Communications: electrical – Aircraft alarm or indicating systems – Potential collision with other aircraft
Reexamination Certificate
1998-11-16
2001-03-27
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Aircraft alarm or indicating systems
Potential collision with other aircraft
C340S435000, C340S903000, C342S029000, C701S301000
Reexamination Certificate
active
06208270
ABSTRACT:
TECHNICAL FIELD
This invention relates to optical sensing, and more particularly to a device and method for detecting hazard obstacles for aircraft.
BACKGROUND
Aircraft flying at a relatively low altitude may be subject to risks of colliding with hazard obstacles such as utility wires hung from towers and other high-rise structures. Therefore, it is desirable to provide aircraft with a hazard detection and warning system to improve the aircraft safety.
One way to detect a hazardous object uses “passive” sensing devices to detect radiation emitted from the object. For example, light-sensitive detectors such as CCDs may be used to capture the image of a hazard object or an infrared detector to sense the thermal radiation of an object.
Another detection scheme uses “active” systems which emit certain electromagnetic waves to actively search for hazardous objects by detecting the reflected electromagnetic waves. The time delay between transmitting and receiving a signal may be used to determine the distance of an object and the phase information of the reflected signal(s) may be analyzed to indicate the relative direction and shape of the object.
One implementation of such active detection scheme is the Radar (i.e., radio detection and ranging), in which radio signals are used to probe a radio-reflective object. Another implementation uses laser pulses as the probing signals to detect light-reflective objects by sensing the reflected laser pulses. Since the laser pulses play the similar role as the radio signals in Radar, the latter is also known as light detection and ranging or “Lidar”.
SUMMARY
The present invention employs the concept of Lidar in a special way to provide a hazard detection and warning system for low-flying aircraft.
One embodiment of the invention projects a laser beam ahead of the aircraft and detects targets closer than some predetermined maximum range from the aircraft. The laser beam is scanned along the perimeter of a predetermined pattern with respect to the aircraft. The scan pattern may be circular or elliptical and centered along the flight direction of the aircraft. At the predetermined maximum range, the scan pattern may be expanded to a size larger than the aircraft forwarded profile.
One aspect of the invention is a combination of the beam scanner and range measurement, which is referred to as “dynamic parallax”. The total propagation time for the laser beam to travel from the aircraft to the target and back to the aircraft due to reflection can be used to allow the scanner to effectively “move” the apparent position of the detector off the target. This sets the maximum and minimum detection range by the placement of the detector.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will become apparent from the description and drawings, and from the claims.
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patent: 4250389 (1981-02-01), Brendl et al.
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patent: 5323259 (1994-06-01), Gibbs
patent: 5448233 (1995-09-01), Saban et al.
patent: 5461357 (1995-10-01), Yoshioka et al.
Fish & Richardson P.C.
Swarthout Brent A.
Thermotrex Corporation
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