Non-contact strip speed measurement using electrostatic sensing and correlation signal-processing techniques

Accurate and reliable strip speed measurement is desirable in many manufacturing industries for both monitoring and control purposes. This paper presents the recent development in non-contact measurement of strip speed using electrostatic sensors in combination with correlation signal-processing techniques. A pair of metal electrodes is used to obtain signals from the moving strip. The speed of the strip is then determined from the known fixed spacing between the electrodes and the time delay between the two signals. Experimental tests were conducted on a motorized strip speed test rig under a range of conditions. An optical tachometer was used as a reference instrument to gauge the accuracy of the strip speed measurement system. The system design considerations, advantages and limitations are addressed. Results demonstrate that the system is capable of measuring strip speed robustly with a relative error not greater than 1.8% and a repeatability of 2.5% over the speed range of 0.8 to 10 m s^-1.