Research And Design Of An Adaptive Lower Limb Rehabilitation Trainer Based On BLDC Closed-loop Control

With the rapid development of today’s social economy,modern medical technology is also progressing.At the same time,the problem of aging population is aggravating,the incidence of the elderly is also rising,and stroke as one of the most common neurological diseases,once suffering from about 70% of the sequelae,and to overcome these sequelae need a certain means of rehabilitation,so how to do a good job of rehabilitation after the disease is the top priority.In the past,doctors tended to watch over patients all the time,which not only consumed a lot of manpower and material resources,but also made the recovery effect very slow.At home and abroad,most of the designs are leg rehabilitation trainers,and the control mode of the trainer is too simple,the power and resistance size can not be changed once set.In this paper,a lower limb rehabilitation trainer that can support unilateral rehabilitation training is designed for patients with hemiplegic stroke.On the premise of introducing adaptive control strategy,the mechanical structure of the rehabilitation trainer is designed,and the hardware and software of the rehabilitation trainer are designed.The research content of this paper includes the following aspects:First of all,understand human dynamics,kinematics and certain rehabilitation concepts.The internal structure and operating principle of brushless DC motor(BLDC),the core component of the control system,are studied and its mathematical model is established.In the control system,because the traditional PID parameters can not be changed once set,the lack of interaction in man-machine interaction,it is not easy to promote the rehabilitation effect.In this paper,an adaptive fuzzy PID and fuzzy variable impedance double closed-loop control system based on BLDC is designed,and active and passive control strategy is added to the lower limb rehabilitation trainer.Use Z55 D BLDC as the core to develop the hardware and software of the system.Draw the hardware full bridge circuit,drive circuit,Hall position detection circuit,sampling circuit and other schematic diagrams in Altium Designer and carry out PCB proofing.At the software end,STM32F103VET6 is the main control chip,and Keil5 is used to design the main program,interrupt program,double closed-loop program and debug the software and hardware.Using unity3 D as the upper computer increased the interest of rehabilitation training.After software and hardware debugging,the lower limb rehabilitation trainer platform was built through unity3 D upper computer,oscilloscope,24 V DC power supply,etc,and the MOS gate source voltage signal,PWM signal and Hall signal waveform were carried out.The speed following performance of adaptive fuzzy PID and traditional PID is tested in passive training,and the adaptive variable resistance performance of the control system with adaptive fuzzy variable impedance control is tested in active training.The results show that the adaptive fuzzy PID overshoot control is about 2%,the error control is about 3%,the adaptive fuzzy variable impedance pressure error is about 2%.The actual waveform of PWM,Hall signal,speed following effect and so on are basically consistent with the simulation waveform.