Abstract: Quadruped animals in the nature realize high energy efficiency locomotion by automatically changing their gait at different speeds. Inspired by this character, an efficient adaptive diagonal gait locomotion controller is designed for quadruped robot. A unique gait planning method is proposed in this paper. As the speed of robot varies, the gait cycle time and the proportion of stance and swing phase of each leg are adjusted to form a variety of gaits. The optimal joint torque is calculated by the controller combined with Virtual Model Control (VMC) and Whole-Body Control (WBC) to realize the desired motion. The gait and step frequency of the robot can automatically adapt to the change of speed. Several experiments are done with a quadruped robot made by our laboratory to verify that the gait can change automatically from slow-trotting to flying-trot during the period when speed is from 0 to 4 m/s. The ratio of swing phase is from less than 0.5 to more than 0.5 to realize the running motion with four feet off the ground. Experiments have shown that the controller can indeed consume less energy when robot runs at a wide range of speeds comparing to the basic controller.

Key words: Quadruped robot , · Gait transition , · Adaptive gait , · Energy efciency