Overall Locomotion Control of a Quadruped Robot with Running Trot Gait

With the four-leg flying phase, the locomotion control of a quadruped robot with running trot gait is much more challenging than normal trot gait. This work firstly decouples the robot’s 6-DOF postures & poses, splitting into five DOFs of a 3D five-linkage mechanism and one DOF of a planner inverted pendulum model. Based on the established approximate kinetics of the 3D five-linkage mechanism, a control method based on virtual spring-damper models is proposed fundamentally, along with a pertinent open-loop hopping controller for the vertical hopping motion, which achieves the stable control on the 3-DOF postures, forward velocity and vertical hopping motion of the torso during the stance phase. The lateral velocity is controlled by selecting the foot positions of the planner inverted pendulum model during the flying phase. A novel event-driven-based finite state machine is presented to solve the sequential switching problem on the torso’s control mode between the stance and flying phase. Final simulation results suggest the feasibility and effectiveness of the proposed locomotion control method.