Torque-Based Velocity Control for Safe Human-Humanoid Interaction

Torque-controlled robots are essential for safe human-robot interaction (HRI). In this paper we address the question of how joint level torque control can be implemented and seamlessly integrated into tasks that require precise velocity control. We present a control scheme that takes a desired velocity and torque as input to generate control output driving the joints at this velocity, and simultaneously realizing compliant behavior for safe HRI. We propose a novel method to integrate torque and velocity control into a single controller. The controller consists of an inner torque control loop embedded in an outer velocity control loop, and is hence called Torque-Based Velocity Control (TBVC). Experiments demonstrating the performance of the proposed control scheme are carried out on the humanoid ARMAR-6.