Enhancing the performance of a rotational speed measurement system through data fusion

Electrostatic sensors with a single electrode or double electrodes have been applied for rotational speed measurement. In order to improve the performance of the rotational speed measurement system based on double electrostatic sensors, a data fusion algorithm is incorporated in the system. Two independent signals are accessible from the electrostatic sensor with double electrodes. From these signals two independent rotational speed measurements are obtained through auto-correlation processing of each signal and the third rotational speed measurement is also achieved by cross-correlating the two signals. A data fusion algorithm is then applied to optimally combine the three measurements. The system with the data fusion algorithm is capable of producing more accurate and more robust measurements than previous double-sensor system with a wider measurement range. Experimental results suggest that the relative error of the improved system is mostly within ±0.5% over the speed range of 200 rpm - 3000 rpm.