Integrable Whole-body Orientation Coordinates for Legged Robots

TL;DR

This paper introduces a new whole-body orientation coordinate for legged robots that depends solely on configuration, approximates total angular momentum, and aids in control and understanding of complex rotational behaviors.

Contribution

It proposes a novel, configuration-dependent orientation coordinate that captures entire system orientation without relying on motion history, improving rotational control.

Findings

Coordinate depends only on system configuration

Demonstrated on hardware with multiple applications

Approximates total system angular momentum

Abstract

Complex multibody legged robots can have complex rotational control challenges. In this paper, we propose a concise way to understand and formulate a \emph{whole-body orientation} that (i) depends on system configuration only and not a history of motion, (ii) can be representative of the orientation of the entire system while not being attached to any specific link, and (iii) has a rate of change that approximates total system angular momentum. We relate this orientation coordinate to past work, and discuss and demonstrate, including on hardware, several different uses for it.