A Digital Force Transducer

A digital force transducer design, more specifically defined as an indirect digital device, is described. This device retains most of the advantages of analog force transducers and incorporates the stability and computer compatibility of digital systems. The digital force transducer is capable of handling forces of up to 700 g, with the sensor currently used, at an 8-bit resolution of 4 g. The interrogate rate is 7 kHz, permitting identification of force frequencies of well over I kHz. The linearity is better than ±0.1 percent±one-half of the least significant bit (LSB), the repeatability is better than ±0.25 percent of full scale. The device design described has been highly reliable over a three-year period seeing almost daily use. The transducer is used as an integral part of an all-digital tensile tester where its performance exceeds that required by the test system. The transducer is economical to design and build when compared to analog transducers coupled to commercial analog-to-digital (A-D) hardware.