Landing Gear Strain Measurement

Landing Gear Strain Measurement

© 2007 United Electronic Industries, Inc. All Rights Reserved.

App Note #015

Landing Gear Strain Measurement — Application:

A

large NASA funded research facility needed a way to test the strength and stability of a landing “gear” designed for use in a future Mars landing vehicle. A prototype of the landing gear was developed and was to be subject to “drop” tests designed to simulate the stress profile of an actual landing. The engineers challenge was to find a system that could sample 90 strain gage inputs (simultaneously) as well as acquire data from accelerometers, rate gyros and quadrature encoders and was: 1) light enough to not compromise the simulated crafts weight or balance, 2) rugged enough to survive 30 g landing forces and 3) could be wired to a host computer with wires light and flexible enough wires not to impact the drop dyanamics. The DNA-PPC8 PowerDNA cube with its 6 I/O slots fit the bill perfectly. Using the 25-channel DNA-AI-225 all 96 analog input channels could be handled with four I/O boards, leaving one slot for the DNA-CT-601 counter board

© 2007 United Electronic Industries, Inc. All Rights Reserved.

for quadrature encoder inputs and on free slot. This means the entire DAQ system fit in a single 4” x 4” x 5.8” cube weighing under four pounds. The PowerDNA Cube’s 50 g shock and 5 g vibration specifications also were up to the task. Finally, the Cube’s wide 9-36 VDC power requirement meant the system could draw power from batteries already on the simulator, leaving only a simple Ethernet cable required to connect the DAQ system to the host PC. The application was developed in LabVIEW RT, and run on standard desktop computer. The PowerDNA products used in the system include: Product Description / Usage 6 slot, PowerDNA Cube DNA-PPC8 DNA-AI-225 25-channel, 24-bit simultaneously sampling A/D cards

used to monitor the strain, accelerometer and rate Gyro channels

DNA-CT-601

8-channel counter timer boards are used as counters to monitor the quadrature encoder input signals.

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Landing Gear Strain Measurement — UEI Products Used:

DNA-PPC8

DNA-AI-225

The PowerDNA® (Distributed Networked Automation) Cube is a compact, rugged, Ethernet based DAQ interface. Its flexibility allows you to configure one or more cubes to match the specific I/O requirements of your application. The PowerDNA Cube is ideally suited for a wide variety of industrial, aerospace and laboratory data acquisition and control applications.

True 24-bit resolution makes DNA-AI-225 offers ultra-high resolution going into the microvolt level across the full input range, with one converter per channel with simultaneous sampling across all 25 independent ADCs and outstanding linearity. Long-term gain and offset drifts, as well as drift vs. temperature ratio, make it useful in a wide range of applications.

© 2007 United Electronic Industries, Inc. All Rights Reserved.

DNA-CT-601 The DNA-CT-601 is a general-purpose counter/timer layer that provides eight independent 32-bit channels, each one having overvoltage protection and optoisolation. They perform up/down counting in a number of flexible modes. The counters also will generate PWM outputs or monitor Quadrature encoder inputs.

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Founded in 1990, UEI is a leader in the computer based data acquisition and control industry. Serving customers world-wide, UEI products based upon PCI, PXI, ISA and Ethernet interfaces offer unequaled performance as well as flexibility. We are committed to providing the highest quality hardware, software and services, enabling engineers and scientists to interface data-acquisition and control hardware to the real world. Through our state-of-the-art technologies we serve the needs of individual researchers and developers as well as OEMs. 27 Renmar Avenue Walpole, MA 02081 Phone: (508) 921-4600 Fax: (508) 668-2350 www.UEIDAQ.com

© 2007 United Electronic Industries, Inc.