Design, Analysis and Path Tracking Servo Controlof 3-PUU Pneumatic Parallel Manipulators with a Stereo Vision Measurement System

• Main Authors: Hao-Ting Lin, 林浩庭
• Other Authors: 江茂雄
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/04142681953277011029

博士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 100 === This study aims to develop two novel three-degree-of-freedom (3-DOF) translational parallel manipulators driven by the nonlinear pneumatic servo system for path tracking servo control with a stereo vision measurement system. The 3-PUU vertical pneumatic parallel manipulator (VPPM) and the 3-PUU pyramid pneumatic parallel manipulator (PPPM) are the proposed parallel manipulators designed and implemented in this thesis. In detail, the mechanical system and the control system are the primary parts for developing the pneumatic 3-DOF translational parallel manipulators. In the mechanical system, each of the pneumatic 3-DOF translational parallel manipulators contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. Based on the structure design theory of the mechanism, the end-effector of the parallel manipulators can achieve three-dimensional motions in the X-Y-Z coordinate system through the three pneumatic cylinders with ideal limb structures. Moreover, the mobility of the manipulator is analyzed by the Kutzbach-Gruebler’s equation. In addition, according to the characteristics of the mechanism, the inverse kinematics and the forward kinematics of the parallel manipulators are proposed by the coordinate transformation theory. The D-H notation method is used to resolve the problem of kinematics inclusive of inverse kinematics and forward kinematics in analytical forms for given the end-effector poses, which is used in the path planning of the end effetor. The pneumatic actuators for the three axes are modeled including the dynamics of the pneumatic servo valve and the cylinder. In the control system, the control scheme is performed to control the three pneumatic actuators for following the computed paths that are solved from the target path of the end effector in the path planning. In order to control the proposed pneumatic parallel manipulators and improve the path tracking accuracy for the pneumatic parallel manipulators, a Fourier series-based adaptive sliding mode controller with H∞ tracking performance (FSB-ASMC+ H∞ controller) is proposed for controlling the pneumatic actuators. The proposed controller first employs a Fourier series-based functional approximation technique to estimate the dynamic models and time-varying uncertainties of the system. Next, further efforts are made to improve the dynamic tracking performance by combining the H∞ tracking strategy with an adaptive sliding-mode control method to make the derived controller robust against approximation errors, un-modeled dynamics and disturbances. In addition, the stereo vision measurement system is used to measure the end-effector of the manipulator. Through a sensor collaboration strategy, the error between the calculated position and the stereo vision measuring position of the end-effector can be improved. The simulations and experiments illustrate the effectiveness and usefulness of the proposed manipulators.