Robust Counterexample-guided Optimization for Planning from Differentiable Temporal Logic

Massachusetts Institute of Technology
A satellite rendezvous mission is specified via signal temporal logic, and a robust plan is found using our counterexample guided optimization method.
A simulation of the chaser satellite safely docking with the target satellite by following the planned trajectory.


Signal temporal logic (STL) lets us encode complex task specifications for autonomous systems, such as the satellite rendezvous task shown on the left. In this task, the chaser satellite must approach the target, but it must respect a set speed limit when too close to the target and it must spend a minimum amount of time loitering in the observation zone. We encode this mission using STL and then apply our novel robust planner to find a trajectory that satisfies these requirements by combing robust, sample-efficient counterexample-guided optimization with fast automatic differentiation of the simulator and STL semantics.

Video

Abstract

Signal temporal logic (STL) provides a powerful, flexible framework for specifying complex autonomy tasks; however, existing methods for planning based on STL specifications have difficulty scaling to long-horizon tasks and are not robust to external disturbances. In this paper, we present an algorithm for finding robust plans that satisfy STL specifications. Our method alternates between local optimization and local falsification, using automatically differentiable temporal logic to iteratively optimize its plan in response to counterexamples found during the falsification process. We benchmark our counterexample-guided planning method against state-of-the-art planning methods on two long-horizon satellite rendezvous missions, showing that our method finds high-quality plans that satisfy STL specifications despite adversarial disturbances. We find that our method consistently finds plans that are robust to adversarial disturbances and requires less than half the time of competing methods. We provide an implementation of our planner online.

Related Links

This work is part of a broader research thread around glass-box formal methods, exploring the use of tools like automatic differentiation to enable more productive design and verification of autonomous systems.

Other work on this theme from our lab include:

BibTeX

@article{dawson2022_robust_stl_planning,
  author    = {Dawson, Charles and Fan, Chuchu},
  title     = {Robust Counterexample-guided Optimization for Planning from Differentiable Temporal Logic},
  journal   = {IROS},
  year      = {2022},
}