High precision force control of pneumatic cylinders considering disturbance suppression with specific frequency

This paper presents a practical control methodology of force control systems using a pneumatic cylinder for polishing machines. The typical machine is composed of the pneumatic cylinder as an actuator, a motor to rotate a whetstone, and a force sensor to detect the force value, where the high precision force control is required to achieve the high precision polish for objects. Vibration generated by the motor with periodic rotation, however, deteriorates the trajectory performance in target press force, resulting in the lower control accuracy of the system. In order to provide the precise force performance, therefore, a simple feedback compensator is designed to improve the disturbance suppression characteristic at specific frequency, where a resonant filter is adopted by paying attention to vector locus of the open-loop characteristic The proposed control approach has been verified by experiments using an actual pneumatic cylinder system.