AN EXPERIMENTAL-ANALYSIS OF ACCURACY AND PRECISION OF A HIGH-SPEED STRAIN-GAUGE SYSTEM BASED ON THE DIRECT-RESISTANCE METHOD

An experimental study about the relative merits of using a high-speed digital-acquisition system to measure directly the strain-gage resistance rather than using a conventional Wheatstone bridge, is carried out. Both strain gages, with a nominal resistance of 120-OMEGA and 1 k-OMEGA, are simulated with precision resistors and the output signals were acquired over a time of 48 and 144 hours; furthermore, the effects in metrological performances caused by a statistical filtering are evaluated. The results show that the implementation of the statistical filtering gains a considerable improvement in gathering strain-gage-resistance readings. On the other hand such a procedure causes, obviously, a loss of performance with regard to the acquisition rate, therefore to the dynamic data-collecting capabilities. In any case the intrinsic resolution of the 12-bit a/d converter, utilized in the present experimental analysis, causes a limitation for measurement accuracy in the range of hundreds-mu-m/m.