Gameplay Filters: Robust Zero-Shot Safety through Adversarial Imagination

TL;DR

The paper introduces the gameplay filter, a novel predictive safety mechanism that uses adversarial simulation to enhance robustness and safety of complex robot control policies in unpredictable real-world conditions.

Contribution

It presents the first full-order safety filter for high-dimensional quadrupedal robots that employs adversarial imagination to improve zero-shot robustness.

Findings

Demonstrates superior safety performance under large perturbations.

Successfully applies to 36-D quadrupedal dynamics.

Shows effectiveness in real-world experiments on different platforms.

Abstract

Despite the impressive recent advances in learning-based robot control, ensuring robustness to out-of-distribution conditions remains an open challenge. Safety filters can, in principle, keep arbitrary control policies from incurring catastrophic failures by overriding unsafe actions, but existing solutions for complex (e.g., legged) robot dynamics do not span the full motion envelope and instead rely on local, reduced-order models. These filters tend to overly restrict agility and can still fail when perturbed away from nominal conditions. This paper presents the gameplay filter, a new class of predictive safety filter that continually plays out hypothetical matches between its simulation-trained safety strategy and a virtual adversary co-trained to invoke worst-case events and sim-to-real error, and precludes actions that would cause failures down the line. We demonstrate the scalability and robustness of the approach with a first-of-its-kind full-order safety filter for (36-D) quadrupedal dynamics. Physical experiments on two different quadruped platforms demonstrate the superior zero-shot effectiveness of the gameplay filter under large perturbations such as tugging and unmodeled terrain. Experiment videos and open-source software are available online: https://saferobotics.org/research/gameplay-filter