Nonelinear Compensation And Robust LQR Control Of 2-DOF PTZ Driven By Brushless DC Motor

With the progress of science and technology,the PTZ equipped with imaging equipment has become an important part of the intelligent monitoring system.The imaging equipment can obtain rich image information,and the PTZ can realize the movement of multiple degrees of freedom.In this way,the intelligent monitoring system can adjust the scope of view through the movement of the PTZ,and obtain the image sequence containing the target information in real time.Combined with effective image algorithm,the target recognition,monitoring and dynamic tracking can be realized.Therefore,the research on the related technology of PTZ system has very important application value.In this paper,a two-degree-of-freedom PTZ system driven by brushless DC motor for dynamic tracking is studied.The mechanical structure design,nonlinear compensation and controller design of the two-degree-of-freedom PTZ system are discussed and studied.Firstly,this paper introduces the mechanical structure design and hardware selection process of the two-degree-of-freedom PTZ.Through the analysis of the advantages and disadvantages of traditional PTZ and the experimental requirements of this paper,the design process of PTZ system is introduced from two aspects of structure design and motion control system.On the one hand,the PTZ system is small in size and simple in assembly.On the other hand,the operation of PTZ system has a good hardware foundation.The drive mode in the structural design adopts belt drive,and the power source is a brushless DC motor.Secondly,the process of system modeling and analysis is illustrated by taking the horizontal motion system of two-degree-of-freedom PTZ as an example.It is the basis of controller design to master the characteristics of system input and output and establish accurate system model.This paper analyzes and describes the input and output characteristics of the system by combining mechanism method and experimental method,and then the nonlinearity of the system is compensated.The effectiveness of the compensation is verified by experiments,The transfer function model of the linear working range is obtained through the pseudo-random response experiment and subspace identification algorithm.Then the order of the system model is reduced to facilitate the controller design,and the uncertainty of the system is analyzed and described.Finally,on the basis of system modeling and analysis,the system loop is divided into speed loop and image loop for controller design.Firstly,LQR output feedback controller based on internal model extension is designed to improve the disturbance rejection and tracking performance of the system.Then,the robust stability constraints that the controller parameters need to meet under the condition of additive uncertainty are given,and then based on model matching In order to avoid the high order of the controller,the image loop adopts PI controller.In this paper,the designed controllers are simulated and analyzed in MATLAB.The results show that the controller designed in this paper can ensure the two-degree-of-freedom PTZ system has good tracking performance and anti-interference performance.