Optimal Time Control of Quadruped Robot Diagonal Gait Based on Half-Robot Model

Controlling highly dynamic quadruped robots is a challenging problem due to the high-dimensional states and complex dynamics of the legged system. In this study, we present a control framework for achieving stable trotting of an 8-DoF quadruped robot using the optimal time control approach. The transit time of the gait cycle is introduced as one of the performance indicators and a simplified half-robot model is proposed according to the characteristics of diagonal gait of a quadruped robot. The optimization problem is solved offline to serve as guidance for the robot's locomotion. Additionally, an anti-slip controller and a balance controller are designed to online modify the robot's actuation. This offline planning plus online modification control framework ensures a stable trotting of the robot. Experimental results on the robotic dog Gol demonstrate the effectiveness of the hybrid control architecture. The complete diagonal gait cycle is accomplished within 0.91 seconds under the corresponding control input constraints.