Improving Test Integrity & Setup
The challenges facing today’s test engineers are more complex than ever. Demands for greater, reliability and safety, combined with new materials and advances in complex electronics can create a perplexing test landscape. Even with the myriad of available test simulations, data recording is an important part of virtually all validation processes.
Measuring a wide range of steady state and transient inputs that aircraft, spacecraft, missiles, rockets, trains, motorsport equipment, and bicycles typically experience during operation, the field data from accelerometers, load cells, strain gages and thermocouples is used for analyzing structural integrity, dynamic test systems and troubleshooting.
The early days of data gathering used large, bulky analog tape recorders that required serious space, as well as external sensor signal conditioning. DC typically powered the recorder via an inverter and the sensor cables were routed via long, complex paths to the many transducers.
Set-up was time-consuming and required a fair amount of ingenuity to get the data acquisition system (DAS) and sensors secured. Extra provisions were also needed to isolate the systems from high shock loads and the dirty test environments.
Today’s DAS systems have evolved to digital recording, integrated signal conditioning and much smaller form factors. And while test set-up and data processing are much easier, there are still the problems inherent with long, complex cable runs.
Longer sensor cabling means more resistance. This can result in under-powering the transducers, signal drop between the transducer and the DAS, noise from cable motion or surrounding electrical interference, and so on. One solution is to position the DAS near the sensor, but that is often easier said than done, especially with today’s compact and electric vehicles.
The next challenge is adverse test environments. For meaningful data, the sensors (and DAS) need to be situated in high interest areas that typically experience environmental extremes including shock, vibration, temperature, humidity and grime. In-situ placement of the DAS also requires system autonomy. In other words, the DAS needs to function in a standalone mode, without a tethered PC or controlling device. Then add size, mass and power considerations and you have a test challenge on your hands.
The SLICE product family developed by DTS (Diversified Technical Systems, Inc.) in Seal Beach, California, overcomes these challenges and is well suited for data acquisition. With SLICE, gathering data is now much easier. Small form factor and embedded options allow the SLICE data acquisition system to be placed near the sensors, thus reducing cabling requirements, improving data integrity and significantly reducing test set-up time.
DTS has specialized in embedded, high integrity data recorders for over 24 years. SLICE MICRO and SLICE NANO are ultra-small, standalone data acquisition systems with full signal conditioning and sensor excitation. SLICE systems are comprised of a Base module containing the system CPU, a USB hub and 7 GB of flash memory for data storage.
Then 3-channel sensor input SLICEs are stacked onto the Base to create a DAS that supports a variety of sensor types including bridge, IEPE, and thermocouples. Each SLICE stack holds up to 24-channels (8 layers) and can be daisy-chained for higher channel count systems. It can record multi-channel tests for hours and stores all data to flash.
A simple interface provides power, trigger and communication signals for full onboard autonomy for RLD gathering. SLICE is shock rated to 500 g and meets NHTSA, ISO 6487 and SAE J211 data acquisition practices.
Another option for data recording is the SLICE PRO system that functions in much the same way as the SLICE MICRO and SLICE NANO but with higher channel density, more onboard memory and an internal rechargeable battery.