Data acquisition of mechanical devices: a new way to think

In today's environment of high speed personal computers and laptops, acquisition system design has remained unaffected. Most systems use interface electronics to convert a mechanical signal representing either positional movement or rate of change into an analog or digital format. This interface is a series of conversions from a complicated electrical signal into a simple one and is done outside the computer to simplify software. With the speed of today's systems, this task is better done in software for many applications. In the world of jet engine testing, sensors on the engine are used to measure parameters while testing the engine; there is the common resistance temperature device (RTD) and thermocouple, but there are also syncros/resolvers, vibration transducers, flowmeters and tachometers. Current state-of-the-art testers rely on expensive electronics to convert these latter signals into analog or digital format, to then be processed through the computer into calibrated and scaled units for display and calculations. These transducers specifically could be measured with simple analog channels and mathematically processed in software, allowing a much simplified and less expensive system both in terms of total system hardware as well as software. Topics covered by this paper will be discussed by individual sensor type. The mathematics involved and LabVIEW methods of measurement will be detailed, including a discussion of the methods used to apply this way of thinking to other types of transducers.