| that the optimized design fully meet the requirements of non-cylindrical holes precision machining.In chapter 3, The linearized dynamic hysteresis model of EGMM is established respectively by theoretical and experimental based on the feature of non-cylindrical holes precision machining, it constituted pure time delay part and linearity aspects to solve the problem of hysteresis and nonlinearity. The open-loop control experiments showed that the inversed model can effectively overcome the hysteresis nonlinearity of EGMM.In chapter 3, the composite control strategy of closed-loop control is proposed to improve the accuracy of EGMM tracking displacements. It applied PID control hybrid with feed-forward compensation and repetitive control for AC and DC powers independently driven coils based on the hysteresis modeling of EGMM and open-loop control experiments. While, the currents control in the bias DC coil applied PI control hybrid with feed-forward compensation to realize the cutting path control on Z-direction. And the currents control in the AC coil applied PD control hybrid with PD control to realize the cutting path control on circumferential-direction. After PID parameters identification and the results of different control methods showed, the composite control strategy improved the tracking displacement accuracy of EGMM significantlyIn chapter 5, the control system hardware and software design based on working principles and EGMM structural. It’s constituted by the host computer PC and programmable real-time control system. And applied Digital Signital Processor (DSP, TMS320F2812) as real-time control system to control two linearity constant current amplifiers, which driven two excitation coils as AC and DC independently. Then, In order to improve the system accuracy and reliability, two eddy-current sensors orthogonal applied, then get the micro-displacement of EGMM as feedback signals in closed-loop control, and it’s proved by experiments.In chapter 6, the experimental platform for EGMM precision machining non-cylindrical holes is built up. Then, the static tested for EGMM including: the relation tests between output displacement, the pre-stress and the biased magnetic field. And the test for systematic frequency response characteristics. The dynamic experiments including: the inverted cone pin-hole in piston precision machining. the inverted cone pin-hole with oval cross-section in piston precision machining. The precision machining results showed, the quality of non-cylindrical holes are fully meet the desired technical indicators, including dimensional accuracy and surface roughness.In chapter 7, the main conclusions of this dissertation are summarized and the future research work is put forward.The non-cylindrical holes of a piston can remarkable increase its using time. Due to the particularity of non-cylindrical holes of a piston, and the problem appeared in non-cylindrical holes precision machining. In order to solve this problem, a new mechanism is proposed using Giant Magnetostrictive Material (GMM) embedded into the component, to realize the non-cylindrical holes precision machining. Some key technologies of Embedded Giant Magnetostrictive Mechanism (EGMM) are studied comprehensively and systematically, such as:The optimize method of EGMM in multi-field and coupled parameters (mechanical, electrical, magnetic and thermal). The structural of excitation coils drive by AC and DC powers independently. The dynamic hysteresis nonlinearity models of EGMM. The design of programmable and real-time control system. The control strategy of non-cylindrical holes precision machining by feed-forward compensation and repetitive control hybrid with PID control. The inference of the pre-stress and the biased magnetic field to the displacement of EGMM. The testing platform of EGMM to precision machining non-cylindrical holes is constructed.In chapter 1, the research background and significance of non-cylindrical holes precision machining by EGMM are stated. Such as:The present technologies of piston with non-cylindrical holes precision machining, the design methods of EGMM, the hysteresis nonlinearity models, the control strategy of micro-displacement tracking, et al. and then the main content of this dissertation and the project significance are proposed with the problems and shortages in the above researches.In chapter 2, based on the needs of non-cylindrical holes precision machining, the structural comparison of excitation coils and the structure of excitation coil driven by AC and DC powers independently is designed, and the multi-objective optimization model of EGMM integrated with electric, magnetic and mechanical parameters are proposed. Then, the multi-objective genetic glgorithm is applied to solve the multi-objective optimization equations of EGMM. The experimental results showed... |
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