Velocity measurement using phase orthogonal spatial filters

The authors developed a velocity measurement system based on a spatial filtering method. A charge coupled device (CCD) line sensor was used to detect the object pattern, and a DSP (TMS32025) performed the spatial filtering calculations. Because the selectivity of the spatial filter was fixed, the measurement accuracy of this approach is generally influenced by the condition of the object pattern. A method that improves the accuracy of the velocity measurement by using two pairs of spatial filters with phases orthogonal spatial weighing functions was developed. The new method of velocity measurement is described with some experimental results