Dynamic Modeling And Control Of Large Load Two Degrees Of Freedom PTZ

With the increasing investment in the research and development of UAVs in the world,the types and markets of the airborne platform are expanding.At present,there are few studies on the dynamics of the platform.Based on the designed large load 2-DOF PTZ,this paper studies the mode,dynamics and control methods of the platform,and carries out dynamic modeling,experiment and control of the platform according to these basic theoretical studies.Firstly,according to the functional requirements of the large load 2-DOF PTZ,the paper determines the main technical indicators and two-degree-of-freedom structure of the platform,gives the overall scheme of the mechanical structure design,and analyses the two mechanisms.The modal analysis of the platform is carried out by using ANSYS software,and the natural frequencies and mode shapes of the platform are obtained.Through the analysis of the natural frequencies and mode shapes,the natural frequencies and mode shapes of the platform are obtained.Through the analysis of the natural frequency and the mode,the stress displacement distribution and the displacement frequency distribution of the platform under working conditions are obtained.Secondly,ADAMS software is used to simulate the dynamics of the platform according to the motion requirements,and the driving moment curves of the two joints are analyzed.The driving moment changes of the platform during operation are obtained,and the influence of the platform on the joint driving moment under load and no-load is determined.Furthermore,according to the designed physical prototype,the actual load of the platform is simulated,and the dynamic experiment of the platform is carried out.The dynamic performance of the experimental verification platform can meet the actual requirements.The D-H parameters of the platform are determined by describing the three-dimensional spatial connecting rods.The coordinate system of the platform is established according to the principle of the additional coordinate system of the connecting rods,and the forward kinematics of the platform is obtained.According to the forward kinematics of the platform,the Lagrange method is used to establish its dynamic equation and solve it.The results of the solution are compared with those of ADAMS simulation to verify the correctness of the established dynamic model.According to the dynamic equation of the platform,the joint moment equation of the platform is deduced,and the system control method based on the moment method is constructed.Finally,taking the large load 2-DOF PTZ as an example,based on the system control law of Torque method,the control system of the virtual prototype is built in MATLAB.The ADAMS virtual prototype model and the control system of the virtual prototype in MATLAB are combined to realize the dynamic control of the platform and analyze the stability of the control model.The results show that the joint simulation system has good response characteristics and trajectory tracking characteristics,and its control system model has good stability.