Multi-Objective Policy Gradients with Topological Constraints

Publication Date

1-1-2022

Document Type

Conference Proceeding

Publication Title

IEEE International Conference on Intelligent Robots and Systems

Volume

2022-October

DOI

10.1109/IROS47612.2022.9982278

First Page

9034

Last Page

9039

Abstract

Multi-objective optimization models that encode ordered sequential constraints provide a solution to model various challenging problems including encoding preferences, modeling a curriculum, and enforcing measures of safety. A recently developed theory of topological Markov decision processes (TMDPs) captures this range of problems for the case of discrete states and actions. In this work, we extend TMDPs towards continuous spaces and unknown transition dynamics by formulating, proving, and implementing the policy gradient theorem for TMDPs. This theoretical result enables the creation of TMDP learning algorithms that use function approximators, and can generalize existing deep reinforcement learning (DRL) approaches. Specifically, we present a new algorithm for a policy gradient in TMDPs by a simple extension of the proximal policy optimization (PPO) algorithm. We demonstrate this on a real-world multiple-objective navigation problem with an arbitrary ordering of objectives both in simulation and on a real robot.

Department

Computer Engineering

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