Signal processing interface for displacement measurement

Abstract

In this paper, we present a signal-processing interface for previously developed inductive displacement sensor, whose inductance is proportional to the displacement. This measurement interface is based on the measuring of the root mean square (RMS) value of the voltage on the sensor. A hardware realization of signal processing interface is described in details. It uses 8 MHz as measuring frequency, which is the highest frequency ensuring good measurement resolution and measuring rate with no accuracy degradation caused by increased resistance due to skin effect. The interface is intended for application in robotics, where fast measurement is needed for precise control of robot actuators, but it can be easily adapted for use in other applications. Measurement results obtained by the interface are compared with values obtained by impedance analyzer and simulation tool. High measurement rate of this method is very useful in systems where continuous and real-time measurement of inductance is needed. The presented method ensures good resolution, accuracy and high measurement rates of very small inductances, in the order of nH. In addition, the interface can be easily adapted for use in other applications (such as measuring capacitance) with no changes in hardware. © 2013 American Scientific Publishers.