Reachability Aware Capture Regions with Time Adjustment and Cross-Over for Step Recovery

TL;DR

This paper introduces advanced balance recovery strategies for humanoid robots, including improved capture region calculations, cross-over step techniques, and time adaptation, demonstrated on a robot navigating rough terrain and recovering from disturbances.

Contribution

It presents novel methods for step adjustment, cross-over recovery, and time adaptation to enhance humanoid robot stability during locomotion.

Findings

Successful recovery from external disturbances in simulation and hardware.

Enhanced stability through cross-over steps and time adjustment.

Robust walking over rough terrain with improved balance control.

Abstract

For humanoid robots to live up to their potential utility, they must be able to robustly recover from instabilities. In this work, we propose a number of balance enhancements to enable the robot to both achieve specific, desired footholds in the world and adjusting the step positions and times as necessary while leveraging ankle and hip. This includes improving the calculation of capture regions for bipedal locomotion to better consider how step constraints affect the ability to recover. We then explore a new strategy for performing cross-over steps to maintain stability, which greatly enhances the variety of tracking error from which the robot may recover. Our last contribution is a strategy for time adaptation during the transfer phase for recovery. We then present these results on our humanoid robot, Nadia, in both simulation and hardware, showing the robot walking over rough terrain, recovering from external disturbances, and taking cross-over steps to maintain balance.