Study On Optical Measurement Techniques Based On Unstable&Moving Platforms In Shooting Range

The ballistic trajectory and pose parameters of the flight object such as missile,shells, which are the basic evidences for the assessment of weapon test and failureanalysis, are measured with intersection method by multiple Optical measurementequipments such as photoelectric theodolite and high-speed photography camera(vidicon) which are placed at fixed point and are used to track and shoot the object. ButThere are some shortcomings of this kind of fixed measurement method, includingfixed effective range, no flexibility, etc. In order to satisfy the measurement demand ofmodern weapons with long-distance and long-time flight, strong maneuverability,optical measurement mode in shooting range gradually develop from the fixed one tothe mobile one, such as vehicle theodolite which works with the mode of mobilesetting,pointing measuremet, airborne optical measurement which can measure in flight.However, there are some difficulties in moving object observation by the opticalequipments fixed on vehicle and airborne platform, mainly including: Thegroundwork of vehicle theodolite, which have to satisfy measurement demand, can’tassure as steady as the one of fixed theodolite, hence, the vehicle platform is easy toproduce a wobble which makes the theodolite difficult to obtain high accuracymeasuring results. Usually, with the limit of the structure and size, a single planecan’t form valid intersection measurement conditions, it cost too much to prepare moreaircraft which calculate the results with intersection method. Currently, a singlemeasurement equipment in an airborne platform can only shoot the object and recordthe image in flight, but can not obtain the trajectory and pose parameters. Two kinds ofbasic theory problem of photogrammetry(videometrics) can be summarized from thetwo difficulties: one is moving object observation problem on disturbedplatform(unstable platform), the other one is moving object observation problem bymonocular camera on mobile platform. The optical measurement problems on unstableplatform and mobile platform are also named as “optical measurement problems onmoving platforms”, together.In order to conquer the optical measurement difficulties on moving platforms,“conversion method for unstable platform to static reference” is proposed to eliminatethe unstable platform caused measurement error in vehicle theodolite application, and"monocular trajectory intersection method" is proposed to implement the trajectory andpose measurement of moving objects by monocular camera on mobile platform. Themethods not only provide new techniques for optical measurement equipments, whichcan only look and record the moving procedure of the object, but can not to get highprecision measuring results, in the current domestic range, but also can be applied toother fields of similar measurement problems, for example,“conversion method for unstable platform to static reference” can be applied to ship deformation measurement,correction of mobile radar level deformation measurement error and other fields,"monocular trajectory intersection method" can be applied to moving targets positioningon tank, etc. The mainly work and innovation points of the dissertation are as follows:1.“conversion method based on relay cameras for unstable platform to staticreference” is put forward to achieve high accuracy measurement of the movement targeton unstable platform. In this method, a static reference is constructed, the relationshipbetween the reference and unstable measurement platform is measured by videometrics,then the error which is caused by unstable factor of the platform can be eliminated, i.e.,the unstable measurement platform is converted to a static reference. The basicelements include: the measurement of the wobble of the unstable platform, forexample, the wobble can be obtained by shooting a cooperation structure fixed on theground as a static reference with cameras put on the unstable platform, as well as byshooting a cooperation structure put on the unstable platform with cameras fixed on theground; the calibration for the relationship between the relay cameras and platform,or between cooperation structure and platform.2. A measurement and correctness system based on “conversion method based onrelay cameras for unstable platform to static reference” for dynamic errors of vehicletheodolite is achieved. A lot of engineering problems such as pose estimation under thecircumstance of cooperation markers which are coverd or kept out, the calibration forthe invariable relationship between the relay cameras and platform, correctness of anglemeasuring data of theodolite,etc. A series of validation experiments and experiments insome practical tasks, which obtain the platform pose variation of two differenttheodolite, and amend angle measurement data, are accomplished and improve theprecision of3D ballistic trajectory.3. Some requirements are not easy to be satisfied when use existing poseestimation methods to measure the theodolite wobble, such as the precision of the spacegeometric relationships between markers in cooperation structure, the precision ofcalibration for cameras, etc. Therefore, a pose variety measuring method for vehicletheodolite platform under simplified configuration conditions is proposed. Thevariations of pitch and yaw angle in two directions, which compose the3D posevariation of the platform, are detected through the two measurement units (eachmeasuring unit is composed by a camera and two cooperate feature points), respectively.4. A positioning method for the moving object by a moving monocular camera, i.e.,"monocular trajectory intersection method", is proposed and improved for opticalmeasurement equipments in airborne platform. The method breaks through thetraditional "point meet" mode, describe one object trajectory in a period of time withparametric function, and get these parameters by solving a set of linear equations directly, then calculate the position, speed, acceleration of the object. The necessary andsufficient conditions are given, and the methods which can confirm the optimal order ofthe parametric function and the best length of time which make the function be the bestto describe the object trajectory in this period of time.5. A pose estimation method for the moving object with a moving monocularcamera by extending "monocular trajectory intersection method" is proposed for opticalmeasurement equipments in airborne platform. The method get the trajectory of severalfeatures in an object by "monocular trajectory intersection method", and get the posevariation of the object according to the mutual relationship of these features, and theinvariability of these features such as the distance is as a criteria for pose optimization.