Input to State Stability of Bipedal Walking Robots: Application to DURUS

TL;DR

This paper establishes conditions for input-to-state stability in bipedal robots, demonstrating stable walking gaits for DURUS despite uncertainties, through theoretical analysis and experimental validation.

Contribution

It provides the first formal sufficiency conditions for input-to-state stability of hybrid walking gaits in complex bipedal robots like DURUS.

Findings

Successful stable walking of DURUS in laboratory environment.

Formal proof of ISS conditions ensuring robustness to uncertainties.

Demonstration of exponential input-to-state stabilization in practice.

Abstract

Bipedal robots are a prime example of systems which exhibit highly nonlinear dynamics, underactuation, and undergo complex dissipative impacts. This paper discusses methods used to overcome a wide variety of uncertainties, with the end result being stable bipedal walking. The principal contribution of this paper is to establish sufficiency conditions for yielding input to state stable (ISS) hybrid periodic orbits, i.e., stable walking gaits under model-based and phase-based uncertainties. In particular, it will be shown formally that exponential input to state stabilization (e-ISS) of the continuous dynamics, and hybrid invariance conditions are enough to realize stable walking in the 23-DOF bipedal robot DURUS. This main result will be supported through successful and sustained walking of the bipedal robot DURUS in a laboratory environment.