一种3自由度并联拟人机械腿的动力学建模及伺服电机峰值力矩预估

Dynamic Modeling and Peak Torque Prediction of Servo Motor for a 3-DOF Parallel Humanoid Mechanical Leg

为了弥补当前拟人机器人结构的不足之处和改善拟人机械腿的通用性和适应性,对一种3自由度并联拟人机械腿的动力学性能进行了研究。基于该机械腿的结构布局特点,推导出其运动学反解方程,研究了各输入速度的变化规律,利用拉格朗日方法建立该机械腿的动力学模型。在该模型的基础上建立伺服电机的预估模型,主要包括对伺服电机转速的预估和对电机转矩的预估,分析了机械腿伺服电机驱动的角速度、驱动力矩的变化规律,得到了机械腿的动力学特性,并对机械腿伺服电机峰值力矩预估模型进行了验证,得到最大预估峰值力矩值为3.195 N·m.分析结果表明,该机械腿机构的驱动角速度和驱动力矩呈周期性变化。伺服电机峰值力矩预估模型为机械腿伺服电机的选型提供了理论参考依据。

In order to make up for the deficiencies of the humanoid robot structure and to improve the versatility and adaptability of mechanical leg,the dynamics property of a parallel mechanical leg is discussed in detail. The inverse kinematics transmission equations for the mechanical leg are derived analytically. Then a dynamics model of the mechanical leg is established using the second Lagrange method.The expressions of inertia moment,Coriolis force-centrifugal force,and gravity are obtained by derivation. Based on the above dynamics model,the peak prediction model of servo motor for the mechanical leg is defined. The change rules of angular velocity and driving torque caused by the mechanical leg servo motor are analyzed,and the dynamics property of the mechanical leg is obtained. Finally the peak prediction model of servo motor for the mechanical leg is validated,and the estimated maximum peak torque is 3. 195 N·m. The results show that the angular speed and driving torque of mechanical leg display present periodic variation. The peak prediction model of servo motor can provide theoretical base for the se-lection of the mechanical leg servo motor.