IPAB Workshop - Subramanian Ramamoorthy

Title:

Programmatically Structured Representations for Robust Autonomy in Robots

Abstract:

A defining feature of robotics today is the use of learning and autonomy in the inner loop of systems that are actually being deployed in the real world, e.g., in autonomous driving or medical robotics. While it is clear that useful autonomous systems must learn to cope with a dynamic environment, requiring architectures that address the richness of the worlds in which such robots must operate, it is also equally clear that ensuring the safety of such systems is the single biggest obstacle preventing scaling up of these solutions. I will discuss an approach to system design that aims at addressing this problem by incorporating programmatic structure in the network architectures being used for policy learning.

 

Firstly, I will present the perceptor gradients algorithm – a novel approach to learning symbolic representations based on the idea of decomposing an agent’s policy into i) a perceptor network extracting symbols from raw observation data and ii) a task encoding program which maps the input symbols to output actions. We show that the proposed algorithm is able to learn representations that can be directly fed into a Linear-Quadratic Regulator (LQR) or a general purpose A* planner. Our experimental results confirm that the perceptor gradients algorithm is able to efficiently learn transferable symbolic representations as well as generate new observations according to a semantically meaningful specification.

 

 

Next, I will describe work on learning from demonstration where the task representation is that of hybrid control systems, with emphasis on extracting models that are explicitly verifi[1]able and easily interpreted by robot operators. Through an architecture that goes from the sensorimotor level involving fitting a sequence of controllers using sequential importance sampling under a generative switching proportional controller task model, to higher level modules that are able to induce a program for a visuomotor reaching task involving loops and conditionals from a single demonstration, we show how a robot can learn tasks such as tower building in a manner that is interpretable and eventually verifiable.

 

I will conclude with glimpses of results from related projects on learning from demonstration, addressing latent spaces that are interpretable, and models that learn attributes of implicit task specifications.

 

References:

1. S.V. Penkov, S. Ramamoorthy, Learning programmatically structured representations with preceptor gradients, In Proc. International Conference on Learning Representations (ICLR), 2019. http://rad.inf.ed.ac.uk/data/publications/2019/penkov2019learning.pdf

2. M. Burke, S.V. Penkov, S. Ramamoorthy, From explanation to synthesis: Compositional program induction for learning from demonstration, https://arxiv.org/abs/1902.10657

 

Bio:

Dr. Subramanian Ramamoorthy is a Reader (Associate Professor) in the School of Informatics, University of Edinburgh, where he has been on the faculty since 2007. He is an Executive Committee Member for the Edinburgh Centre for Robotics. He received his PhD in Electrical and Computer Engineering from The University of Texas at Austin in 2007. He is a Turing Fellow at the Alan Turing Institute, an Emeritus Member of the Young Academy of Scotland at the Royal Society of Edinburgh, and has been a Visiting Professor at Stanford University and the University of Rome “La Sapienza”.  He also serves as Vice President - Prediction and Planning at FiveAI, a UK-based startup company focussed on developing a technology stack for autonomous vehicles. His research focus is on robot learning and decision-making under uncertainty, with particular emphasis on achieving safe and robust autonomy in human-centered environments.