Bionics Design Of Artificial Leg And Experimental Modeling Research Of Pneumatic Artificial Muscle (PMA)

A large number of the performance test experiments need to do during the process of the research and development of intelligent prostheses(IP),However, it is not realistic to let the limb disabled wear prostheses to conduct a great deal of experiments which need to be reproducible. Consequently, this paper provides an ideal experimental platform which is based on research combination of human simulating robots and intelligent prostheses for performance testing of intelligent prostheses, and then it is conducive to develop better intelligence prosthetic products. Artificial leg as an important part of the experimental platform during the process of IP, its main function is to simulate normal gait of the healthy leg of the disabled and to provide the trajectory of gait follow the target for intelligent bionic leg. Therefore, the anthropomorphic design of the artificial leg has a very important significance for the study of entire heterogeneous biped walking robot.Basing on the analysis of physical structure and motion mechanism of the human lower limbs, the entire mechanical system of the artificial leg is designed, including hip, knee and ankle joints. In order to make the artificial leg better simulate gait trajectory of healthy leg of disabled, a four-bar mechanism is adopted as the mechanical structure of the knee joint, thus overcoming the problem of unnatural gait of artificial leg of biped robot caused by single-axis knee joint. In terms of driving, pneumatic artificial muscles (PMA) are used as the driving source of the knee joint, thereby avoiding large stiffness and other issues caused by using servo motors or hydraulic devices. Taking full consideration of the structure and size of the human healthy leg, the structure and size of the artificial leg is made be close to the corresponding parts of the human leg as much as possible during the overall structural design.Due to pneumatic artificial muscles (PMA) itself nonlinear, it is very difficult to realize the PMA’s modeling by the way of analytic calculation, so a mathematic model of PMA is established by the experimental modeling methods. What’s more, an experimental platform is built for performance testing of pneumatic artificial muscle, and its property is analyzed respectively under the conditions of equal pressure, equal length, equal load, and establish the mathematical relationship of output power, shrinkage rate and input pressure, and then establish its precise mathematical model by using least squares method to conduct parameter identification of the model.In summary, the principle of joint is driven by PMA is analyzed in detail and the driven approach is chosen. Then a mathematical model of joint is driven is established on the basis of the dynamics analysis of the PMA. In the end, adopting virtual prototyping technology (VPT) to build a united simulation platform, and to conduct kinematics and dynamics simulation of the artificial leg, we realize the control simulation based on PID control algorithm.