Ultra-precision machining requires high motion resolution. The nonlinear factors and stability are two ma-jor factors to be faced in designing ultra-precision controllers. The design of the machine motion controller is very important in ultra-precision machining. A ballscrew driving stage with resolution of 5 nm and the micro movement characteristics of this mechanism have been researched

respectively. The mechanism is a nonlinear system in micro movement condition. A controller named gain self-turning controller based on motion error (GSTCBE) is also pro-posed

which has been proved to be more stable than traditional PID controller. The controller is charaterized by higher tracking accuracy in micro and macro motion scope.