Design Of High Precision Distributed Double Closed Loop System For Stepping Motor

Stepper motor is widely used in industrial production and automation control because of its simple control mode,accurate positioning without cumulative error,and high cost performance ratio.The traditional stepper motor is often controlled by openloop control,and the operation effect depends largely on the design structure of the motor itself.With the continuous improvement of the requirements for the response stability and operation accuracy of the controlled equipment,and the continuous improvement of the equipment complexity,it is often necessary to control multiple motors independently or jointly under actual working conditions,and with the continuous improvement of the operation and processing ability of the new microprocessor.The stacked control chip is often used in multi-motor control,which increases the equipment cost and wastes the chip performance.Therefore,the design of control system to achieve accurate and stable distributed control of multi-motor has practical engineering theoretical significance and practical value.In view of the above problems,this thesis conducts the following research :(1)A double closed-loop vector control system is designed to realize the high precision demand of the motor.For the two-phase hybrid stepper motor,the vector pulse width modulation method is designed based on the double H-bridge inverter.The fuzzy sliding mode controller is used in the closed-loop speed outer loop.The fuzzy sliding mode control(FSMC)is suitable for the control of the nonlinear stepper motor system under uncertain conditions.The key control parameters of the sliding mode are adjusted in real time by the system state fuzzy control to improve the speed and control quality of the sliding mode control.The integral sliding surface is used to improve the initial state position of the system.In order to optimize the sliding mode approaching speed and weaken the chattering of the sliding mode process.The exponential reaching law with the constant velocity term is designed and the saturation function is replaced by the traditional switching function.The controlled system under the fuzzy sliding mode controller has good accuracy,rapidity and robustness.(2)For the relatively unstable start-stop section of the motor,the direct start-stop motor may have the problem of out-of-step overshoot and overshoot.The open-loop variable speed curve control for the start-stop section of the motor can ensure the smooth start of the motor and reduce the stop shock to improve the motion stability and dynamic performance.Compared with different types of variable speed curves and implementation methods,the design of sine S acceleration and deceleration curve can complete the control requirements.(3)For the realization of motor distributed control,MCU + FPGA is selected as the controller structure,which meets the multi-motor control and has good expansibility.The control execution chain from the host computer,MCU,FPGA to the drive motor is determined.The control chain is combined with the communication mode of CAN +FSMC bus.The control rules are determined according to the definition of communication data according to the transmission protocol.The upper computer interface is built based on Labview to realize distributed control.(4)In order to ensure the feasibility and practicability of the designed control system,a double closed-loop vector control model based on fuzzy sliding mode is built for simulation and comparison test.The simulation results verify the superiority of the control model in the dynamic and steady state performance.The hardware circuit is designed and the hardware experimental platform is built to complete the practical test under different working conditions.The experimental results prove the efficiency of the distributed control strategy.The control system has good anti-disturbance and selfrecovery ability.The actual motion effect of the stepper motor meets the requirements of stability and high precision.The overall design achieves the expected effect.