Safety in Admittance Control using Reference Trajectory Shaping

TL;DR

This paper introduces a switched model reference admittance control framework that ensures safety and compliance in human-robot interaction by shaping reference trajectories and guaranteeing safety through invariance control.

Contribution

It proposes a novel method for variable admittance parameter generation with safety guarantees and robustness, validated through simulations and real-time experiments.

Findings

Effective safety and compliance in simulations

Robustness against disturbances demonstrated

Real-time implementation confirms practicality

Abstract

This paper presents a switched model reference admittance control framework to achieve safe and compliant human-robot collaboration through reference trajectory shaping. The proposed method generates variable admittance parameters according to task compliance and task-space safety requirements. Additionally, a disturbance bound is incorporated to enhance robustness against disturbances. Safety guarantees are explicitly established by integrating invariance control, ensuring that the reference trajectory remains within the admissible region. Stability of the switched system is analyzed using a common quadratic Lyapunov function, which confirms asymptotic convergence of the tracking error. The effectiveness of the approach is demonstrated through simulations on a two link manipulator and comparisons with existing methods are also presented. Furthermore, real time implementation on a single link manipulator validates the practical feasibility of the controller, highlighting its ability to achieve both compliance and safety in physical interaction scenarios.