During the latest ten years, development in the industry of machine tools has been growing rapidly in our country. Since industry automation is highly demanded, the study about CNC is therefore extensively proceeded. Owing to request for higher quality, the machine tool must achieve the high speed and high precision. There are three factors in precise motion control : the accuracy of reference command, the design of servo control structure, and machine structure. However the part of machine structure attains to maturity. The design of the control system need to include good motion control and correct reference command. NURBS can represent analytic curves and free-form curves accurately and easily. Cross-coupled control is able to adjust the dynamic system of each axis to reduce the contour errors. It is expected to improve control performance in terms of contour errors by combine NURBS reference command and the cross-coupled control framework. Keywords¡Gmachine tool, NURBS, cross-coupled control

As the electronic products are gotten smaller and the quantity of output is to be requested, the trend of the needs for speed and accuracy is more precise. Therefore, upgrading the speed and the accuracy of contour error on tracking control has become an important point. This research is focus on the improvement of tracking error and contour error. In tracking error, we propose that the compensation of friction disturbance is by building friction model. And then adaptive robust controller is used to eliminate other disturbance. Finally, velocity feedforward controller is used to improve system dynamic response and to remove the effect of time delay. The combination of such controllers can improve tracking error directly and contour error indirectly. In contour error, we use cross-coupled controller to coordinate the motors and to reform contour error. On the association of such controllers, we propose the design method of cross-coupled controller, to replace the traditional way of try-and-error, and improving contour error again. Finally, the above improving strategies are verified by the simulation and experimental results.

As the electronic products are getting more and more small, the trend of the needs for speed and accuracy is more precise. Therefore, upgrading the speed and the accuracy of contour error on tracking control has become an important point. This research is focus on the improving of contour error and terminus error. In the contour error, we design the acceleration /deceleration profile based on digital FIR filter. And then remodel the compensatory method of cross-coupled controller, making the design of controller parameter easier, and getting better efficiency. And further, we get the time-variable gain by curve of contour error, making the accuracy better. In terminus error, according to two-step control, we switch the controller in deceleration region, not only directly improving the terminus error, but also improving the contour error. Finally, the above improved strategies are verified by the simulation and experimental results.