My publications


Nanjangud S, Blacker P, Bandyopadhyay S, Gao Y (2018) Robotics and AI-Enabled On-Orbit Operations With Future Generation of Small Satellites,Proceedings of the IEEE 106 (3) pp. 429-439 Institute of Electrical and Electronics Engineers (IEEE)
The low-cost and short-lead time of small satellites
has led to their use in science-based missions, earth observation,
and interplanetary missions. Today, they are also key instruments
in orchestrating technological demonstrations for on-orbit
operations (O3) such as inspection and spacecraft servicing with
planned roles in active debris removal and on-orbit assembly.
This paper provides an overview of the robotics and autonomous
systems (RASs) technologies that enable robotic O3 on smallsat
platforms. Major RAS topics such as sensing & perception,
guidance, navigation & control (GN&C) microgravity mobility
and mobile manipulation, and autonomy are discussed from the
perspective of relevant past and planned missions.
Nanjangud S, Eke F (2016) Approximate Solution to the Angular Speeds of a Nearly-Symmetric Mass-Varying Cylindrical Body,The Journal of the Astronautical Sciences 64 (2) pp. 99-117 American Astronautical Society
This paper examines the rotational motion of a nearly axisymmetric rocket type system with uniform burn of its propellant. The asymmetry comes from a slight difference in the transverse principal moments of inertia of the system, which then results in a set of nonlinear equations of motion even when no external torque is applied to the system. It is often difficult, or even impossible, to generate analytic solutions for such equations; closed form solutions are even more difficult to obtain. In this paper, a perturbation-based approach is employed to linearize the equations of motion and generate analytic solutions. The solutions for the variables of transverse motion are analytic and a closed-form solution to the spin rate is suggested. The solutions are presented in a compact form that permits rapid computation. The approximate solutions are then applied to the torque-free motion of a typical solid rocket system and the results are found to agree with those obtained from the numerical solution of the full non-linear equations of motion of the mass varying system.
Nanjangud S, Eke F (2018) Angular momentum of free variable mass systems is partially conserved,Aerospace Science and Technology 79 pp. 1-4 Elsevier
Variable mass systems are a classic example of open systems in classical mechanics with rockets being a standard practical example. Due to the changing mass, the angular momentum of these systems is not generally conserved. Here, we show that the angular momentum vector of a free variable mass system is fixed in inertial space and, thus, is a partially conserved quantity. It is well known that such conservation rules allow simpler approaches to solving the equations of motion. This is demonstrated by using a graphical technique to obtain an analytic solution for the second Euler angle that characterizes nutation in spinning bodies.
Nanjangud Angadh (2018) Geometry of motion and nutation stability of free axisymmetric variable mass systems,Nonlinear Dynamics 94 (3) pp. 2205-2218 Springer Verlag
In classical mechanics, the ?geometry of motion? refers to a development to visualize the motion of freely spinning bodies. In this paper, such an approach of studying the rotational motion of axisymmetric variable mass systems is developed. An analytic solution to the second Euler angle characterizing nutation naturally falls out of this method, without explicitly solving the nonlinear differential equations of motion. This is used to examine the coning motion of a free axisymmetric cylinder subject to three idealized models of mass loss and new insight into their rotational stability is presented. It is seen that the angular speeds for some configurations of these cylinders grow without bounds. In spite of this phenomenon, all configurations explored here are seen to exhibit nutational stability, a desirable property in solid rocket motors.
Nanjangud Angadh, Blacker Peter C., Young Alex, Saaj Chakravarthini M., Underwood Craig I., Eckersley Steve, Sweeting Martin, Bianco Paolo (2019) Robotic architectures for the on-orbit assembly of large space telescopes,Proceedings of the Advanced Space Technologies in Robotics and Automation (ASTRA 2019) symposium European Space Agency (ESA)
Space telescopes are our ?eyes in the sky? that enable unprecedented
astronomy missions and also permit Earth
observation integral to science and national security. On
account of the increased spatial resolution, spectral coverage,
and signal-to-noise ratio, there is a constant clamour
for larger aperture telescopes by the science and surveillance
communities. This paper addresses a 25 m modular
telescope operating in the visible wavelengths of the electromagnetic
spectrum; such a telescope located at geostationary
Earth orbit would permit 1 m spatial resolution of
a location on Earth. Specifically, it discusses the requirements
and architectural options for a robotic assembly
system, called Robotic Agent for Space Telescope Assembly
(RASTA). Aspects of a first-order design and initial
laboratory test-bed developments are also presented.
Nanjangud Angadh, Underwood Craig I., Bridges Christopher P., Saaj Chakravarthini M., Eckersley Steve, Sweeting Martin, Biancod Paolo (2019) Towards Robotic On-Orbit Assembly of Large Space Telescopes: Mission Architectures, Concepts, and Analyses,Proceedings of the International Astronautical Congress, IAC pp. 1-25 International Astronautical Federation
Over the next two decades, unprecedented astronomy missions could be enabled by space telescopes larger than the
James Webb Space Telescope. Commercially, large aperture space-based imaging systems will enable a new generation
of Earth Observation missions for both science and surveillance programs. However, launching and operating
such large telescopes in the extreme space environment poses practical challenges. One of the key design challenges
is that very large mirrors (i.e. apertures larger than 3m) cannot be monolithically manufactured and, instead, a segmented
design must be utilized to achieve primary mirror sizes of up to 100m. Even if such large primary mirrors
could be made, it is impossible to stow them in the fairings of current and planned launch vehicles, e.g., SpaceX?s
Starship reportedly has a 9m fairing diameter. Though deployment of a segmented telescope via a folded-wing design
(as done with the James Webb Space Telescope) is one approach to overcoming this volumetric challenge, it is considered
unfeasible for large apertures such as the 25m telescope considered in this study. Parallel studies conducted
by NASA indicate that robotic on-orbit assembly (OOA) of these observatories offers the possibility, surprisingly,
of reduced cost and risk for smaller telescopes rather than deploying them from single launch vehicles but this is
not proven. Thus, OOA of large aperture astronomical and Earth Observation telescopes is of particular interest to
various space agencies and commercial entities. In a new partnership with Surrey Satellite Technology Limited and
Airbus Defence and Space, the Surrey Space Centre is developing the capability for autonomous robotic OOA of large
aperture segmented telescopes. This paper presents the concept of operation and mission analysis for OOA of a 25m
aperture telescope operating in the visible waveband of the electromagnetic spectrum; telescopes of this size will be
of much value as it would permit 1m spatial resolution of a location on Earth from geostationary orbit. Further, the
conceptual evaluation of robotically assembling 2m and 5m telescopes will be addressed; these missions are envisaged
as essential technology demonstration precursors to the 25m imaging system.