Adaptive Energy-Based Robot Control for Physical Human-Robot Interaction: A Less Conservative Approach

Abstract

Passivity-based control theory has emerged as a promising framework for physical human-robot interaction by explicitly enforcing the energetically passive relation. However, maintaining passivity at all times may overly limit the task execution capability of the robot, potentially increasing human physical workload. Furthermore, interaction safety can be violated in conventional passivity-based control approaches due to ignoring stored energy level and energy rate constraints. In this paper, an adaptive energy-based robot control is proposed for physical human-robot interaction by extending the passivitybased control and integrating additional safety constraints. Specifically, this method alleviates the inherent conservatism of conventional passivity-based control by ensuring passivity in the closed-loop system only when the system's energy exceeds a predefined threshold, while allowing more flexible behaviors otherwise. Additionally, adaptive control parameter laws, stored energy level saturation, and energy rate constraints are integrated into the control method to enhance task performance and safe interaction. Numerical simulation and human-in-the-loop co-carrying experiment are conducted to validate the feasibility and effectiveness of the proposed approach.