Assessment Of Motion Parameters Of A Moving Object Through Image Processing

Abstract

On this paper, we set out a system which deals with the extraction of speed and position vectors of a target in an image sequence with standard technological elements within a minimum time. The application field, we want to deal with is the one of robotics and the automatic tracking of vehicules. The strategy which is used to build such a system requires three complementary techniques : optics, electronics and data processing of which respective functions are filtering, the operation of difference and the calculation of dynamic parameters. The speed of optical treatments combined with electronics leads to a real time isotrope edge detector, it's space cut-off frequency being adjustable. Based on the unsharp masking technique this extractor carries out the difference between a sharp image and the same image which has been previously defocussed. Therefore this modified image is quantized according to statistical criteria. This process optimizes the number of quantization levels useful for a given S.N.R. in order to reduce the size of the digital image. It means to reduce further calculation time. At last a fast template matching algorithm is carried out from partial correlation functions. These functions are calculated for each level of quantization and modified by a relative weighting. Lastly, a simple numerical calculation assesses the speed and position of the target. The performances of this process allow us to reach calculation times below 200 ms on a standard 3 MIPS processor when dealing with most of the tracking problems and in presence of "noise" as well. For instance, this device can either measure the automatic tracking of an all roads vehicule in a field, or the automatic hold of an object moving on an assembly line thanks to a robot.