High Precision Control Study Of Remote Sensing Camera Posture Based On Angular Momentum Balancing Decoupling And Improved Active Disturbance Rejection Control

A remote sensing camera with fast and accurate scanning function is used in many fields such as:military reconnaissance for doing precision strike,initiative search for conducting field rescue,observe airflow for weather forecasting,etc.These cameras work in weightless environments,and a small disturbance will bring a significant impact,therefore,a high quality control performance for the attitude control system of these cameras is required.Due to influence of movement coupling between in control shafts of remote sensing camera attitude and low quality control performance in terms of low speed and position control performance,the control quality of remote sensing camera attitude control system still needs to improve.In this context,a study on precise control of remote sensing camera was conducted.The present study was based on an active disturbance rejection control strategy and an angular momentum balancing to eliminate decoupling effect.The study consists four phases.In the first phases,a mathematical model for attitude control system of remote sensing camera was established.The mathematical model focuses on angular momentum balance decoupling mechanism,current-loop,speed-loop,and position-loop of system actuator(permanent magnet synchronous motor).In the second phases,angular momentum balance decoupling mechanism for remote sensing camera attitude control system was designed.The working principle of the angular momentum balance decoupling mechanism was designed as follow:the reverse torque of motor stator was passed through the speedometer in steps which drive the angular momentum balancing wheel in reverse direction to obtain a reverse angular momentum.This angular momentum has the same magnitude but opposite direction to the angular momentum produced by motor rotor drive remote sensing camera spindle.This phenomenon results in internal angular momentum balance of the angular momentum balance decoupling mechanism,and the elimination of movement coupling between remote sensing camera attitude control shafts was completed.In the third phases,an improved active disturbance rejection control strategy was studied in my paper.Because this control strategy uses a large number of nonlinear functions,and the improved active disturbance rejection control strategy is a nonlinear control strategy.Therefore,a new nonlinear function which can realize smooth switching was designed through simulation and calculation.The core components of the active disturbance rejection control strategy include extended state observer and nonlinear state error feedback law were improved based on this function.In addition,a tracking differentiator and a disturbance compensation device were designed.Combine the four parts together,the improved active disturbance rejection control strategy was designed.The working principle of the improved active disturbance rejection control strategy was designed as following:the tracking differentiator was used to arrange the transient process,tracking system's states and the various derivatives of these states,solve the problem between overshoot amount and rapid corresponding,and provide quality input signals.The nonlinear dynamics,model uncertainty,and external disturbances of the control system were extended to a new state,and the improved extended state observer was implemented to observe this state.The overtime variation of the control system was predicted and compensated for in real time using the improved extended state observer.The improved nonlinear state error feedback was adopted to restrain the residual errors of the system,and provide optimal position control law for control system.The disturbance compensation device was used to compensate for the total disturbance.Then,simulations were carried out for the improved active disturbance rejection control strategy,and results show that the improved active disturbance rejection control strategy exhibits better tracking ability,faster response speed and smaller overshoot than the traditional active disturbance rejection control strategy and traditional PI control.In final phases,a remote sensing camera attitude control system based on an active disturbance rejection control strategy and an angular momentum balancing to eliminate decoupling effect was designed include current-loop,speed-loop,and position-loop active disturbance rejection controller.Following this design,the system performance was evaluated through simulation and experimental.Because influence of movement coupling between remote sensing camera attitude control shafts was eliminated by the angular momentum balance decoupling mechanism,and control performance of the remote sensing camera attitude control system was improved.On the other hand,the active disturbance rejection control strategy does not depend on the mathematical model of controlled object,estimate and compensate for all kinds of disturbances in real-time,and not only control the system's states,also control each order differential of the states,therefore,the control performance of the remote sensing camera attitude control system was improved once again.Thus,the simulation results and experimental results all show that the remote sensing camera attitude control system based on the improved active disturbance rejection control strategy and using an angular momentum balancing to eliminate decoupling effect exhibits better dynamic and static performance than traditional control strategy.The remote sensing camera attitude control system based on the improved active disturbance rejection control strategy and using an angular momentum balancing to eliminate decoupling effect was designed in this paper,and a good control accuracy was obtained.Furthermore,it provides valuable exploration for the application of angular momentum balancing decoupling mechanical methods in solving control problems,along with anti-interference and high-precision control under complex environment.