Research On Robust Tracking Control Technology Of Two Degree-of-Freedom Manipulator

With the continuous development of new technologies,new applications of manipulators have been promoted in various fields,and the demand for high-performance and high-precision manipulators is becoming more and more urgent.The robustness of the general controller is not strong enough and it is difficult to achieve high-precision control when there are modeling errors and external disturbances in the manipulator system.How to solve the controller design problem of this kind of manipulator has become a hot topic,which attracts the attention of scholars.In this thesis,a series of research work has been carried out around the design and implementation of the robust controller of the manipulator,including the construction of the platform of the manipulator system,the establishment of the mathematical model of the manipulator and the design of the controller of the manipulator.The main contents of this paper are summarized as follows:Firstly,the hardware and software platform of the manipulator system is designed independently.In the hardware part,a two-degree-of-freedom manipulator is manually constructed by using servo motor,and the control motherboard is designed based on STM32 chips,including schematic drawing and PCB production.In the software part,the control system of the manipulator is reasonably structured,and a set of upper computer control software of the manipulator is designed based on MFC for system debugging and drawing real-time system tracking control curve.Then,kinematics and dynamics models of a two-degree-of-freedom manipulator system platform are established.The kinematic relationship of the manipulator is briefly described by means of geometric analysis.Referring to the relevant literature of robot modeling,based on Lagrange modeling method,a general dynamic mathematical model of manipulator is given.Considering the modeling error and external disturbance of the manipulator,the dynamics model of the manipulator is improved,and the modeling error term and external disturbance torque term are introduced in the system.Next,based on the neural network disturbance observer,the tracking controller of the manipulator is designed.A neural network disturbance observer is used to estimate the complex disturbance of the system,and the disturbance estimation is used as a feed-forward compensation in sliding mode controller.The neural network disturbance observer not only improves the robustness of the sliding mode controller,but also improves the chattering problem of the sliding mode controller.The simulation results show that the designed composite controller can realize the stable tracking control of the manipulator,which is verified by experiments.Following,based on the high-order disturbance observer,the tracking controller of the manipulator is designed.A high order disturbance observer with a hypothetical disturbance model is designed to estimate the complex disturbances of the system.Based on the estimators of high order disturbance observer,a composite controller is designed,and the influence of control parameters on the performance of the controller is qualitatively analyzed.The simulation results show that the higher order disturbance observer has better disturbance estimation ability than the general disturbance observer.The effectiveness and robustness of the composite controller are verified by the experimental results.Finally,based on ADRC technology,the tracking controller of manipulator is designed.For SISO system,the design principle of general linear ADRC is analyzed.The decoupling of the two-degree-of-freedom manipulator is processed.The error generated by the decoupling part is incorporated into the composite disturbance of the system,which is estimated by extended state observer.Besides,two linear ADRC are embedded in the manipulator system in parallel.The simulation and experimental results show that the controller has good tracking performance and robustness.