Methodological Study On Quantifying The 3D Activity Of Human Ankle With EMG Information

With the improvement of living standards,health problems have attracted the attention of people,especially the injuries of ankle.Surveys have shown that the incidence rate of ankle injuries is growing,and ranking second after lower limb injuries.However,the main reference index for evaluating its rehabilitation is the joint range of motion.At present,the researchers at home and abroad have done a lot of researches on the measurement of the joint range of motion and the design of rehabilitative robots.The overall expression of movements in the various directions and the detection of joint range of motion are ignored.In this paper,the quantification of ankle's 3D motion space with electromyography signal and the detection of the maximum rotation angle were realized by analyzing and processing the rotation angle of ankle and the surface electromyography signal.The specific contents of this article include these aspects:Firstly,in this study,the angle's information and surface electromyography signal were collected from 30 subjects during the measurement of ankle's joint range of motion.By extracting the time domain characteristic value of surface electromyography signal-integral electrical values and the frequency domain characteristic value-mean power frequency,the methods for detecting the state that the ankle had rotated to the maximum angle were obtained in time domain and frequency domain according to the rules that characteristic values changed with rotation angle.After testing,the accuracy of detection was about 80%.In order to improve the accuracy of detection,a nonlinear classification model based on support vector machine was established to identify the maximum rotation angle of ankle,and its accuracy was 93.8%.Secondly,by collecting the angle's information of ankle's maximum varus,maximum eversion,maximum intorsion,maximum extorsion at each dorsal flexure and plantar flexion rotation angle,the quantification of ankle's 3D motion space was realized by establishing a mathematical mode.The size and boundary curve of 3D motion space were obtained.Compared to the experimental group and the control group,there was a significant difference between the two groups(P<0.01).It indicates that the 3D motion space obtained by this method can be used as an index to evaluate ankle's flexibility and rehabilitation.At the same time,it provides more perfect data for the trajectory planning of ankle-rehabilitative instrument.Thirdly,in order to improve the accuracy of ankle's 3D motion space,the electromyography signal was integrated into the quantization of 3D motion space.The detection methods of joint range of motion based on surface electromyography signal were used to check the boundary points of 3D motion space,and the 3D motion space fused with electromyography signal was obtained by eliminating non boundary points.Then,it was compared with the 3D motion space obtained before the fusion of electromyography signal.This research provides more accurate data and overall indicators for the rehabilitation evaluation of ankle,and provides data support for the trajectory planning of rehabilitative robot,and provides a theoretical basis for the rehabilitation research of other joints.