Simple Minigyro Achieves Accuracy
Laurel M. Sheppard
WILMINGTON, Mass. -- Measuring angular rotation is essential to the proper operation of missile guidance systems, satellites, automotive skid control and navigation systems, and other applications. Commercially available gyros can be limited in size, accuracy, sensitivity and durability, but higher performance comes at a premium. For instance, gyros with a sensitivity of about 1° per hour can cost $5000 to $10,000 each.
IntelliSense Corp. has designed an optical minigyro that displays the same level of sensitivity for about $250 each in volume, said Doug Finke, vice president of marketing. The low cost is the result of inexpensive components, limited assembly and audio-frequency electronics.
The device has an accuracy of 200 pulses per minute and an angle random walk of 0.01° per square-root hour. Other advantages include a wide dynamic range, a high immunity to shock and vibration (because there are no moving parts), and a compact design. The components fit in a 2 x 2 x 2-cm package, compared with 15 x 15 x 13 cm for a conventional gyro. "Most of today's gyros can't survive high-vibration environments like might be found in oil drilling, like ours can," Finke said.
The gyro consists of four major components: a waveguide integrated into a glass chip, a laser diode light source, two photodetectors to collect the data and electronics to process it. The device operates on the sagnac effect. Tunable light is injected into clockwise and counterclockwise resonator fields, and photodiodes detect the light output at the end of each path. The resulting path lengths produce different resonant wavelengths. Angular motion is calculated by analyzing the shift in those wavelengths.
IntelliSense has a prototype and is looking for a partner to help market the product, said Christos Monovoukas, manager of the integrated optics group. "If things go as planned, we expect our product to be on the market in one or two years."
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