Research On Position Servo Control System For Voice Coil Motor

Voice coil motor is a kind of DC motor based on the Lorentz force principle, it has good static and dynamic performance and control characteristics. As it can obtain rectilinear motion without any revolving gear, there is no transmission machinery wear. Therefore it can achieve precise position servomechanism, especially in occasions of the precision machining of short stroke high-frequency reciprocating linear motion it has broad application prospects.To the applications of voice coil motor position servomechanism, this thesis makes a major study of voice coil motor control system's development, mathematical model, simulation study, actual system structure and related test as well as test data analysis.Initially this article describes the basic structure and working principle of voice coil motor. Based on this it sets up a mathematical model of the motor, reveals the transfer function relationship, and makes an analysis on the dynamic characteristics and optimal control parameters.Then based on the mathematical model of voice coil motor the thesis makes a study on control strategies of the voice coil motor, and creates a simulation model of voice coil motor position servomechanism. According to the characteristics of servomechanism, it creates a triple closed-loop control system including the position and current closed-loop. The current loop is implemented by hardware circuitry, in order to achieve the rapid follow of the system current. The position loop is completed by the DSP2808. The position feedback is achieved by linear scales. The position loop is completed by position feed forward control and position feedback PID control, in order to compensate for the dynamic lag and improve the response speed of the system.According to the work done above, the software and hardware of the voice coil motor position servomechanism are designed. Hardware system mainly designs the power driving circuit of the system, DSP, its peripheral circuits, electric level matching circuit and interface circuit. Software design includes the design of the main program, the interrupt program, the program of the motor's auto zero, the control algorithm program and filtering program.