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Journal of ZheJiang University (Engineering Science)  2021, Vol. 55 Issue (1): 89-95    DOI: 10.3785/j.issn.1008-973X.2021.01.011
    
Continuous kinematics prediction of lower limbs based on phase division
You-kang DUAN1,2(),Xiao-gang CHEN1,*(),Jian GUI3,Bin MA3,4,Shun-fen LI1,Zhi-tang SONG1
1. Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 200125, China
4. China Research Institute JIU YI, Shanghai 201200, China
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Abstract  

A method of establishing a prediction model for each gait phase was adopted in order to achieve more accurate prediction of continuous movement of lower limbs for specific individual movement characteristics and use a shorter time to train the prediction model. The prediction model of the current phase was used to predict the joint angle after identifying the current gait phase. Support vector machine (SVM) was used to verify the proposed method. The experimental results show that the prediction method of continuous motion of lower limbs based on phase division has higher prediction accuracy and shorter model training time than the prediction method of joint angle modeling of the entire motion state. The correlation coefficients between the predicted results of the hip, knee, and ankle joints and the true values are all greater than 0.99. The average root mean square error of the predicted angle values and the true values is less than 2° each time, and the training time is shortened by 4.0~5.0 times.



Key wordsphase division      motion intention recognition      joint angle prediction      exoskeleton robot      surface electromyography     
Received: 12 May 2020      Published: 05 January 2021
CLC:  V 445  
  TP 391  
Corresponding Authors: Xiao-gang CHEN     E-mail: dyk@mail.sim.ac.cn;chenxg@mail.sim.ac.cn
Cite this article:

You-kang DUAN,Xiao-gang CHEN,Jian GUI,Bin MA,Shun-fen LI,Zhi-tang SONG. Continuous kinematics prediction of lower limbs based on phase division. Journal of ZheJiang University (Engineering Science), 2021, 55(1): 89-95.

URL:

http://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2021.01.011     OR     http://www.zjujournals.com/eng/Y2021/V55/I1/89


基于相位划分的下肢连续运动预测

为了实现针对特定个体的运动特点进行更精确的下肢连续运动预测和用更短的时间开展预测模型训练,采用对每个步态相位都建立预测模型的方法. 在识别出当前的步态相位后,使用当前相位的预测模型进行关节角度的预测. 使用支持向量机(SVM),对提出的方法进行验证. 实验表明,采用基于相位划分的下肢连续运动预测方法相比于对整个运动状态进行关节角度建模的预测方法,具有更高的预测精度和更短的模型训练时间. 髋、膝、踝关节的预测结果与真实值的相关系数均大于0.99,每次预测的角度与真实值的平均均方根误差均小于2°,训练时间缩短4.0~5.0倍.


关键词: 相位划分,  运动意图识别,  关节角度预测,  外骨骼机器人,  表面肌电信号 
Fig.1 Division of several gait periods
Fig.2 Flow chart of lower limb continuous motion prediction algorithm based on phase division
Fig.3 Electromyographic signals of several motion states of medial gastrocnemius muscle
Fig.4 Uphill and jogging experiments
Fig.5 Gait phase recognition
Fig.6 Joint angle prediction of 6 km/h jogging state using whole data to training prediction model
Fig.7 Prediction of joint angle based on phase division at 6 km/h jogging state
方法 C $ \overline R $
本文方法 0.99
文献[7]方法 0.93 5.83°
文献[10]方法 0.92 6.87°
文献[17]方法 0.96 2.37°
Tab.1 Comparison of prediction accuracy between this method and other methods
Ntr $t/{\rm{s}}$ $T/{\rm{s}}$ A
500 0.1323 0.0358 3.70
1000 0.4130 0.0835 4.95
1500 0.8443 0.1587 5.32
2000 1.2419 0.2762 4.50
2500 2.1432 0.4579 4.68
3000 2.8276 0.6230 4.54
3500 3.6642 0.8696 4.21
4000 4.8305 1.1120 4.34
Tab.2 Comparison of training time between two algorithms
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