Simplified strategy of the dynamic model of a 6-UPS parallel kinematic machine for real-time control

This paper deals with the simplification of the dynamic model of a 6-UPS parallel kinematic machine (PKM), and a simplified strategy of the dynamic model for real-time control application is presented. The dynamic model is derived by using the Newton–Euler approach, and a detailed decomposition of the dynamic model is realized by decomposing the inertial forces and moments of legs and platform. The movement of the moving platform is divided into constant velocity movement and accelerating/decelerating movements. The movements in constant velocity movement and accelerating/decelerating movements of the moving platform are simulated by converting the movement of the moving platform into discrete-time motion. By investigating the contribution of each term in the dynamic model to the driving force, the secondary factors of the dynamic model in each type of movement are determined respectively and simplified strategies are proposed. In order to verify the simplified strategy, the simulation is done again, which shows that the computational efficiency of the solution to the inverse dynamics is improved greatly. The simplified error of the dynamic model is very small, and the simplified object for real-time control application can be well satisfied. Moreover, a simulation based on continuous trajectory movement of the moving platform is performed to validate the simplified strategy. The simplified method is not only suited for Stewart platform-based PKM, but also can be applied to other kinds of PKM.