Research On Technique Of Static Datum Transformation For Unstable Platform

Optical measurement equipment and radar measurement equipment requires a stable platform in order to ensure all the observation data processing in same coordinate system.However,in many applications,measuring equipment's platform may be shaking in small amplitude affected by environment or hardwares.On this condition,measuring equipment's platform is to be defined as an unstable platform and measuring equipment's datum will keep changing with its platform,which will decrease accuracy of measuring equipment.Therefore,it's necessary to measure unstable platform's shaking and transform the unstable platform to a static datum.We call this method technique of static datum transformation for unstable platform(SDT).In launching site and shooting range,it requires optical equipment and radar equipment more mobile in order to adjust new aircraft's characteristics,e.g.long endurance,large flying range and maneuver.Therefore,it's necessary to solve the problem of SDT.Traditional optical equipments have a high measuring accuracy,but lack of mobility.So with the purpose of improving optical equipments' mobility,more and more vehicle-mounted theodolite has been used in shooting range.But so far vehicle-mounted theodolite can only realize motor transportation and then ground observation.If can realize non-landing measuring,vehicle-mounted theodolite will truly have mobility.The main problem of non-landing measuring is that vehicle-mounted theodolite platform is unstable platform and need to transform the unstable platform to static datum.Take vehicle-mounted theodolite as an object,SDT need solve two problems:(1)Measure and correct unstable platform's shaking.(2)Locate and orientate the measuring equipment on heeling condition.First,measure platform's shaking through Double-Transforming Measuring Method with External Datum(DTMM).Second,correct theodolite's observation data with platform's shaking.Finally,transform theodolite's observation data from local coordinate system to reference coordinate system.The main innovation points of this thesis include:1.Propose DTMM for measuring problem of unstable platform's shakingTo solve unstable platform's shaking measuring problem,Dr.Zhou proposed Double-Transforming Relative Measuring Method.This method requires a high-precision level status,which is difficult for large tracking equipment.In order to avoid the high-precision level adjustment,the paper proposes DTMM.The main idea of DTMM is that: place a small level-datum outside vehicle-mounted theodolite and solve the theodolite platform's pose related to its level condition by comparing theodolite level condition and shaking condition with external level-datum.The DTMM's innovations may be mainly reflected in two aspects.First is that level adjusting process with high precision at the stage of preparation is moved to external level-datum,which improves work efficiency to a large extent.Second is that lower the calibration accuracy standard of fixed relationship by initial alignment between vehicle-mounted theodolite platform and external level-datum.The main factors influencing DTMM's accuracy include calibration accuracy of camera intrinsic parameters and image distortion,camera pose estimation accuracy and calibration accuracy of fixed relationship between camera and theodolite.Propose a calibration method for camera intrinsic parameters and image distortion decoupling with extrinsic parametersCamera intrinsic parameters and image distortion is the imaging model parameters,which is a key factor of camera pose estimation.Most calibration methods take camera intrinsic parameters,image distortion and extrinsic parameters as unknown parameters and solve them simultaneously.Then in order to reduce reprojection error,it's necessary to optimize all the unknown parameters.But in this case,extrinsic parameters' error may adjust to intrinsic parameters and image distortion,which will increase calibration error of intrinsic parameters and image distortion.A new calibration method based IAC is proposed in the paper.The method realizes decoupled calibration between intrinsic parameter,image distortion and extrinsic parameters.The method improves calibration accuracy of camera intrinsic parameters and image distortion to a certain extent.Propose an evaluation strategy for camera pose estimation methodsThere are many camera pose estimation algorithms based point correspondences,but lack of evaluation strategy,which increases selection difficulty for algorithms in applications.We propose an evaluation strategy for camera pose estimation algorithms under specific cost function,including 3 parameters: precision,efficiency and success rate of domain optimal solution.This method can provide a scientific foundation for selection of camera pose estimation algorithms,which has important theoretical significance and application value.Propose a hand-eye calibration method based on Schur matrix decompositionHand-eye calibration is the core of fixed relationship calibration.Hand-eye calibration accuracy directly determines fixed relationship calibration accuracy.The paper proposes a hand-eye calibration method based Schur matrix decomposition.The method improves efficiency,accuracy and stability.And more importantly,the method realizes auto filter of observation data quality and auto delete of outliers.2.Location and orientation correction method for measuring equipment on heeling condition.This paper proposed a location and orientation correction method for measuring equipments on heeling condition.First,complete measuring equipments' location and orientation process on heeling condition,and then transform the location and orientation results from heeling condition to level condition using unstable platform shaking data measured by DTMM.3.Design a static datum transformation system for unstable platform.Takes vehicle-mounted theodolite as an object,the paper designs a static datum transformation system for unstable platform and complete experiments in real shooting range environment.The results indicate that SDT can improve vehicle-mounted theodolite's accuracy to a large extent for non-landing measuring.Accuracy and mobility is future direction of measuring equipment.The problem of unstable platform shaking is a key difficulty need to be solved.The improved static datum transformation technique for unstable platform is simple and feasible.Above all,the technique avoids level adjusting with high precision at stage of preparation,which has important theoretical significance and application value.