Application of Fuzzy Logic to Design of Functional Neuromuscular Stimulation Controller

• Main Authors: Wei-Cheng Liu, 劉威呈
• Other Authors: Ming-Shaung Ju
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/77621945205491128823

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 94 === Abstract The functional neuromuscular stimulation (FNS) is a major method in neural engineering for restoring the patients who lose the connection between central and peripheral nervous systems. IN FNS an implanted electrode, e.g. cuff electrode contacts with the peripheral nerve and the amplitude and pulse-width of the stimulus current is controlled by an electrical stimulator. Due to the time-varying characteristics of muscle recruitment and fast fatigue of artificially stimulated muscles, it is necessary to develop a method which can simultaneously control the amplitude and pulse-width of the stimulus and combined with feedback control algorithms to yield better FNS. The goal of this thesis is to develop a simplified amplitude/pulse-width modulation (SAWM) technique and combined with a PID and three fuzzy controls, namely, Fuzzy PD, Fuzzy PI, Fuzzy PD+I to the isometric ankle torque control of anesthetized rabbits. The rabbit’s ankle was fixed at natural and various positions in the range of motion and different control algorithms were employed to test the step response of the FNS system. Experimental results showed that: (1) Fuzzy PD has fast response, small overshoot percentage but high sensitivity to disturbance and large steady-state error (2) Fuzzy PD+I has fast response, small overshoot percentage and small steady-state error (3) Fuzzy PI has smallest steady-state error, smaller settling time, smoother control signal but large overshoot percentage. For the integrated time multiplied by absolute error (ITAE), the Fuzzy PI is superior to others. From the results, one may conclude that the SAWM technique is effective in preventing the fatigue of stimulated muscles. Fuzzy PI control is better than PID control and it is adaptive to the ankle position for isometric torque control on anesthetized rabbits.