Harmonising Safety Paradigms: Energy-Aware Control of Active Response and Passive Compliance for Safety-Critical Robotic Tasks

Abstract

Ensuring safety in robotic manipulation is increasingly critical as robots become integrated into human-shared environments for complex physical interaction tasks. This paper presents an energy-aware control framework that combines active responses with passive compliance for safety-critical robotic manipulation. Specifically, Control Barrier Functions (CBFs) are employed for active collision avoidance with detected obstacles, which are then integrated with fallback safety actions to resolve potential violation of CBF constraints. Complementing this active safety paradigm, a passive safety paradigm is implemented to mitigate post-collision impacts by monitoring energy variance and limiting power exchanges. Furthermore, an energy tank is incorporated to enforce passivity of the robot, which is crucial to address potential instability issues in variable impedance control. To make the tank adaptive to varying energy requirements arising from dynamic environments and unpredictable events, we propose a novel, task-agnostic tank recharging condition without compromising the system's passivity guarantee. The effectiveness of the proposed control framework is validated through experiments on a KUKA iiwa 14 robot.