Study On The Intermuscular Coupling Characteristics In The Coordinated Motion Of Upper Limb

Human motor control system is highly complex and non-linear.The coordinated movement of upper limbs,as a necessary condition for self-living principle in daily life,is the result of coordinated contraction and interaction between the muscles related to movement controlled by the central nervous system.Electromyography(EMG)signal generated during exercise represents the response information of the motor control system.The relationship between different muscles reflects in the intermuscular coupling interaction,which reflects the control and domination information of the nervous system to the motor muscle.The intermuscular coupling strength reflects the activation and coordination of the muscles,and then evaluates the function of the motor control system.Therefore,the characteristics of intermuscular coupling and its changing regularity are the hot issues to explore the mechanism of the coordination and integration of the muscle and neural motor system.Firstly,this paper elaborated generation mechanism and characteristics of EMG signal,and summarized the research status and application progress of intermuscular coupling analysis algorithms.Considering the characteristics of the intermuscular coupling relationship and the deficiencies of the existing analysis methods,which can't synchronize multiscale decomposition and can not describe the nonlinear coupling relationship between muscles,the main research contents of this paper was proposed.From the point of multiscale and non-linear characteristics of EMG signal,the analysis method of intermuscular coupling characteristics was improved and expanded based on the traditional coherence analysis.Secondly,aiming at the frequency band characteristics of the intermuscular coupling relationship and the traditional coherence analysis can not describe the multiscale characteristics of EMG signal,a multiscale synchronous decomposition model of the intermuscular coupling analysis based on multivariate empirical mode decomposition-coherence was constructed.The multichannel EMG signals were decomposed synchronously to obtain the characteristic frequency band information of thesame scale and frequency,and the coherence of the characteristic frequency band was divided.This method was applied to analyze the intermuscular coupling characteristics of healthy subjects under different static grip forces of upper limbs.The results showed that this method can provide a new idea for the study on multiscale characteristics of intermuscular coupling.Thirdly,aiming at the nonlinear characteristics of the motion control system reflects in the intermuscular coupling,the intermuscular cross-frequency coupling analysis model based on wavelet packet-n:m coherence was constructed.The information of the EMG signal at different frequency points was obtained,and the nonlinear coupling relationship between muscles was described by the n:m cross-frequency coherence analysis of the characteristic signal at different frequency ratios.This method was applied to elbow flexion and extension with constant grip force of healthy subjects.The results showed that the method can quantitatively describe the cross-frequency nonlinear coupling characteristics of EMG signals under specific motor.Finally,the coupling analysis method proposed in this paper was applied to the study of intermuscular coupling analysis in the process of upper limb coordinated motion of stroke patients,and the differences of intermuscular coupling between stroke patients and healthy subjects are compared and analyzed.The results showed that there was a certain degree of lack of intermuscular coupling in stroke patients.The research results quantitatively analyzed the motor function of patients from the angle of intermuscular coupling,which had theoretical basis and reference for the formulation of rehabilitation training strategies for patients,and at the same time verified the effectiveness of the research methods in this paper.