| The movement of the upper limbs of the human body is the result of the interaction of multiple muscles under the control of the central nervous system(CNS),which is manifested as the phenomenon of mutual coupling between the movement-related muscles.The electromyography(EMG)generated in this process contains a wealth of motion control information.By studying the coupling relationship between multi-channel EMG,it is possible to explore the control mechanism of the CNS and the coordination and cooperation of motor muscles.Firstly,the generation mechanism and application of several common physiological electrical signals are analyzed,and surface electromyography(s EMG)is selected as the basic research method based on the research content and characteristics of this paper.In this paper,the research and application status of s EMG based intermuscular coupling are reviewed.Considering the limitations of existing intermuscular coupling analysis methods,and using signal processing methods such as granger causality analysis and consistency analysis to establish a multi-channel EMG signal directivity and nonlinear coupling analysis model.Secondly,in view of the causal coupling characteristics of information interaction between multiple muscles,this paper designs a reasonable wrist flexion and extension continuous exercise test,collects s EMG related to wrist movement of healthy subjects,and further designs the corresponding s EMG preprocessing method;the latter s EMG uses a multivariate causal analysis method--partial directional coherence(PDC)to analyze the causal coupling between multiple muscles;combined with the results of the time domain analysis,6 pairs of muscle pairs with strong correlation with wrist flexion and extension were selected.The experimental results show that this method can effectively analyze the causal information transmission relationship among multi-channel EMG signals.Thirdly,in view of the directional coupling characteristics of the information interaction between muscles,and in order to further explore the directional information transmission between wrist muscle groups and its time-frequency variation,a time varying PDC analysis(TV-PDC)method is proposed.The multi-channel EMG signal is synchronously windowed on the time-domain scale and short-time fourier transform(STFT)is used.The PDC analysis method is used to study the s EMG characteristics under continuous wrist flexion and extension movements,so as to realize information exchange analysis between muscles in different time-frequency scales.The analysis results show that this method can describe the changes of the directional coupling characteristics between muscles over time.Fourthly,in view of the non-linear coupling characteristics of the information interaction between muscles,based on the consistency analysis theory,a time-varying N:M coherence analysis method(TV-NMC)is proposed and applied to s EMG analysis of muscle pairs related to wrist flexion and extension.Firstly,the nonlinear coupling characteristics of different muscle pairs at different frequency ratios are compared and analyzed.Secondly,the time domain s EMG is windowed,and the NMC is calculated after STFT to realize the nonlinear information interaction analysis between two signals at different time-frequency scales.The results show that this method can effectively describe the time-varying relationship of nonlinear coupling characteristics of muscles under different frequency ratios.Finally,the multi-channel intermuscular coupling characteristic analysis method is applied to the EMG signals of wrist flexion and extension in stroke patients,and the results are compared with those of healthy subjects.The results show that the strength of intermuscular coupling of stroke patients is significantly lower than that of healthy people,and there are different degrees of lack of coupling.The analysis results describe the motor function state of patients from different angles,and then explore the control mechanism of motor disorders in stroke patients at the theoretical level,which further illustrates the effectiveness of the multi-channel intermuscular coupling method proposed in this paper.It can provide reference value for the evaluation of the patient's rehabilitation function status. |
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