U.S. patent application number 15/176229 was filed with the patent office on 2017-07-13 for senising on uavs for mapping and obstacle avoidance.
The applicant listed for this patent is Alberto Daniel Lacaze, Karl Nicholas Murphy, Raymond Paul Wilhelm, III. Invention is credited to Alberto Daniel Lacaze, Karl Nicholas Murphy, Raymond Paul Wilhelm, III.
Application Number | 20170201738 15/176229 |
Document ID | / |
Family ID | 59275062 |
Filed Date | 2017-07-13 |
United States Patent
Application |
20170201738 |
Kind Code |
A1 |
Lacaze; Alberto Daniel ; et
al. |
July 13, 2017 |
SENISING ON UAVS FOR MAPPING AND OBSTACLE AVOIDANCE
Abstract
Structured light approaches utilize a laser to project features,
which are then captured with a camera. By knowing the disparity
between the laser emitter and the camera, the system can
triangulate to find the range. Four, 185 degree field-of-view
cameras provide overlapping views over nearly the whole unit
sphere. The cameras are separated from each other to provide
parallax. A near-infrared laser projection unit sends light out
into the environment, which is reflected and viewed by the cameras.
The laser projection system will create vertical lines, while the
cameras will be displaced from each other horizontally. This
relative shift of the lines, as viewed by different cameras,
enables the lines to be triangulated in 3D space. At each point in
time, a vertical stripe of the world will be triangulated. Over
time, the laser line will be rotated over all yaw angles to provide
full a 360 degree range.
Inventors: |
Lacaze; Alberto Daniel;
(Potomac, MD) ; Murphy; Karl Nicholas; (Rockville,
MD) ; Wilhelm, III; Raymond Paul; (Gaithersburg,
MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lacaze; Alberto Daniel
Murphy; Karl Nicholas
Wilhelm, III; Raymond Paul |
Potomac
Rockville
Gaithersburg |
MD
MD
MD |
US
US
US |
|
|
Family ID: |
59275062 |
Appl. No.: |
15/176229 |
Filed: |
June 8, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62175231 |
Jun 13, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 7/4813 20130101;
B64C 2201/108 20130101; B64C 2201/14 20130101; H04N 2013/0081
20130101; G01B 11/2545 20130101; G01S 17/42 20130101; G01S 7/4816
20130101; G01S 17/48 20130101; B64C 2201/024 20130101; G01B 11/245
20130101; H04N 13/128 20180501; G01B 11/2518 20130101; H04N 13/254
20180501; G01S 7/4815 20130101; B64C 2201/162 20130101; H04N 13/271
20180501; G01S 17/933 20130101; B64C 39/024 20130101; B64C 2201/123
20130101; G01S 17/89 20130101; B64C 2201/027 20130101; H04N 13/243
20180501; G01S 17/08 20130101 |
International
Class: |
H04N 13/02 20060101
H04N013/02; G01S 17/93 20060101 G01S017/93; G01S 7/481 20060101
G01S007/481; B64D 47/08 20060101 B64D047/08; H04N 5/232 20060101
H04N005/232; B64C 39/02 20060101 B64C039/02; B64C 27/08 20060101
B64C027/08; G01S 17/89 20060101 G01S017/89; G01S 17/02 20060101
G01S017/02 |
Claims
1. A sensing device for UAVs, comprising: a UAV; a structured light
sensor; the structured light sensor configured to use the size of
the quadrotor, in order to provide a disparity requirement; and a
computer or microprocessor to process the structured light sensor
information; and the computer or microprocessor sending the
structured light sensor information to one or more recipients.
2. The sensing device for UAVs of claim 1, wherein the processing
is used for obstacle avoidance.
3. The sensing device for UAVs of claim 1, wherein the processing
is used for mapping the surroundings.
4. The sensing device for UAVs of claim 1, wherein the UAV is a
quadrotor.
5. The sensing device for UAVs of claim 1, wherein the structured
light sensor is rotated; and the rotation is accomplished by a
mechanism on the vehicle.
6. The sensing device for UAVs of claim 1, wherein the structured
light sensor is rotated; and the rotation is accomplished by moving
the body of the vehicle.
7. The sensing device for UAVs of claim 1, wherein the structured
light sensor is rotated; and the rotation is accomplished by at
least one of a mechanism on the vehicle and moving the body of the
vehicle, or a combination of the two.
8. The sensing device for UAVs of claim 1, wherein multiple lines
are used, one horizontal line and one vertical line, to increase
the coverage.
9. The sensing device for UAVs of claim 1, further comprising a
time-of-flight sensor.
10. A sensing device for UAVs, comprising a quadrotor; one or more
line time-of-flight sensors; a computer or microprocessor to
process range information; and the computer or microprocessor
sending the range information to one or more recipients.
11. The sensing device for UAVs of claim 10, wherein the processing
is used for obstacle avoidance.
12. The sensing device for UAVs of claim 10, wherein the processing
is used for mapping the surroundings.
13. The sensing device for UAVs of claim 10, wherein the line
time-of-flight sensor is rotated; and the rotation is accomplished
by a mechanism on the vehicle.
14. The sensing device for UAVs of claim 10, wherein the line
time-of-flight sensor is rotated; and the rotation is accomplished
by moving the body of the vehicle.
15. The sensing device for UAVs of claim 10, wherein the line
time-of-flight sensor is rotated; and the rotation is accomplished
by at least one of a mechanism on the vehicle and moving the body
of the vehicle, or a combination of the two.
16. The sensing device for UAVs of claim 10, further comprising a
structured light sensor.
17. The sensing device for UAVs of claim 16, wherein multiple lines
are used, one horizontal line and one vertical line, to increase
the coverage.
18. The sensing device for UAVs of claim 10, wherein the UAV is a
quadrotor.
19. A sensing device for UAVs, comprising: a plurality of fisheye
cameras; the cameras are separated from each other to provide
parallax; four, 185 degree field-of-view cameras provide
overlapping views over nearly the whole unit sphere; a plurality of
laser line scanners; the near-infrared laser projection unit sends
light out into the environment, which is reflected and viewed by
the cameras; the laser projection system creates vertical lines,
while the cameras will be displaced from each other horizontally`
this relative shift (stereo disparity) of the lines, as viewed by
different cameras, enables the lines to be triangulated in 3D
space; at each point in time, a vertical stripe of the world will
be triangulated; over time, the laser line will be rotated over all
yaw angles to provide full 360 degree range sensing capabilities;
the two laser line projectors are used to create a line that can
then be sensed with the omnidirectional cameras; each imager is
composed of a camera module, a spectral filter, and a wide-angle
compound lens; an optical bandpass filter can be installed to
attenuate incoming ambient light; if no filter is installed, the
imaging system can be used as a visible light imager to provide
full 360 degree RGB imagery in addition to point clouds; a laser
projection unit consists of a solid-state laser diode, laser
pulsing circuitry, aspheric collimation lens, beam splitter, small
rotating mirror, and laser line lens; the laser circuitry pulses
the laser while also providing a frame trigger to each imager; the
laser light is collimated into a beam using a small aspheric lens
directly in front of the laser; the laser beam is then split into
an upward and downward beam; each beam is reflected off a small
rotating mirror coupled to a laser line lens; the upward beam
creates a laser line that extends from horizontal to positive 80
degrees pitch; the downward beam creates a laser line that extends
from horizontal to negative 80 degrees pitch; the structured light
sensor will be able to measure 360 degrees horizontally and 160
degrees vertically; at each point in time, the sensor will generate
approximately 2080 vertical range measurements; each imager
capturing approximately 180 images/second, the sensor will be able
to generate over 370 k points per second; the yaw scan rate can be
varied, depending upon the current mission needs; the sensor can be
operated with a fine yaw resolution and slow scan rate, providing
detailed scans of the environment; or, the sensor can be operated
with a faster yaw rate, providing faster updates at a coarser rate;
and since this device relies on triangulation, the range accuracy
will be dependent on range.
20. The sensing device for UAVs of claim 19, comprising: a UAV; one
or more range sensors that are used to sense the surrounding
environment; a time-of-flight line sensor to perform the same task
as shown with the structured light sensor; and a vertical sensing
plan aligned with the direction of travel.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Patent
Application Ser. 62/175,231, entitled "SENISING ON UAVS FOR MAPPING
AND OBSTACLE AVOIDANCE", filed on 13 Jun. 2015. The benefit under
35 USC .sctn.119(e) of the United States provisional application is
hereby claimed, and the aforementioned application is hereby
incorporated herein by reference.
FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable
SEQUENCE LISTING OR PROGRAM
[0003] Not Applicable
TECHNICAL FIELD OF THE INVENTION
[0004] The present invention relates to UAVs. More specifically,
the present invention is related to providing structured light and
time of flight sensors on UAVs for obstacle avoidance and creating
mapping capabilities.
BACKGROUND OF THE INVENTION
[0005] There are few sensors that are well suited for autonomous
mobility and mapping functions on small aerial platforms. LADAR
choices that can fit the SWAP requirements are severely limited;
few LADARs are available within the SWAP. One option, the single
line sensor, needs to be configured into an up-down tilt
configuration, the so called "yes-yes" ladar, or into a side to
side pan configuration, so called "no-no" ladar, in order to get
the coverage needed to traverse a complex environment.
[0006] Some other sensors provide a relatively small vertical
field-of-view. Quadrotors of a small size and weight create
significant pitch when traveling at high speeds. This pitch can be
as high as 45 degrees when traveling at high speeds, or when
quadrotors are used in windy areas.
[0007] Therefore, if a sensor with relatively small vertical field
of view is installed horizontally, the vehicle will be blind in the
direction of travel at high speeds. Once again, there is a need of
a tilt mechanism.
[0008] The other approach, which better fits the SWAP constraints
of a quadrotor, is stereo vision--or structure from motion.
However, in both cases, poor lighting of an indoor
environment--together with the lower quality optics camera
combinations that can be carried with the quads--makes it a poor
choice. Many attempts like this have been performed in the past few
years, with very poor results.
Definitions
[0009] LADAR (also known as LIDAR) is an optical remote sensing
technology that can measure the distance to, or other properties of
a target by illuminating the target with light, often using pulses
from a laser. LIDAR technology has application in geomatics,
archaeology, geography, geology, geomorphology, seismology,
forestry, remote sensing and atmospheric physics, as well as in
airborne laser swath mapping (ALSM), laser altimetry and LIDAR
contour mapping. The acronym LADAR (Laser Detection and Ranging) is
often used in military contexts. The term "laser radar" is
sometimes used, even though LIDAR does not employ microwaves or
radio waves and therefore is not radar in the strict sense of the
word.
[0010] In computing, a graphical user interface (GUI, commonly
pronounced gooey) is a type of user interface that allows users to
interact with electronic devices using images rather than text
commands. GUIs can be used in computers, hand-held devices such as
MP3 players, portable media players or gaming devices, household
appliances and office equipment. A GUI represents the information
and actions available to a user through graphical icons and visual
indicators such as secondary notation, as opposed to text-based
interfaces, typed command labels or text navigation. The actions
are usually performed through direct manipulation of the graphical
elements.
[0011] MAPHAC is a 3D scanning device for measuring the
three-dimensional shape of an object using projected light patterns
and a camera system.
[0012] A quadcopter, also called a quadrotor helicopter or
quadrotor, is a multirotor helicopter that is lifted and propelled
by four rotors. Quadcopters are classified as rotorcraft, as
opposed to fixed-wing aircraft, because their lift is generated by
a set of rotors (vertically oriented propellers). Unlike most
helicopters, quadcopters use two sets of identical fixed pitched
propellers; two clockwise (CW) and two counter-clockwise (CCW).
These use variation of RPM to control lift and torque. Control of
vehicle motion is achieved by altering the rotation rate of one or
more rotor discs, thereby changing its torque load and thrust/lift
characteristics.
[0013] A Small Unmanned Ground Vehicle (SUGV) is a lightweight, man
portable Unmanned Ground Vehicle (UGV) capable of conducting
military operations in urban terrain, tunnels, sewers, and caves.
The SUGV aids in the performance of manpower-intensive or high-risk
functions (i.e. urban Intelligence, Surveillance, and
Reconnaissance (ISR) missions, chemical/Toxic Industrial Chemicals
(TIC), Toxic Industrial Materials (TIM), reconnaissance, etc.).
Working to minimize Soldiers' exposure directly to hazards, the
SUGV's modular design allows multiple payloads to be integrated in
a plug and play fashion.
[0014] An Unmanned Ground Vehicle (UGV) is a vehicle that operates
while in contact with the ground and without an onboard human
presence. UGVs can be used for many applications where it may be
inconvenient, dangerous, or impossible to have a human operator
present. Generally, the vehicle will have a set of sensors to
observe the environment, and will either autonomously make
decisions about its behavior or pass the information to a human
operator at a different location who will control the vehicle
through teleoperation. The UGV is the land-based counterpart to
unmanned aerial vehicles and remotely operated underwater vehicles.
Unmanned robotics are being actively developed for both civilian
and military use to perform a variety of dull, dirty, and dangerous
activities.
[0015] SWAP constraints are directed to size, weight, and power of
a military platform as defined by the military for a given platform
and providing a basis for which a platform and utilize components
from various manufacturers.
SUMMARY OF THE INVENTION
[0016] Structured light approaches utilize a laser to project
features, which are then captured with a camera. By knowing the
disparity between the laser emitter and the camera, the system can
triangulate to find the range. In order to accommodate these
sensors on a quadrotor, modifications will be done to the location
of the camera and the laser emitters as taught by the present
invention.
[0017] The proposed configuration makes use of multiple fisheye
cameras and laser line scanners. Four, wide degree field-of-view
cameras provide overlapping views over nearly the whole unit
sphere. The cameras are separated from each other to provide
parallax. A near-infrared laser projection unit sends light out
into the environment. If the light hits objects in the environment
it is reflected and viewed by the cameras.
[0018] The laser projection system will create vertical lines,
while the cameras will be displaced from each other horizontally.
This relative shift (stereo disparity) of the lines, as viewed by
different cameras, enables the lines to be triangulated in 3D
space. At each point in time, a vertical stripe of the world will
be triangulated. Over time, the laser line will be rotated over all
yaw angles to provide full 360 degree range sensing
capabilities.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated herein a
form a part of the specification, illustrate the present invention
and, together with the description, further serve to explain the
principles of the invention and to enable a person skilled in the
pertinent art to make and use the invention.
[0020] FIG. 1. MAPHAC is a structured light sensor that is designed
for SUGVs.
[0021] FIG. 2 Point cloud generated by MAPHAC, color-coded for
range. The point cloud shows a leaning ladder, and a variety of
office clutter.
[0022] FIG. 3a. Quad copter with four imagers and laser projection
system.
[0023] FIG. 3b. Approximate field-of-view of a single imager.
[0024] FIG. 3c. Overhead view of combined field-of-view of all
imagers.
[0025] FIG. 3d. Side-view of combined field-of-view of all
imagers.
[0026] FIG. 4. Two laser line projectors are used to create a line
that can then be sensed with the omnidirectional cameras.
[0027] FIG. 5. Complete field of view showing laser and
cameras.
[0028] FIG. 6. Expected range error of structured light sensor.
[0029] FIGS. 7a and 7b. Prototype sensing plane configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0030] In the following detailed description of the invention of
exemplary embodiments of the invention, reference is made to the
accompanying drawings (where like numbers represent like elements),
which form a part hereof, and in which is shown by way of
illustration specific exemplary embodiments in which the invention
may be practiced. These embodiments are described in sufficient
detail to enable those skilled in the art to practice the
invention, but other embodiments may be utilized and logical,
mechanical, electrical, and other changes may be made without
departing from the scope of the present invention. The following
detailed description is, therefore, not to be taken in a limiting
sense, and the scope of the present invention is defined only by
the appended claims.
[0031] In the following description, numerous specific details are
set forth to provide a thorough understanding of the invention.
However, it is understood that the invention may be practiced
without these specific details. In other instances, well-known
structures and techniques known to one of ordinary skill in the art
have not been shown in detail in order not to obscure the
invention. Referring to the figures, it is possible to see the
various major elements constituting the apparatus of the present
invention.
[0032] Structured light approaches utilize a laser to project
features, which are then captured with a camera. By knowing the
disparity between the laser emitter and the camera, the system can
triangulate to find the range. In sharp contrast, with conventional
stereo and structure from motion, poor lighting actually improves
the range and accuracy of this sensor. There is also no need to
have rich features in the environment, since the laser "projects
its own features." Therefore, it will even work on featureless
walls and floors.
[0033] One such approach is presented in FIG. 1, which is currently
installed on a SUGV (small unmanned ground vehicle). It is designed
to create very high density point clouds for mapping applications
at two megapixels per second. FIG. 1 illustrates where a MAPHAC 100
is a structured light sensor that is designed for SUGVs.
[0034] FIG. 2, shows the scan of a typical cluttered room as a
point cloud 200, including a ladder 201, a camera with a tripod
202, chairs 203, lamps 204, etc. In FIG. 2 the point cloud 200
generated by an MAPHAC is color-coded for range. The point cloud
200 shows a leaning ladder 201, and a variety of office clutter.
The current incarnation of MAPHAC 100 is designed to become a
substitute for a SUGV antenna, where it can serve as both an
autonomous mobility sensor and radio antenna.
[0035] In order to accommodate these sensors on a quadrotor,
modifications will be done to the location of the camera and the
laser emitters. However, the core electronics and software have
already been designed, but never used in this combination. The
sensor is designed to meet the unique needs of an autonomous
multicopter for indoor and outdoor environments, including:
Large-field of view for obstacle avoidance and mapping;
Light-weight system with minimal moving parts; Accurate ranges at
short distances, with decreasing accuracy at longer ranges; Use of
eye-safe lasers, while providing resilience to ambient light; and a
Predicted weight under 150 grams.
[0036] The proposed configuration makes use of multiple fisheye
cameras and laser line scanners. Four, 185 degree field-of-view
cameras provide overlapping views over nearly the whole unit
sphere. The cameras are separated from each other to provide
parallax. A near-infrared laser projection unit sends light out
into the environment, which is reflected and viewed by the cameras.
The laser projection system will create vertical lines, while the
cameras will be displaced from each other horizontally. This
relative shift (stereo disparity) of the lines, as viewed by
different cameras, enables the lines to be triangulated in 3D
space.
[0037] At each point in time, a vertical stripe of the world will
be triangulated. Over time, the laser line will be rotated over all
yaw angles to provide full 360 degree range sensing capabilities as
illustrated by FIGS. 3a, 3b, 3c, and 3d.
[0038] FIG. 3a illustrates a Quad copter 300 with four imagers 301,
302, 303, and 304 and laser projection system 305. FIG. 3b
illustrates an approximate field-of-view 306 of a single imager
301. FIG. 3c illustrates an overhead view of combined field-of-view
307 of all imagers 301, 302, 303, and 304. FIG. 3d illustrates a
side-view of combined field-of-view 308 of all imagers.
[0039] FIG. 4 illustrates where two laser line projectors 401 and
402 are used to create a line 403 that can then be sensed with the
omnidirectional cameras.
[0040] Each imager is composed of a camera module, a spectral
filter, and a wide-angle compound lens. The camera must be small in
size and weight, while providing high sensitivity and a wide
dynamic range. Depending on mission requirements, an optical
bandpass filter can be installed to attenuate incoming ambient
light. If no filter is installed, the imaging system can be used as
a visible light imager to provide full 360 degree RGB imagery in
addition to point clouds.
[0041] A laser projection unit consists of a solid-state laser
diode, laser pulsing circuitry, aspheric collimation lens, beam
splitter, small rotating mirror, and laser line lens. The laser
circuitry pulses the laser while also providing a frame trigger to
each imager. The laser light is collimated into a beam 403 and 404
using a small aspheric lens directly in front of the laser. The
laser beam is then split into an upward and downward beam 403 and
404. Each beam 403 and 404 is reflected off a small rotating mirror
coupled to a laser line lens. The upward beam 403 creates a laser
line that extends from horizontal to positive 80 degrees pitch,
while the downward beam 404 creates a laser line that extends from
horizontal to negative 80 degrees pitch.
[0042] The proposed field-of-view (shown in FIG. 4) shows the
field-of-view of the projected lines 403 and 404. FIG. 5 shows the
combined field-of-view of the cameras 405 and 406 and laser
projectors 308.
[0043] The structured light sensor will be able to measure 360
degrees horizontally and 160 degrees vertically. At each point in
time, the sensor will generate approximately 2080 vertical range
measurements. With each imager capturing approximately 180
images/second, the sensor will be able to generate over 370 k
points per second.
[0044] The yaw scan rate can be varied, depending upon the current
mission needs. The sensor can be operated with a fine yaw
resolution and slow scan rate, providing detailed scans of the
environment; or, the sensor can be operated with a faster yaw rate,
providing faster updates at a coarser rate.
[0045] Since this device relies on triangulation, the range
accuracy will be dependent on range. The expected range error 600
is shown in FIG. 6 in graph format.
[0046] A second approach is to use a time-of-flight line sensor to
perform the same task as shown with the structured light sensor.
The line sensors can be organized as seen in FIGS. 7a and 7b.
[0047] One more possible configuration is the same as shown in
FIGS. 7a and 7b, but with the vertical sensing plan 700 aligned
with the direction of travel 701.
[0048] The system is composed of a quadrotor, or other UAV, and one
or more range sensors that are used to sense the surrounding
environment.
[0049] Thus, it is appreciated that the optimum dimensional
relationships for the parts of the invention, to include variation
in size, materials, shape, form, function, and manner of operation,
assembly and use, are deemed readily apparent and obvious to one of
ordinary skill in the art, and all equivalent relationships to
those illustrated in the drawings and described in the above
description are intended to be encompassed by the present
invention.
[0050] Furthermore, other areas of art may benefit from this method
and adjustments to the design are anticipated. Thus, the scope of
the invention should be determined by the appended claims and their
legal equivalents, rather than by the examples given.
* * * * *