Study On The Active Control Of Bearing Spindle Locus By Action Of Electric Magnetization

Non-circular shaped structure of parts can remarkable increase its performance and useful life. Due to the particularity of non-circular shaped cross-section, the problems for machining such parts appear. Addressing the locus active control of bearing under the action of electric magnetization, an active spindle locus control has been studied in order to provide a new solution for it. On the synthetically analysis of conventional and latest development of noncircular machining approaches and various servo drive, the idea which is expected to be used for non-circular machining is proposed, that based on rotor locus control of journal bearing system using controllable electromagnetic force. The method is that the oil film force is taken as the main supporting force and the electromagnetic force taken as controlling force, by adjusting the field current the acting force between electromagnet and rotor can be modulated, thereby the rotor locus can be controlled.The elementary theoretical research for journal bearing system is carried out, and the motion model and dynamic model of the shaft are constructed. On that basis the Reynolds equation of oil film pressure distribution equation and oil film thickness expression for shaft under Euler rotation are developed. The oil film force distribution is solved in difference method and oil film moment is calculated in Simpson integral method. The expression of electromagnetic torque is developed and the rotor locus is carried out in kinematical method. The disturbed Reynolds equation for bearing of local linearization is established, and the eight characterization factors of bearing system are theoretically computed, then the influence of rotating speed and field current to these factors is investigated, last the non-dimensional dynamic model of the controlled plant is created and analysis of the control scheme.The robust Hoo control strategy for the locus control of the shaft is studied, the controlled plant is observable and controllable, and so it can be decoupled by states feedback. Based on global optimal genetic algorithm the robust Hoo mixed sensitivity controller is studied, its controlled outputs can track the reference signals precisely and it also can inhibit external perturbation at the same time, but owing to decoupling matrix is sensitive to model perturbation the controller can only apply to model with no or small perturbation. Based on robust H∞loop shaping technology the controller is designed directly to the coupled system, it is a input-output decoupling controller, its order is reduced for easier of implementation, this controller has a good performance both on disturbance attenuation and perturbation suppression, it presents strong robust performance and robust stability.The rotor locus control experiment of the system is stydied, the hardware in loop simulation based on xPC Target technique is proposed. The experiment is partly carried out, such as construction of the xPC Target platform, communication test between host PC and target PC, I/O board for analogue input and output test, calibration of the capacitive displacement transducer and so on. Due to time constraints and laboratory conditions, the hardware in loop simulation experiment of the rotor locus control is not completed.