四足机器人结构柔顺化设计与性能评价

Design and Evaluation of the Compliant Structure for a Quadruped Robot

摘要: 针对刚性四足机器人动态行走时的躯体姿态不平稳和地面冲击力大等问题，通过借鉴哺乳类四足动物的躯体结构，提出了一种以局部被动自由度为特征的四足机器人柔顺化结构，即，在刚性四足机器人腿部末端添加由压簧约束的直线移动副构成弹性腿部，在腰部添加由扭簧约束的横滚、偏转两个方向的转动副，形成柔性腰部。采用中枢模式发生器(CPG)方法建立了四足机器人的轨迹控制模型，结合力学分析和样机试验确定柔顺结构各个弹性自由度的刚度系数。物理样机运动实验表明，柔顺结构能够有效的降低四足机器人行走时的地面冲击力，减小躯干姿态变化程度，从而提高机器人行走的平稳性。

Abstract: 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.