Forcefree Control for Hydraulic Stewart Manipulator

Forcefree control is a control method that compensates for the robot's friction, gravity, and inertial forces, and allows the operator to generate passive motion by applying a small amount of operating force. In this paper, Forcefree control strategy for the realization of a hydraulic Stewart manipulator developed by Jilin University is studied. Forcefree control is achieved by the following method: Generating the desired trajectory with the force signal detected by the pressure sensor placed on the cylinder, and driving the Stewart mechanism to move. The compensate item of gravity and friction in the force signal are built and applied in the controller. With the controller, the operator can drive the system with light force or have force feeling of different forces during the work process. The experiment shows the effect of separate compensation and complete compensation of the forces.