Exploiting Friction in Torque Controlled Humanoid Robots

TL;DR

This paper explores how to leverage joint friction in torque-controlled humanoid robots to improve control strategies, challenging the common practice of friction compensation, with experiments conducted on the iCub robot.

Contribution

It introduces a novel approach to utilize friction in the control architecture of humanoid robots, enhancing stability and control performance.

Findings

Friction can be exploited to improve joint stability.

Using friction benefits high-level control objectives.

Experiments demonstrate practical advantages on iCub.

Abstract

A common architecture for torque controlled humanoid robots consists in two nested loops. The outer loop generates desired joint/motor torques, and the inner loop stabilises these desired values. In doing so, the inner loop usually compensates for joint friction phenomena, thus removing their inherent stabilising property that may be also beneficial for high level control objectives. This paper shows how to exploit friction for joint and task space control of humanoid robots. Experiments are carried out using the humanoid robot iCub.