The Control Research Of Cnc Machining Center Gantry Synchronous Magnetic Levitation System

Gantry CNC machine tool is a major processing equipment in modern industrial filed, its processing precision affect the precision of industrial parts and equipments in certain extent. At this stage, the main factor affecting precision is that the existence of friction between the fixed rails and moving beam, in order to eliminate friction, in this paper adopting magnetic levitation technology, make beam suspend over the rail, so that eliminate friction essentially and improve machining accuracy. Meanwhile, the mobile gantry CNC beam suspension system is synchronous suspension. In this paper, for the linear and nonlinear suspension systems, synchronization controllers are designed, to ensure synchronization suspension at both ends of the beam, to further improve precision.First, access to a large number of relevant literatures, and has a deep understanding for the applications of magnetic levitation technology, synchronous control and application and CNC machine tools system; a mathematical model of machine suspension system is established based on previous studies and analysis the stability of system. Then prove that the system is a nonlinear unstable system in theoretically.Second, the nonlinear system is linearized at the equilibrium point. For the linear single-suspension system, designs PID and disturbance observer controller as single-loop controller. After achieveing stable suspension, for the double suspension system, designs T-S fuzzy synchronous controller. The simulation results show that this control scheme can achieve synchronous suspension stability.Third, because the linearized model will bring the original error, in order to appproach realistic system, in this paper, for the nonlinear single-suspension system designs two kinds of fuzzy controllers with self-turning ability. One method is to change the quantization scale factors; another is fuzzy control based on optimization function. Both methods can achieve real-time adjustment of controller parameters accroding to the varity of inputs. Simulation results show that selftruning quantization scale factors control scheme has fast response speed, but fuzzy control based on optimization function has suppression ability to interference.Finally, for the nonlinear synchronous suspension system, designs two kinds of synchronous control schemes. One scheme is to adopt dual closed-loop feedforward controller as single-loop controller, adopt fuzzy controller as synchronous controller. Another scheme is to adopt fuzzy adaptive controller as single loop controller, adopt cross-coupling control as synchronous controller. Simulation results show that dual closed-loop feedforward fuzzy synchronous controller has strong suppression ability to interference, but fuzzy adaptive cross-coupling synchronous controller has fast response speed. Both schemes have good synchronization performance.In this paper, for the linear and nonlinear system designs different controllers, each controller can make the beam suspended stability, eliminates friction, and achieves high position accuracy and high synchronization accuracy to meet the high precision repuirement.