Research Of Control System For Portable Biofeedback Electrical Stimulator

Motor dysfunction is caused by the injury of the nervous system or muscle tissue,which makes the body unable to control itself to achieve the desired action according to its own will.The main causes of motor dysfunction include sequelae caused by diseases such as stroke and functional impairment caused by accidents such as traffic accidents.With the development of aging population and social urbanization,the number of patients with motor dysfunction is increasing year by year.It is of practical social significance and application value to carry out research on rehabilitation training for patients with motor dysfunction.Biofeedback electrical stimulation equipment is an important medical instrument for rehabilitation training of motor dysfunction.By comparing the advantages and disadvantages of the existing equipment working mode,the control system adopts the working mode combining EMG feedback,manual selection and machine automatic selection to carry out exploratory research.The latest standard YY0505-2012 stipulates that all active medical devices need to pass the EMC test,while most existing products in the market fail to pass the EMC test.The development of the control system should consider electromagnetic compatibility to meet the technical requirements of the new standard.The hardware of control system takes STM32F103RCT6 MCU of STMicroelectronics as the main control chip.The design of man-machine interaction interface is based on the 7-inch serial touch screen of DWIN Technology Co.,Ltd.The surface electromyography signals of human body are collected by the surface electrodes.The pre-amplifier circuit is realized by operational amplifier OPA2604 and instrument amplifier AD8221.The filtering circuit is implemented by AD8625 with four internal operational amplifiers.The analog-to-digital conversion circuit is realized by 14-bit special chip called LTC1417.The technology of floating power supply,shield driving and right leg driving is introduced to reduce the common mode interference.Driving signal of low frequency current stimulation pulse is generated by in-chip DAC and PWM modulation.According to the stimulation parameters set by the user and the intensity of the collected surface EMG signal,the output intensity of the stimulation pulse is controlled by the algorithm.The system uses sensors to detect the patient's temperature and pulse,increasing the safety of rehabilitation training.The software of control system is written based on C language,and the embedded real-time operating system called ?C/OS-II is transplanted to STM32 processor by Keil IDE.The man-machine interaction interface is based on DGUS development system,designed by using DGUS Tool 7.383.After the test of hardware,software and the whole machine,control system has basically accomplished the design objectives,which realizes the acquisition feedback of surface EMG signal and the output of low-frequency current pulse with setting parameters.Through the EMC test,control system has been verified to be safe and reliable.The design of man-machine interaction interface is beautiful and easy to use.This design provides reference for follow-up study of similar products.