Dynamics analysis of the 3-[P（RR-RRR）SR] kinematically redundant parallel mechanism

ObjectiveCompared with conventional parallel mechanisms, kinematic redundant parallel mechanisms offer advantages such as a larger orientation workspace and the ability to avoid singular configurations. However, their degree of mobility (<italic>L</italic>) is greater than the number of degrees of freedom (<italic>n</italic>) of the end effector, which results in an excessive number of rigid bodies and makes dynamic modeling more difficult. Therefore, a dynamic modeling method based on the principle of virtual work was proposed for the 3-[P(RR-RRR)SR] kinematic redundant parallel mechanism, further simplifying the modeling process.MethodsFirstly, generalized variables were selected in the high-dimensional generalized space corresponding to the degree of mobility (<italic>L</italic>) of the mechanism. The kinematic transfer relations between the velocity and acceleration of each component within the mechanism and the system output velocity and acceleration were derived, and the Jacobian matrices of each component and the generalized variable were solved. Then, the dynamic model of the parallel mechanism was established using the principle of virtual work. Finally, the model was simulated by tracking the quintic polynomial trajectory of the end effector and compared with the calculation results of Adams software.ResultsThe analysis results indicate that the maximum relative error between the theoretical and simulated values of the driving force/torque at each joint is only 1.58%. This demonstrates the accuracy and reliability of the model, and also suggests that this method can provide reference for in-depth analysis of the dynamic characteristics of the mechanism and research on control strategies.