Capacitive Sensing Based Knee-Angle Continuous Estimation by BP Neural Networks

  • Dongfang Xu
  • Qining WangEmail author
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11740)


In this paper, we propose a capacitive sensing based method for knee joint angle continuous estimation. The motion capture system is used to record the position information of knee joint and output knee joint angel as a fitting target. Two capacitance rings are fixed on the thigh and shank to record the relaxation and contraction of muscles. Three healthy subjects participate in the study. Based on BP (back propagation) neural networks, the map relationships (i.e. model) between capacitance signals and knee joint angles are built. In the continuous estimation of angle, capacitance signals are fed into the model, and then we can get the estimated angles. The error (root mean square) and the cross-correlation coefficient are 4.4\(^\circ \) and 97.01% between the estimated knee joint angles (based on capacitance signals) and actual keen knee-angle. The results show that capacitive sensing method is effective and feasible to estimate the joint angles.


Capacitive sensing Knee joint angle Continuous estimation BP neural networks 



This work was supported by the National Key R&D Program of China (No. 2018YFB1307302, 2018YFF0300606), the National Natural Science Foundation of China (No. 91648207, 61533001), the Beijing Nova Program (No. Z141101001814001) and the Beijing Municipal Science and Technology Project (No. Z181100009218007).


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Authors and Affiliations

  1. 1.The Robotics Research Group, College of EngineeringPeking UniversityBeijingChina
  2. 2.Beijing Innovation Center for Engineering Science and Advanced Technology (BIC-ESAT)Peking UniversityBeijingChina
  3. 3.Beijing Engineering Research Center of Intelligent Rehabilitation EngineeringBeijingChina

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