Research On Active Disturbance Rejection Control Of Wrist Tremor Suppression System Based On Functional Electrical Stimulation

Pathological tremor is more common in the elderly population,the pathogenesis is more complex,manifested as non-subjective conscious rhythmic movement of body parts,commonly seen in the wrist.Although it will not endanger the patient’s life,it will greatly affect their daily life.Because the conventional diagnosis and treatment methods have their own problems,the curative effect is not good,and it is difficult to meet the needs of patients.In this research,in order to provide patients with an effective tremor suppression scheme that can meet their needs,an auxiliary tremor suppression control system for wrist tremor suppression is designed based on functional electrical stimulation technology.In view of the complex physiological structure characteristics of the wrist musculoskeletal system,in order to ensure the effect of tremor suppression control,this thesis applies the active disturbance rejection control to design of the wrist tremor suppression system based on functional electrical stimulation to ensure that the system can effectively suppress the wrist tremor while outputting safer and more comfortable electrical stimulation pulse signals.The main research contents are as follows:(1)The Hammerstein model structure is used to model the radial side muscles and the radius of the wrist.According to the muscle stimulation characteristics in the actual experiment,the musculoskeletal model is simplified,and the parameter identification experiment is designed.Through verification,it is found that the model can better reflect the output response characteristics of the wrist musculoskeletal system under the condition of electrical stimulation.(2)Considering the modeling error of the wrist musculoskeletal system model and the uncertainty of the actual musculoskeletal system,this research applies the active disturbance rejection control to design of the wrist tremor suppression control system,and combines the model linearization control to estimate and eliminate the total disturbance of the system,including nonlinearity and modeling uncertainty as internal disturbance and tremor signal as external disturbance,so as to ensure the control accuracy of the system.(3)In this research,the influence of the measurement noise existing at the output port on the tremor suppression control system in the actual application process is considered,and an active disturbance rejection control scheme based on cascade control strategy is designed,and the effect of noise on the performance of the active disturbance rejection controller is analyzed from the perspective of frequency domain.Then,an improved control scheme is proposed.The model-assisted active disturbance rejection controller is used as the inner loop of the cascade structure,and an improved cascade active disturbance rejection controller is designed.(4)Numerical simulation and comparative analysis are carried out on the different controllers designed,and experimental verification is carried out with reference to the simulated data based on the built wrist tremor suppression system.The corresponding scheme of the human-induced tremor suppression experiment is formulated,and the comparative experiments of different controllers are set up.The experimental results show that the improved cascaded active disturbance rejection controller proposed in this thesis has higher tremor suppression ability and better control performance.