Xiufeng Zhang

A novel prosthetic knee joint with a parallel spring and damping mechanism

Prosthetic knee joint (PKJ) is an important apparatus for trans-femoral amputees to regain walking ability. This study has two objectives: (1) to design a high performance and low-cost passive PKJ and (2) to evaluate the performance of the PKJ. In the proposed PKJ design, a four-bar linkage was employed as the mechanical structure, and parallel spring and damper were used as the two connecting rods of the four-bar linkage. With the parallel spring, the length of the connecting rod is variable and a buffer flexion angle can be generated, which was consistent with that of the human knee joint. The damper was used to regulate the swing speed of the shank. Through theoretical analysis, modeling, and simulation, key parameters of the mechanical structure were optimized. Finally, experimental studies were conducted to test the performance of the PKJ, including fatigue test and gait analysis. The results showed that the designed PKJ is reliable and the gait of PKJ is close to the healthy subject. Moreover, it is comfortable and showed no adverse effects on the amputee during the walking experiment.

Design of a novel bionic prosthetic knee joint

Purpose This paper aims to find a new method that could be applied to the high and mid-grade prosthesis knee joint. Design/methodology/approach Based on analysis, calculation, modeling, simulation and experimental study of the motion law of knee joint, this paper not only determines the structure and parameters of the knee joint and calculates the instantaneous center but also analyzes the stance stability and completes the optimization. With the help of experimental tests (fatigue test and gait curve test), the quality and performance of the designed knee joint is verified. Findings The experimental results show that the gait curve of the designed knee joint is much closer to health people. The designed prosthesis knee joint, with adjustable swing speed and gait curve which are close to health limb, has a better performance when compared to the ordinary knee joint with four-bar linkage structure. Originality/value This paper developed a prosthesis knee joint based on a novel design method that could be applied to the “high and mid” grade prosthesis knee joint and verified its function on an amputee performed the lower amputation, which could provide theoretical support for researches and designs related to prosthesis knee joint in future.

Optimizing strap designs of upper limb prostheses

The precise positioning design of upper limb prostheses is important for patients with upper limb disability. In this study, we propose an upper limb prosthesis with a negative pressure design. Mechanical analysis is performed to obtain the force and moment equilibrium equations. Then, the individual discipline feasible method is performed to decouple the original problem into a three-sub-discipline problem. A minimum of three shoulder straps of tension is obtained during optimization using the Isight harness scheme. The prosthetic socket can be firmly attached to the human body. Further experiments verify that the proposed device meets the basic requirements of wearing.

An Adaptive Feature Extraction and Classification Method of Motion Imagery EEG Based on Virtual Reality

With the aim to solve the problems such as low classification accuracy and weak anti-disturbances in brain–computer interfaces (BCI) of motion imagery, a new method for recognition of electroencephalography (EEG) was proposed in this work, which combined the wavelet packet transform and BP neural network. First, EEG is decomposed by wavelet packet analysis. Then, distance criterion is selected to measure the separable value of the feature frequency bands. Furthermore, the optimal basis of wavelet packet is attained by using a fast search strategy of “from the bottom to the top, from left to right.” The classification feature is extracted by choosing the part wavelet package coefficient, which can attain higher classification evaluation value according to the optimal basis of wavelet packet. And then, the optimal bands are combined with BP neural network. The experimental results show that the proposed method can choose the feature bands of EEGs adaptively, and the highest classification accuracy is 94 %. The correctness and validity of the proposed method is proved. Lastly, establish the virtual robot in MATLAB and use the classification results to control the robot’s arm motion.

Design and Application of Auditory Evoked EEG Processing Platform Based on Matlab

To improve the processing speed and efficiency of imaging EEG signals, a processing system based on Matlab GUI and Virtual Reality sink which integrates various algorithms such as Independent Component Analysis, Hilbert–Huang Transform, Support Vector Machine, etc., is designed in this paper. The EEG data used is collected based on a novel auditory evoked method proposed in this paper. The experimental results indicate that the novel evoked method has preferable recognition that can reach to 87.2 %, and the classification results can control the movement of the designed virtual arm accurately. This research provides a certain theory and experiment basis for the research of the stroke rehabilitation robot based on the imaging movement EEG signal of auditory evoking.

Research and Development for Upper Limb Amputee Training System Based on EEG and VR

It is necessary to have electromyogram (EMG) training before installing an EMG prosthetic for upper extremity amputees. Aiming to improve the training effect, in this paper a training system based on EMG and virtual reality (VR) is designed. The hardware and software of the training system were designed. And based on the VR technology and EMG technology, in this paper an interesting game in the software has been developed. Meanwhile some experiments were done in the hospital. After actual upper limb amputee experiment, the feasibility and rationality of the system is proved. This paper develops an upper limb amputees training system which has a lively and interesting game, can actively mobilize the amputees’ subjective training initiative, which has good effects and positive meanings for clinical prosthetics installation and usage.

Research on Bionic Mechanism of Shoulder Joint Rehabilitation Movement

In view of the clinical need of rehabilitation training to the human upper limb, the paper puts forward a novel exoskeleton device for shoulder rehabilitation. Based on the analysis of anatomy and biomechanics of shoulder joint, a novel bionic mechanism with 5° of freedom was proposed in the exoskeleton device. Then, the designs of mechanisms’ scheme and mechanical structure to bionic mechanism were performed successively. The bionic mechanism of shoulder joint was optimized to match the physiological motion of anatomical center of rotation adaptively and improves the compatibility of human-machine kinematic chain. It is expected that the research will provide a reference method to the study of bionic mechanism in rehabilitation training related to other joints.