Research On Closed-loop Motor Speed Control System In OCT Endoscope Probe

Optical coherence tomography(OCT)is a new type of high-resolution,non-invasive,high-speed imaging method that plays an increasingly important role in medical imaging and clinical diagnosis.Among them,endoscopic circular OCT scanning uses motor-driven endoscopic probe for high-speed rotation and is suitable for imaging of human luminal organ tissues,such as gastrointestinal tract and blood vessels,and has high clinical value.In the image reconstruction of the circular scan,how to ensure the accuracy and stability of the motor speed has become a key issue in ensuring the imaging quality,and has important practical significance.Brushless DC Motor(BLDCM)is a new type of DC motor widely used,which improves many of the shortcomings of conventional brushed DC motors.In this paper,BLDCM is used to drive the rotation of the OCT endoscope probe,and a control system of the motor speed is designed to realize fast,accurate and small overshoot adjustment of the speed.This article first built a speed control software and hardware system.The system uses the MSP430F5529 microcontroller as the central processor,and realizes functions such as speed A/D conversion,Pulse-Width Modulation(PWM)output speed control,and host computer serial port communication.The host computer software was developed using Python based on the Windows system and implemented a graphical interface for setting,stopping,and feedback of rotation speed.In the control method,this paper compares the parameters adjustment and simulation of PID control and fuzzy adaptive PID control.This paper first analyzes and models the BLDCM structure,obtains the mathematical model of the motor,and determines its transfer function.Then based on the transfer function of the controlled object,the two control methods are simulated and compared.For ordinary PID control,this paper makes use of Matlab PID Tuner for parameter tuning and Matlab Simulink for simulation.For fuzzy self-adaptive PID control,this paper carries out fuzzy controller design,including fuzzy interface design,establishment of fuzzy rules table,and fuzzy The choice of decision method was then simulated using Matlab Simulink.The simulation results show that the Fuzzy-PID control method has the advantages of fast adjustment time and zero overshoot,and is in line with the control requirements of BLDCM in this system.This paper implements the Fuzzy-PID algorithm based on MSP430F5529 single-chip microcomputer.The algorithm uses C language for programming.The experimental results show that the system can achieve more accurate and rapid speed control of brushless DC motor.