Model-based motion tracking control of an electric 3DoF parallel motion platform

A heave-pitch-roll parallel-type motion platform used extensively for flight simulation applications is considered. ¹² It introduces a novel configuration of the mechanism which benefits in two important aspects, better weight balancing due to utilizing a vertically mounted pneumatic actuator and better synchronization and higher stiffness due to the use of a new configuration of scissors. A model-based nonlinear control based on dynamics inversion is applied to the system. Dynamic model of low complexity is employed that describes the predominant dynamics of the system that is appropriate for real-time applications. The controller is then applied to the complete dynamic model that takes into account both the legs´ mass and inertia and actuators´ frictions. The accuracy of the model is verified by comparison with an equivalent model built in simMechanics. Simulations with typical desired trajectory inputs are presented and a good performance of the controller is achieved with two outstanding properties, an asymptotic convergence of error to zero and a high bandwidth. The bandwidth can further be increased by increasing the break frequency of the derivative filter. In addition, the controlled system presents an overall linear closed loop system that keeps its control specifications in entire the workspace.