The Research Of Cartesian Pneumatic Manipulator On Trajectory Tracking Control

Although rectangular coordinate type pneumatic manipulator cannot be used to perform more complex tasks like the type of joint manipulator, but it has been used widely in industrial production because of its advantages of relatively simple structure, low cost and easy implementation of control. At present, rectangular coordinate type pneumatic manipulator are used for implementing point to point tasks, and it is also partly used for performing simple continue path tasks. This paper is based on the existing laboratory equipment, and combines with the main characteristics of pneumatic position servo. The precondition of this paper is the process tasks of the space continue path movement of manipulator. The aim of this paper is on the advantage and disadvantage of the system features, and is accordingly to design a space path control method of such manipulator.Firstly, this paper introduces the devolopment process and research status of the pnumatic manipulator. Then intruduces rectangular coordinate type pneumatic manipulator structures, describes the relationship between each connecting rod of the manipulator, and models kinematics model of the manipulator. This paper also makes the path planning by adopting the method of inverse kinematics displacement of the joint based on the kinematics model, finishes the simulation analysis of space linear motion of manipulator and proves the rationality and effectiveness of ADAMS path planning, which means it can save system resources.Secondly, the principle of pneumatic servo system is analyzed, the linearized models of pneumatic manipulator three-axis model are solved out. It gets time and frequency response curves of each three-axis, and finds the deficiencies in rapid trajectory tracking control of this system that is natural frequency and damping ratio is to low. Also, The role of system parameters are analyzed which played in improving the system performance and obtains their mutual change relationships. Taking into account the problems of the manipulator in this article, this study, under the premise of the comparison of several control strategies, designs the trajectory tracking controller of the manipulator by adopting the PID correction method, which is simple and easy to achieve, and Terminal sliding mode control method based on high order one with nonlinearity system. By simulation comparison, it is found that the tracking capability of the conventional PID control method is poor and the tracking range of the conventional PID control method is small, so the conventional PID control method doesn’t have good tracking results as the control method to use the manipulator. Whereas the terminal sliding control method of high order one with nonlinearity can make tracking error, when the manipulator tracks the space straight line, become large only in the time period of not fully reaching the convergence of point in time, but it can fully track the target trajectory after reaching the convergence time. The tracking ability will be greatly improved, and it can be close to the sliding surface from any initial point, and it also has the robustness of outside interference and system uncertainty and meets the requirements of accurate tracking task of the manipulator trajectory.Finally, taking into account the requirements of the servo tracking, this paper has proposed the controller implementation of "PC+motion control card" and described the structure of controller hardware system and the needed structure function of the software, which lays a foundation for the further experimental studies.