Study On Accurate Positioning Technology Of Tool In The Noncircular Turning System

Supported by the project fund from Natural Science Foundation of Zhejiang Province—"Research on New Configuration of the Noncircular Turning System of High-frequency and High-precision"(No.Y107792) and Natural Science Foundation of Ningbo City—"Research on Application of Piezoelectric Materials in the Noncircular Turning System"(No.2008A610037), the research theme of this dissertation is the accurate positioning technology of tool in the noncircular turning system. Considering the research tasks and research status both in China and abroad, this dissertation adopts the approach of theoretical analysis, numerical calculation, computer simulation and experimental study, achieves the designs of overall program of the noncircular turning system and its special tool-post structure, tests the output characteristics and uses a Duhem model to establish the hysteresis model of the piezoelectric micro-displacement actuator, accomplishes the designs of controller based on fuzzy PID algorithm, establishes an accurate positioning system and carries out relevant experimental studies.In chapter one, the background and significance of the research are introduced, the development-trend and current research situation both in China and abroad of noncircular turning field are elaborated.In chapter two, the overall design of the noncircular turning system is proposed firstly with considering research status both in China and abroad, and then the instrumentations used in this project and their specifications are introduced.In chapter three, the characteristics, applications and the actuating principle of the piezoelectric micro-displacement actuator are introduced. After measureing and analying the static and dynamic output characteristics of force and displacement of the piezoelectric actuator, a nonlinear hysteresis model based on the Duhem model of the actuator is established.In chapter four, the parameters of flexible hinge structure and its special tool-post are calculated by theoretical calculation, and solid models are established with ProE Wildfire 3.0. And then the flexible hinge structure and its special tool-post are verified in this chapter with the finite element software.In chapter five, after solving the transfer function and control models of the accurate positioning system, the control algorithm is researched and the controllers of this system are designed and simulated by computer, including the PID controller, PID feed-back controller with the Duhem model as a feed forward segment, fuzzy PID controller, etc. In chapter six, the relevant experimental researches on the accurate positioning system with self-designed system are elaborated. Experimental results show that, the relative precision of output displacement is less than 5%, the experimental curve and the theoretical curve present a very good fitting, to achieve the precise positioning control of the tool in the noncircular turning system.In the last chapter, the study contents and conclusions of this dissertation have been summarized, and the further research works have been forecasted.