Feedforward Control for Underactuated Bipedal Walking on Varying Compliant Slopes

In this paper, a feedforward control strategy is proposed to enable stable underactuated bipedal walking on varying compliant slopes with a known inclination angle to handle with the variation in natural environments. First, spring-damper units were employed in the horizontal and vertical directions to model the compliant ground, which is described as a rigid kinematical chain coupled with a spring-damper system. Second, a new definition of stable underactuated bipedal walking based on the walking speed was provided. Stable walking is achieved by adjusting the velocity of the bipedâ s center of mass (CoM) within limits that have been proved to allow at least one walking cycle. Based on the definition of stability and inspired by the gait characteristics of human walking on varying slopes, the proposed feedforward control strategy was based on the motion state of a robotâ s CoM. Speed control is realized by adjusting the displacement of the CoM with the change of slope to achieve stable walking. Finally, simulation experiments were conducted to validate the proposed controller. The simulation results demonstrate that stable walking is achieved on varying compliant slopes by implementing the proposed control strategy.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author