Model Verification and Design of Speed Control System of Water Driven Stage

The present paper describes a design of speed control system of the water driven stage that has been developed for a feed table of an ultra-precision machine tool. The stage has a piston-cylinder mechanism to drive a table of the stage. Since the piston-cylinder mechanism is used, the flow rate supplied to the piston-cylinder controls the speed of the table. For diamond turning applications, the constant feed motion of the stage is highly desirable in order for obtaining fine diamond-turned surfaces. In the present paper, mathematical models of the water driven stage and a flow control valve are introduced. Based on the derived models, a conventional P-I control system is then designed in order to achieve desired control performances, aiming no steady-state error and minimized extraneous disturbance effects on the response. Performances of the designed controller are studied through experiments and simulations.