Dr Chakravarthini Saaj

Lecturer, Head of Robotics Research Group

Qualifications: BTech MTech, PhD, CEng, FHEA, FBIS, SMIEEE, SMAIAA, MIET

Email:
Phone: Work: 01483 68 2225
Room no: U19 BA 01

Further information

Biography

Dr. Chakravarthini Saaj heads the Robotics Research Group at the Surrey Space Centre (SSC), where she specialises in Space and Medical Robots. Since 2007, Chakravarthini is a lecturer at the University of Surrey and prior to this post, she was a Post-Doctoral Research Fellow at SSC. She was a Visiting Research Associate at King’s College London from 2005 to 2007. She also worked as a Post-Doctoral Research Fellow at the Technical University Hamburg-Harburg, Germany from 2002-2003.

Chakravarthini received her BTech first class honours with distinction in Electrical and Electronics Engineering from the College of Engineering Trivandrum, India. She was awarded Masters degree in Control Systems with distinction and first rank by the same institute. In 2003, the Indian Institute of Technology Bombay, awarded a PhD for her work in the field of discrete-time sliding mode control.  

Chakravarthini is a Chartered Engineer with the Engineering Council, UK; Fellow of the British Interplanetary Society, UK; Senior Member of IEEE, Senior member of AIAA and a member of IET. She has numerous publications in international journals and conferences to her credit. Since 2002, she has been a reviewer of IEEE and IET journals and various conferences. She has authored and co-authored many successful research proposals in collaboration with leading national and international research groups. She is an external evaluator for various funding agencies.

Chakravarthini is a Fellow of the Higher Education Authority, UK and has extensive undergraduate and postgraduate teaching experience. From 2007 to 2012, she served as a Science, Technology, Engineering and Mathematics (STEMNET) ambassador for the schools and colleges in the UK and continues to actively promote engineering and space education in the UK.

Research Interests

Chakravarthini's research interests are mainly in the area of developing innovative robotic devices for Space and Surgical applications. Her expertise is in the area of bio-robotics, locomotion and control of legged and wheeled planetary rovers, modelling and control of rigid and soft manipulators, systems engineering using Unified Modelling Language and System Modelling Language, Control and sensing of surgical robots for minimally invasive surgery and Sliding Mode Control. More details can be found in the Robotics Research Group page.

Current Projects:

  1. Principal Investigator for the Astrium Space Transportation funded SysML MOTIVE project (Project value:£177K; March 2013-February 2015)
  2. Principal Investigator from the University of Surrey for the European Commission funded FP7 STIFF-FLOP project (Project value: > €7M; University of Surrey circa: €906K; January 2012-December 2015).
  3. Technical Manager and Principal Investigator for the European Commission funded FP7 FASTER project (Project value: €2M€; University of Surrey circa: €500K; November 2011-October 2014)
  4. Principal Investigator for the European Space Agency Networking Partnership Initiative (Project value: €83K; October 2010-to date)
  5. Principal Investigator for the Engineering and Physical Science Research Council and Astrium Ltd, UK, Industrial Case Studentship (Project value: £88K; October 2009-to date)

Past Projects:

  1. Principal Investigator - System Modelling and Requirements Verification of Robotic Spacecraft, Astrium Space Transportation GmbH, Bremen, Germany (Project value: £230K; August 2010-November 2012).
  2. Principal Investigator - SysML project with the Surrey Space Centre and Surrey Satellite Technology Ltd (September 2011-September 2012).
  3. Principal Investigator- Reference soil characterisation for ExoMars rover locomotion subsystem, Surrey Space Centre, UK (Project value: £25K; 2009-2010)
  4. Co-Investigator - Lunar Robotics Challenge, European Space Agency (Project value: £50K; 2008)
  5. Co-Investigator- Magnolia-1: A low cost pin-point landing system for planetary landers, Surrey Satellite Technology Ltd and Mississippi State University, US (Project value: £120K; 2007-2008)
  6. Co-Investigator- Autonomous Navigation and Control of Planetary Rovers, Surrey Space Centre, UK (2007-2008)
  7. Co-Investigator- Electrostatic Forces for Satellite Swarm Navigation and Reconfiguration, European Space Agency (Project value: €25K; 2006-2007)
  8. Co-Investigator- The Science and Technology behind Galileo- Europe’s GPS, Engineering and Physical Science Research Council, UK (2005-2006)
  9. Visiting Research Associate - Non-linear Observer for Slip Estimation of Tracked Vehicles, King's College London, UK (2004-2006).
  10. Visiting Research Associate - Robust Fast Output Sampling Sliding Mode Control for Discrete-time Non-linear System, Indian Institute of Technology, Bombay (2004)
  11. Research Fellow- Identification of Linear Parameter-Varying Models for Gain-Scheduling Control, Technical University Hamburg Harburg, Germany (2002-2003).
  12. PhD- Discrete Sliding Mode Control using Output Feedback, Indian Institute of Technology, Bombay (1999-2002)

Research Collaborations

Chakravarthini has established links with the following leading international groups:

Space Agencies:

ESA, DLR, NASA and ISRO

Industries:

EADS Astrium (Germany, France and UK)

Space Applications Services NV, Belgium

Surrey Satellite Technology Ltd, UK

LIQUIFER Systems Group, Austria

Astri Polska, Poland

Shadow Robot Company Ltd, UK

Przemyslowy Instytut Automatyki I Pomiarow, Poland

Karl Storz Endoscopes, Germany

QinetiQ, UK

BAE Systems, UK

Universities and Research Institutes:

King's College London, UK

German Research Centre for Artificial Intelligence, Germany

Scuola Superiore Sant’Anna, Italy

Foundation Tecnalia Research and Innovation, Spain

Italian Institute of Technology, Italy

Hebrew University of Jerusalem, Israel

University of Siegen, Germany

Fundacja Rozwoju Kardiochirurgii, Poland

Universita Degli Studi Di Torino, Italy

University of Bremen, Germany

Indian Institute of Technology, Bombay

Technical University Hamburg-Harburg, Germany

Mississippi State University, US

Cornell University, US

Virginia Tech, US

University of Kent, UK

Indian Institute of Space Science and Technology, India

 

Medical End-Users: 

European Association for Endoscopic Surgery, Netherlands

Guy's and St. Thomas Hospital, UK

Royal Surrey County Hospital, UK

Publications

Highlights

  • Smith B, Saaj CM, Allouis E. (2012) 'ANUBIS - Artificial Neuromodulation Using a Bayesian Inference System'. MIT Press Neural Computation,
  • Saaj CM, Scott G. (2012) 'The development of a soil trafficability model for legged vehicles on granular soils'. Elsevier Journal of Terramechanics, 49 (3-4), pp. 133-146.
    doi: 10.1016/j.jterra.2011.12.002
  • Chhaniyara S, Brunskill C, Yeomans B, Matthews M, Saaj CM, Richter L, Ransom S. (2012) 'Terrain trafficability analysis and soil mechanical property identification for planetary rovers: A survey'. Elsevier Journal of Terramechanics, 49 (2), pp. 115-128.
    doi: 10.1016/j.jterra.2012.01.001
  • Brunskill C, Patel N, Gouache TP, Scott GP, Saaj CM, Matthews M, Cui L. (2011) 'Characterisation of martian soil simulants for the ExoMars rover testbed'. Elsevier Journal of Terramechanics, 48 (6), pp. 419-438.
    doi: 10.1016/j.jterra.2011.10.001
    Full text is available at: http://epubs.surrey.ac.uk/105840/
  • Gouache TP, Brunskill C, Scott G, Saaj CM, Matthews M, Cui L, Patel N. (2011) 'Soil simulant sourcing for the ExoMars rover testbed'. Elsevier Journal of Planetary and Space Science, 59 (8), pp. 779-787.
    doi: 10.1016/j.pss.2011.03.006
    Full text is available at: http://epubs.surrey.ac.uk/105841/

    Abstract

    ExoMars is the European Space Agency (ESA) mission to Mars planned for launch in 2018, focusing on exobiology with the primary objective of searching for any traces of extant or extinct carbon-based micro-organisms. The on-surface mission is performed by a near-autonomous mobile robotic vehicle (also referred to as the rover) with a mission design life of 180 sols Patel et al. (2010). In order to obtain useful data on the tractive performance of the ExoMars rover before flight, it is necessary to perform mobility tests on representative soil simulant materials producing a Martian terrain analogue under terrestrial laboratory conditions. Three individual types of regolith shown to be found extensively on the Martian surface were identified for replication using commercially available terrestrial materials Patel (2011), sourced from UK sites in order to ensure easy supply and reduce lead times for delivery. These materials (also referred to as the Engineering Soil Simulants (ES-x) are: a fine dust analogue (ES-1); a fine aeolian sand analogue (ES-2); and a coarse sand analogue (ES-3). Following a detailed analysis, three fine sand regolith types were identified from commercially available products. Each material was used in its o -the-shelf state, except for ES-2, where further processing methods were used to reduce the particle size range. These materials were tested to determine their physical characteristics, including the particle size distribution, dry bulk density, particle shape (including angularity / sphericity) and moisture content. The results are analysed to allow comparative analysis with existing soil simulants and the published results regarding in-situ analysis of Martian soil on previous NASA missions. The findings have shown that in some cases material properties vary significantly from the specifications provided by material suppliers. It has confirmed that laboratory testing is necessary to determine the actual parameters and that standard geotechnical processes are suitable for doing so. The outcomes have allowed the confirmation of each simulant material as suitable for replicating their respective regolith types.

  • Scott GP, Saaj CM. (2009) 'BIOLOGICALLY INSPIRED ROBOTS TO ASSIST AREONAUTS ON THE MARTIAN SURFACE'. BRITISH INTERPLANETARY SOC JBIS-J BRIT INTERPLA, 62 (5), pp. 175-186.
  • Saaj CM, Underwood C, Noakes C, Park WG, Moore T. (2008) 'The Science and Technology behind Galileo- Europe’s GPS’'. Journal of the British Interplanetary Society, 61 (3), pp. 91-98.

Journal articles

  • Yeomans B, Saaj CM, van Winnedael M. (2013) 'Walking Planetary Rovers - a New Approach to Modelling Leg Thrust in Granular Soils'. Journal of Terramechanics,
    [ Status: Accepted ]
  • Smith B, Saaj CM, Allouis E. (2012) 'ANUBIS - Artificial Neuromodulation Using a Bayesian Inference System'. MIT Press Neural Computation,
  • Scott GP, Saaj CM. (2012) 'The development of a soil trafficability model for legged vehicles on granular soils'. Journal of Terramechanics, 49 (3-4), pp. 133-146.
    doi: 10.1016/j.jterra.2011.12.002
  • Saaj CM, Scott G. (2012) 'The development of a soil trafficability model for legged vehicles on granular soils'. Elsevier Journal of Terramechanics, 49 (3-4), pp. 133-146.
    doi: 10.1016/j.jterra.2011.12.002
  • Chhaniyara S, Brunskill C, Yeomans B, Matthews M, Saaj CM, Richter L, Ransom S. (2012) 'Terrain trafficability analysis and soil mechanical property identification for planetary rovers: A survey'. Elsevier Journal of Terramechanics, 49 (2), pp. 115-128.
    doi: 10.1016/j.jterra.2012.01.001
  • Brunskill C, Patel N, Gouache TP, Scott GP, Saaj CM, Matthews M, Cui L. (2011) 'Characterisation of martian soil simulants for the ExoMars rover testbed'. Elsevier Journal of Terramechanics, 48 (6), pp. 419-438.
    doi: 10.1016/j.jterra.2011.10.001
    Full text is available at: http://epubs.surrey.ac.uk/105840/
  • Gouache TP, Brunskill C, Scott G, Saaj CM, Matthews M, Cui L, Patel N. (2011) 'Soil simulant sourcing for the ExoMars rover testbed'. Elsevier Journal of Planetary and Space Science, 59 (8), pp. 779-787.
    doi: 10.1016/j.pss.2011.03.006
    Full text is available at: http://epubs.surrey.ac.uk/105841/

    Abstract

    ExoMars is the European Space Agency (ESA) mission to Mars planned for launch in 2018, focusing on exobiology with the primary objective of searching for any traces of extant or extinct carbon-based micro-organisms. The on-surface mission is performed by a near-autonomous mobile robotic vehicle (also referred to as the rover) with a mission design life of 180 sols Patel et al. (2010). In order to obtain useful data on the tractive performance of the ExoMars rover before flight, it is necessary to perform mobility tests on representative soil simulant materials producing a Martian terrain analogue under terrestrial laboratory conditions. Three individual types of regolith shown to be found extensively on the Martian surface were identified for replication using commercially available terrestrial materials Patel (2011), sourced from UK sites in order to ensure easy supply and reduce lead times for delivery. These materials (also referred to as the Engineering Soil Simulants (ES-x) are: a fine dust analogue (ES-1); a fine aeolian sand analogue (ES-2); and a coarse sand analogue (ES-3). Following a detailed analysis, three fine sand regolith types were identified from commercially available products. Each material was used in its o -the-shelf state, except for ES-2, where further processing methods were used to reduce the particle size range. These materials were tested to determine their physical characteristics, including the particle size distribution, dry bulk density, particle shape (including angularity / sphericity) and moisture content. The results are analysed to allow comparative analysis with existing soil simulants and the published results regarding in-situ analysis of Martian soil on previous NASA missions. The findings have shown that in some cases material properties vary significantly from the specifications provided by material suppliers. It has confirmed that laboratory testing is necessary to determine the actual parameters and that standard geotechnical processes are suitable for doing so. The outcomes have allowed the confirmation of each simulant material as suitable for replicating their respective regolith types.

  • Saaj CM, Lappas V, Schaub H, Izzo D. (2010) 'Hybrid propulsion system for formation flying using electrostatic forces'. ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER AEROSPACE SCIENCE AND TECHNOLOGY, 14 (5), pp. 348-355.
    doi: 10.1016/j.ast.2010.02.009
  • Scott GP, Saaj CM. (2009) 'BIOLOGICALLY INSPIRED ROBOTS TO ASSIST AREONAUTS ON THE MARTIAN SURFACE'. BRITISH INTERPLANETARY SOC JBIS-J BRIT INTERPLA, 62 (5), pp. 175-186.
  • Saaj CM, Underwood C, Noakes C, Park WG, Moore T. (2008) 'The Science and Technology behind Galileo- Europe’s GPS’'. Journal of the British Interplanetary Society, 61 (3), pp. 91-98.
  • Saaj CM, Lappas V, Richie D, Schaub H, Izzo D. (2007) 'Hybrid propulsion system for spacecraft swarm aggregation using Coulomb force'. BRITISH INTERPLANETARY SOC JBIS-J BRIT INTERPLA, 60 (7), pp. 268-274.
  • Peck MA, Streetman B, Saaj CM, Lappas V. (2007) 'Spacecraft formation flying using Lorentz forces'. BRITISH INTERPLANETARY SOC JBIS-JOURNAL OF THE BRITISH INTERPLANETARY SOCIETY, 60 (7), pp. 263-267.
  • Saaj CM, Bandyopadhyay B, Unbehauen H. (2004) 'A minor correction to "A new algorithm for discrete-time sliding mode control using fast output sampling feedback"'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE T IND ELECTRON, 51 (1), pp. 244-247.
    doi: 10.1109/TIE.2003.821899
  • Saaj CM, Bandyopadhyay B. (2003) 'Variable structure model following controller using non-dynamic multirate output feedback'. TAYLOR & FRANCIS LTD INTERNATIONAL JOURNAL OF CONTROL, 76 (13), pp. 1263-1271.
    doi: 10.1080/0020717031000147502
  • Bandyopadhyay B, Saaj CM. (2002) 'Algorithm on robust sliding mode control for discrete-time system using fast output sampling feedback'. IEE-INST ELEC ENG IEE P-CONTR THEOR AP, 149 (6), pp. 497-503.
    doi: 10.1049/ip-cta:20020703
  • Saaj CM, Bandyopadhyay B, Unbehauen H. (2002) 'A New Algorithm For Discrete-Time Sliding Mode Control Using Fast Output Sampling Feedback'. IEEE Transactions on Industrial Electronics, 51 (1), pp. 244-247.
  • Saaj CM, Bandyopadhyay B. (2001) 'Output Feedback Sliding Mode Control of Linear Second Order Systems-A Moving Switching Line Approach'. Systems Science Journal, 27 (3), pp. 5-22.

Conference papers

  • Saaj CM, Lappas V, Richie D, Peck M, Streetman B, Schuab H. 'Spacecraft Formation Flying and Reconfiguration with Electrostatic Forces'. Colorado: 30th Annual AAS Guidance and Control Conference
  • Saaj CM, Lappas V, Richie D, Schuab H. 'Hybrid Propulsion using Coulomb Force for Spacecraft Swarm Aggregation'. Kos, Greece: 10th European Control Conference
  • Lewinger WA, Comin F, Ransom S, Richter L, Al-Milli S, Spiteri C, Gao Y, Saaj CM. 'Multi-Level Soil Sensing Systems to Identify Safe Trafficability Areas for Extra-Planetary Rovers'. ESA/ESTEC, Noordwijk, the Netherlands: 12th Symposium on Advanced Space Technologies in Robotics and Automation
    [ Status: Accepted ]
  • Nevatia YH, Gancet J, Bulens F, Vögele T, Sonsalla RU, Saaj CM, Lewinger WA, Matthews M, Cabrera FJC, Gao Y, Allouis E, Imhof B, Ransom S, Richter L, Skocki K. 'Improved Traversal for Planetary Rovers through Forward Acquisition of Terrain Trafficability'. Karlsruhe, Germany: 2013 IEEE International Conference on Robotics and Automation Planetary Rovers Workshop
    [ Status: Accepted ]
  • Nevatia Y, Bulens F, Gancet J, Gao Y, Al-Mili S, Sonsalla RU, Kaupisch TP, Fritsche M, Vögele T, Allouis E, Skocki K, Ransom S, Saaj CM, Matthews M, Yeomans B, Richter L. 'Safe Long-Range Travel for Planetary Rovers through Forward Sensing'. ESA/ESTEC, Noordwijk, the Netherlands: 12th Symposium on Advanced Space Technologies in Robotics and Automation
    [ Status: Accepted ]
  • Mahmood W, Ali Shah S, Saaj CM. 'Vision Based Hazard Detection and Obstacle Avoidance for Planetary Landing'. Islamabad, Pakistan: International Bhurban Conference on Applied Science and Technology
  • Saaj CM, Lappas V, Richie D, Schaub H, Gazi V. 'Satellite Formation Flying: Robust Algorithms for Propulsion, Path Planning and Control'. Budapest: European Control Conference
  • Saaj CM, Lappas V, Richie D, Peck M, Streetman B, Schaub H. 'Spacecraft Formation Flying and Aggregation using Electrostatic Forces'. Proc. Advanced Space Vehicle Control Workshop, Guildford: Advanced Space Vehicle Control Workshop
  • Yeomans B, Saaj CM, van Winnedael M. (2013) 'Modelling Leg / Terrain Interaction for a Legged Planetary Micro-Rover'. ESA/ESTEC, Noordwijk, the Netherlands: 12th Symposium on Advanced Space Technologies in Robotics and Automation
    [ Status: Accepted ]
  • Saaj CM, Bandyopadhyay S, Bandyopadhyay B. (2012) 'Stability Analysis of Small Satellite Formation Flying and Reconfiguration Missions in Deep Space'. IEEE Variable Structure Systems (VSS), 2012 12th International Workshop on, Mumbai, India: 12th Int. Workshop on Variable Structure Systems, pp. 285-290.
    doi: 10.1109/VSS.2012.6163516
    Full text is available at: http://epubs.surrey.ac.uk/27657/

    Abstract

    Close-proximity (10-150 m) formation flying using low cost, small satellites is an emerging field. In such missions, control of satellite formations is a challenging problem and requires robust on-board control systems. This paper describes a modified approach to designing Sliding Mode Control (SMC) for satellite formation and reconfiguration missions, in deep space with external disturbances. Based on this dynamic model, a new approach for implementing path planning of satellites using Artificial Potential Field (APF) method is presented in this paper. This paper discusses stability of the sliding surfaces designed using gradient of the potential function for the closed loop system. The stability analysis is demonstrated by presenting a scenario in which six satellites aggregates to form an octahedron formation and subsequently reconfigure to a hexagon formation. This paper thus presents further progress in the state of-the-art of path planning and control for the framework of satellite formation and reconfiguration missions.

  • Chhaniyara S, Saaj CM, Meadiger B, Althoff-Kotzias M, Ahrns I. (2011) 'SysML based system engineering: A case study for Space Robotic Systems'. 62nd International Astronautical Congress, Cape Town, South Africa: 62nd International Astronautical Congress
    Full text is available at: http://epubs.surrey.ac.uk/27656/
  • Yeomans B, Saaj CM. (2011) 'Walking Rover Trafficability - Presenting a Comprehensive Analysis and Prediction Tool'. Springer Lecture Notes in Computer Science: Towards Autonomous Robotic Systems, Sheffield, UK: TAROS 2011: 12th Conference Towards Autonomous Robotic Systems 6856, pp. 348-359.
    doi: 10.1007/978-3-642-23232-9_31
    Full text is available at: http://epubs.surrey.ac.uk/27659/

    Abstract

    Although walking rovers perform well in rocky terrain, their performance over sands and other deformable materials has not been well studied. A better understanding of walking rover terramechanics will be essential if they are to be actually deployed on a space mission. This paper presents a comprehensive walking rover terramechanics model incorporating slip and sinkage dependencies. In addition to quantifying the leg / soil forces, the superior trafficability potential of a walking rover in deformable terrain is demonstrated, and a control approach is described which can reduce the risk inherent in traversing soils with unknown physical parameters. This work enhances the state of the art of legged rover trafficability and highlights some potential benefits from deploying micro-legged rovers for future surface exploration missions.

  • Smith B, Saaj CM, Allouis E. (2011) 'Evolving legged robots using biologically inspired optimization strategies'. IEEE Tianjin, China: IEEE International Conference on Robotics and Biomimetics, pp. 1335-1340.
    doi: 10.1109/ROBIO.2010.5723523
    Full text is available at: http://epubs.surrey.ac.uk/27650/

    Abstract

    When designing a legged robot a small change in one variable can have a significant effect on a number of the robot’s characteristics, meaning that making tradeoffs can be difficult. The algorithm presented in this paper uses biologically inspired optimization techniques to identify the effects of changing various robot design variables and determine if there are any general rules which can be applied to the design of a legged robot. Designs produced by this simulation are also compared to existing robot designs and biological systems, showing that the algorithm produces results which require less power than other robots of a similar mass, and which share a number of characteristics with biological systems.

  • Chhaniyara S, Saaj CM, Maediger B, Althoff-Kotzias M, Ahrns I. (2011) 'Model based system engineering for space robotic systems'. Proceedings of 11th Symposium on Advanced Space Technologies in Robotics and Automation, Noordwijk, Netherlands: ASTRA 2011
    Full text is available at: http://epubs.surrey.ac.uk/27652/

    Abstract

    The success of the Space robotic missions heavily relies on the performance of many interconnected systems and systems of systems. Deep understanding of the mission requirements, accurate system modelling and effective communication between systems, systems of systems and the outside world are critical to the success of these missions. This paper presents a thorough review of past and current system engineering practices and highlights the importance of Model Based System Engineering (MBSE), where model is a central artifact. This paper presents early work on the implementation of Systems Modelling Language (SysML) for modelling multimodal sensor system, which is part of the project INVERITAS for satellite servicing application. This paper also put forwards SysML based system engineering profile structure. The modular package structure would provide excellent portability and will help to create knowledge base for future projects.

  • Yeomans B, Saaj CM. (2011) 'Progress Towards Robust Mobility Analysis for a Legged Planetary Fetch Rover'. Proceedings of 11th Symposium on Advanced Space Technologies in Robotics and Automation, Noordwijk, Netherlands: ASTRA 2011
    Full text is available at: http://epubs.surrey.ac.uk/27658/

    Abstract

    Legged rovers offer a potentially superior alternative to wheeled locomotion for the exploration of challenging planetary terrains. Compared with a wheeled vehicle, a walking rover will have improved agility, slope climbing and rough terrain capability. However, when it comes to the analysis of the interaction with deformable terrain, surprisingly little study has been made of the terramechanics applicable to the type of micro - legged vehicle that might be deployed on a future mission. This paper describes progress towards a robust mobility model of legged vehicle performance on sands and other deformable terrains, applicable to a diverse range of vehicle and soil combinations. Software tools are described which aid analysis of terrain interaction, assist with optimisation of the vehicle design, and generate vehicle controller inputs enabling more reliable go / no go decisions to be made, optimisation of path planning, and management of vehicle gait and foot positioning.

  • Saaj CM, Bandyopadhyay B, Bandyopadhyay S. (2010) 'Development of Sliding Mode Controller for Small Satellite in Planetary Orbital Environment Formation Flying Missions'. Prague: 61st International Astronautical Congress
  • Yeomans B, Smith B, Murton S, Saaj CM. (2010) 'Biologically inspired nanorovers-Sample return using lightweight hybrid actuation'. Prague, Czech Republic: 61st International Astronautical Congress, pp. 6820-6831.
    Full text is available at: http://epubs.surrey.ac.uk/27647/

    Abstract

    This paper describes further progress in the design of a low mass, biologically inspired nanorover suitable for Mars surface exploration and sample return missions. An advanced legged vehicle is presented, incorporating a hybrid DC motor and Shape Memory Alloy (SMA) actuation system to minimise mass and conserve power. Previous work demonstrated that an ultra low mass vehicle could be designed using composite materials. Innovations in this new design include hybrid lightweight DC motor / SMA technology for high power / mass ratio whilst minimising power use, and steps to achieve proportional control of both DC motors and SMA actuators, although work on this area continues in order to resolve problems with proportional control of SMA. Agility is improved using legs with increased angular displacement, which facilitates attitude control over steep and uneven landscapes and enables implementation of biologically- inspired locomotion techniques such as crawling and sideways walking, and adding a third degree of freedom which allows the rover to display an extensive array of gait and pose options. System control applies embedded systems technology running a Linux operating system, force sensors are installed on each leg to provide feedback of terrain interaction for gait management purposes, and power storage capacity and efficiency are improved, enabling the vehicle to carry sufficient power reserves for meaningful excursion durations. The vehicle incorporates an innovative lightweight sample collection arm which uses two servo motors and two SMA actuators. This allows it to collect approximately 2cm3 of sample. Mass is minimised by using a combination of aluminium and Carbon Fibre Reinforced Polymer (CFRP). Total system mass is less than 1 kg, offering the opportunity for a swarm of rovers to form part of the overall Mars mission. These vehicles would take advantage of their superior agility and ability to traverse difficult landscapes and complement the operation of a larger wheeled mother rover - the mother vehicle would carry larger scale science and navigation equipment, as well as on board power resources, whereas the smaller vehicle can be dispatched to climb through rocky and steep terrain or deep into fissures to retrieve samples from the most interesting locations, returning to the mother rover for power and to deposit the sample.

  • Scott G, Saaj CM. (2010) 'Measuring and Simulating Soil Deformation of a Legged Microrover on Planetary Surfaces'. AIAA Space 2009 Conference
  • Mahmood W, Saaj CM. (2010) 'Pinpoint Planetary Landers: Vision Based Hazard Detection and Obstacle Avoidance'. Budapest, Hungary: European Control Conference
  • Saaj CM, Bandyopadhyay S, Bandyopadhyay B. (2010) 'Robust Control and Path Planning Algorithms for Small Satellite Formation Flying Missions'. International Astronautical Federation Proceedings of 60th International Astronautical Congress, Daejeon, Republic of Korea: IAC 2009: 60th International Astronautical Congress, pp. 3786-3792.
  • Saaj CM, Ibrahim H. (2010) 'Collision Avoidance and Control of Multi-Agent Systems'. Trivandrum, India: International Conference on Control, Communication and Computing
  • Smith B, Saaj CM. (2009) 'Biologically Inspired Nano-rovers: Innovative and Low Cost Technologies using Shape Memory Alloys'. Proceedings of 60th International Astronautical Congress, Daejeon, Republic of Korea: 60th International Astronautical Congress
    Full text is available at: http://epubs.surrey.ac.uk/725234/

    Abstract

    This paper details the design and construction of a biologically inspired nanorover prototype for exploring Mars. Although all Martian exploration vehicles to date have been wheeled, a six legged design was selected for this rover so as to improve its trafficability across rough terrains, since the main focus of this project was miniaturisation, with a goal of building a rover which weighed less than 1kg. To this end, shape memory alloy actuators were used instead of conventional rotary motors, due to their small size and mass, and carbon fibre was used as the main construction material. The rover was analysed using a combination of empirical results and computer simulation, in particular a simulation tool being developed at the University of Surrey called the Legged Performance and Traction Predicting Tool (LPTPT), with results suggesting that the design could be the basis of a successful planetary exploration vehicle.

  • Khorram A, Parsa S, Saaj CM. (2009) 'Trajectory Planning and Control of Robot Arm for Planetary Surface Sample Missions'. Proc. 60th International Astronautical Congress, Daejeon, Republic of Korea: 60th International Astronautical Congress
  • Parsa S, Saaj CM. (2009) 'Robot Assisted Satellite Servicing: Novel Motion Control Algorithm using Sliding Mode Control'. Thessaloniki, Greece: International Conference on Space Technology
  • Saaj CM, Sancho D. (2009) 'Assessment of Artificial Potential Field Methods for Navigation of Planetary Rovers'. Budapest: European Control Conference
  • Smith BGR, Scott GP, Saaj CM. (2009) 'Biorobotics: Innovative and Low Cost Technologies for Next Generation Planetary Rovers'. IEEE RAST 2009: PROCEEDINGS OF THE 4TH INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN SPACE TECHNOLOGIES, Istanbul, TURKEY: 4th International Conference on Recent Advances in Space Technologies, pp. 732-737.
    doi: 10.1109/RAST.2009.5158288
    Full text is available at: http://epubs.surrey.ac.uk/27649/

    Abstract

    This paper details some of the various robotics projects which have been inspired by the natural world, and which the authors believe will have an impact on the future of robotic space exploration. This includes both hardware-centric projects such as RiSE, and projects which concentrate more on software and control such as Swarm-bots. The authors outline two of the biologically inspired planetary explorer robots currently under investigation at the University of Surrey.

  • Parsa S, Saaj CM. (2008) 'On-Orbit Servicing: Novel Algorithms for Motion Control of Robot Manipulators'. Proc. 10th ESA Workshop on Advanced Space Technologies for Robotics and Automation, Noordwijk, The Netherlands: 10th ESA Workshop on Advanced Space Technologies for Robotics and Automation
  • Scott G, Saaj CM. (2008) 'Walking Micro-rovers for Planetary Exploration: Investigation into the Mechanics of Soil-Footprint Interaction'. Turin, Italy: Society of Terrain Vehicles Systems Conference
  • Scott G, Saaj CM. (2008) 'The Interaction between Walking Robot Footprint Shapes and Planetary Soil Deformation'. San Diego, USA: Proceedings of the AIAA Space 2008 Conference
  • Scott G, Saaj CM, Moxey E. (2008) 'Modelling Soil Traction for more Effective Control of Walking Planetary Rovers'. Edinburgh, UK: Towards Autonomous Robotic Systems Conference
  • Scott G, Meirion-Griffith C, Saaj CM, Moxey E. (2008) 'A Comparative Study of the deformation of Planetary Soils under Tracked and Legged Rovers'. San Diego: AIAA Space 2008 Conference
  • Saaj CM, Lappas V, Gazi V. (2006) 'Spacecraft Swarm Navigation and Control using Artificial Potential Field and Sliding Mode Control'. Proc. IEEE International Conference on Industrial Technology, Mumbai, India: IEEE International Conference on Industrial Technology (Paper Id. IF-011819), pp. 2646-2651.
  • Saaj CM, Bandyopadhyay B. (2004) 'Discrete Time Sliding Mode Control Using Output Samples'. Vilanova I la Geltru, Spain,: Proc. 8th IEEE International Workshop on Variable Structure Systems
  • Saaj CM, Bandyopadhyay B. (2004) 'Output Feedback Variable Structure Control of Non-linear Systems by Feedback Linearization'. Stuttgart, Germany: Proc. 6th IFAC Symposium on Nonlinear Control Systems
  • Saaj CM, Bandyopadhyay B. (2003) 'Discrete-Time Sliding Mode Control Using Fast Output Sampling Feedback'. Cambridge, UK: Proc. 7th European Control Conference
  • Saaj CM. (2002) 'Output Feedback Sliding Mode Control for MIMO Discrete Time Systems'. Barcelona, Spain: Proc. 15th IFAC World Congress on Automatic Control
  • Saaj CM, Bandyopadhyay B. (2002) 'Discrete Sliding Mode Control by Non-Dynamic Multirate Output Feedback'. Sarajevo, Bosnia & Herzegovina: Proc. 7th IEEE International Workshop on Variable Structure Systems
  • Saaj CM, Bandyopadhyay B. (2001) 'A New Three Level Output Feedback Sliding Mode Control For Discrete System'. Kolkata, India: Proc. Int. Conf. on Control, Instrumentation and Information Communication,

Teaching

Chakravarthini teaches the following modules, for which she is the module coordinator:

• 2007- to date: Year 4 (FHEQ Level 7) Space Robotics (24 contact hours; ~20 students)
• 2008- to date: Year 3 (FHEQ Level 6) Power Electronics (33 contact hours; ~30 students)
• 2013-to date: Year 2 (FHEQ Level 5) Electronics IV- Analogue Electronics for  Power Systems, Electrical Machines and Power (22 contact hours; ~90 students)
• 2009-2012: Year 2 (FHEQ Level 5) Electronics VI- Analogue Electronics, Machines and Power (22 contact hours; ~90 students)
• 2008-2009: Year 2 (FHEQ Level 5) Power Conversion (22 contact hours; ~85 students)

She is also the Personal Tutor for Year 1, Year 2, Year 3 and Year 4/MSc students (32 contact hours per year).

Departmental Duties

  • EEE Programme Coordinator: Chakravarthini is the designer and coordinator of the new Electrical and Electronic Engineering (EEE) degree programme. Further details are available at EEE.
  • Outreach Coordinator: She is the coordinator of outreach activities pertaining to the Surrey Space Centre. More updates are available at the link on Outreach and Invited Lectures.
  • IT Coordinator: She is also responsible for managing the Surrey Space Centre's IT infrastructure.

Outreach and Invited Lectures

  • SSC Outreach Speaker (2005- to date): Chakravarthini has represented the Surrey Space Centre in her role as an Outreach/Public Engagement Speaker at various national and international events and has delivered over 40 lectures. Jointly with the University of Nottingham, she conducted exhibitions at the National Space Centre, Leicester for the Galileo Public Engagement Project funded by EPSRC in 2005-2006. A selection of outreach/invited lectures delivered at national and international levels are listed at the bottom of this page.
  • Royal Institution Master Class Coordinator (2013-2014): Chakravarthini is the coordinator of the Royal Institution’s Engineering Master Class programme for 13-15 year olds. This event will be hosted by the University of Surrey in 2014.
  • STEM Ambassador (2008- to date): Chakravarthini is a Science, Technology, Engineering and Mathematics (STEM) Ambassador and has delivered lectures to over 2000 students at various schools and colleges in the UK.
  • Sterling Group UK Speaker (2010-2011): Chakravarthini has represented the University of Surrey at various events organised by the British Council, India and the Sterling Group, UK. She has visited over 20 engineering institutions in India and delivered lectures to over 5000 students.

  • Flying Lecturer (2008-2010): Chakravarthini was awarded the Visiting Lectureship ("Flying Lecturer") by the EngineeringUK (formerly the Engineering & Technology Board) in 2008. She delivered several lectures at various colleges in England and Wales. This two year 'Engineers Make It Happen' campaign was sponsored by the Royal Academy of Engineering, Elsevier publications and PKP Communicators. This campaign aimed at inspiring young students to take up career in Engineering.

  • SET for Work Mentor (2005-2008): Chakravarthini also served as a Mentor for the project “SET for Work”- a joint partnership of University of Leicester and IEEE (UK & Republic of Ireland) Section and funded by WISE (formerly the UK Resource Centre for Women in Science, Engineering & Technology).

Outreach/Public/Invited lectures at national and international levels:

1. 17 July 2007: Lecture for visitors from Hawaii Space Flight Laboratory, University of Surrey, UK

2. 24 January 2008: Conducted guided tour for ten Heads of Science from local independent schools, University of Surrey, UK

3. 18 March 2008: Lecture for visitors from U3A Astronomy Group, University of Surrey, UK

4. 1 April 2008: Invited lecture at Technical University Hamburg Harburg, Germany

5. 2 April 2008: Invited lecture at University of Bremen, Germany

6. 14 July 2008: Lecture for University of Surrey Headstart programme, UK

7. 25 July 2008: Lecture for international students from Pakistan, University of Surrey, UK

8. 4th August 2008: Invited lecture at Indian Institute of Technology Bombay, India

9. 8th August 2008: Invited lecture at College of Engineering Trivandrum, Kerala, India

10. 13th August 2008: Invited lecture at National Institute of Technology Calicut, India

11. 19th August 2008: Invited lecture at Indian Institute of Technology Madras, India

12. 12th September 2008: Lecture at Engineering and Technology Board, UK

13. 19th November 2008: Lecture for teachers and students from Cobham International School, University of Surrey, UK

14. 3rd December 2008:  Engineering and Technology Board’s lecture at Coleg Sir Gar, Llanelli, UK

15. 6th January 2009: Space at Surrey lecture for school students and teachers from Surrey, Kent and Hampshire, University of Surrey, UK

16. 5th March 2009: Invited lecture at Wallington School for Girls, Surrey, UK.

17. 17th March 2009:  International Year of Astronomy 2009, Guildford Astronomical Society lecture, University of Surrey, UK.

18. 21stApril 2009: Lecture and guided tour for visitors from the King Alfred Probus Club, Hampshire, UK.

19. 25th March 2009: Invited lecture at Alton College, Hampshire, UK

20. 6th May 2009: Lecture and guided tours for students and teachers from Oakmeeds Community College, Burgess Hill at University of Surrey, UK.

21. 7th July 2009: Second invited lecture at Alton College, Hampshire, UK

22. 8th July 2009: Invited lecture at Astrium, Stevenage, UK.

23. 14th January 2010: Guided tour organized by the South East – India Partnership Network (SE-IPNet) Consortium for the honourable Indian Union Minister of Human Resource Development (Mr. Kapil Sibal) and delegation, UK.

24. 10th March 2010: Guided tour for students from Warwick University, UK.

25. 29th March 2010: Invited lecture at Indian Institute of Space Science and Technology, Trivandrum, India.

26. 30th March 2010: Invited lecture at College of Engineering, Trivandrum, India.

27. 8th April 2010: Sterling group lecture at Anna University, Chennai, India.

28. 9th April 2010: Sterling group lecture at Hindustan University, Chennai, India.

29. 12th April 2010: Sterling group lecture at PES Institute of Technology, Bangalore, India.

30. 13th April 2010: Sterling group lecture at Jain University, Bangalore, India.

31. 5th February 2011: Invited lecture at A. D. Patel Institute of Technology, Gujarat, India.

32. 9th February 2011: Invited lecture at Disneyland for Work Experience students, Paris, France.

33. 5th April 2011: Lecture and guided tour for visitors from the King Alfred Probus Club, Hampshire, UK.

34. 25th July 2011: Sterling group lecture at Rajagiri Engineering College, Cochin, India.

35. 26th July 2011: Sterling group lecture at Model Engineering College, Cochin, India.

36. 28th July 2011: Sterling group lecture at Sri Krishna College of Engineering and Technology, Coimbatore, India.

37. 29th July 2011: Sterling group lecture at Amrita School of Engineering, Coimbatore, India.

38. 26th September 2011: Invited lecture at Southampton University, UK.

39. 13th September 2012: University Global Partnership Network Lecture to delegates from the North Carolina State University and University of São Paulo, University of Surrey, UK.

40. 24th September 2012: Lecture for PG Induction Day, University of Surrey, UK.

41. 25th September 2012: Guided tour for Ms. Lavinia Sealy, Chair of Surrey County Council, UK.

42. 26th September 2012: Invited lecture and guided tour to Mr. Simon Butler-Manuel and Mr. Anil Tailor from the Department of Gynaeoncology, Royal Surrey County Hospital, UK.

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