| Due to the dwindling of the land resources, the importance of the ocean exploration becomes more and more obvious. The research of the deep-sea manipulator is taken seriously by all over the world. The main contribution of this thesis is to realize a sliding mode controller for position tracking of a special 2-degree-of-freedom and 3-founctional deep-sea robotic arm. This thesis includes the following parts:Firstly, this thesis establishes the math model of the servo system that consists of a brushless DC servo motor, a driver for the motor, and a single-degree-of-freedom joint. Then, the speed-closed-loop PI controller is designed to adjust the servo system to become the standardâ… model system.Secondly, friction is one of the major limitations in performing high precision manipulation tasks. It affects both static and dynamic performance. And, this thesis introduces the friction compensation based on LuGre dynamic model to promote the system performance and the Kalman filter to eliminate the system noise. After that, the simulation experiments are done with the MATLAB/Simulink tools, and the simulation result verifies the validity of the proposed method.Thirdly, according to the theory of sliding mode variable structure control, this thesis discusses a design method of sliding mode variable structure controller based on the Exponential Approach Law. To solve the problem of chattering excited by the sliding mode controller, this thesis improves the design of the sliding mode controller and introduces the theory of bound layer and a saturation function. In conditions of constant payload and variable payload, the simulation experimental results from different position tracking reference inputs show the correctness of the improved sliding mode controller.Finally, on the base of the existed hardware condition, the control algorithm program is designed according to the objective of the project based on VxWorks RTOS. It is successfully applied to the real-time servo control after debugged. |
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