Where am I? Sensors and Methods for Mobile Robot Positioning
Where am I? Sensors and Methods for Mobile Robot Positioning
Where am I? Sensors and Methods for Mobile Robot Positioning
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Chapter 4: <strong>Sensors</strong> <strong>for</strong> Map-Based <strong>Positioning</strong> 127<br />
4.3.2 Safety First Systems Vehicular Obstacle Detection <strong>and</strong> Warning System<br />
Safety First Systems, Ltd., Plainview, NY, <strong>and</strong> General Microwave, Amityville, NY, have te<strong>am</strong>ed<br />
to develop <strong>and</strong> market a 10.525 GHz microwave unit (see Figure 4.37) <strong>for</strong> use as an automotive<br />
blind-spot alert <strong>for</strong> drivers when backing up or changing lanes [Siuru, 1994]. The narrowb<strong>and</strong> (100-<br />
kHz) modified-FMCW technique uses patent-pending phase discrimination augmentation <strong>for</strong> a 20-<br />
fold increase in achievable resolution. For ex<strong>am</strong>ple, a conventional FMCW system operating at<br />
10.525 GHz with a 50 MHz b<strong>and</strong>width is limited to a best-case range resolution of approximately<br />
3 meters (10 ft), while the improved approach can resolve distance to within 18 centimeters (0.6 ft)<br />
out to 12 meters (40 ft) [SFS]. Even greater accuracy <strong>and</strong> maximum ranges (i.e., 48 m — 160 ft) are<br />
possible with additional signal processing.<br />
Figure 4.37: Safety First/General Microwave Corporation's Collision<br />
Avoidance Radar, Model 1707A with two antennas. (Courtesy of Safety<br />
First/General Microwave Corp.)<br />
A prototype of the system delivered to Chrysler Corporation uses con<strong>for</strong>mal bistatic microstrip<br />
antennae mounted on the rear side panels <strong>and</strong> rear bumper of a minivan, <strong>and</strong> can detect both<br />
stationary <strong>and</strong> moving objects within the coverage patterns shown in Figure 4.38. Coarse range<br />
in<strong>for</strong>mation about reflecting targets is represented in four discrete range bins with individual TTL<br />
output lines: 0 to 1.83 meters (0 to 6 ft), 1.83 to 3.35 meters (6 to 11 ft), 3.35 to 6.1 meters (11 to<br />
20 ft), <strong>and</strong> > 6.1 m (20 ft). Average radiated power is about 50 µW with a three-percent duty cycle,<br />
effectively eliminating adjacent-system interference. The system requires 1.5 A from a single 9 to<br />
18 VDC supply.
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