Search

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.

The automatic classification of epileptic electroencephalogram (EEG) is important for the diagnosis and treatment of epilepsy. In this paper, an epileptic EEG classification method based on wavelet multi-scale analysis and particle swarm optimization is proposed. Firstly, the multi-scale is carried out to the original EEG to extract its sub-bands of different frequency. Secondly, the Hurst exponent and the sample entropy are used to extract the EEG signals and its sub-bands. Finally, the particle swarm optimization (PSO) algorithm is used to optimize the parameters of the extreme learning machine (ELM), and the obtained eigenvector is put to PSO-ELM to realize the purpose of classification of epileptic EEG. The proposed method in this paper achieved 99.7% classification accuracy for the discrimination between epileptic ictal and interictal EEG, which is superior to those methods in other studies.

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.

A pneumatic drive device for testing and evaluating lower-limb prostheses was designed, which is based on the ISO 10328 requirements for structural testing of lower-limb prosthetic. It can measure the structural strength and fatigue life of the lower-limb prosthesis at both heel-strike and toe-off moments, during which the knee joint bears the largest stress. The device well meets the testing requirements according to the current operation.

A passive above knee prosthesis being currently in use does not respond adequately to the needs of daily living activities of an amputee due to its limited functions. Therefore, this study deals with design of an active above knee prosthesis. The essential part of this prosthesis is the knee joint actuator based on active control of basic flexion and extension functions of the knee joint with the DC motor. The failure of a single sensor has catastrophic consequences on control. Small inertial measurement unit adhereing to the sound leg and two electrodes on stump detect the sound leg gesture and stump SEMG. Using echo control scheme for gait control, which modified knee trajectory from sound leg attitude value and SEMG switch signal.

For the optional control to artificial lower limb and natural gait, an artificial limb model with myoelectrical control was presented, and the recognition method based on support vector machine was discussed. The electromyography signal after pretreating and wavelet packet analyzing was stored in company with the motion of lower limb. Then support vector machine was used to build a model and found the relationship between electromyography signal and motion of leg. Finally, continuous angles of knee joint were used to control artificial limb device. Simulation results show that electromyography signal and angles of knee joint have strong relationship, and this algorithm obtains preferable forecast result

This paper proposes a new-type prosthesis model and control mechanism, represents an ongoing investigation of voluntary and natural control of lower limb prosthesis using the myoelectric signals. First of all, myoelectric signals, which are sampled from the lower limb during the subjects walked normally on the three kinds terrains, such as flat, slop and stair, are extracted the motion features with Wavelet packet decomposition. And then these features are sent into LVQ neural network to classify. In the end sending the new signals into the network, the high identification ratio was obtained. The greatest characteristic of the Robot-Prosthesis is that it can be controled at will, when the active control should offered corresponding parameter to the execution part for different terrain.