Compliance control based for a quadruped robot walking over rough terrain

It is well-known that the walking gait for quadruped robots has great potential to travel over rough terrain because of its higher flexibility and better environment adaptability. This paper presents a control framework for a quadruped robot walking over rough terrain, which includes such features: First, a preview controller is designed to create an appropriate body trajectory to realize the desired ZMP; Second, a new optimal force distribution is presented by minimizing the sum of the weighted torque efforts of the robot; Third, a contact force based compliance controller is designed to increase robustness in face of unknown and unanticipated disturbances. Simulations were performed with no four feet supporting period, the robot model successfully fast walking over rough terrain and going upstairs and downstairs. Then in the experiments, the quadruped robot achieved going upstairs with a stair of 0.15m. Simulations and experiments demonstrate the effectiveness of our compliance control strategy.