Research On Control Method Of Magnetorheological Fluid Semi-active Boring Bar

With the continuous development of industry, high speed cutting technology is applied in all works such as machinery, material, biological medicine, aerospace, and Marine vessels. But there is easy to occur tremor phenomenon which has great influence on the workpiece machining accuracy for the limitations of length to diameter ratio of the boring bar arm in the deep hole processing. So combined with the national natural science fund project “Nonlinear dynamics and control of the semi-active dynamic damping boring bar”, this paper chose the method of optimal control of the semi-active boring bar based on the MRF through introducing MRF into the damping boring bar.The selection of control method for semi-active boring bar based on MRF, had a very strong influence on damping performance of the boring bar system.The mechanical model of MRF was established, according to the mechanism and characteristics of MRF, and the model was imported into the dynamic model of boring bar. The study showed that by the applications of MRF to boring bar vibration reduction it could realize stepless change of boring bar rigidity and damping and regulate the dynamic characteristics of boring bar system online real-time, which could reach the goal of vibration attenuation.Three control methods which were PID control, fuzzy control and furry-PID control were designed for the semi-active boring bar which was based on MRF. For PID control, the structure was designed, the parameters, such as the ratio of the coefficients, the integration time and the differential time, were determined. At the same time, the Simulink model of PID control was established in MATLAB, and the simulation was compared with passive control. A deep research on fuzzy control was carried out, and the control rules of different weighting factors were designed. The Simulink model of fuzzy control was established in MATLAB. Through the comparative analysis of the simulation results, selected an optimal one from three kinds of fuzzy control rules as the fuzzy control rules in the comparison of different control methods in this paper. The structure of fuzzy PID control was designed, the various initial parameters were selected, and the Simulink model was established in MATLAB.Finally, through the comparison of PID control, fuzzy control and fuzzy PID control, the optimal control method was taken out, which from the comparison of evaluation indices for the performance of three boring bars as displacement, velocity and acceleration, to prove the validity and feasibility of the proposed control method.