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

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.