Whole-body Multi-contact Motion Control for Humanoid Robots Based on Distributed Tactile Sensors

TL;DR

This paper presents a novel multi-contact motion control method for humanoid robots that utilizes distributed tactile sensors on limbs to enhance stability and enable complex whole-body contacts in confined environments.

Contribution

It extends existing extremity contact control to include intermediate limb contacts using deformable tactile sensors and feedback control, verified through simulations and real robot experiments.

Findings

Distributed tactile sensors improve contact force measurement.

Enhanced feedback control stabilizes multi-contact motions.

Successful demonstration of complex multi-contact behaviors on a humanoid robot.

Abstract

To enable humanoid robots to work robustly in confined environments, multi-contact motion that makes contacts not only at extremities, such as hands and feet, but also at intermediate areas of the limbs, such as knees and elbows, is essential. We develop a method to realize such whole-body multi-contact motion involving contacts at intermediate areas by a humanoid robot. Deformable sheet-shaped distributed tactile sensors are mounted on the surface of the robot's limbs to measure the contact force without significantly changing the robot body shape. The multi-contact motion controller developed earlier, which is dedicated to contact at extremities, is extended to handle contact at intermediate areas, and the robot motion is stabilized by feedback control using not only force/torque sensors but also distributed tactile sensors. Through verification on dynamics simulations, we show that the developed tactile feedback improves the stability of whole-body multi-contact motion against disturbances and environmental errors. Furthermore, the life-sized humanoid RHP Kaleido demonstrates whole-body multi-contact motions, such as stepping forward while supporting the body with forearm contact and balancing in a sitting posture with thigh contacts.