Research On Robust Control For Linear Servo System On CNC

After the period of 90's, because of the development of computer science, micro-electronics, and modern control theory, Electrical Machinery and its interrelated subjects develop swiftly and violently. It is feasible and inevitable that digital control method has been taking the place of analog control method in this field. At the same time, the technology about the linear motor is widely used in the precise location field. Especially, with there quirement of the digital controlled machine tools increasing, the hyper speed, the hyper precision, the hyper reactivity, what is called zero mechanical gearing control theory, are easy to put in practice for the linear motor's servo system. The permanent magnet linear synchronous motors (PMLSM) have the advantages of high speed, high efficient, high dependability performances etc., meanwhile has many characters such as low noise, low cost and long life. With the development of the new material, the PMLSM has been rapidly developed and widely applied in recent year.The robust control theory has studied system's uncertainty specially to the system the influence, is suitable specially for the CNC machine tool permanent magnet linear synchronous servo system. This article first elaborated the robust control theory and the linear servo system vector control theory, then has designed the double closed loop robust controller for the linear servo system. Has designed the PI electric current controller in the electric current circle, but has designed the H_∞speed controller in the speed circle, and used LMI (linear matrix inequality) method to carry on the solution .the simulation results show that the design of the controller than the method for the Riccati controller has better robustness. Simultaneously has designed the closed-loop pole region disposition robust controller using the LMI method to the linear servo system, designs the controller compared to only uses the LMI method to have the better dynamic performance. After having considered permanent magnetism linear synchronous motor's model uncertainty, also used the LMI method to design for it has considered the circular closed-loop pole region disposition H_∞robust controller.