轮腿混合机器人机械腿动力学建模与驱动预估

摘要

提出了一种可以同时实现迈步行走、有动力轮式机动、无动力轮旱冰式滑行3种运动方式的轮腿混合四足军用机器人,它采用一种基于3-UPS机构的6自由度并联机械腿,对并联机械腿进行了动力学建模与驱动参数峰值预估.通过矢量回路法推导出机械腿的机构传递映射模型,并建立了机构的雅可比矩阵;采用非保守系统的拉格朗日方程建立了机械腿的动力学模型,得到了驱动参数与机械腿的运动函数之间的显式方程.通过机械腿的动力学模型,对6个伺服电机的驱动转速、力矩进行了峰值预估分析,计算出各伺服电机中的最大理论转速为19.7 r/s,最大理论力矩为71 mN·m.通过一个具体的机械腿设计方案和结构参数算例,分析了机器人按照“1-2-34”循环步态迈步行走过程中,其6个伺服电机的瞬时转速、瞬时力矩随时间的变化规律曲线,并计算出此算例的伺服电机最大转速为15.3 r/s,最大力矩为48.1 mN·m,均小于预估模型中的预估理论极限峰值,通过计算得出算例的伺服电机选型预估功率为77 W,算例结果证明了所建立的驱动参数峰值预估模型的合理性.%A new type of wheel-leg hybrid quadruped robot is proposed,which has four 6-DOF mechanical legs based on 3-UPS parallel mechanism.The dynamics of mechanical legs are modeled,and their driving parameters are predicted.The vector chain method is used to establish a transfer model of 3-UPS parallel mechanism,and the Jacobian matrix is established.A dynamics model of mechanical legs is established based on the Lagrange equation,and the drive force acted on the mechanism is given.The peak prediction model of servo motors for driving speed and torque is analyzed based on the dynamics model.The calculated result shows that the peak value of rotating speed of driving motor is 19.7 r/s,and the peak value of torque of driving motor is 71 mN· m.A design scheme of mechanical leg and its structure parameters are used to obtain the changes of driving speeds and torques of 6 motors over time.The calculated results show that the peak speed of driving motor is 15.3 r/s,and its peak torque is 48.1 mN· m,which are all less than the predicted limit values.The predicted peak power of servo motors is 77 (W).It proves that the dynamic analysis and the peak prediction model of driving parameters of the mechanical leg are very reasonable.