DSP’s Image Processing And Error Evaluation Technology In Spatial Straightness Error Measurement

Spatial straightness error measurement is one of the basic items of the measurement field,but also a important item of project manufacture. With the development of science andtechnology, there is a higher demand for straightness measurement for a longer measuringrange and higher precision. A long range spatial straightness error measuring system wasdeveloped in this paper, which use non-diffracting beam as the benchmark of the spatial lineand use CCD as the measurement device to embody the straightness deviation and useDM6437of TI Co. as the core of data processing unit. The main task of this paper can besummarized as three parts just as follows:(1)Proposed an algorithm that appropriate to process the Bessel imageThe main characteristics of the non-diffracting beam image was analyzed and by full useof which the Image processing algorithm was developed. With a view to the algorithmcompatibility of fixed-point DSP, an algorithm was presented that use the center of gravitymethod partly as the first center and the center of Generalized Hough Transform as the secondcenter and by which then the whole circle was generated. Do ellipse fitting by all thestatistical characteristic points of the composition of the circle at last and the sub-pixelaccuracy center of Bessel image was obtained. The algorithm was tested by usingexperimental images.(2)Developed an application software for image processing based on DSPFor processing of video stream that captured by the CCD, TI’s multi-media digital signalprocessor DM6437was selected as the processing platform. The performance of DM6437was introduced and the storage of the YUV video format was analyzed. When developing thesoftware of the system that based in DSP, the GIO/FVID model was selected and FVIDfunction was called in application level to manage the video channel.(3)Proposed a method to evaluate spatial straightness errorWith the ideology of median plane projecting and rotating the axis of minimumenclosure cylinder in determined–direction, a new algorithm was presented in this paper toevaluate the spatial straightness error. After analyzing the experimental data and Compared with other methods, the searching direction is determined and there is no iteration in thisalgorithm. The result of this method is precise and the method is very robust. The straightnesserror of the lead rail of a lathe was measured in this paper at last to check the reliability of thesystem and the error-evaluation method.