Design and Evaluation of the Compliant Structure for a Quadruped Robot

It can cause large ground impact force and postural instability when a rigid quadruped robot walks on the ground. To improve walking performances, a bio-inspired compliant structure was designed for a quadruped robot, which features four elastic legs and two flexible waist joints. The elastic legs are composed of a linear sliding pair con- strained by compression spring at the end of each leg. The flexible waist is constituted with two rotating joints in roll and yaw, which are constrained by torsion springs. A center pattern generator (CPG) model was established, used as the trajectory planner of the robot. Mechanical analysis and physcial experiments were combined to determine the stiffness of all the springs. Comparative experiments show that the elastic legs can effectively reduce the ground impact force and the flexible waist can decrease the swing of the body, which contribute to achieve higher postural stability when the quadruped robot walks on the ground.

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