PARAMETER SELECTION FOR CORRELATION-BASED PARTICLE-VELOCITY SENSORS

Two optical sensors were developed to measure velocities of glass bead s, soybeans, and chopped wheat straw Velocities were determined using a cross-correlation method derived through fast Fourier transformation s. Optimum sampling frequencies and sample sizes within different velo city ranges were determined for real-time velocity measurements. Stati stical analysis showed that the optimum sample size is determined main ly by the size and type of the particles. For the glass beads, soybean s, and chopped wheat straw the optimum sample sizes were 512, 128, and 256, respectively. Once the sample size is determined the optimum sam pling frequency can be determined based on the range of velocity to be measured With the optimum measurement parameters selected, the measur ement errors can be limited within 5%, 6%, and 3% for glass beads, soy beans, and chopped wheat straw, respectively. This method is insensiti ve to particle shape and color For real-time measurement, digital sign al processing using the fast Fourier transformation method is recommen ded.