Omnidirectional Bipedal Walking with Direct Fused Angle Feedback Mechanisms

TL;DR

This paper introduces an omnidirectional bipedal gait control method using direct fused angle feedback, demonstrating stable walking on a humanoid robot through simple, model-free feedback mechanisms.

Contribution

It presents a novel feedback control framework based on fused angles and an LQR tuning approach for stabilizing omnidirectional bipedal walking.

Findings

Successful stabilization of bipedal gait on a humanoid robot

Effective use of fused angles for orientation feedback

Simple, model-free feedback mechanisms can achieve stable walking

Abstract

An omnidirectional closed-loop gait based on the direct feedback of orientation deviation estimates is presented in this paper. At the core of the gait is an open-loop central pattern generator. The orientation feedback is derived from a 3D nonlinear attitude estimator, and split into the relevant angular deviations in the sagittal and lateral planes using the concept of fused angles. These angular deviations from expected are used by a number of independent feedback mechanisms, including one that controls timing, to perform stabilising corrective actions. The tuning of the feedback mechanisms is discussed, including an LQR-based approach for tuning the transient sagittal response. The actuator control scheme and robot pose representations in use are also addressed. Experimental results on an igus Humanoid Open Platform demonstrate the core concept of this paper, that if the sensor management and feedback chains are carefully constructed, comparatively simple model-free and robot-agnostic feedback mechanisms can successfully stabilise a generic bipedal gait.