Automated Transitions Between Walking and Running in Legged Robots

Abstract

This paper addresses the synthesis of controllers for walk-to-run transition (WRT) and run-to-walk transition (RWT) in legged robots with adjustable leg compliance. Inspired by human kinematics, we propose a detailed procedure for the WRT and RWT in an adjustable-stiffness spring and mass model, and derive control parameters that ensure effective gait transitions. The WRT is achieved by modulating the compliance of the leg in a piecewise constant way during the transition stride. In the RWT, in addition to the leg compliance, we modulate the touchdown angle of attack. The merits of the approach proposed are demonstrated via a simulation that incorporates the control of walking, followed by a transition to running with first increasing and then decreasing speed, and finally a transition back to walking.