An analytical method for the inverse dynamic analysis of the Stewart platform with asymmetric-adjustable payload

This article presents the dynamic analysis and simulation for a nonlinear model of a Stewart platform with asymmetric-adjustable payload, based on Lagrangian approach. Due to the asymmetry of payload, the moment of inertia matrix is not diagonal and computing their terms is more complicated than for a symmetric load. Previous research about dynamic analysis of the Stewart platform are mostly considering static and symmetric payload, while numerous applications may have asymmetric payload such as satellite antenna trackers or surgical tables and so on. This article considers an asymmetric-adjustable payload applied to a Stewart platform, deriving the dynamic equations of the model. Moreover, the moment of inertia matrix and Coriolis-centrifugal terms matrices, which are useful for control analysis of the robot, are obtained. In addition, to verify the correctness of the model, the system has been modelled in ADAMS engineering software and the inverse dynamic solution has been developed by both analytical (Lagrangian formulation) and simulation (ADAMS) methods. The results show that the analytical model is so reliable and accurate that it can be used for dynamic analysis in other similar problems. Finally, the singularities of the model are determined.