STUDY OF PNEUMATIC MOTION BASE CONTROL CHARACTERISTICS

摘要

From the good environmental security nature, pneumatic system attracts interest of industrial field. In recent years, parallel link motion base is prosperously used for virtual reality simulator such as amusement device and so on. Stuart-platform type 6 degree of freedom parallel link motion base was constructed using pressure controlled proportional valve by pneumatics. Positioning of motion base was made by inverse kinematics for central coordinate of platform. But accuracy of position control was not satisfactory by conventional PID control, because of low stiffness caused by compressibility of air, friction force and parameter fluctuation. Therefore, positioning dynamics comparison was made between present meter-in-meter-out pressure control and bi-directional proportional servo valve. Also, two kinds of robust control schemes were attempted and compared with PID controller. The first robust control is disturbance observer that compensates parameter fluctuation of the control object by estimation of disturbance, such as friction and non-linearity of servo system. The second control scheme is simple adaptive control (SAC), which is assumed effective in highly non-linear, pneumatic servo system.