Modeling of Visco-Elastic Environments for Humanoid Robot Motion Control

TL;DR

This paper introduces a continuum-based visco-elastic contact model for humanoid robot motion control, enabling real-time walking on compliant terrains and improving robustness over traditional rigid contact models.

Contribution

It extends classical spring-damper models to large contact surface orientations and integrates this into a real-time whole-body control strategy for humanoid robots.

Findings

Successful simulation of humanoid walking on visco-elastic terrains

Improved robustness compared to rigid contact models

Effective real-time control implementation

Abstract

This manuscript presents a model of compliant contacts for time-critical humanoid robot motion control. The proposed model considers the environment as a continuum of spring-damper systems, which allows us to compute the equivalent contact force and torque that the environment exerts on the contact surface. We show that the proposed model extends the linear and rotational springs and dampers - classically used to characterize soft terrains - to the case of large contact surface orientations. The contact model is then used for the real-time whole-body control of humanoid robots walking on visco-elastic environments. The overall approach is validated by simulating walking motions of the iCub humanoid robot. Furthermore, the paper compares the proposed whole-body control strategy and state of the art approaches. In this respect, we investigate the terrain compliance that makes the classical approaches assuming rigid contacts fail. We finally analyze the robustness of the presented control design with respect to non-parametric uncertainty in the contact-model.