Variable Speed Running on Kneed Biped Robot with Underactuation Degree Two

Abstract

This paper presents control strategies for speed regulation on a running kneed biped with underactuation degree two. The robot under consideration has passive compliant knees and a unique hip actuator. In order to achieve variable speed running, a set of desired gaits (each at a different speed) is designed with the controlled Lagrangian method for the under-actuated robot. Then an event-based control law is applied to stabilize the running gait according to the running speed specification, and an energy shaping control is added to enlarge the domain of attraction as well as improve the convergence rate. At last a transitional control law is developed for smooth transitions between different running gaits. The effectiveness of our approach is verified by numerical simulations.