Research On Intelligent Control Techniques Of Parallel Machine Tools

Parallel Machine Tools (PMTs) ,also know as Virtual Axis Machine Tools ( VAMTs) ,are a new kinds of machine tools which came into being since 1990's. These kinds of machine tools are the product of the combination of machine tools technology and robot technology. PMTs have following advantages: very good stiffness weight ratio, large feed speed, high machine precision, simple mechanical structure etc. compared with the traditional machine tools. These characteristics make PMTs have very vast applications.Intelligent control techniques such as: the control based on neural network (NN) , fuzzy control etc. are used widely in the control of machine tool, robot, instrument. Error compensation control based on NN, parallel calculation and parallel control technology based on DSP, fuzzy control strategy are studied systematically in this thesis. The thesis includes the following five aspects: a) introduce characteristics, application and development summary of parallel machine tool and intelligent control, b) introduce of fundamental knowledge, c) the research of error compensation control, d) the research of parallel calculation and parallel control, e) the research of fuzzy control.According to the characteristics of PMTs, such as: very good stiffness to weight ratios, large feed speed, high position accuracy, simple mechanicalstructure etc. a real time error compensation control scheme which is based on BP neural network is proposed. The inverse kinematic problems for the PMT are trained, and then error compensation problem of PMT is solved by using this trained neural network. Finally, a simulation example for error compensation of a 3-coordinate PMT is given for illustration. The results of simulation show that the control strategy is very efficient, and the position error for PMT can be reduced greatly after compensation.A strategy of parallel calculation and parallel control for trajectory planning of Parallel Machine Tools is proposed based on multiple TMS320F206 DSP chips. Inverse kinematic analysis for PMTs is investigated. The flow charts for parallel calculation and parallel control are given. A simulation example of a 3-coordinate PMT is presented for illustration. The results show that the technique is advanced and is of benefit to real-time control for PMTs.A effective fuzzy control strategy for Parallel Machine Tools is presented,which is independent of precise mathematical model is of practical meanings. A method of fuzzy rules for the controller is described according to the linguistic information. Compared with the traditional PID control method, the proposed fuzzy logic controller yields salient controlling characteristics and strong robustness.