Research On Prediction Tracking Control On Moving Bed

With the development of the application of electro-optical tracking control system,such system has been gradually installed on the moving platform to enhance the mobility,flexibility and universality of it.The electro-optical tracking system on the moving platform can be affected by the carrier disturbance.The disturbance is transmitted directly to the optical path and deteriorates the tracking accuracy greatly.Satellite-to-earth quantum communication needs to establish a communication link with high-precision up-and-down alignment.One of the core problems is how to suppress the jitter of the satellite carrier to ensure the stability of the optical communication path.Based on the traditional ground-based electro-optical tracking system,the vehicle-mounted,shipborne and on-board electro-optical systems have been rapidly improved,which not only changes the carrier,but also brings new challeges – new target types.In recent years,due to the development of low altitude UAV(Unmanned Aerial Vehicle)technology,it has brought new challenges to the city's low altitude security.Using the electro-optical tracking system to track targets like UAVs has been identified as a completely new and effective way to respond quickly,accurately without causing collateral damage.Compared with the traditional ballistic targets and space targets,low-altitude targets have the characteristics of slow speed,small volume,large acceleration and flexible maneuvering,which limit the traditional tracking methods greatly.In general,from the current development of electro-optical systems,the change of platform and target put forward higher requirements.To be especially pointed out,the system disturbance rejection ability and maneuvering target tracking ability need strong enhancement.Therefore,aiming at the problems above,the research issues of this project is to further improve the disturbance rejection ability and tracking ability of the electro-optical systems on moving platforms.This paper studies the above problems separately.A series of effective methods have been proposed from the disturbance prediction and target maneuvering prediction.In the aspect of disturbance suppression,the concept of disturbance observation and compensation based on acceleration measurement,of which the compensation controller design is carried out by theoretical analysis of the control loop,is introduced into the traditional multi-loop control.This method ignores the low-frequency disturbance compensation and can effectively enhance the disturbance suppression ability at middle-frequency,of which the stronggest performance can be up to 15 dB.On this basis,this paper optimized the disturbance observer method further and proposed an enhanced disturbance observer control method.The essence of the method is to move forward the compensation node,and the feedback controller is used to replace the feedforward compensation controller.Theoretically,the compensation loop is much closer to the perfect compensator,which could effectively enhance the system's low frequency disturbance rejection ability.The compensation controller of the enhanced disturbance observer control presents the differential characteristic,so the essence of this method can be regarded as jerk feedforward control of disturbance.However,the above methods all achieve better accuracy by increasing the control complexity of the system,and how to further simplified the control structure to ensure system accuracy needs to be explored.In order to solve this problem,a plug-in acceleration disturbance feedback control method based on acceleration measurement is proposed in this paper.The traditional acceleration feedback is improved by a new feedback control constructed by disturbance observer.The control structure is simplified,which is in favor of engineering implementation.Through a series of simulation and experimental verification,the method can improve both low and middle frequency effectively.In terms of tracking,the electro-optical system is based on the visual tracking strategy.In order to further improve the feedforward performance,an error observer based feedforward technique is proposed for the system tracking.Its essence is to use the combination of the visual error provided by the CCD and the output of the position loop controller to realize a high gain observer to observe and estimate the target position and then realize the feedforward of the target position and reduce the CCD tracking error.Therefore,the performance of feedforward is only dependent on the CCD measurement input and that simplifies the feedforward frame.This method can effectively improve the low-frequency tracking accuracy of the system.On this basis,further optimization of the algorithm,which changes the feedforward node,can effectively improve the low and middle frequency tracking capability of the system.Aiming at the targe characteristics of slow target and large acceleration,the composite control mode constructed by feedforward and feedback is used to improve the gimbal tracking performance.In this paper,the feedforward theory is analyzed,and the target speed prediction based on orthogonal least square method is proposed.Compared with the traditional Kalman prediction algorithm,the new algorithm takes the unaligned time error into consideration,which has small delay and high accuracy,resulting in a better feedforward performance.In addition,because the target is a low-altitude target,the background features are complex and often appear in the field of view of wires,towers,birds and other interfering targets,which all could easily lead to target extraction errors,even to lose of the target.The essence of orthogonal least square algorithm is fitting extrapolation,so it can also be used for position prediction,which can be used when a wrong target is extracted.So this algorithm can be used for position extrapolation to solve the problem of short-term penetration of barriers and target loss caused by over-maneuvering.