Research On The 4-D Coordinate Measurement System With CCD Technology

Loading missiles on the emissive vehicle automatically, the positional relationship between the emissive vehicle and loading vehicle must be acquired.With the development of Single Chip Micyoco - SCM, Charge Coupled Devices - CCD - are used widely in the field of noncontact position measurement. But for the noncontact position measuring systems that are used interiorly or overseas, some can't acquire both the distance parameters and the angle parameters, others are very complicated because of the using of more than one CCD detectors.A noncontact 3-D position measurement system is introduced in this thesis. The system is composed of a planner array CCD detector, real time image analysis and quick data calculation system, which can survey the positional relationship between the haloid lamp objects on the emissive vehicle and the measuring system on the loading vehicle. The principle of the measurement is discussed and the parameter calculating equation is derived. At last, with the knowledge of trigonometry and error theory, the measuring precision of the system is analyzed.This article introduced a system can measured the parameter between the emissive vehicle and loading vehicle by using only one group CCD detector to meet the measure requirement with the feature such as simple structure, fast, accuracy and high precision.Main job and feature as following:(1) To introduce research result applied with CCD noncontact technology both domestic and abroad and basic institution by military EO system. Considering the merits and defects available with noncontact measuring system, an 4-D coordinate measuring system consist of CCD, telecentric optical lay out on image plane, real-time image process and fast data resolve calculate was put forward. Haloid lamp at the end of emissive vehicle is used as the target of measurement. All parameters after image process and data calculated can be obtained when CCD detector pass the telecentric optical lay out on image plane and received aimed image. (2) To introduce basic work principle of CCD, basic character parameter of CCD, present mainly basic principle and applied condition of optical system-telecentric system. And present separately the principle of sight error and measure error between objective optical system and telecentric system.(3) To calculate and establish model of two vehicle face-to-face with 4-target area array CCD and 4-target linear array CCD and 3-target array, and edit 3-target area array CCD simulation program. After analyze, compare under three circumstances of mathematics'calculate, establish model process, we can conclude: 1) 4-target method has clear space relationship, simple mathematical model, less calculate process, but its prerequisite is rather strict, require two vehicles level parallel with horizontal line or make two vehicle at same level by adjust and minus two parameters for 4-target calculate. 2) 3-target method may judge the parallel extent of the two vehicle or omit adjust process and improve the measurement speed by simple the structure system. To apply the method on the measurement of space location relation of any two 3-D practically. 3) 4-target( 3-target) face array CCD method cut the motion step, shorten measurement time, make less error and improve accuracy compare with linear array.(4) Take the 4-target linear array CCD method as an example, focus on analyze the key section structure design and set up. After analyze and compare four key technologies like image data, subpixel, imitate process and digital process, author proposed the initial solution scheme. It is adopt TMS320VC33 processor to finish image data collection. To get CCD spot energy center by several image element output message through gravity method. To realize subpixel for sub element accuracy, adopt CDS and PDA related technology and use high density special processor chip and provide electricity and full isolate technology process according to the character of CCD detector. Transport data with pingpang structure by 4 FIFO.(5) For better scheme, imitate research and accuracy analyze the 4-target area array CCD method and 4-target linear array. Edit 4-target area array CCD method and 4-target linear array CCD method to imitate calculate program. Compute the measurement accuracy of every parameter at different range. The system error is mainly decided by analyze the theory and experiment result: 1) The dimension (H, L) between targets: the distance is larger, the error value is smaller. Increase the distance will increase the detection range; require CCD with larger image element area. 2) The accuracy between targets and focus distance accuracy of optical system. The error belongs to system error can be exclude by system adjust. 3) CCD element dimension: it is the main resource of system error. The error by CCD is the half when test. Therefore it can improve the system measurement accuracy by using smaller image dimension.(6) By comparison with three measurements method, concluded that use area array CCD system structure simple, measuring speed fast, error of angle measure smaller. But Y direction with larger measurement error, relative linear array CCD is rather expensive at same circumstance. The error on X, Y, Z direction of linear array CCD system is rather smaller. When measuring, its scope increased due to horizontal rotate scanning, it increased the detection time and added angle error.Linear array CCD should be used when the measuring vehicle face to face if the measuring scope larger and measuring speed lower. Area array should be used if need real-time measurement.The system at imitation period in laboratory has just been finished due to time factors. The target spot has some divergence with the practical haloid lamp required. It is different between measurement place and real war environment. 4-target area array CCD system, 3-target area array CCD systems haven't been finished yet according to practical experiment and accuracy test job. CCD image system and DSP processor unit is only at initial structure design and build. They have not been tested. The CCD 4-D coordinate measurement application it feasible from theory analyze and experiment result.The 4-D coordinate measurement system introduced in this article has the characters with simple structure, fast, accuracy and high precision from the theory analyze and experiment result. It can provide a new thought and method for noncontact measurement technology with applied engineering value.