Dual Linear Motors Cross-Coupling Synchronized Control In Gantry-moving Type Milling Machine Tool

Based on the National Natural Science Foundation project named "Theory of Dynamic Precision Synchronization Traverse and Research of Realization Methods for Linear Servo Dual Position Loops System(No.50075057)" and the Liaoning Province Natural Science Foundation project named "Research of Dual Linear Motors Synchronous Control in large gantry-moving type milling machine tool(20052045)",for high precision of gantry-moving type milling machine,dual linear motors servo system has been researched to acquire better cross-coupling synchronized control method.The thesis presents three methods,and has compared them.In the strategy of robust synchronization control for dual linear motors based on QFT (Qualitative Feedback Theory),for the control problem of the synchronized feed of dual linear motors in gantry-moving type milling machine tool,a compound control strategy combing cross-coupling controller with QFT robust controller was presented to implement the synchronized feed of dual linear motors in gantry-moving type milling machine tool. The matched degree between the two synchronized axes was increased by cross-coupling controller,so as to reduce the position synchronization errors.QFT robust controller was served as the speed controller to reduce the influence on the synchronization precision, which was caused by the uncertainties,such as the parametric variations of linear motor and the other disturbances.In the strategy of second order sliding mode cross coupling control for dual linear motors based on QFT,it was suggested that QFT robust controller was associate with a second order sliding mode cross-coupling synchronized controller which can reduce the influence on the synchronization precision that was caused by the uncertainties,such as the machine coupling on the fan-out of the double velocity loops,the parametric variations of linear motor and the external disturbances.The super-twisting algorithm,which can remove the twitter phenomenon of the variable structure whose relative degree is one,was adopted by the control of the second order sliding mode variable structure.In the strategy of second order sliding mode cross coupling control for dual linear motors based on PDFF,a Pseudo-Derivative Control with Feedforward Gain(PDFF) control was applied to the speed controller design of subsystem,which greatly improved the capability of the anti-jamming and the speed of response.At the same time,a second order sliding mode cross-coupling synchronized controller was presented.The three simulation results show that the proposed control schemes are robust greatly and may achieve the position dynamic synchronization under the condition of asymmetry load.