Research On Artificial Leg Control System Modeling,Simulation And Physical Experiment

The conception of Biped Robot with Heterogeneous Legs(BRHL)is aimed at designing an ideal experimental platform and facilitating the research and development of intelligent prosthetic limb,combined with the relatively mature technology of humanoid robot.During the research and development of intelligent prosthetic limb,artificial leg of BRHL simulates the healthy leg of amputees to complete a large number of repeated walking experiments instead of amputees.So that it is significant to guarantee the humanoid performance and ideal motion control of the artificial leg for BRHL.Around the artificial leg movement control system,the mainly contents of this paper are studied as follows:(1)The bionic design of artificial leg is carried out,the four-bar bionic knee structure is optimized.In order to meet the requirement of artificial leg movement control,the kinematics and dynamics modeling are deduced,and verified through the comparison of MATLAB and ADAMS simulation.The four-bar knee instantaneous center of rotation movement is analyzed and verified that meets the J-curve of human knee movement.Given the lots of nonlinearity and uncertainty factors of artificial leg knee actuator,the least squares is used to fit static mathematical model of pneumatic artificial muscle(PAM)according to the experimental data.Besides dynamic mathematical model of PAM is deduced by referring Sanville's gas mass flow rate equation,and the result is verified by Simulink simulation.(2)Based on the analysis about the artificial leg knee control requirements,and in view of the complex modeling problems,PID controller is designed at the start which has a certain robustness and adaptability and does not require an accurate model.Because the PID controller is not very ideal for the control of nonlinear system,the nonlinear sliding mode controller(SMC)is designed.Due to the shortage of this controller,such as jitter and the problem of inverse model,referring to the domestic and foreign relevant scholars control experience,RBF neural network intelligent algorithm on SMC is used to approach the nonlinear and uncertainty factors,and realizes the knee ideal trajectory tracking control.(3)Finally,the control system of artificial leg is built based on the National Instrument NI-ComapctRIO controller and the corresponding PCBs are designed and welded.Software programming and GUI design is realized by LabVIEW.Then the hip and ankle joints servo motors and knee joint movement closed loop control are debugged respectively.At last,the control of artificial leg is finished and the experimental results are analyzed.