Sagittal SLIP-anchored task space control for a monopode robot traversing irregular terrain

Abstract

As a well-explored template that captures the essential dynamical behaviors of legged locomotion on sagittal plane, the spring-loaded inverted pendulum (SLIP) model has been extensively employed in both biomechanical study and robotics research. Aiming at fully leveraging the merits of the SLIP model to generate the adaptive trajectories of the center of mass (CoM) with maneuverability, this study presents a novel two-layered sagittal SLIP-anchored (SSA) task space control for a monopode robot to deal with terrain irregularity. This work begins with an analytical investigation of sagittal SLIP dynamics by deriving an approximate solution with satisfactory apex prediction accuracy, and a two-layered SSA task space controller is subsequently developed for the monopode robot. The higher layer employs an analytical approximate representation of the sagittal SLIP model to form a deadbeat controller, which generates an adaptive reference trajectory for the CoM. The lower layer enforces the monopode robot to reproduce a generated CoM movement by using a task space controller to transfer the reference CoM commands into joint torques of the multi-degree of freedom monopode robot. Consequently, an adaptive hopping behavior is exhibited by the robot when traversing irregular terrain. Simulation results have demonstrated the effectiveness of the proposed method.

3D-SLIP model based dynamic stability strategy for legged robots with impact disturbance rejection

“…Yu developed a dead-beat controller for the SLIP runner to regulate the apex state based on approximate apex return map 23 – 25 . He also proposed Sagittal SLIP-anchored task space control for a monopode robot traversing irregular terrain 26 . Schmitt and Clark proposed the AER control strategy based on active energy addition and removal by leg compression and leg extension 27 .…”