Input to State Stability of Bipedal Walking Robots: Application to DURUS
This work addresses stability challenges for bipedal robots, which is incremental as it applies existing theoretical concepts to a specific robot system.
The paper tackled the problem of achieving stable bipedal walking in robots under uncertainties by establishing sufficiency conditions for input to state stable hybrid periodic orbits, resulting in successful and sustained walking of the 23-DOF robot DURUS in a lab environment.
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.