Design Of Control System For Eating Tableware For Patients With Hand Tremor

Parkinson's disease and essential tremor are very common dyskinesias.Tremor of hands is the common symptom of both diseases,with a particular frequency which is usually between 3.5-7.5Hz.According to statistics,the probability of suffering from PD in the elderly over 65 years old in China is 1.7%.At present,there are more than 3 million parkinsonian patients in China.The oscillatory movement of hands makes it extremely hard for patients with PD or ET to complete daily activities such as eating,which increases manpower and economic burden of society.Therefore,smart medical auxiliary equipment developed for patients with hand tremor are increasingly accepted by patients and their families.As a result,the thesis provided an in-depth analysis of the dynamic model of some smart anti-shake spoon,taking the spoon as the research object.Focusing on the compensation method of the backlash nonlinearity,the unconventional double closed-loop control system is designed with anti-shake control as the core purpose.In order to output low speed and high torque,the micro-DC motor with gearbox is chosen as actuator of the spoon.The dead zone model is chosen as the backlash nonlinear model,and the dynamic model of the spoon is established using inertia method in this thesis.Then the state space equation of the spoon system is established as well.According to the need that the head of the spoon and food on it are supposed to be relatively static under the circumstances of continuous hand-shake interference and constant load change,an special algorithm for controlling the acceleration of the outer loop and the position of the inner loop is proposed.The control output of inner loop is derived using backstepping method for the compensation of the nonlinearity of backlash and immediate response to the position tracking.Based on simulation tests,the backstepping control algorithm compared with conventional PI control algorithm is proved to have better performance: faster response,higher position tracking accuracy and more stable transmission torque.Adaptive fuzzy PI control algorithm is adopted for the outer loop to achieve anti-shake control.In accord to the simulation results,the algorithm designed in this thesis can offset 86% dithering of the spoon head and performed well.At the end of the thesis,the design control algorithm is implemented on the embedded software of the anti-shake spoon prototype.The vibration table is used to simulate the hand tremor.Control parameters are constantly debugged through lots of experiments.Finally,the spoon prototype achieved good anti-shake performance with the offset of 75% of the tremor.