Key Technologies For Shipboard Optoelectronic Tracking And Pointing Based On Feedforward Control

Shipboard Optoelectronic Tracking System, mainly used for target acquisition,tracking and pointing, is a set of optoelectronic devices which adopted manytechnologies like image processing, signal processing, control technology andprecision optics. Shipboard Optoelectronic Tracking System has a pivotal role inshipboard optoelectronic countermeasure, at-sea accurate measurement, carrier-basedaircraft landing guidance and so on. However, the naval ship sailing on the sea wouldbe wobbled that was a result of effected by many complex factors like wave and wind.The optoelectronic tracking system would do the same shaking with the naval shipbecause of it is a rigid connection between them, which would largely increase thedifficulty of target acquisition, tracking and pointing. So the Shipboard OptoelectronicTracking System need to solve more technological problems comparing with theground-based optoelectronic tracking system. On the other hand, with the developmentof science and technology, there is a general tendency that the targets would be inhigh-speed and strong mechanization, which would put forward higher requirements ofacquisition, tracking and pointing to the photoelectric tracking system.This paper aimed to improve the tracking and pointing accuracy of ShipboardOptoelectronic Tracking System. According to the process procedure of system data,the time-aligned of posture data, the initial installation error between SINS (StrapdownInertial Navigation System) and optoelectronic tracking system and the influence onthe tracking caused by the shaking of naval ship, the motion of target and the rotatingof field had been studied in this paper.Firstly, this paper gave a brief introduction about the servo system ofoptoelectronic tracking system and verified the fact that it could greatly improve thetracking accuracy adopting feed-forward of input. And on this basis, the three factorsincluding the time non-synchronous of front-end multi-sensor data time, the trackingerror of the shaking of naval ship and the motion of target, the rotating of field effectedby the shaking of naval ship, that seriously affect the tracking accuracy ofoptoelectronic tracking system were analyzed.Secondly, this paper analyzed the importance of the front-end data alignment andintroduced the common method of data alignment. The quaternion as a tool to describeattitude was introduced and the model of parameter sphere vector interpolation method,which used to align the time of posture data of attitude quaternion, was put forward onthe basis of the physical significance of quaternion used to describe the attitude. Themodel could better reflect the physical significance of posture quaternion and be morein line with the result of actual situation comparing with the common interpolationmethod. Meanwhile, the method that using the least square method principle tocalibrate the relationshipmatrix between the platform system and the device systemwas put forward in the premise of the SINS self-calibration. Then, the characteristics of target observed by shipboard optoelectronic trackingequipment were analyzed and the model of target’s position in the device systemeffected by the posture of naval ship was derived. On this basis, the two casesincluding remote and little maneuvering target and close quarters and largemaneuvering target was analyzed the mainly influence of system’s feed-forwardquantity. According to the characteristics of target observed by shipboardoptoelectronic tracking equipment, a selected threshold indirect measurement filteringmethod, which could decrease the state estimation error of system byprocessing theobserved quantity and constrainting the first-order derivative of system state quantityin thefiltering process that would make the first-order derivative’s estimation offiltering result more accurate, was put forward contrasting the common filteringalgorithm.Finally, the impact of the view field rotation on pointing of shipboardoptoelectronic tracking devices was analyzed. The rotation angle of the view fieldunder a certain posture of naval ship and device pointing was derived with introducinga perspective projection coordinates and defining the rotation angle of view field. Theresults of error sources and transfer relationship is analyzed and validated bysimulation results.