Dynamics Modeling and Servomotor Parameter Estimation of a 3-Spherical-Prismatic-Revolute Parallel Mechanism

Parallel mechanisms have been widely used due to their high rigidity and good dynamic performance. Dynamics modeling and servomotor parameter estimation are the main contents in the design of parallel mechanisms. A method for the rigid body dynamics model of 3-SPR parallel mechanism is proposed using the reaction wrenches and velocity twists applied upon the joints. The velocity and acceleration analysis of joints and limbs in the 3-SPR parallel manipulator are discussed in detail by using screw theory and Lie bracket. Then the reaction wrenches and velocity twists applied upon the joints are established, followed by the actuated force of three actuators are obtained based on the virtual work principle. The method to estimate servomotor parameters is proposed by evaluating the peak torques and the average moments of inertia of the actuators, providing a theoretical foundation for the determination of servomotor specifications.