Physical Human-Robot Interaction: A Dynamic Transition Scheme Between Admittance and Hybrid Control Modes
The present work introduces a transition strategy to implement a hybrid force/admittance control scheme for collaborative robots in physical Human-Robot Interaction (pHRI). The architecture utilizes orthogonal projections to decouple force and motion subspaces. By evaluating the magnitude and time derivatives of a 6-DoF force sensor, a continuous transition function is synthesized to discriminate between intentional human contact and accidental impacts. The method enables the system to switch between admittance and hybrid control modes, eliminating control discontinuities. Uniform Ultimate Boundedness (UUB) of the closed-loop system is proven via Lyapunov analysis. Validation on an xArm-5 manipulator confirms that the transition bounds the error energy during impacts, enhancing safety and versatility during execution.