Invariant Error Dynamics Controller for a 6-dof Electrohydraulic Stewart Platform

The study of the invariant error dynamics controller for a six-degrees-of-freedom (dof) electrohydraulic Stewart platform is presented. Rigid body and electrohydraulic models, including servovalve dynamics are employed. Friction is also included in the mechanical model. The developed controller employs the dynamic and hydraulic model of the system and yields the six servovalve input current vector, in analytical form. Using mechanism inverse kinematics, the desired Cartesian trajectories yield desired actuator length trajectories. Simulations with typical desired trajectories are presented and a good performance of the controller is obtained.