| Lower limb prostheses is a kind of product used to replace human's disable lower limbs, so it's performance has a direct influence on the safety and comfort of the limb disabled. At present, during the development of intelligent prosthesis (IP), plentiful, various and repeated walking tests should be conducted. However, due to amputee's physical limitation, it is very difficult to do these. Based on the research and analysis of biped robot, this paper, integrating the study of the IP and biped robot, uses the artificial leg imitating amputee's health leg, and the other one imitating the IP fixed with amputee. As gait tracking target of IP, artificial leg mainly simulates the walking of amputee's health leg. So, its performance is critical for the quality of IP. Therefore, it is significant to conduct research on artificial leg.In order to achieve a better gait anthropomorphic, we have designed whole structure of artificial leg, including mechanism of every joint and motion style. To overcome the unnatural gait of artificial leg of biped robot, we mainly design structure of knee joint. By comparing and analyzing the strengths and weaknesses of single axis joint with 4-bar closed chain knee joint, we adopt 4-bar closed chain knee joint to solve the unnatural gait problem. In addition, by analyzing the research of pneumatic artificial muscle (PMA), we adopt PMA to provide drive force for knee joint, establish its mathematical model, and design test schemes used to fit the model, loading foundation of practical application of PMA. In the paper, we deduce the mathematic model of single degree of freedom joint, and give structural solution of this joint.As object of study, we adopt Virtual Prototyping Technology (VPT) to establish united simulation platform based on multi-software, conduct simulation based on PID control algorithm, and analyze error causes according to the simulation results. Then, we improve the control algorithm and adopt fuzzy-PID, reducing the error. |
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