Journal of Bionic Engineering (2023) 20:119–135  https://doi.org/10.1007/s42235-022-00267-0 

Hybrid Active-Passive Prosthetic Knee: A Gait Kinematics and Muscle Activity Comparison with Mechanical and Microprocessor-Controlled Passive Prostheses 

Xiaoming Wang1,2,3,4 · Qiaoling Meng1,3,4 · Shaoping Bai2  · Qingyun Meng5  · Hongliu Yu1,3,4

1 Institute of Rehabilitation Engineering and Technology, University of Shanghai for Science and Technology, Shanghai 200093, China
2 Department of Materials and Production, Aalborg University, 9220 Aalborg, Denmark
3 Shanghai Engineering Research Center of Assistive Devices Institute of Rehabilitation Engineering and Technology, Shanghai 200093, China
4 Key Laboratory of Neural-Functional Information and Rehabilitation Engineering of the Ministry of Civil Afairs, Shanghai 200093, China
5 Shanghai University of Medicine and Health Sciences, Shanghai 201318, China 

Abstract  Existing microprocessor-controlled passive prosthetic knees (PaPKs) and active prosthetic knees (AcPKs) cannot truly simulate the muscle activity characteristics of the active–passive hybrid action of the knee during the normal gait. Diferences in EMG between normal and diferent prosthetic gait for diferent phases were never separately analyzed. In this study, a novel hybrid active–passive prosthetic knee (HAPK) is proposed and if and how muscle activity and kinematics changes in diferent prosthetic gait are analyzed. The hybrid hydraulic-motor actuator is adopted to fully integrate the advantages of hydraulic compliance damping and motor efciency, and the hierarchical control strategy is adopted to realize the adaptive predictive control of the HAPK. The kinematic data and EMG data of normal gait and diferent prosthetic gait were compared by experiments, so as to analyze the changes in the muscle activity and spatio-temporal data per phase compared to normal walking and the adaptations of amputees when walking with a diferent kind of prosthesis (the mechanical prosthesis (MePK), the PaPK and the HAPK). The results show that changes in prosthetic gait mainly consisted of decreased self-selected walking speed, gait symmetry and maximum knee fexion, increased frst double support phase duration, muscle activation in both opposed and prosthetic limb and inter-subject variability. The diferences between controls and MePK, PaPK and HAPK decreases sequentially. These results indicate that the hybrid active–passive actuating mode can have positive efects on improving the approximation of healthy gait characteristics. 

Keyword  Bionic prosthetic knee · Hybrid active–passive actuator · EMG · Muscle activity · Gait kinematics

ig. 1 Knee angle and power during a typical gait cycle when walking on level ground