Inverse Dynamics Control of Compliant Hybrid Zero Dynamic Walking
This work addresses the challenge of stable and adaptable walking for compliant bipedal robots, which is incremental as it builds on existing methods like inverse dynamics and trajectory optimization.
The authors tackled the problem of controlling bipedal locomotion on a highly underactuated and compliant robot by developing a trajectory planning and control architecture using offline trajectory optimization and online inverse dynamics control, achieving effective walking in simulation and on hardware across various speeds and terrains, including handling unplanned disturbances outdoors.
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.