Research On Functional Electrical Stimulation System For Suppressing Pathological Tremor Of Upper Limb

Pathological tremor is a common disease in the elderly, often associated with Parkinson, stroke and other diseases. Part of the patient’s body such as limbs and legs can produce rhythmic shaking involuntarily. Conventional treatments such as surgery and drugs have a high cost, side effects and other shortcomings, so the study of a new tremor suppressing approach has great practical significance. In this paper, Functional Electrical Stimulation(FES) system is studied theoretically to suppress the tremor, and finally the feasibility of FES tremor suppressing system is verified by experiments.Firstly, the feedback signal of the tremor suppressing system is analyzed, and a bandlimited linear combiner algorithm based on CPG(BLC-CPG) is proposed to separate the elbow angle. BLC-CPG algorithm is with minimal phase delay, which solve the timeliness requirement of the feedback signal that required by control system. Besides, BLC-CPG algorithm has high accuracy of fitting, and the high and low frequency of signal separated by BLC-CPG algorithm have low coupling, which meet the accuracy requirements of the feedback signal. Compared with other algorithm, the BLC-CPG algorithm shows its great superiority, and finally real-measured signal is employed to test the feasibility of BLC-CPG algorithm.The control system of FES tremor suppressing system is designed. Improved single neuron adaptive PID is employed as the controller. Weighted quadratic objective function learning rule is proposed to improve the control algorithm, and the simulation results show the effect of improvement. An immune regulator based on the body’s immune system is employed to adjust the overall gain K of control system, which improves the dynamic characteristics of the control system. A co-simulation platform with Open Sim and Simulink is built to simulate and verify the control system. The control system is compared with other control algorithm to verify its advantageous effects.The stimulator of FES system is designed. Firstly, the parameters of FES are analyzed, and the design target is determined. Then, the structure of stimulator is designed from the point of view of hardware, including the constant current output part, the control part and the power supply part. And from the point of view of software, the software architecture and process are determined, and the FES Instruction Set which is for communication of host PC and stimulator is designed. Finally, the stimulator is made into practicality and the output of stimulator is measured to verify the performance of the stimulator.Finally, the synthetic experiment of FES tremor suppression is conducted. First, the platform of experiment is built. The signal acquisition system of MYO band is built, and the human upper limb coordinate system is established, so the angle of elbow joint can be obtained by mathematical transformation. Tremor Suppression Rate(Rst) and Fluctuation of Tremor(Dflu) are proposed to evaluate the effect of FES tremor suppression system. The whole experiment are in two perspectives of open-loop and closed-loop. Three parts of experiment are conducted respectively, including static tremor suppressing experiment, eating with a spoon tremor suppressing experiment and wearing glasses tremor suppressing experiment. Finally, the data from experiment is analyzed, and the conclusions of FES tremor suppression system are drawn.