Sorniotti A., Gruber P., De Nijs W. (2019) Yaw Rate and Sideslip Angle Control through Single Input Single Output Direct Yaw Moment Control, IEEE Transactions on Control Systems Technology Institute of Electrical and Electronics Engineers (IEEE)
Electric vehicles with independently controlled
drivetrains allow torque-vectoring, which enhances active safety
and handling qualities. This paper proposes an approach for the
concurrent control of yaw rate and sideslip angle based on a single
input single output (SISO) yaw rate controller. With the SISO
formulation, the reference yaw rate is firstly defined according to
the vehicle handling requirements, and is then corrected based on
the actual sideslip angle. The sideslip angle contribution
guarantees a prompt corrective action in critical situations such as
incipient vehicle oversteer during limit cornering in low tire-road
friction conditions. A design methodology in the frequency domain
is discussed, including stability analysis based on the theory of
switched linear systems. The performance of the control structure
is assessed via: i) phase-plane plots obtained with a non-linear
vehicle model; ii) simulations with an experimentally validated
model, including multiple feedback control structures; and iii)
experimental tests on an electric vehicle demonstrator along step
steer maneuvers with purposely induced and controlled vehicle
drift. Results show that the SISO controller allows constraining
the sideslip angle within the predetermined thresholds and yields
tire-road friction adaptation with all the considered feedback
controllers.
Zanchetta Mattia, Tavernini Davide, Sorniotti Aldo, Gruber Patrick, Lenzo Basilio, Ferrara Antonella, Sannen Koen, De Smet Jasper, De Nijs Wouter (2019) Trailer control through vehicle yaw moment control: Theoretical analysis and experimental assessment, Mechatronics 64 102282 Elsevier
This paper investigates a torque-vectoring formulation for the combined control of the yaw rate and hitch angle of an articulated vehicle through a direct yaw moment generated on the towing car. The formulation is based on a single-input single-output feedback control structure, in which the reference yaw rate for the car is modified when the incipient instability of the trailer is detected with a hitch angle sensor. The design of the hitch angle controller is described, including the gain scheduling as a function of vehicle speed. The controller performance is assessed by means of frequency domain and phase plane analyses, and compared with that of an industrial trailer sway mitigation algorithm. In addition, the novel control strategy is implemented in a high-fidelity articulated vehicle model for robustness assessment, and experimentally tested on an electric vehicle demonstrator with four on-board drivetrains, towing two different conventional single-axle trailers. The results show that: (i) the torque-vectoring controller based only on the yaw rate of the car is not sufficient to mitigate trailer instability in extreme conditions; and (ii) the proposed controller provides safe trailer behaviour during the comprehensive set of manoeuvres, thus justifying the additional hardware complexity associated with the hitch angle measurement.
Ricco Marco, Zanchetta Mattia, Cardolini Rizzo Giovanni, Tavernini Davide, Sorniotti Aldo, Chatzikomis Christoforos, Velardocchia Mauro, Geraerts Marc, Dhaens Miguel (2019) On the design of yaw rate control via variable front-to-total anti-roll moment distribution, IEEE Transactions on Vehicular Technology IEEE
In vehicle dynamics, yaw rate control is used to improve the cornering response in steady-state and transient conditions. This can be achieved through an appropriate anti-roll moment distribution between the front and rear axles of a vehicle with controllable suspension actuators. Such control action alters the load transfer distribution, which in turn provokes a lateral tire force variation. With respect to the extensive set of papers from the literature discussing yaw rate tracking through active suspension control, this study presents: i) A detailed analysis of the effect of the load transfer on the lateral axle force and cornering stiffness; ii) A novel linearized single-track vehicle model formulation for control system design, based on the results in i); and iii) An optimization-based routine for the design of the non-linear feedforward contribution of the control action. The resulting feedforward-feedback controller is assessed through: a) Simulations with an experimentally validated model of a vehicle with active anti-roll bars (case study 1); and b) Experimental tests on a vehicle prototype with an active suspension system (case study 2).

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