Safe Control of Quadruped in Varying Dynamics via Safety Index Adaptation

TL;DR

This paper introduces Safety Index Adaptation (SIA), a real-time method enabling quadruped robots to maintain safe control despite changing dynamics like payload variations, with proven theoretical guarantees and successful hardware experiments.

Contribution

The work presents a novel real-time safety index adaptation method that ensures safe control of quadruped robots under varying dynamics, validated through theory and hardware tests.

Findings

SIA guarantees forward invariance and finite-time convergence to safe regions.

Hardware experiments show effective obstacle avoidance with payload changes.

Theoretical analysis confirms the safety guarantees of SIA.

Abstract

Varying dynamics pose a fundamental difficulty when deploying safe control laws in the real world. Safety Index Synthesis (SIS) deeply relies on the system dynamics and once the dynamics change, the previously synthesized safety index becomes invalid. In this work, we show the real-time efficacy of Safety Index Adaptation (SIA) in varying dynamics. SIA enables real-time adaptation to the changing dynamics so that the adapted safe control law can still guarantee 1) forward invariance within a safe region and 2) finite time convergence to that safe region. This work employs SIA on a package-carrying quadruped robot, where the payload weight changes in real-time. SIA updates the safety index when the dynamics change, e.g., a change in payload weight, so that the quadruped can avoid obstacles while achieving its performance objectives. Numerical study provides theoretical guarantees for SIA and a series of hardware experiments demonstrate the effectiveness of SIA in real-world deployment in avoiding obstacles under varying dynamics.