Very High Speed Digital Accelerometer

1. Description
2. Application

Description

• No analog to digital signal conversion.
• Fast Fourier transform performed by sensor.
• Dynamic range: > 160 dB
• Evaluated for crashbag sensor by GM.

Figure 1: Off-axis input - demo of axis isolation

• 1024 bits per mark at 60 Hz sampling = 17.06 second/mark.
• No false output during 2+ timing marks (34.12+ seconds) shown.

Figure 2: Gravity on-axis as input demo of single axis sensitivity

• Front impact crash bag sensor designed to read acceleration in positive x-axis only.
• Dual axis available if dynamic range reduced.

Figure 3: Launch & free-fall with multi-impacts output

• Sensor attached to heavy steel plate.
• Fell 30" to concrete.
• Note: response to 1st & 2nd impacts before stopping.
• Note: no drift in rest position.

Accelerometer/Transducer release letter from Hughes Aircraft

Hughes Aircraft superior performance award

Application

http://geopubs.wr.usgs.gov/open-file/of03-159/of03-159.pdf
http://scitation.aip.org/getpdf/servlet/GetPDFServlet
?filetype=pdf&id=EASPEF000021000001000091000001

TREMOR: A Wireless, MEMS Accelerograph for Dense Arrays

By John R. Evans, Robert H. Hamstra, Jr., Paul Spudich, Christoph Kundig, Patrick Camina, and John A. Rogers

Open-file Report 03-159

...

Table 1. A classification of strong-motion instruments.

Class	Resolution *	Retail Cost
A	≥ 20 bits ≥ 120 dB	~$7000, quantity 100
B	16-19 bits 96-114 dB	~$2500, quantity 1000
C	12-15 bits 72-90 dB	<$1000, quantity 10,000

* For RMS noise versus full-scale range.

...