Strain measurement by oscillator circuit sensor using dummy gauge

Abstract

The strain measurement system using a CMOS inverter oscillator circuit is simple and can be omit an amplifier because a counting device measures frequency changes of circuit voltage output caused by resistance changes of a strain gauge. Moreover, the miniaturization and the creation of a wireless system become possible easily, and this system is an effective method which can be applied to large-scale strain measurement and strain measurement on rotating elements. However, this measuring method may be subject to the influences of temperature properties of elements used in the circuit and an external noise, because the resistance change of a strain gauge is measured directly by the oscillator circuit. In this study, static tensile tests were carried out and the tensile strains were measured by using this measuring method. Through the test results, it has been shown that, by using a dummy gauge in addition to a strain gauge for measurement and taking the difference of both output results, the influences have been deleted and the measurement accuracy has been improved.