Observer Based Sliding Mode Trajectory Tracking Control Of Industrial Robot

With rapid development of technological state in the world, industrial robots have been widely applied to practical production. As the increasing complexity of controlled objects, controllers and control tasks, the demands for robot control are rising gradually. The robot system is not only a complex nonlinear system with multi-input and multi-output and highly coupled, but also always suffers the influence of external disturbance, un-modeled dynamics, measuring error and some other uncertain factors. So it is hard to obtain the precise model of a robot system, further more, it brings more difficulties to study the control of the systems. Sliding mode control has been widespread used in control area due to its character of strong robustness, quick response and so on. In this dissertation, a sliding mode trajectory tracking controller based on observer is designed to tackle the quick and accurate tracking issue of a double-jointed SCARA robot under the condition of external disturbance and immeasurable angular velocity. A sliding mode control law is designed under the assistance of an observer for the state estimation under the condition that only angular position is measurable, and the boundary layer method is adopted for diminishing the chattering effect of sliding mode scheme. The convergence of the observer and the stability of the controller are analyzed in the sense of Lyapunov stability theory. The simulation studies are carried out with Matlab to verify the robustness and effectiveness of the proposed observer based control strategy, and the simulation results show that the estimated states converge to the actual ones and the controlled trajectory track the desired trajectory quickly and accurately. The main research work is as follows:First of all, the control of robot system is summarized in terms of the composition of a robot control system, the research status of main control methods. The sliding mode control scheme is reviewed, which is a deeply concerned method in the industrial robot control area.Secondly, the dynamical model and the dynamic characteristics of robotic manipulators system are established and analyzed. Considering the state observer used in this dissertation, the fundamental and the design approaches of some observers are investigated at first. And Luenberger observers are designed for two kinds of Lipschitz nonlinear systems classified by the linear relation between the output and state of systems. The designed observers employ Linear Matrix Inequality (LMI) for the gain matrix quick and accurate selection. Lastly, the convergence and stability of the designed observers are verified by Matlab.Then, it is studied on the existence and reaching conditions of sliding mode control, how to ensure the dynamic performance and the solution of the chattering effect. Considering a robotic manipulators dynamic model, a general sliding mode controller is designed to realize the trajectory tracking control, and the stability of the designed controller is proved with Lyapunov stability theory. Lastly, the simulation studies are made with Matlab, which further verify the stability and effectiveness of the designed sliding mode controller.Finally, in this dissertation, a sliding mode trajectory tracking controller based on observer is designed to tackle the quick and accurate tracking issue of a double-jointed SCARA robot under the condition of external disturbance and immeasurable angular velocity. Firstly, the transformation from the robot system to a Lipschitz nonlinear system by the analysis of system variables is given. After the sliding mode observer designed, a sliding mode control law is designed with the angular velocity estimation, while the control precision is improved with the angle estimation. And the boundary method is adopted to diminish the chattering effect. The convergence of the observer and the stability of the controller are analyzed in the sense of Lyapunov stability theory. The simulation studies are carried out with Matlab to further verify the robustness and effectiveness of the proposed observer based sliding mode control strategy.