Inverse Dynamics Control of Compliant Hybrid Zero Dynamic Walking

TL;DR

This paper introduces a novel inverse dynamics control framework for compliant hybrid zero dynamic walking, enabling stable bipedal locomotion across various speeds on underactuated robots, demonstrated through simulation and hardware tests.

Contribution

It develops a trajectory planning and control architecture using offline polynomial trajectories and a floating-base inverse dynamics controller for compliant walking.

Findings

Successful simulation and hardware implementation of walking.

Effective disturbance rejection on unplanned outdoor terrain.

Open-source code availability for reproducibility.

Abstract

We present a trajectory planning and control architecture for bipedal locomotion at a variety of speeds on a highly underactuated and compliant bipedal robot. A library of compliant walking trajectories are planned offline, and stored as compact arrays of polynomial coefficients for tracking online. The control implementation uses a floating-base inverse dynamics controller which generates dynamically consistent feedforward torques to realize walking using information obtained from the trajectory optimization. The effectiveness of the controller is demonstrated in simulation and on hardware for walking both indoors on flat terrain and over unplanned disturbances outdoors. Additionally, both the controller and optimization source code are made available on GitHub.