DILIGENT-KIO: A Proprioceptive Base Estimator for Humanoid Robots using Extended Kalman Filtering on Matrix Lie Groups

TL;DR

This paper introduces DILIGENT-KIO, a novel estimator for humanoid robots that uses extended Kalman filtering on matrix Lie groups to accurately estimate the robot's floating base and contact states, demonstrated on iCub.

Contribution

It develops a geometrically meaningful estimator on matrix Lie groups for humanoid robot base estimation, improving convergence and accuracy over existing methods.

Findings

Fast convergence for large initial errors

Accurate estimation of base position and orientation

Validated on iCub humanoid platform

Abstract

This paper presents a contact-aided inertial-kinematic floating base estimation for humanoid robots considering an evolution of the state and observations over matrix Lie groups. This is achieved through the application of a geometrically meaningful estimator which is characterized by concentrated Gaussian distributions. The configuration of a floating base system like a humanoid robot usually requires the knowledge of an additional six degrees of freedom which describes its base position-and-orientation. This quantity usually cannot be measured and needs to be estimated. A matrix Lie group, encapsulating the position-and-orientation and linear velocity of the base link, feet positions-and-orientations and Inertial Measurement Units' biases, is used to represent the state while relative positions-and-orientations of contact feet from forward kinematics are used as observations. The proposed estimator exhibits fast convergence for large initialization errors owing to choice of uncertainty parametrization. An experimental validation is done on the iCub humanoid platform.