U.S. patent application number 15/017263 was filed with the patent office on 2017-08-10 for visual landing aids for unmanned aerial systems.
The applicant listed for this patent is Alex Barchet, Jordan Holt, Jeremy Sarao. Invention is credited to Alex Barchet, Jordan Holt, Jeremy Sarao.
Application Number | 20170225800 15/017263 |
Document ID | / |
Family ID | 59496758 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170225800 |
Kind Code |
A1 |
Holt; Jordan ; et
al. |
August 10, 2017 |
VISUAL LANDING AIDS FOR UNMANNED AERIAL SYSTEMS
Abstract
Visual landing aids including a series of contrasting circles
and polygons for unmanned aerial vehicles that are capable of being
accurately detected over a wide range of angles and distances by an
unmanned aerial vehicle equipped with a camera and shape detection
capabilities. The visual landing said may be implemented using
contrasting colors for the pattern which reflect visible and/or UV
or infrared light, or by light emitting elements. In some examples,
the landing aids includes a secondary smaller version of the
landing aid shape pattern that is embedded within the larger
pattern, to enable greater detection range while facilitating
close-in precision guidance. In still further examples, light
emitting elements may be pulsed at a rate that is synchronized with
the camera shutter on the unmanned aerial vehicle to further
enhance accurate detection.
Inventors: |
Holt; Jordan; (Portland,
OR) ; Sarao; Jeremy; (Portland, OR) ; Barchet;
Alex; (Hood River, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Holt; Jordan
Sarao; Jeremy
Barchet; Alex |
Portland
Portland
Hood River |
OR
OR
OR |
US
US
US |
|
|
Family ID: |
59496758 |
Appl. No.: |
15/017263 |
Filed: |
February 5, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06K 9/3216 20130101;
B64C 39/024 20130101; G08G 5/0026 20130101; G08G 5/0069 20130101;
B64F 1/007 20130101; B64F 1/18 20130101; B64C 2201/127 20130101;
B64C 2201/18 20130101; B64C 19/00 20130101; G08G 5/025 20130101;
G08G 5/0021 20130101; B64C 2201/027 20130101; G06K 9/00637
20130101; B64C 2201/141 20130101 |
International
Class: |
B64F 1/18 20060101
B64F001/18; B64C 19/00 20060101 B64C019/00; G08G 5/00 20060101
G08G005/00; G08G 5/02 20060101 G08G005/02 |
Claims
1. A visual landing aid for unmanned aerial vehicles, comprising: a
background; and a plurality of shapes in a color that contrasts
with the background arranged in a mathematically verifiable pattern
that is useful for determining the orientation and distance of an
unmanned aerial vehicle to relative to the visual landing aid, the
plurality of shapes comprising a plurality of circles each of the
same diameter, wherein each of the plurality of shapes is spaced
apart from each other at least the diameter of one of the plurality
of circles, and the plurality of shapes are capable of being
recognized by a camera and image processing system on board the
unmanned aerial vehicle.
2. (canceled)
3. The visual landing aid of claim 2, wherein the one or more
shapes further comprise one or more polygons, each of the one or
more polygons having an area equal to or greater than that of the
circle.
4. The visual landing aid of claim 2, wherein the one or more
shapes comprise: a first pattern; and a second pattern that is a
reduced-size mirror image of the first pattern.
5. The visual landing aid of claim 2, wherein the one or more
shapes comprise: a first pattern; and a second pattern that is a
reduced-size reversed-contrast image of the first pattern.
6. The visual landing aid of claim 1, wherein the one or more
shapes are arranged in a pattern on the background that is
distinguishable from the environment surrounding the visual landing
aid.
7. The visual landing aid of claim 1, wherein the one or more
shapes are painted upon the background in a color that is
contrasting in the visual spectrum.
8. The visual landing aid of claim 1, wherein the one or more
shapes are comprised of one or more illuminated elements.
9. The visual landing aid of claim 1, wherein the one or more
shapes are visible to an infrared camera.
10. A system for assisting automatic landing of an unmanned aerial
vehicle, comprising: a visual target further comprised of a
plurality of shapes in a contrasting color from a background, the
plurality of shapes comprising a plurality of circles each of the
same diameter and spaced from each other at least the diameter of
one of the plurality of circles; at least one camera capable of
detecting the visual target; a processor unit in data communication
with the camera for detecting the visual target; and a flight
controller system in data communication with the processor unit for
guiding the unmanned aerial vehicle relative to the visual
target.
11. The system of claim 10, wherein the camera, processor unit, and
flight controller system are all located onboard the unmanned
aerial vehicle.
12. The system of claim 10, wherein the visual target further
comprises one or more polygons.
13. The system of claim 12, wherein the one or more shapes of the
visual target reflect visible light.
14. The system of claim 12, wherein the one or more shapes of the
visual target reflect infrared light.
15. The system of claim 12, wherein the one or more shapes of the
visual target emit light.
16. The system of claim 15, wherein the one or more shapes of the
visual target emit light in a pulsed fashion that is synchronized
to the frame rate of the camera.
17. An unmanned aerial vehicle landing system, comprising: an
unmanned aerial vehicle, further comprising a camera, an image
processing unit in data communication with the camera, and a flight
controller in data communication with the image processing unit;
and a visual landing aid, further comprising a background of a
first color, and a plurality of shapes of a second color that
visually contrasts with the first color, the plurality of shapes
arranged in a mathematically verifiable pattern; wherein: the image
processing unit is capable of detecting the mathematically
verifiable pattern of the visual landing aid when the visual
landing aid is within the camera's view, the plurality of shapes
further comprise a plurality of circles of identical size, spaced
apart from each other at least the diameter of one of the plurality
of circles, and the flight controller is capable of directing the
unmanned aerial vehicle relative to the visual landing aid on the
basis of the detected mathematically verifiable pattern.
18. The landing system of claim 17, wherein the plurality of shapes
further comprise at least one polygon.
19. The landing system of claim 18, wherein the plurality of shapes
further comprise: a first mathematically verifiable pattern; and a
second mathematically verifiable pattern of a reduced size that is
contained within the first mathematically verifiable pattern.
20. The landing system of claim 19, wherein the second
mathematically verifiable pattern provides a landing point for the
unmanned aerial vehicle.
Description
BACKGROUND
[0001] The present disclosure relates generally to landing systems
for unmanned aerial vehicles. In particular, visual landing aids
for camera-equipped unmanned aerial vehicles are described.
[0002] Known systems and methods for landing for unmanned aerial
vehicles are not entirely satisfactory for the range of
applications in which they are employed. For example, existing
systems and methods typically employ either GPS positioning, some
type of laser or radar range finding, human intervention or manual
control, or some combination of the foregoing. GPS positioning is
subject to potential loss of satellite signal, and to be fully
effective requires the loading of a terrain database into the
unmanned aerial vehicle's flight controller. Without the terrain
database, the unmanned aerial vehicle will not know its height
above ground in order to make a correct landing and, in any event,
can suffer limited precision. Laser or radar range finding requires
additional equipment on the unmanned aerial vehicle which
diminishes payload, and while providing accurate vertical guidance,
does not by itself provide for homing into a particular designated
landing target. Human intervention and manual control, while being
accurate, is subject to pilot error and precludes a fully
autonomous mission profile.
[0003] Finally, conventional landing targets may be subject to
false positives and/or may require special hardware for detection.
Landing aids that use radio beacons may be subject to jamming or
glitches.
[0004] Thus, there exists a need for landing aids that improve upon
and advance the design of known systems and methods for landing
unmanned aerial vehicles. Examples of new and useful landing aids
relevant to the needs existing in the field are discussed
below.
[0005] Disclosure addressing one or more of the identified existing
needs is provided in the detailed description below. Examples of
references relevant to visual landing aids include U.S. Patent
References: U.S. Pat. No. 7,705,879 and patent application
publication US20090009596. The complete disclosures of the above
patents and patent applications are herein incorporated by
reference for all purposes.
SUMMARY
[0006] The present disclosure is directed to a visual landing aid
comprised of a series of circles and polygons for unmanned aerial
vehicles that is capable of being accurately detected over a wide
range of angles and distances by an unmanned aerial vehicle
equipped with a camera and shape detection capabilities. The visual
landing aid may be implemented using contrasting colors for the
pattern which reflect visible and/or UV or infrared light, or by
light emitting elements. In some examples, the landing aid includes
a secondary smaller version of the landing aid shape pattern that
is embedded within the larger pattern, to enable greater detection
range while facilitating close-in precision guidance. In still
further examples, the light emitting elements may be pulsed at a
rate that is synchronized with the camera shutter on the unmanned
aerial vehicle to further enhance accurate detection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A through 1F are diagrams of various arrangements of
visual landing aids.
[0008] FIG. 2A is a diagram of a second arrangement for a visual
landing aid, showing a secondary precision target pattern embedded
in the primary pattern that is presented in reverse contrast.
[0009] FIG. 2B is a diagram of the second arrangement for a visual
landing aid depicted in FIG. 2A, showing the secondary precision
target pattern embedded in the primary pattern presented in the
same contrast as the primary pattern.
[0010] FIG. 3 is a perspective view of an unmanned aerial vehicle
(UAV) in a flight setting where the visual landing aid can be used
to guide the UAV in for a landing.
[0011] FIG. 4 is a block diagram of the components on board a UAV
for image processing and detection of a visual landing aid to be
used to guide the UAV relative to the position of the visual
landing aid.
DETAILED DESCRIPTION
[0012] The disclosed visual landing aids will become better
understood through review of the following detailed description in
conjunction with the figures. The detailed description and figures
provide merely examples of the various inventions described herein.
Those skilled in the art will understand that the disclosed
examples may be varied, modified, and altered without departing
from the scope of the inventions described herein. Many variations
are contemplated for different applications and design
considerations; however, for the sake of brevity each and every
contemplated variation is not individually described in the
following detailed description.
[0013] Throughout the following detailed description, examples of
various visual landing aids are provided. Related features in the
examples may be identical, similar, or dissimilar in different
examples. For the sake of brevity, related features will not be
redundantly explained in each example. Instead, the use of related
feature names will cue the reader that the feature with a related
feature name may be similar to the related feature in an example
explained previously. Features specific to a given example will be
described in that particular example. The reader should understand
that a given feature need not be the same or similar to the
specific portrayal of a related feature in any given figure or
example.
[0014] With reference to FIGS. 1A-4, a first example of a visual
landing aid, landing aid 100, will now be described. Landing aid
100 functions to provide a fixed ground reference useful by an
unmanned aerial vehicle that is in flight to effect a precision
landing. Landing aid 100 is designed to be detectable by a wide
range of camera resolutions, at a wide range of distances, and in
any orientation. Moreover, landing aid 100 is intended to allow an
unmanned aerial vehicle to determine its orientation with respect
to landing aid 100. The reader will appreciate from the figures and
description below that landing aid 100 addresses shortcomings of
conventional visual landing aids.
[0015] For example, by providing a predetermined and fixed landing
point on the ground, landing aid 100 does not require the unmanned
aerial vehicle to rely upon a GPS database or onboard range finding
equipment. Landing aid 100 can allow an unmanned aerial vehicle to
guide itself into a landing point using only an onboard camera,
which is typically carried by unmanned aerial vehicles, and a
processing module capable of performing shape detection and
interfacing with the unmanned aerial vehicle's flight controller.
Further, landing aid 100 allows the unmanned aerial vehicle to land
itself precisely upon or near landing aid 100 completely
autonomously, without the need for human intervention. Landing aid
100, when implemented as a reflective target, is not itself subject
to equipment failure, and the shapes and colors of landing aid 100
can be selected so as to minimize false positives.
[0016] Landing aid 100 for unmanned aerial vehicles (UAVs) includes
a background 102, upon which are located one or more shapes 104 in
a color that contrasts with the background. Shapes 104 are arranged
in a mathematically verifiable pattern that is useful for
determining the orientation and distance of an unmanned aerial
vehicle (UAV) 300 to relative to the landing aid 100. The shapes
104 are capable of being detected by a camera and then recognized
by an image processing system on board UAV 300. In other examples,
landing aid 100 may include additional or alternative features,
such as a pulsed light source and possibly a beacon for
synchronizing with a camera located onboard UAV 300.
[0017] As can be seen in FIGS. 1A through 1F, shapes 104 comprise
at a minimum a plurality of circles, and can optionally include one
or more polygons 108, typically implemented as a rectangle, as seen
in FIGS. 1A and 1F, or as one or more conjoined rectangles, as can
be seen in FIGS. 1C and 1D. Each shape 104 has a minimum height
106, and is accordingly separated from all other shapes 104 by at
least minimum height 106, or preferably some integer multiple of
minimum height 106. It is seen in the figures that the various
shapes are arranged in an approximate grid-like fashion, and in a
pattern that is unique from all orientations, viz. there is no
mirroring of the pattern. This arrangement allows for ready
detection by UAV 300 and further allows UAV 300 to determine its
orientation relative to landing aid 100. Orientation determination
is useful if a landing approach is best effected from only certain
directions, such as where high terrain or obstacles surround most
of a landing site, or where landing systems such as hooks or nets
are employed that require UAV 300 to approach from a particular
direction to be snagged by the landing system.
[0018] The selection of circles and polygons on landing aid 100 is
intended to reduce false positives against most terrain. However,
other types of shapes that are detectable by machine shape
detection algorithms can be used for landing aid 100 without
departing from the disclosed invention. Moreover, other types of
machine readable patterns, such as bar codes, 2D matrices such as
QR codes, and other types of tags may be integrated into landing
aid 100 in order to reduce false positives, and to accurately and
positively identify a desired landing target.
[0019] One conventional implementation of landing aid 100 has
background 102 rendered in white, with shapes 104 rendered in
black, to provide maximum contrast. Alternatively, where landing
aid 100 is located within a predominantly light background,
background 102 may be rendered in black, with shapes 104 rendered
in white. Still further, background 102 and shapes 104 may be
rendered in any combination of colors and/or shades that
sufficiently contrast against each other as well as the surrounding
background. For example, where a landing aid 100 is placed within a
predominantly green background, background 102 may be colored in a
contrasting color such as red or blue, with shapes 104 rendered in
a color that contrasts against background 102. Thus, landing aid
100 is colored in such a fashion to be clearly detectable against
the surrounding environment. These various colors can be rendered
using paint, ink, or any other material that is reflective of the
desired colors in the visible light spectrum.
[0020] In addition to materials capable of reflecting and/or
absorbing visible light, the shape patterns on landing aid 100 can
be rendered using any material or method capable of rendering the
shape patterns in a sufficiently contrasting fashion that can be
detected by a camera system on UAV 300. For example, landing aid
100 could be rendered using materials that are reflective of
non-visible light, such as infrared or ultraviolet. Using infrared
reflective material for shapes 104 would allow UAV 300, when
equipped with a suitable infrared-sensitive camera, to locate
landing aid 100 in low-visibility or low-visible light conditions.
Furthermore, landing aid 100 could be rendered using light emitting
materials, such as lamps or LEDs, thereby allowing detection by and
guidance of UAV 300 in night or total darkness conditions, where a
landing aid 100 implemented using purely reflective materials would
be undetectable. Where landing aid 100 is implemented using light
emission, the light emission may be continuous or optionally
pulsed, which will be addressed in greater detail herein.
[0021] FIGS. 1A through 1F demonstrate multiple possible patterns
of shapes, although it will be appreciated by a person skilled in
the relevant art that possible patterns are not limited to the
depicted examples. The use of varying patterns allows landing aid
100 to be tailored so as to clearly contrast with the surrounding
environment. Furthermore, the flight controller of unmanned aerial
vehicle 300 can be programmed to recognize and track in on a single
pattern, thereby allowing several landing targets, each specific to
a particular UAV 300 to be placed proximate to each other.
[0022] Landing aid 100 can be scaled to any size, with larger sizes
being detectable at greater ranges, but having a practical limit of
needing to be within the field of view of whatever camera is
installed upon UAV 300. If landing aid 100 is too large, then UAV
300 will be unable to track in once landing aid 100 exceeds the
field of view of UAV 300's camera as UAV 300 draws near to landing
aid 100. The limit of potential detectability of landing aid 100
will depend upon the resolution of the camera installed upon UAV
300. In keeping with Nyquist's Theorem, landing aid 100 is only
detectable when the size of shapes 104 cover approximately four
pixels of the imaging sensor of UAV 300's camera; if shapes 104 do
not cover at least four pixels, they will become indistinct due to
aliasing. Thus, the higher the resolution of UAV 300's camera, the
smaller the associated pixels, and the greater the range of
potential detection of landing aid 100.
[0023] Turning attention to FIGS. 2A and 2B, a second variation of
landing aid 100 will now be described. Landing aid 200 includes
many similar or identical features to landing aid 100. Thus, for
the sake of brevity, each feature of landing aid 200 will not be
redundantly explained. Rather, key distinctions between landing aid
200 and landing aid 100 will be described in detail and the reader
should reference the discussion above for features substantially
similar between the two landing aids.
[0024] As can be seen in FIG. 2A, landing aid 200 includes a
background 202 with a series of shapes 204 set upon background 202
in contrasting colors. The configuration and contrasting colors
and/or shades of shapes 204 are identical to landing aid 100.
However, landing aid 200 also includes a close range target 206
which is embedded within one of the shapes 204, which is preferably
rendered in the same color or shade of background 202, thus causing
close range target 206 to contrast with surrounding shape 204. The
pattern of close range target 206 is preferably identical to the
pattern of shapes 204, but scaled down sufficiently with respect to
the size of landing aid 200 so as to become effective once UAV 300
approaches close enough so that landing aid 200 exceeds the field
of view of a camera attached to UAV 300. Thus, landing aid 200 can
be made larger than would be possible with landing aid 100, by
essentially nesting subsequently smaller landing aids so that UAV
300 always has a target within the field of view of its camera
until landing.
[0025] FIG. 2B, which depicts a landing aid 200, shows a variation
of landing aid 200 depicted in FIG. 2A. Close range target 208,
however, is rendered as a smaller version of landing aid 200, with
a small background and shapes that match the colors and/or shading
of background 202 and shapes 204.
[0026] It should be appreciated that, depending upon the size of
landing aid 200, close range targets 206 and 208 can further have
additional, smaller close range targets embedded within them, for
even greater precision. Furthermore, while close range targets 206
and 208 are depicted as having an identical pattern to landing aid
200, this is not necessary; close range targets 206 and 208 can be
different patterns, which can further signal a close range to UAV
300, or possibly trigger additional landing preparations in UAV
300, such as extending landing gear. Still further, close range
targets 206 and 208 do not need to be centered within the middle of
landing aid 200. The close range target can be located anywhere
upon landing aid 200 so long as it sufficiently contrasts against
background 202 or shapes 204, depending upon its location. It
should also be appreciated that close range targets 206 and 208
need not match the colors of background 202 and shapes 204, but can
be in additional different contrasting colors, as light emissive
elements, or can be implemented to reflect or emit non-visible
spectrum light such as UV or infrared.
[0027] FIG. 3 depicts landing aid 100 in use with UAV 300. UAV 300
is shown with a camera 302, which is capable of detecting landing
aid 100, which in turn is rendered in a fashion as described above
that is within the visual detection range of camera 302. Camera 302
is able to locate landing aid 100 along angle of view 310. By
centering landing aid 100 within the field of view of camera 302.
UAV 300 can make a precise approach to landing by following angle
of view 310, where landing aid 100 simply continually increases in
size as UAV 300 approaches. Furthermore, where camera 302 is
mounted on a gimbal, the angle of camera 302 relative to landing
aid 100 can be determined. Where UAV 300 is equipped with GPS
location, its altitude above ground can be known. As depicted in
FIG. 3, a right triangle can be visualized between landing aid 100
and UAV 300. By combining the angle of camera 302 with GPS
altitude, the distance to landing aid 100 can be approximated using
well-known trigonometric techniques, such as the law of sines.
[0028] UAV 300 is any unmanned aerial vehicle that is equipped with
electronics and guidance systems typical for its size, so long as
UAV 300 is equipped with camera 302. The size can range from small
UAVs such as the DJI Phantom series of quadcopters (www.dii.com) to
large scale UAV systems in use by military and government
organizations, such as the General Atomics MQ-9 Reaper.
[0029] Turning to FIG. 4, the components of an image detection
system that can be implemented on UAV 300 for detecting landing aid
100 are shown. The image detection system is comprised of a camera
402, which is in data communication with an image processor 404.
Image processor 404 in turn feeds information about the location of
landing aid 100 into flight controller 406, which in turn controls
the motors 408 and/or flight controls 410 of UAV 300 so as to guide
UAV 300 relative to landing aid 100. Camera 402 is any standard
camera that is suitable for being attached to UAV 300, and with UAV
300's payload parameters. Camera 402 and landing aid 100 must be
compatible insofar as camera 402 must be capable of imaging landing
aid 100. Camera 402 accordingly may be sensitive to infrared,
ultraviolet, visible light, or a combination of the foregoing, as
appropriate to how the shapes are rendered on landing aid 100.
Camera 402 may use CCD, CMOS, or any other suitable imaging
technology now known or later developed.
[0030] Image processor 404 receives a video stream from camera 402,
and performs an initial shape detection upon the video stream,
specifically to identify circles and polygons. Shape detection may
be carried out using any suitable algorithm now known or later
developed in the relevant art that is capable of conveying the
geometry and location in the field of view of each detected shape,
such as convolution, correlation, edge detection, Hough transform,
or a combination of techniques. The selection of technique or
techniques can be tailored to the processing power of image
processor 404 and the relative needs for speed and accuracy. Once
shape detection is carried out, a second pattern matching algorithm
is carried out to detected the presence of landing aid 100 within
camera 402's field of view, to ensure that identification is
accurate, and not a false positive.
[0031] A further step may be carried out for certain
implementations of landing aid 100 that are illuminated for night
or low-light direction. Landing aid 100 can be implemented with a
pulsed light source, that repeatedly flashes. By synchronizing the
flashing of landing aid 100 with the frame rate of camera 402 at a
ratio of two to one, landing aid 100 can be made to appear only
every other frame of the video stream from camera 402. Detection of
landing aid 100 can then be accomplished by simple comparison
between frames, with the difference between frames revealing the
position of landing aid 100. Landing aid 100 and camera 402 can be
synchronized by reference to an external time base, such as a GPS
receiver installed on both UAV 300 and landing aid 100 that can
provide a common synchronized time base. Other synchronizing
methods may also be possible, including a radio beacon either on
UAV 300 or landing aid 100 that signals shutter actuation or light
pulsing, respectively. These later methods are useful where camera
402 may have a variable frame rate. It will be understood by a
person skilled in the relevant art that using GPS as a common time
base for synchronization alone, apart from a real-time exchange of
information between UAV 300 and landing aid 100 will require a
prior determined common frame and pulse rate.
[0032] For the example landing aid pattern depicted in FIGS. 1C, 2A
and 2B, the L-shaped arrangement of the circles is detected. Each
of the three circles corresponds to a point i, j and k. Point i is
at the corner of the L-shape, point j is located along the long
axis of the L-shape, and point k is located along the short axis.
It is observed that the example landing aid pattern is arranged
with a 1:2 ratio, where point k is located two diameters of a
circle from point i, and point j is located four diameters from
point i. Thus, the relationship of Dx(ij)*2=Dx(ik)*4, or
Dx(ij)*2=neg(Dx(ik)*4) is used on any detected circles of
approximately equal diameter to locate landing aid 100 within the
field of view of camera 402. Observe that the negated version of
the relationship equation is useful for detecting landing aid 100
when the L-shape is presented in reverse.
[0033] It will be appreciated by a person skilled in the relevant
art that the foregoing algorithm is specific to the examples in the
listed figures. The parameters of the foregoing algorithm will be
varied to accommoxdate the differing spacing between circles in
other examples, such as seen in FIGS. 1A, 1B, 1D, 1E and 1F, or any
other patterns devised for landing aid 100. Varying the detection
parameters of the foregoing algorithm allows for discrimination and
isolation of one particular pattern when multiple targets are
within camera 402's field of view.
[0034] Once image processor 404 has detected and determined the
location of landing aid 100, it can pass directional information to
flight controller 406 for directing UAV 300 relative to landing aid
100. Such information can be used to direct UAV 300 to perform a
predetermined flight path, such as reorienting UAV 300 to a certain
position relative to landing aid 100, and automatically bringing
UAV 300 in to land. Flight controller 406 can be a commercial
off-the-shelf flight controller, such as the open source
ArduPilotMega or DJI's Naza line of flight controllers, or can be
custom developed to interact with image processor 404 in a more
complex fashion. The algorithms that flight controller 406 uses to
direct UAV 300 are well known in the art, and any such algorithms
now known or later developed may be utilized, depending upon the
mission parameters for UAV 300.
[0035] It will be recognized by a person skilled in the relevant
art that the disclosed visual landing aids can be utilized for
purposes other than just landing. By providing a fixed visual point
of reference on the terrain, a UAV 300 can navigate with respect to
the fixed point of reference so long as the landing aid is visible
within UAV 300's camera. In one possible alternative use, a series
of landing aids could be supplied at various points along a
predetermined course, which could then be used by UAV 300 to
navigate the predetermined course. By varying the patterns of the
various landing aids, UAV 300 could be programmed to perform
different actions as it approaches each consecutive different
landing aid. Moreover, the disclosed visual landing aids have
applicability beyond UAVs, and can be deployed any place a visual
target that is readily identifiable and trackable by machine vision
is desired. Such applications could include space and maritime
docking procedures, in-air refueling, and assistance to landing
manned aircraft, to name a few possible alternative
applications.
[0036] The disclosure above encompasses multiple distinct
inventions with independent utility. While each of these inventions
has been disclosed in a particular form, the specific embodiments
disclosed and illustrated above are not to be considered in a
limiting sense as numerous variations are possible. The subject
matter of the inventions includes all novel and non-obvious
combinations and subcombinations of the various elements, features,
functions and/or properties disclosed above and inherent to those
skilled in the art pertaining to such inventions. Where the
disclosure or subsequently filed claims recite "a" element, "a
first" element, or any such equivalent term, the disclosure or
claims should be understood to incorporate one or more such
elements, neither requiring nor excluding two or more such
elements.
[0037] Applicant(s) reserves the right to submit claims directed to
combinations and subcombinations of the disclosed inventions that
are believed to be novel and non-obvious. Inventions embodied in
other combinations and subcombinations of features, functions,
elements and/or properties may be claimed through amendment of
those claims or presentation of new claims in the present
application or in a related application. Such amended or new
claims, whether they are directed to the same invention or a
different invention and whether they are different, broader,
narrower or equal in scope to the original claims, are to be
considered within the subject matter of the inventions described
herein.
* * * * *