U.S. patent application number 16/917668 was filed with the patent office on 2021-01-21 for stability systems for tethered unmanned aerial vehicles.
The applicant listed for this patent is RSQ-SYSTEMS US LLC. Invention is credited to Mike Blavier, Mathieu Buyse, Jean Marc Coulon.
Application Number | 20210016881 16/917668 |
Document ID | / |
Family ID | 1000005131643 |
Filed Date | 2021-01-21 |
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United States Patent
Application |
20210016881 |
Kind Code |
A1 |
Buyse; Mathieu ; et
al. |
January 21, 2021 |
STABILITY SYSTEMS FOR TETHERED UNMANNED AERIAL VEHICLES
Abstract
An unmanned aerial vehicle including a body, a platform, a
rotor, a tether cable, and an actuation system. The platform is
coupled to the body such that the platform is rotatable relative to
the body about a first horizontal axis of rotation. The rotor is
rigidly coupled to the platform such that the rotor and the
platform rotate together about the first horizontal axis of
rotation. The tether cable extends away from the body and is
coupled to the body such that the tether cable is rotatable
relative to the body about a second horizontal axis of rotation.
The first and second horizontal axes of rotation are normal to a
vertical plane. The actuation system is configured to rotate the
platform in a clockwise direction about the first horizontal axis
of rotation when the tether cable rotates in a counter-clockwise
direction about the second horizontal axis of rotation.
Inventors: |
Buyse; Mathieu; (Genval,
BE) ; Coulon; Jean Marc; (Sant Julia de Loria,
AD) ; Blavier; Mike; (Vilvoorde, BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RSQ-SYSTEMS US LLC |
COLLEGE STATION |
TX |
US |
|
|
Family ID: |
1000005131643 |
Appl. No.: |
16/917668 |
Filed: |
June 30, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15912130 |
Mar 5, 2018 |
10696396 |
|
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16917668 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64C 39/022 20130101;
B64C 2201/14 20130101; B64C 2201/027 20130101; B64C 2201/123
20130101; B64C 39/024 20130101 |
International
Class: |
B64C 39/02 20060101
B64C039/02 |
Claims
1. An unmanned aerial vehicle comprising: a body; a platform
coupled to the body such that the platform is rotatable relative to
the body about a first horizontal axis of rotation normal to a
vertical plane extending through the body; a rotor rigidly coupled
to the platform such that the rotor and the platform rotate
together about the first horizontal axis of rotation; a tether
cable extending away from the body and coupled to the body such
that the tether cable is rotatable relative to the body about a
second horizontal axis of rotation normal to the vertical plane;
and an actuation system configured to rotate the platform in a
clockwise direction about the first horizontal axis of rotation
when the tether cable rotates in a counter-clockwise direction
about the second horizontal axis of rotation.
2. The unmanned aerial vehicle of claim 1, wherein the vertical
plane is a first vertical plane, wherein the platform coupled to
the body such that the platform is rotatable relative to the body
about a third horizontal axis of rotation normal to a second
vertical plane, wherein the second vertical plane extending through
the body and orthogonal to the first vertical plane, wherein the
tether cable coupled to the body such that the tether cable is
rotatable relative to the body about a fourth horizontal axis of
rotation normal to the second vertical plane, and wherein the
actuation system further configured to rotate the platform in the
clockwise direction about the third horizontal axis of rotation
when the tether cable rotates in the counter-clockwise direction
about the fourth horizontal axis of rotation.
3. The unmanned aerial vehicle of claim 1, wherein the actuation
system further configured to rotate the platform an angular
distance based on a relative angle between the tether cable and the
body.
4. The unmanned aerial vehicle of claim 3, wherein the actuation
system further configured to rotate the platform the same angular
distance as the tether cable.
5. The unmanned aerial vehicle of claim 1, further comprising an
electronic controller configured to determine a tension of the
tether cable, increase an angular speed of the rotor when the
tension of the tether cable decreases, and decrease the angular
speed of the rotor when the tension of the tether cable
increases.
6. The unmanned aerial vehicle of claim 1, wherein the tether cable
configured to provide power to the unmanned aerial vehicle.
7. The unmanned aerial vehicle of claim 1, wherein the tether cable
configured to transmit data from the unmanned aerial vehicle.
8. The unmanned aerial vehicle of claim 1, wherein the tether cable
configured to couple the body to an external coupling.
9. An unmanned aerial vehicle comprising: a body; a platform
coupled to the body such that the platform is rotatable relative to
the body about a first horizontal axis of rotation normal to a
vertical plane extending through the body; a rotor rigidly coupled
to the platform such that the rotor and the platform rotate
together about the first horizontal axis of rotation; a tether
cable extending away from the body and coupled to the body such
that the tether cable is rotatable relative to the body about a
second horizontal axis of rotation normal to the vertical plane;
and a pulley system coupled to the tether cable and to the
platform, wherein the pulley system configured to rotate the
platform in a clockwise direction about the first horizontal axis
of rotation when the tether cable rotates in a counter-clockwise
direction about the second horizontal axis of rotation.
10. The unmanned aerial vehicle of claim 9, wherein the pulley
system including a first pulley positioned proximate to a first
side of the platform, a second pulley positioned proximate to a
second side of the platform opposite the first side, a first cable
supported by the first pulley and coupled to the tether cable and
to the second side of the platform, and a second cable supported by
the second pulley and coupled to the tether cable and to the first
side of the platform.
11. The unmanned aerial vehicle of claim 9, wherein the vertical
plane is a first vertical plane, wherein the platform coupled to
the body such that the platform is rotatable relative to the body
about a third horizontal axis of rotation normal to a second
vertical plane, wherein the second vertical plane extending through
the body and orthogonal to the first vertical plane, wherein the
tether cable coupled to the body such that the tether cable is
rotatable relative to the body about a fourth horizontal axis of
rotation normal to the second vertical plane, and wherein the
pulley system further configured to rotate the platform in the
clockwise direction about the third horizontal axis of rotation
when the tether cable rotates in the counter-clockwise direction
about the fourth horizontal axis of rotation.
12. The unmanned aerial vehicle of claim 9, wherein the pulley
system further configured to rotate the platform an angular
distance based a relative angle between the tether cable and the
body.
13. The unmanned aerial vehicle of claim 12, wherein the pulley
system further configured to rotate the platform the same angular
distance as the tether cable.
14. The unmanned aerial vehicle of claim 9, further comprising an
electronic controller configured to determine a tension of the
tether cable, increase an angular speed of the rotor when the
tension of the tether cable decreases, and decrease the angular
speed of the rotor when the tension of the tether cable
increases.
15. An unmanned aerial vehicle comprising: a body; a platform
coupled to the body; an electronic actuator configured to rotate
the platform relative to the body about a first horizontal axis of
rotation normal to a vertical plane extending through the body; a
rotor rigidly coupled to the platform such that the rotor and the
platform rotate together about the first horizontal axis of
rotation; a tether cable extending away from the body and coupled
to the body such that the tether cable is rotatable relative to the
body about a second horizontal axis of rotation normal to the
vertical plane; and an electronic controller configured to
determine movement of the tether cable relative to the body, and
drive the electronic actuator to rotate the platform in a clockwise
direction about the first horizontal axis of rotation when the
tether cable rotates in a counter-clockwise direction about the
second horizontal axis of rotation.
16. The unmanned aerial vehicle of claim 15, wherein the electronic
actuator includes a motor and an arm, wherein the arm coupled to
the motor and to the platform such that rotation of the motor
causes rotation of the platform about the first horizontal axis of
rotation.
17. The unmanned aerial vehicle of claim 15, wherein the vertical
plane is a first vertical plane, wherein the electronic actuator is
a first electronic actuator, wherein the unmanned aerial vehicle
further comprising a second electronic actuator configured to
rotate the platform relative to the body about a third horizontal
axis of rotation normal to a second vertical plane, wherein the
second vertical plane extending through the body and orthogonal to
the first vertical plane, wherein the tether cable coupled to the
body such that the tether cable is rotatable relative to the body
about a fourth horizontal axis of rotation normal to the second
vertical plane, and wherein the electronic controller further
configured to drive the second electronic actuator to rotate the
platform in the clockwise direction about the third horizontal axis
of rotation when the tether cable rotates in the counter-clockwise
direction about the fourth horizontal axis of rotation.
18. The unmanned aerial vehicle of claim 15, wherein the electronic
controller further configured to determine a relative angle between
the tether cable and the body, and drive the electronic actuator to
rotate the platform an angular distance based on the relative angle
between the tether cable and the body.
19. The unmanned aerial vehicle of claim 18, wherein the electronic
controller further configured to drive the electronic actuator to
rotate the platform the same angular distance as the tether
cable.
20. The unmanned aerial vehicle of claim 15, wherein the electronic
controller further configured to determine a tension of the tether
cable, increase an angular speed of the rotor when the tension of
the tether cable decreases, and decrease the angular speed of the
rotor when the tension of the tether cable increases.
Description
BACKGROUND
[0001] Unmanned aerial vehicles (UAVs) including remotely piloted
and autonomous drones are used in a wide variety of applications
such as surveillance, filming, and exploration. In some situations,
an unmanned aerial vehicle is tethered to an object via a cable to
collect data in the area around the object. For example, an
unmanned aerial vehicle may be tethered to a car to collect
pictures, audio, and video of the area around the car when a
collision occurs. As an unmanned aerial vehicle flies through the
air, gusts of wind or other disturbances may cause unintended
movement which impedes the unmanned aerial vehicle's ability to
collect data. For example, unintended movement may cause an
on-board camera to become off-centered and images or recordings of
the camera to become blurry or unclear. Thus, there is a need for a
system of maintaining alignment between an unmanned aerial vehicle
and an attached cable while the unmanned aerial vehicle is in
flight.
SUMMARY
[0002] The disclosure provides an unmanned aerial vehicle. In one
embodiment, the unmanned aerial vehicle includes a body, a
platform, a rotor, a tether cable, and an actuation system. The
platform is coupled to the body such that the platform is rotatable
relative to the body about a first horizontal axis of rotation. The
rotor is rigidly coupled to the platform such that the rotor and
the platform rotate together about the first horizontal axis of
rotation. The tether cable extends away from the body and is
coupled to the body such that the tether cable is rotatable
relative to the body about a second horizontal axis of rotation.
The first horizontal axis of rotation and the second horizontal
axis of rotations are normal to a vertical plane that extends
through the body. The actuation system is configured to rotate the
platform in a clockwise direction about the first horizontal axis
of rotation when the tether cable rotates in a counter-clockwise
direction about the second horizontal axis of rotation.
[0003] The disclosure also provides an unmanned aerial vehicle. In
one embodiment, the unmanned aerial vehicle includes a body, a
platform, a rotor, a tether cable, and a pulley system. The
platform is coupled to the body such that the platform is rotatable
relative to the body about a first horizontal axis of rotation. The
rotor is rigidly coupled to the platform such that the rotor and
the platform rotate together about the first horizontal axis of
rotation. The tether cable extends away from the body and is
coupled to the body such that the tether cable is rotatable
relative to the body about a second horizontal axis of rotation.
The first horizontal axis of rotation and the second horizontal
axis of rotations are normal to a vertical plane that extends
through the body. The pulley system is configured to rotate the
platform in a clockwise direction about the first horizontal axis
of rotation when the tether cable rotates in a counter-clockwise
direction about the second horizontal axis of rotation.
[0004] The disclosure further provides an unmanned aerial vehicle.
In one embodiment, the unmanned aerial vehicle includes a body, a
platform, an electronic actuator, a rotor, a tether cable, and an
electronic controller. The platform is coupled to the body. The
electronic actuator is configured to rotate the platform relative
to the body about a first horizontal axis of rotation. The rotor is
rigidly coupled to the platform such that the rotor and the
platform rotate together about the first horizontal axis of
rotation. The tether cable extends away from the body and is
coupled to the body such that the tether cable is rotatable
relative to the body about a second horizontal axis of rotation.
The first horizontal axis of rotation and the second horizontal
axis of rotations are normal to a vertical plane that extends
through the body. The electronic controller is configured to
determine movement of the tether cable relative to the body. The
electronic controller is also configured to drive the electronic
actuator to rotate the platform in a clockwise direction about the
first horizontal axis of rotation when the tether cable rotates in
a counter-clockwise direction about the second horizontal axis of
rotation.
[0005] Other aspects and embodiments will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is an unmanned aerial vehicle tethered to a truck via
a tether cable, in accordance with some embodiments.
[0007] FIG. 2 is a partial sectional view of an unmanned aerial
vehicle including a pulley system and a tether cable at rest along
a reference axis, in accordance with some embodiments.
[0008] FIG. 3 is a partial sectional view of the unmanned aerial
vehicle of FIG. 2 rotated 90 degrees about the Z-axis, in
accordance with some embodiments.
[0009] FIG. 4 is a partial sectional view of the unmanned aerial
vehicle of FIG. 2 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0010] FIG. 5 is a partial sectional view of the unmanned aerial
vehicle of FIG. 3 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0011] FIG. 6 is a block diagram of an unmanned aerial vehicle
including electronic actuators, in accordance with some
embodiments.
[0012] FIG. 7 is a partial sectional view of the unmanned aerial
vehicle of FIG. 6 including a tether cable at rest along a
reference axis, in accordance with some embodiments.
[0013] FIG. 8 is a partial sectional view of the unmanned aerial
vehicle of FIG. 7 rotated 90 degrees about the Z-axis, in
accordance with some embodiments.
[0014] FIG. 9 is a partial sectional view of the unmanned aerial
vehicle of FIG. 7 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0015] FIG. 10 is a partial sectional view of the unmanned aerial
vehicle of FIG. 8 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0016] FIG. 11 is a block diagram of an unmanned aerial vehicle
including a variable rotor thrust stabilization system, in
accordance with some embodiments.
[0017] FIG. 12 is a perspective view of an underside of the
unmanned aerial vehicle of FIG. 11, in accordance with
embodiments.
[0018] FIG. 13 is a perspective view of a topside of the unmanned
aerial vehicle of FIG. 11, in accordance with embodiments.
[0019] FIG. 14 is a partial sectional view of the unmanned aerial
vehicle of FIG. 11 including a tether cable at rest along a
reference axis, in accordance with some embodiments.
[0020] FIG. 15 is a partial sectional view of the unmanned aerial
vehicle of FIG. 14 rotated 90 degrees about the Z-axis, in
accordance with some embodiments.
[0021] FIG. 16 is a partial sectional view of the unmanned aerial
vehicle of FIG. 14 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0022] FIG. 17 is a partial sectional view of the unmanned aerial
vehicle of FIG. 15 after the tether cable rotates away from the
reference axis, in accordance with some embodiments.
[0023] Skilled artisans will appreciate that elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale. For example, the dimensions of
some of the elements in the figures may be exaggerated relative to
other elements to help to improve understanding of embodiments
illustrated.
[0024] The apparatus and method components have been represented
where appropriate by conventional symbols in the drawings, showing
only those specific details that are pertinent to understanding
various embodiments so as not to obscure the disclosure with
details that will be readily apparent to those of ordinary skill in
the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0025] Before any embodiments are explained in detail, it is to be
understood that no embodiment is necessarily limited in its
application to the details of construction and the arrangement of
components set forth in the following description or illustrated in
the following drawings. Other embodiments are possible and
embodiments described are capable of being practiced or of being
carried out in various ways.
[0026] It should also be noted that a plurality of different
structural components may be utilized to implement the disclosure.
Furthermore, and as described in subsequent paragraphs, the
specific configurations illustrated in the drawings are intended to
exemplify certain embodiments. Alternative configurations are
possible.
[0027] FIG. 1 is a diagram of one example embodiment of an unmanned
aerial vehicle (UAV) 105. The unmanned aerial vehicle 105 includes
a tether cable 110 that couples the unmanned aerial vehicle 105 to
an object. In the embodiment illustrated in FIG. 1, the tether
cable 110 couples the unmanned aerial vehicle 105 to a coupling 115
that is affixed to a truck 120. In other embodiments, the tether
cable 110 may tether the unmanned aerial vehicle 105 to a fixed
structure (for example, a building). In other embodiments, the
tether cable 110 may tether the unmanned aerial vehicle 105 to a
user via a wearable device such as a pin. Alternatively, a user may
hold the tether cable 110.
[0028] FIGS. 2 through 5 are diagrams of one example embodiment of
an unmanned aerial vehicle 200. In FIGS. 2 through 5, the unmanned
aerial vehicle 200 includes the tether cable 110, a body 205, a
platform 210, a shaft 215, a plurality of rotors 220, and a pulley
system 225. The body 205 includes a first end 230 and a second end
235. The second end 235 of the body 205 is opposite from the first
end 230 of the body 205.
[0029] In FIGS. 2 through 5, the platform 210 is positioned
proximate to the first end 230 of the body 205 and is at least
partially exposed. The platform 210 is coupled to the body 205 such
that the platform 210 is rotatable relative to the body 205 about a
first horizontal axis of rotation 240 (illustrated in FIGS. 3 and
5). The tether cable 110 is coupled to the body 205 such that the
tether cable 110 is rotatable relative to the body 205 about a
second horizontal axis of rotation 242 (illustrated in FIGS. 3 and
5). The first horizontal axis of rotation 240 and the second
horizontal axis of rotation 242 are both normal to a first vertical
plane 244 extending through the body 205. The platform 210 is also
rotatable relative to the body 205 about a third horizontal axis of
rotation 246 (illustrated in FIGS. 2 and 4). The tether cable 110
is also rotatable relative to the body 205 about a fourth
horizontal axis of rotation 248 (illustrated in FIGS. 2 and 4). The
third horizontal axis of rotation 246 and the fourth horizontal
axis of rotation 248 are both normal to a second vertical plane 250
extending through the body 205. The second vertical plane 250 is
orthogonal to the first vertical plane 244. The first horizontal
axis of rotation 240 is orthogonal to the third horizontal axis of
rotation 246. The second horizontal axis of rotation 242 is
orthogonal to the fourth horizontal axis of rotation 248.
[0030] The plurality of rotors 220 are rigidly coupled to the
platform 210 (via the shaft 215) such that the plurality of rotors
220, the shaft 215, and the platform 210 rotate together about the
first horizontal axis of rotation 240 and the third horizontal axis
of rotation 246.
[0031] In FIGS. 2 through 5, the pulley system 225 is disposed
primarily within the body 205 and includes, among other things, a
first pulley 255A, a second pulley 255B, a third pulley 255C, a
fourth pulley 255D, a first cable 260A, a second cable 260B, a
third cable 260C, and a fourth cable 260D. As illustrated in FIG.
2, the first cable 260A is supported by the first pulley 255A. The
first cable 260A wraps around the first pulley 255A and couples to
the platform 210. The second cable 260B is supported by the second
pulley 255B. The second cable 260B wraps around the second pulley
255B and couples to the platform 210. The first cable 260A and the
second cable 260B are arranged in an "X" shape. In other words, the
first pulley 255A is positioned proximate a first side 265A of the
platform 210 and the second pulley 255B is positioned proximate a
second side 265B of the platform 210. The second side 265B of the
platform 210 is opposite from the first side 265A of the platform
210. The first cable 260A wraps around the first pulley 255A and
couples to an edge of the second side 265B of the platform 210. The
second cable 260B wraps around the second pulley 255B and couples
to an edge of the first side 265A of the platform 210.
[0032] As illustrated in FIG. 3, the third cable 260C is supported
by the third pulley 255C. The third cable 260C wraps around the
third pulley 255C and couples to the platform 210. The fourth cable
260D is supported by the fourth pulley 255D. The fourth cable 260D
wraps around the fourth pulley 255D and couples to the platform
210. The third cable 260C and the fourth cable 260D are arranged in
an "X" shape. In other words, the third pulley 255C is positioned
proximate a third side 265C of the platform 210 and the fourth
pulley 255D is positioned proximate a fourth side 265D of the
platform 210. The fourth side 265D of the platform 210 is opposite
from the third side 265C of the platform 210. The third cable 260C
wraps around the third pulley 255C and couples to an edge of the
fourth side 265D of the platform 210. The fourth cable 260D wraps
around the fourth pulley 255D and couples to an edge of the third
side 265C of the platform 210.
[0033] The tether cable 110, the first cable 260A, the second cable
260B, the third cable 260C, and the fourth cable 260D are joined
together at a connection point 270. In the embodiment illustrated
in FIGS. 2 through 5, the connection point 270 is positioned
external to the body 205 and proximate to the second end 235.
Alternatively, the connection point 270 may be positioned internal
to the body 205. The tether cable 110 extends away from the body
205 (and the connection point 270) in a direction generally
opposite from the lift direction of the rotors 220. At rest, the
tether cable 110 extends away from the body 205 along the
intersection of the first vertical plane 244 and the second
vertical plane 250, as illustrated in FIGS. 2 and 3. Hereinafter,
the intersection of the first vertical plane 244 and the second
vertical plane 250 is referred to as the reference axis (not
shown). As the unmanned aerial vehicle 200 flies through the air,
gusts of wind or other disturbances (for example, movement of the
object to which the tether cable 110 is attached to) cause the
tether cable 110 to rotate out of alignment with the reference
axis.
[0034] In some situations, during a disturbance, the tether cable
110 may rotate about the second horizontal axis of rotation 242, as
illustrated in FIG. 4. Alternatively or in addition, the tether
cable 110 may rotate about the fourth horizontal axis of rotation
248, as illustrated in FIG. 5. Since the tether cable 110 couples
the unmanned aerial vehicle 200 to another object, rotation about
the second horizontal axis of rotation 242 or the fourth horizontal
axis of rotation 248 increases the tension in at least one of the
first cable 260A, the second cable 260B, the third cable 260C, and
the fourth cable 260D. The pulley system 225 realigns the tether
cable 110 with the reference axis after a disturbance.
[0035] As illustrated in FIG. 4, the tether cable 110 may rotate in
a first direction 275 about the second horizontal axis of rotation
242 (for example, a counter-clockwise direction). Rotation of the
tether cable 110 in the first direction 275 increases the tension
in the tether cable 110 and the first cable 260A. The increased
tension in the first cable 260A provides a tensile force to the
second side 265B of the platform 210, which rotates the platform
210 in a second direction 280 about the first horizontal axis of
rotation 240 (for example, a clockwise direction). The second
direction 280 is opposite from the first direction 275.
Alternatively, rotation of the tether cable 110 in the second
direction 280 about the second horizontal axis of rotation 242
increases tension in the tether cable 110 and the second cable
260B. The increased tension in the second cable 260B provides a
tensile force to the first side 265A of the platform 210, which
rotates the platform 210 in the first direction 275 about the first
horizontal axis of rotation 240.
[0036] As illustrated in FIG. 5, the tether cable 110 may rotate in
a third direction 285 about the fourth horizontal axis of rotation
248 (for example, a clockwise direction). Rotation of the tether
cable 110 in the third direction 285 increases the tension in the
tether cable 110 and the fourth cable 260D. The increased tension
in the fourth cable 260D provides a tensile force to the third side
265C of the platform 210, which rotates the platform 210 in a
fourth direction 290 about the third horizontal axis of rotation
246 (for example, a counter-clockwise direction). The fourth
direction 290 is opposite from the third direction 285.
Alternatively, rotation of the tether cable 110 in the fourth
direction 290 about the fourth horizontal axis of rotation 248
increases tension in the tether cable 110 and the third cable 260C.
The increased tension in the third cable 260C provides a tensile
force to the fourth side 265D of the platform 210, which rotates
the platform 210 in the third direction 285 about the third
horizontal axis of rotation 246.
[0037] In some embodiments, the tether cable 110 and the platform
210 rotate the same angular distance, regardless the direction the
body 205 rotates. As a first example, as illustrated in FIG. 4, the
tether cable 110 rotates about 15 degrees in the first direction
275 and the platform 210 rotates about 15 degrees in the second
direction 280. As a second example, as illustrated in FIG. 5, the
tether cable 110 rotates about 20 degrees in the third direction
285 and the platform 210 rotates about 20 degrees in the fourth
direction 290.
[0038] Rotation of the platform 210, with respect to the body 205,
changes the orientation of the shaft 215 and the plurality of
rotors 220 with respect to the body 205. The orientation of the
plurality of rotors 220 after the platform 210 rotates creates a
flow of air that realigns the tether cable 110 with the reference
axis. In other words, after the platform 210 has rotated the
orientation of the plurality of rotors 220, the body 205 moves
longitudinally toward the coupling (not shown) in order to decrease
the relative angle between the tether cable 110 and the reference
axis. As the relative angle between the tether cable 110 and the
reference axis decreases, the platform 210 rotates in the opposite
direction so that the platform 210 is again orthogonal to the first
vertical plane 244 and the second vertical plane 250. The unmanned
aerial vehicle 200 returns to an equilibrium position when the
tether cable 110 is realigned with the reference axis, and the
platform 210 is perpendicular to the first vertical plane 244 and
the second vertical plane 250.
[0039] In some embodiments, motors are coupled to the pulley system
225 to bring the tether cable 110 back to the equilibrium position.
For example, a motor coupled to the first pulley 255A exerts a
rotational torque on the first pulley 255A to pull the body 205 of
the unmanned aerial vehicle 200 back to the equilibrium position
when the tether cable 110 rotates about the second horizontal axis
of rotation 242. As a further example, a motor coupled to the third
pulley 255C exerts a rotational torque on the third pulley 255C to
pull the body 205 of the unmanned aerial vehicle 200 back to the
equilibrium position when the tether cable 110 rotates about the
fourth horizontal axis of rotation 248.
[0040] While in flight, wind may blow against the unmanned aerial
vehicle 200. In some embodiments, in order to limit gusts of wind
from pivoting the body 205 with respect to the reference axis, one
or more weights (not shown) are positioned proximate to the second
end 235 of the body 205. The weights provide the unmanned aerial
vehicle 200 with a greater moment of inertia, increasing the force
required to rotate the body 205 of the unmanned aerial vehicle 200.
Alternatively or in addition, the body 205 includes a center of
mass proximate to the second end 235 of the body 205.
[0041] The unmanned aerial vehicle 200 illustrated in FIGS. 2
through 5 and described herein is provided as one example of such a
system. The unmanned aerial vehicle 200 may include fewer,
additional, or different components in different configurations
than the unmanned aerial vehicle 200 illustrated in FIGS. 2 through
5. For example, in some embodiments, the pulley system 225 includes
additional pulleys and cables to control rotation about more than
two horizontal axes of rotation. Alternatively, in some
embodiments, the pulley system 225 includes fewer pulleys and
cables to control rotation about only one horizontal axis of
rotation.
[0042] Further, the pulley system 225 illustrated in FIGS. 2
through 5 and described herein is just one example of a mechanical
actuation system for the unmanned aerial vehicle 105. FIGS. 6
through 10 are diagrams of one example embodiment of an unmanned
aerial vehicle 300 including an electronic actuation system. The
unmanned aerial vehicle 300 illustrated in FIG. 6 includes a
propulsion system 302, an electronic controller 305, a power supply
module 310, a communication module 315, a user interface 320, a
first electronic actuator 325, a second electronic actuator 330,
and a plurality of sensors 335. The unmanned aerial vehicle 300
illustrated in FIGS. 6 through 10 and described herein may include
fewer, additional, or different components in different
configurations than the unmanned aerial vehicle 300 illustrated in
FIGS. 6 through 10. For example, in some embodiments, the unmanned
aerial vehicle 300 includes more than one electronic
controller.
[0043] The propulsion system 302 provides sustained flight of the
unmanned aerial vehicle 300. The propulsion system 302 illustrated
in FIG. 6 includes lift motors 340, gears 345, and the plurality of
rotors 220. The lift motors 340 generate torque which is delivered
to the plurality of rotors 220 via the gears 345. The plurality of
rotors 220 rotate to provide sustained flight of the unmanned
aerial vehicle 300.
[0044] The electronic controller 305 includes, among other things,
an electronic processor 350 (for example, a microprocessor), memory
355, an input/output interface 360, and a bus. The bus connects
various components of the electronic controller 305 including the
memory 355 to the electronic processor 350. The memory 355 includes
read only memory (ROM), random access memory (RAM), an electrically
erasable programmable read-only memory (EEPROM), other
non-transitory computer-readable media, or any combination thereof.
The electronic processor 350 is configured to retrieve program
instructions and data from the memory 355 and execute, among other
things, instructions to perform the methods described herein.
Alternatively or in addition, the memory 355 is included in the
electronic processor 350. The input/output interface 360 includes
routines for transferring information between components within the
electronic controller 305 and other components internal and
external to the unmanned aerial vehicle 300. In some embodiments,
the electronic controller 305 also includes, among other things, a
plurality of additional passive and active components such as
resistors, capacitors, inductors, integrated circuits, and
amplifiers. These components are arranged and connected to provide
a plurality of electrical functions to the electronic controller
305 including, among other things, filtering, signal conditioning,
voltage regulation, or a combination thereof.
[0045] The power supply module 310 supplies a nominal AC or DC
voltage to the unmanned aerial vehicle 300. In some embodiments,
the power supply module 310 is powered by one or more batteries or
battery packs included in the unmanned aerial vehicle 300 (for
example, rechargeable batteries). Alternatively or in addition, the
power supply module 310 is powered by mains power having nominal
line voltages between, for example, 100 volts AC and 240 volts AC
and frequencies of approximately 50 hertz to 60 hertz.
Alternatively or in addition, the tether cable 110 may include one
or more electrical conduits that transmit electric power to the
power supply module 310. In some embodiments, the power supply
module 310 is configured to supply lower voltages to operate
circuits and components within the unmanned aerial vehicle 300.
[0046] The communication module 315 is configured to provide
communications between the unmanned aerial vehicle 300 and other
components within an unmanned aerial system (for example, remote
servers). The communication module 315 transmits signals to one or
more communication networks and receives signals from the
communication networks wirelessly, via wires, via fibers, or a
combination thereof. In some embodiments, signals include, for
example, data, data packets, or a combination thereof. The
communication networks may be implemented using various networks,
for example, a cellular network, the Internet, a Bluetooth.TM.
network, a wireless local area network (for example, Wi-Fi), a
wireless accessory Personal Area Networks (PAN), cable, an Ethernet
network, satellite, a machine-to-machine (M2M) autonomous network,
and a public switched telephone network. In some embodiments, the
communication module 315 receives and transmits data via the tether
cable 110. For example, the tether cable 110 may include wires,
fibers, or both.
[0047] The user interface 320 is included to control the operation
of the unmanned aerial vehicle 300. The user interface 320 can
include any combination of digital and analog input devices
required to achieve a desired level of control for the unmanned
aerial vehicle 300. For example, the user interface 320 can include
a touch-screen display, a plurality of knobs, dials, switches,
buttons, and the like.
[0048] As illustrated in FIG. 7, the unmanned aerial vehicle 300
further includes the tether cable 110, the body 205, the platform
210, and the shaft 215. Also as illustrated in FIG. 7, the first
electronic actuator 325 includes a first motor 365 and a first
plurality of arms 370. The first plurality of arms 370 are coupled
to the first motor 365 and to the first side 265A of the platform
210 such that rotation of first motor 365 causes rotation of the
platform 210 about the first horizontal axis of rotation 240. The
electronic controller 305 drives the first electronic actuator 325
to change the position of the platform 210 about the first
horizontal axis of rotation 240. For example, the electronic
controller 305 sends one or more control signals to the first
electronic actuator 325 which causes the first motor 365 to
rotate.
[0049] The second electronic actuator 330 includes a second motor
375 and a second plurality of arms 380. The second plurality of
arms 380 are coupled to the second motor 375 and to the third side
265C of the platform 210 such that rotation of second motor 375
causes rotation of the platform 210 about the third horizontal axis
of rotation 246. The electronic controller 305 drives the second
electronic actuator 330 to change the position of the platform 210
about the third horizontal axis of rotation 246. For example, the
electronic controller 305 sends one or more control signals to the
second electronic actuator 330 which causes the second motor 375 to
rotate.
[0050] The tether cable 110 is coupled to the body 205 such that
the tether cable 110 is rotatable relative to the body 205 about a
fifth horizontal axis of rotation 385 (illustrated in FIGS. 8 and
10). The fifth horizontal axis of rotation 385 is normal to the
first vertical plane 244. The tether cable 110 is also rotatable
relative to the body 205 about a sixth horizontal axis of rotation
390 (illustrated in FIGS. 7 and 9). The sixth horizontal axis of
rotation 390 is normal to the second vertical plane 250.
[0051] The plurality of sensors 335 include sensors for determining
the movement of the tether cable 110 relative to the body 205. In
some embodiments, the plurality of sensors 335 include one or more
sensors for determining the relative angle between the tether cable
110 and the body 205 (for example, rotary encoders, tilt sensors,
and angular position sensors). Alternatively or in addition, the
plurality of sensors 335 include one or more strain gauges
positioned, for example, proximate to the second end 235 of the
body 205 (not shown). In some embodiments, the tether cable 110 is
coupled to a deformable portion on the second end 235 of the body
205. The deformable portion on the second end 235 of the body 205
deforms as the tension in the tether cable 110 changes (for
example, due the movement of the tether cable 110). The one or more
strain gauges determine measurements of the deformation. The
electronic processor 350 determines the angular displacement of the
tether cable 110 relative to the reference axis based on the
measurements of the one or more strain gauges.
[0052] In some embodiments, the plurality of sensors 335 include
sensors for determining the tension of the tether cable 110. For
example, the plurality of sensors 335 can include cable tension
meters, dynamometers, strain gauges, or a combination thereof.
[0053] In some embodiments, the plurality of sensors 335 include
sensors for determining the location, the position, the motion, and
the orientation of the unmanned aerial vehicle 300. For example,
the plurality of sensors 335 can include global positioning system
(GPS) sensors, barometers, accelerometers, gyroscopes,
magnetometers, distance sensors (for example, ultrasonic sensors,
radar sensors, and LIDAR sensors), or a combination thereof.
[0054] In some embodiments, the plurality of sensors 335 include
sensors for recording the environment around the unmanned aerial
vehicle 300. For example, the plurality of sensors 335 can include
image sensors (for example, cameras) and audio sensors (for
example, microphones), or both. In some embodiments, the image
and/or audio data captured by the sensors 335 can be stored with
the memory 355 for future access. Alternatively or in addition, the
image and/or audio data captured by the sensors 335 can be
transmitted to an external electronic device (for example, via the
tether cable 110). Attentively or in addition, the image and/or
audio data captured by the sensors 335 can be transmitted to
emergency responders to assist in emergency operations. For
example, when the unmanned aerial vehicle 300 is deployed from a
car after a collision, emergency responders can use the image
and/or audio data captured by the sensors 335 to determine the
extent of injuries suffered by occupants of the car.
[0055] At rest, the tether cable 110 extends away from the body 205
along the reference axis (i.e., along the intersection of the first
vertical plane 244 and the second vertical plane 250), as
illustrated in FIGS. 7 and 8. When the tether cable 110 becomes
misaligned with the reference axis, the electronic controller 305
drives the first electronic actuator 325 and the second electronic
actuator 330 to rotate the platform 210 such that the orientation
of the plurality of rotors 220 creates a flow of air that realigns
the tether cable 110 with the reference axis. The electronic
controller 305 determines movement of the tether cable 110 based at
least in part on data from the plurality of sensors 335.
[0056] As illustrated in FIG. 9, the tether cable 110 may rotate in
the first direction 275 about the fifth horizontal axis of rotation
385 (for example, a counter-clockwise direction). Responsive to
detecting rotation of the tether cable 110 in the first direction
275 about the fifth horizontal axis of rotation 385, the electronic
controller 305 drives the first electronic actuator 325 to rotate
the platform 210 in the second direction 280 about the first
horizontal axis of rotation 240 (for example, a clockwise
direction). The tether cable 110 may also rotate in the second
direction 280 about the fifth horizontal axis of rotation 385.
Responsive to detecting rotation of the tether cable 110 in the
second direction 280 about the fifth horizontal axis of rotation
385, the electronic controller 305 drives the first electronic
actuator 325 to rotate the platform 210 in the first direction 275
about the first horizontal axis of rotation 240.
[0057] As illustrated in FIG. 10, the tether cable 110 may rotate
in the third direction 285 about the sixth horizontal axis of
rotation 390 (for example, a clockwise direction). Responsive to
detecting rotation of the tether cable 110 in the third direction
285 about the sixth horizontal axis of rotation 390, the electronic
controller 305 drives the second electronic actuator 330 to rotate
the platform 210 in the fourth direction 290 about the third
horizontal axis of rotation 246 (for example, a counter-clockwise
direction). The tether cable 110 may also rotate in the fourth
direction 290 about the sixth horizontal axis of rotation 390.
Responsive to detecting rotation of the tether cable 110 in the
fourth direction 290 about the sixth horizontal axis of rotation
390, the electronic controller 305 drives the second electronic
actuator 330 to rotate the platform 210 in the third direction 285
about the third horizontal axis of rotation 246.
[0058] In some embodiments, the electronic controller 305 drives
the first electronic actuator 325 and the second electronic
actuator 330 to rotate the platform 210 the same angular distance
as the tether cable 110. As a first example, as illustrated in FIG.
9, the electronic controller 305 rotates the platform 210 about 15
degrees in the second direction 280 when the tether cable 110
rotates about 15 degrees in the first direction 275. As a second
example, as illustrated in FIG. 10, the electronic controller 305
rotates the platform 210 about 10 degrees in the fourth direction
290 when the tether cable 110 rotates about 10 degrees in the third
direction 285.
[0059] Slack in the tether cable 110 between the body 205 and an
external coupling can cause a portion of the tether cable 110 to
become caught on an obstruction (for example, a power line pole).
Thus, in some embodiments, the electronic controller 305 adjusts
the angular speeds (for example, the rotations per minute (RPM)) of
the plurality of rotors 220 to keep the tether cable 110 taut
(i.e., straight). For example, the electronic controller 305 may
determine the tension in the tether cable 110 using the plurality
of sensors 335 and increase the angular speeds of the plurality of
rotors 220 when the tension of the tether cable 110 decreases. In
addition, the electronic controller 305 may decrease the angular
speeds of the plurality of rotors 220 when the tension of the
tether cable 110 increases. In some embodiments, the electronic
controller 305 adjusts the angular speeds of the plurality of
rotors 220 to keep the tension of the tether cable 110 within a
predetermined range. For example, the electronic controller 305 may
increase the angular speeds of the plurality of rotors 220 to keep
the tension of the tether cable 110 above a predetermined minimum
amount of tension at which the tether cable 110 may become slack.
In addition, the electronic controller 305 may decrease the angular
speeds of the plurality of rotors 220 to keep the tension of the
tether cable 110 below a predetermined maximum amount of tension at
which the tether cable 110 may break.
[0060] In some embodiments, the unmanned aerial vehicle 200
illustrated in FIGS. 2 through 5 includes all or some of the
components of the unmanned aerial vehicle 300 illustrated in FIGS.
6 through 10. For example, the unmanned aerial vehicle 200 may
include an electronic controller and sensors configured to perform
all or some of the functions described herein as being performed by
the electronic controller 305 and the plurality of sensors 335. In
some embodiments, the unmanned aerial vehicle 200 determines the
tension in the tether cable 110 by measuring torque on the first
pulley 255A, the second pulley 255B, the third pulley 255C, and the
fourth pulley 255D using, for example, torque sensors.
[0061] FIGS. 11 through 17 are diagrams of one example embodiment
of an unmanned aerial vehicle 400 including a variable rotor thrust
stabilization system. The unmanned aerial vehicle 400 illustrated
in FIG. 11 includes a propulsion system 402, an electronic
controller 405, a power supply module 410, a communication module
415, a user interface 420, and a plurality of sensors 425. The
unmanned aerial vehicle 400 illustrated in FIGS. 11 through 17 and
described herein may include fewer, additional, or different
components in different configurations than the unmanned aerial
vehicle 400 illustrated in FIGS. 11 through 17. For example, in
some embodiments, the unmanned aerial vehicle 400 includes more
than one electronic controller.
[0062] The propulsion system 402 provides sustained flight of the
unmanned aerial vehicle 400. The propulsion system 402 illustrated
in FIG. 11 includes four lift motors (for example, a first lift
motor 430, a second lift motor 432, a third lift motor 434, and a
fourth lift motor 436) and four rotors (for example, a first rotor
440, a second rotor 442, a third rotor 444, and a fourth rotor
446). Each of the four lift motors 430-436 generates torque which
is delivered to one of the four rotors 440-446. For example, the
first lift motor 430 generates torque which is delivered to the
first rotor 440. The four rotors 440-446 rotate to provide
sustained flight of the unmanned aerial vehicle 400.
[0063] The electronic controller 405 includes, among other things,
an electronic processor 450 (for example, a microprocessor), memory
455, an input/output interface 460, and a bus. The bus connects
various components of the electronic controller 405 including the
memory 455 to the electronic processor 450. The memory 455 includes
read only memory (ROM), random access memory (RAM), an electrically
erasable programmable read-only memory (EEPROM), other
non-transitory computer-readable media, or any combination thereof.
The electronic processor 450 is configured to retrieve program
instructions and data from the memory 455 and execute, among other
things, instructions to perform the methods described herein.
Alternatively or in addition, the memory 455 is included in the
electronic processor 450. The input/output interface 460 includes
routines for transferring information between components within the
electronic controller 405 and other components internal and
external to the unmanned aerial vehicle 400. In some embodiments,
the electronic controller 405 also includes, among other things, a
plurality of additional passive and active components such as
resistors, capacitors, inductors, integrated circuits, and
amplifiers. These components are arranged and connected to provide
a plurality of electrical functions to the electronic controller
405 including, among other things, filtering, signal conditioning,
voltage regulation, or a combination thereof.
[0064] The power supply module 410 supplies a nominal AC or DC
voltage to the unmanned aerial vehicle 400. In some embodiments,
the power supply module 410 is powered by one or more batteries or
battery packs included in the unmanned aerial vehicle 400 (for
example, rechargeable batteries). Alternatively or in addition, the
power supply module 410 is powered by mains power having nominal
line voltages between, for example, 100 volts AC and 240 volts AC
and frequencies of approximately 50 hertz to 60 hertz.
Alternatively or in addition, the tether cable 110 may include one
or more electrical conduits that transmit electric power to the
power supply module 410. In some embodiments, the power supply
module 410 is configured to supply lower voltages to operate
circuits and components within the unmanned aerial vehicle 400.
[0065] The communication module 415 is configured to provide
communications between the unmanned aerial vehicle 400 and other
components within an unmanned aerial system (for example, remote
servers). The communication module 415 transmits signals to one or
more communication networks and receives signals from the
communication networks wirelessly, via wires, via fibers, or a
combination thereof. In some embodiments, signals include, for
example, data, data packets, or a combination thereof. The
communication networks may be implemented using various networks,
for example, a cellular network, the Internet, a Bluetooth.TM.
network, a wireless local area network (for example, Wi-Fi), a
wireless accessory Personal Area Networks (PAN), cable, an Ethernet
network, satellite, a machine-to-machine (M2M) autonomous network,
and a public switched telephone network. In some embodiments, the
communication module 415 receives and transmits data via the tether
cable 110. For example, the tether cable 110 may include wires,
fibers, or both.
[0066] The user interface 420 is included to control the operation
of the unmanned aerial vehicle 400. The user interface 420 can
include any combination of digital and analog input devices
required to achieve a desired level of control for the unmanned
aerial vehicle 400. For example, the user interface 420 can include
a touch-screen display, a plurality of knobs, dials, switches,
buttons, and the like.
[0067] As illustrated in FIGS. 12 and 13, the unmanned aerial
vehicle 400 further includes the tether cable 110, a body 462, and
a recess 464. Also, as illustrated in FIGS. 12 and 13, each of the
four rotors 440-446 are positioned in different quadrants of the
body 462.
[0068] The body 462 is rotatable about a first horizontal axis of
rotation 466 (illustrated in FIGS. 14 and 16). The tether cable 110
is coupled to the body 462 such that the tether cable 110 is
rotatable relative to the body 462 about a second horizontal axis
of rotation 468 (illustrated in FIGS. 14 and 16). The first
horizontal axis of rotation 466 and the second horizontal axis of
rotation 468 are both normal to a first vertical plane 470
extending through the body 462.
[0069] The body 462 is also rotatable about a third horizontal axis
of rotation 472 (illustrated in FIGS. 15 and 17). The tether cable
110 is also rotatable relative to the body 462 about a fourth
horizontal axis of rotation 474 (illustrated in FIGS. 15 and 17).
The third horizontal axis of rotation 472 and the fourth horizontal
axis of rotation 474 are both normal to a second vertical plane 476
extending through the body 462. The second vertical plane 476 is
orthogonal to the first vertical plane 470. The first horizontal
axis of rotation 466 is orthogonal to the third horizontal axis of
rotation 472. The second horizontal axis of rotation 468 is
orthogonal to the fourth horizontal axis of rotation 474.
[0070] In the embodiment illustrated, the recess 464 is
domed-shaped and the tether cable 110 is coupled near a crown of
the recess 464. This configuration enables the tether cable 110 to
be coupled to body 462 as close as possible to the center of
gravity of the body 462. In other words, the offset between the
first horizontal axis of rotation 466 and the second horizontal
axis of rotation 468 is minimized. In addition, this configuration
minimizes the offset between the third horizontal axis of rotation
472 and the fourth horizontal axis of rotation 474.
[0071] While in flight, the first rotor 440 and the third rotor 444
rotate in a direction that is opposite from the direction of
rotation of the second rotor 442 and the fourth rotor 446. For
example, the first rotor 440 and the third rotor 444 clockwise and
the second rotor 442 and the fourth rotor 446 rotate
counter-clockwise. In addition, while hovering as illustrated in
FIGS. 14 and 15, the angular speed of each of the four rotors
440-446 is equal to each other.
[0072] At rest, the tether cable 110 extends away from the body 462
along the reference axis (i.e., along the intersection of the first
vertical plane 470 and the second vertical plane 476), as
illustrated in FIGS. 14 and 15. When the tether cable 110 becomes
misaligned with the reference axis, the electronic controller 405
adjusts the angular speeds of the four rotors 440-446 to rotate the
body 462 such that the orientation of the four rotors 440-446
creates a flow of air that realigns the tether cable 110 with the
reference axis. The electronic controller 405 determines movement
of the tether cable 110 based at least in part on data from the
plurality of sensors 425. The plurality of sensors 425 includes one
or more sensors such as any combination of the sensors described
above in relation to the plurality of sensors 335. For example, the
plurality of sensors can includes sensors for determining the
movement of the tether cable 110 relative to the body 462 and the
tension of the tether cable 110.
[0073] As illustrated in FIG. 16, the tether cable 110 may rotate
in a first direction 478 about the second horizontal axis of
rotation 468 (for example, a counter-clockwise direction).
Responsive to detecting rotation of the tether cable 110 in the
first direction 478 about the second horizontal axis of rotation
468, the electronic controller 405 adjusts the angular speeds of
the four rotors 440-446 to rotate the body 462 in a second
direction 480 about the first horizontal axis of rotation 466 (for
example, a clockwise direction). For example, the electronic
controller 405 drives the first lift motor 430 and the fourth lift
motor 436 to increase the angular speeds of the first rotor 440 and
the fourth rotor 446, and drives the second lift motor 432 and the
third lift motor 434 to decrease the angular speeds of the second
rotor 442 and the third rotor 444.
[0074] In some embodiments, the electronic controller 405 adjusts
the angular speeds of the four rotors 440-440 such that the total
thrust remains constants. For example, the electronic controller
405 decreases the angular speeds of the second rotor 442 and the
third rotor 444 by amounts that are substantially equal to the
amounts of increase of the angular speeds of the first rotor 440
and the fourth rotor 446.
[0075] The tether cable 110 may also rotate in the second direction
480 about the second horizontal axis of rotation 468. Responsive to
detecting rotation of the tether cable 110 in the second direction
480 about the second horizontal axis of rotation 468, the
electronic controller 405 adjusts the angular speeds of the four
rotors 440-446 to rotate the body 462 in the first direction 478
about the first horizontal axis of rotation 466. For example, the
electronic controller 405 drives the first lift motor 430 and the
fourth lift motor 436 to decrease the angular speeds of the first
rotor 440 and the fourth rotor 446, and drives the second lift
motor 432 and the third lift motor 434 to increase the angular
speeds of the second rotor 442 and the third rotor 444.
[0076] As illustrated in FIG. 17, the tether cable 110 may rotate
in a third direction 482 about the fourth horizontal axis of
rotation 474 (for example, a clockwise direction). Responsive to
detecting rotation of the tether cable 110 in the third direction
482 about the fourth horizontal axis of rotation 474, the
electronic controller 405 adjusts the angular speeds of the four
rotors 440-446 to rotate the body 462 in a fourth direction 484
about the third horizontal axis of rotation 472 (for example, a
counter-clockwise direction). For example, the electronic
controller 405 drives the first lift motor 430 and the second lift
motor 432 to decrease the angular speeds of the first rotor 440 and
the second rotor 442, and drives the third lift motor 434 and the
fourth lift motor 436 to increase the angular speeds of the third
rotor 444 and the fourth rotor 446.
[0077] The tether cable 110 may also rotate in the fourth direction
484 about the fourth horizontal axis of rotation 474. Responsive to
detecting rotation of the tether cable 110 in the fourth direction
484 about the fourth horizontal axis of rotation 474, the
electronic controller 405 adjusts the angular speeds of the four
rotors 440-446 to rotate the body 462 in the third direction 482
about the third horizontal axis of rotation 472. For example, the
electronic controller 405 drives the first lift motor 430 and the
second lift motor 432 to increase the angular speeds of the first
rotor 440 and the second rotor 442, and drives the third lift motor
434 and the fourth lift motor 436 to decrease the angular speeds of
the third rotor 444 and the fourth rotor 446.
[0078] In some embodiments, the electronic controller 405 adjusts
the angular speeds of the four rotors 440-446 based in part on the
amount of rotation of the tether cable 110. In other words, the
electronic controller 405 adjusts the angular speeds of the four
rotors 440-446 greater when the tether cable 110 rotates farther
away from the reference axis. For example, the electronic
controller 405 adjusts the angular speeds of the four rotors
440-446 by small amounts when the angle between the tether cable
110 and the references axis is small, and adjusts the angular
speeds of the four rotors 440-446 by large amounts when the angle
between the tether cable 110 and the reference axis is large.
[0079] In some embodiments, the electronic controller 405 adjusts
the angular speeds of the four rotors 440-446 to rotate the body
462 the same angular distance as the tether cable 110. As a first
example, as illustrated in FIG. 16, the electronic controller 405
adjusts the angular speeds of the four rotors 440-446 to rotate the
body 462 about 15 degrees in the second direction 480 when the
tether cable 110 rotates about 15 degrees in the first direction
478. As a second example, as illustrated in FIG. 17, the electronic
controller 405 adjusts the angular speeds of the four rotors
440-446 to rotate the body 462 about 20 degrees in the fourth
direction 484 when the tether cable 110 rotates about 20 degrees in
the third direction 482.
[0080] In some embodiments, the electronic controller 405 adjusts
the angular speeds of the four rotors 440-446 to keep the tether
cable 110 taut (i.e., straight). For example, the electronic
controller 405 may determine the tension in the tether cable 110
using the plurality of sensors 425 and increase the angular speeds
of the four rotors 440-446 when the tension of the tether cable 110
decreases. In addition, the electronic controller 405 may decrease
the angular speeds of the four rotors 440-446 when the tension of
the tether cable 110 increases. In some embodiments, the electronic
controller 405 adjusts the angular speeds of the four rotors
440-446 to keep the tension of the tether cable 110 within a
predetermined range. For example, the electronic controller 405 may
increase the angular speeds of the four rotors 440-446 to keep the
tension of the tether cable 110 above a predetermined minimum
amount of tension at which the tether cable 110 may become slack.
In addition, the electronic controller 405 may decrease the angular
speeds of the four rotors 440-446 to keep the tension of the tether
cable 110 below a predetermined maximum amount of tension at which
the tether cable 110 may break.
[0081] Although aspects have been described in detail with
reference to certain preferred embodiments, variations and
modifications exist within the scope and spirit of one or more
independent aspects as described.
* * * * *