U.S. patent application number 10/641461 was filed with the patent office on 2005-02-24 for methods and systems for controlling wheel brakes on aircraft and other vehicles.
Invention is credited to Radford, Michael A..
Application Number | 20050040286 10/641461 |
Document ID | / |
Family ID | 34104637 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050040286 |
Kind Code |
A1 |
Radford, Michael A. |
February 24, 2005 |
METHODS AND SYSTEMS FOR CONTROLLING WHEEL BRAKES ON AIRCRAFT AND
OTHER VEHICLES
Abstract
Methods and systems for controlling wheel brakes on aircraft and
other vehicles. In one embodiment, a method for slowing a vehicle
on the ground can include applying a first brake to a first wheel
and a second brake to a second wheel. The method can further
include determining if a first speed sensor associated with the
first wheel and a second speed sensor associated with the second
wheel are operative. When the first and second speed sensors are
operative, the first and second brakes can be controlled according
to a first routine. Conversely, when at least one of the first and
second speed sensors is inoperative, the first and second brakes
can be controlled according to a second routine.
Inventors: |
Radford, Michael A.; (Mill
Creek, WA) |
Correspondence
Address: |
PERKINS COIE LLP
PATENT-SEA
P.O. BOX 1247
SEATTLE
WA
98111-1247
US
|
Family ID: |
34104637 |
Appl. No.: |
10/641461 |
Filed: |
August 14, 2003 |
Current U.S.
Class: |
244/111 ;
188/264R; 303/126; 303/191 |
Current CPC
Class: |
B60T 2270/416 20130101;
B64C 25/46 20130101; B60T 2210/13 20130101; B60T 8/325 20130101;
B60T 8/1703 20130101 |
Class at
Publication: |
244/111 ;
188/264.00R; 303/126; 303/191 |
International
Class: |
B60T 008/86 |
Claims
1. A method for slowing a vehicle on the ground, the vehicle having
at least first and second wheels for supporting at least a portion
of the vehicle on the ground, the vehicle further having a first
brake and a first speed sensor associated with the first wheel, and
a second brake and a second speed sensor associated with the second
wheel, the method comprising: receiving a first control input to
slow the vehicle; in response to receiving the first control input,
applying the first brake to the first wheel and the second brake to
the second wheel; determining if the first and second speed sensors
are operative; when the first and second speed sensors are
operative, determining if a first speed of the first wheel differs
from a second speed of the second wheel by a preset amount; and if
the first speed differs from the second speed by the preset amount,
changing the application of at least one of the first and second
brakes; when at least one of the first and second speed sensors is
inoperative, continuing to apply the first brake to the first wheel
and the second brake to the second wheel while receiving the first
control input.
2. The method of claim 1 wherein changing the application of at
least one of the first and second brakes includes releasing at
least one of the first and second brakes if the first wheel speed
differs from the second wheel speed by the preset amount.
3. The method of claim 1 wherein: when the first and second speed
sensors are operative, changing the application of at least one of
the first and second brakes includes releasing at least one of the
first and second brakes if the first wheel speed differs from the
second wheel speed by the preset amount; and when at least one of
the first and second speed sensors is inoperative, continuing to
apply the first brake to the first wheel and the second brake to
the second wheel includes continuing to apply the first and second
brakes if the first wheel speed differs from the second wheel speed
by the preset amount.
4. The method of claim 1 wherein changing the application of at
least one of the first and second brakes includes releasing the
first brake if the speed of the first wheel is slower than the
speed of the second wheel by the preset amount.
5. The method of claim 1 wherein changing the application of at
least one of the first and second brakes includes: releasing the
first brake if the speed of the first wheel is slower than the
speed of the second wheel by the preset amount; and releasing the
second brake if the speed of the second wheel is slower than the
speed of the first wheel by the preset amount.
6. The method of claim 1 wherein the first speed sensor includes a
first electrical generator driven by the first wheel, and wherein
determining if the first and second speed sensors are operative
includes determining if the first generator is outputting an
electrical signal.
7. The method of claim 1 wherein the vehicle is an aircraft having
at least a first wheel truck and a second wheel truck, and wherein
applying the first brake to the first wheel and the second brake to
the second wheel includes applying the first and second brakes on
the first wheel truck.
8. The method of claim 1 wherein the vehicle is an aircraft having
at least a first wheel truck and a second wheel truck, and wherein
applying the first brake to the first wheel and the second brake to
the second wheel includes applying the first and second brakes to
tandem wheels on the first wheel truck.
9. The method of claim 1 wherein the vehicle is an aircraft having
at least a first wheel truck and a second wheel truck, and wherein
applying the first brake to the first wheel and the second brake to
the second wheel includes applying the first and second brakes to
side-by-side wheels on the first wheel truck.
10. The method of claim 1, further comprising: receiving a second
control input to allow the vehicle to roll free; and in response to
receiving the second control input, releasing the first brake from
the first wheel and the second brake from the second wheel.
11. A method for slowing a vehicle on the ground, the vehicle
having a wheel for supporting a portion of the vehicle on the
ground, the vehicle further having a brake and a speed sensor
associated with the wheel, the method comprising: receiving a
control input to slow the vehicle; in response to receiving the
control input, applying the brake to the wheel; determining if the
speed sensor is operative; when the speed sensor is operative,
determining if a first speed of the wheel differs from a second
speed associated with the speed of the vehicle by a preset amount,
the first speed being determined with the speed sensor; and if the
first speed differs from the second speed by the preset amount,
changing the application of the brake; when the speed sensor is
inoperative, continuing to apply the brake to the wheel while
receiving the control input.
12. The method of claim 11 wherein changing the application of the
brake includes releasing the brake if the first speed differs from
the second speed by the preset amount.
13. The method of claim 11 wherein changing the application of the
brake includes releasing the brake if the first speed is slower
than the second speed by the preset amount.
14. The method of claim 11 wherein: when the speed sensor is
operative, changing the application of the brake includes releasing
the brake if the first speed is slower than the second speed by the
preset amount; and when the speed sensor is inoperative, continuing
to apply the brake to the wheel includes continuing to apply the
brake if the first speed is slower than the second speed by the
preset amount.
15. The method of claim 11 wherein the vehicle further includes a
speed measurement device separate from the speed sensor for
measuring vehicle speed, and further comprising determining the
second speed of the vehicle with the speed measurement device.
16. The method of claim 11 wherein the first speed is a first wheel
speed and the second speed is a second wheel speed, and further
comprising: determining a vehicle speed with an inertial reference
unit; and converting the vehicle speed to the second wheel
speed.
17. The method of claim 11 wherein the control input is a first
control input, and further comprising: receiving a second control
input to allow the vehicle to roll free; and in response to
receiving the second control input, releasing the brake from the
wheel.
18. A method for slowing a vehicle on the ground, the vehicle
having at least first and second wheels for supporting at least a
portion of the vehicle on the ground, the vehicle further having a
first brake and a first speed sensor associated with the first
wheel, and a second brake and a second speed sensor associated with
the second wheel, the method comprising: receiving a control input
to slow the vehicle; in response to receiving the control input,
applying the first brake to the first wheel and the second brake to
the second wheel; determining if the first speed sensor is
operative; when the first speed sensor is operative, determining if
a rate-of-change of speed of the first wheel exceeds a preset
rate-of-change of speed, the rate-of-change of speed of the first
wheel being determined with the first speed sensor; and if the
rate-of-change of speed of the first wheel exceeds the preset
rate-of-change of speed, changing the application of at least the
first brake; when the first speed sensor is inoperative,
determining if the second speed sensor is operative; when the
second speed sensor is operative, determining if a rate-of-change
of speed of the second wheel exceeds the preset rate-of-change of
speed; and if the rate-of-change of speed of the second wheel
exceeds the preset rate-of-change of speed, changing the
application of at least the first brake.
19. The method of claim 18 wherein: when the first speed sensor is
operative, changing the application of at least the first brake
includes releasing the first brake if the rate-of-change of speed
of the first wheel exceeds the preset rate-of-change of speed; and
when the first speed sensor is inoperative, changing the
application of at least the first brake includes releasing the
first brake if the rate-of-change of speed of the second wheel
exceeds the preset rate-of-change of speed.
20. The method of claim 18 wherein: when the first speed sensor is
operative, changing the application of at least the first brake
includes releasing the first brake if a deceleration of the first
wheel exceeds the preset rate-of-change of speed; and when the
first speed sensor is inoperative, changing the application of at
least the first brake includes releasing the first brake if a
deceleration of the second wheel exceeds the preset rate-of-change
of speed.
21. A method for slowing a vehicle on the ground, the vehicle
having at least first, second, and third wheels for supporting at
least a portion of the vehicle on the ground, the vehicle further
having a first brake and a first speed sensor associated with the
first wheel, a second brake and a second speed sensor associated
with the second wheel, and a third brake and a third speed sensor
associated with the third wheel, the method comprising: receiving a
control input to slow the vehicle; in response to receiving the
control input, applying the first brake to the first wheel, the
second brake to the second wheel, and the third brake to the third
wheel; determining if the first, second, and third speed sensors
are operative; when the first, second, and third speed sensors are
operative, determining if a first speed of the first wheel differs
from an average speed of the second and third wheels by a preset
amount; and if the first speed differs from the average speed by
the preset amount, changing the application of at least the first
brake; when at least the first speed sensor is inoperative,
continuing to apply the first brake to the first wheel while
receiving the first control input.
22. The method of claim 21 wherein when the first, second, and
third speed sensors are operative, changing the application of at
least the first brake includes releasing the first brake if the
first speed of the first wheel is less than the average speed of
the second and third wheels by the preset amount.
23. The method of claim 21 wherein: when the first, second, and
third speed sensors are operative, changing the application of at
least the first brake includes releasing the first brake if the
first speed of the first wheel is less than the average speed of
the second and third wheels by the preset amount; and when at least
the first speed sensor is inoperative, continuing to apply the
first brake to the first wheel includes continuing to apply the
first brake if the first speed of the first wheel is less than the
average speed of the second and third wheels by the preset
amount.
24. A method for slowing a vehicle on the ground, the vehicle
having a wheel for supporting a portion of the vehicle on the
ground, the vehicle further having a brake and a speed sensor
associated with the wheel, the method comprising: receiving a
control input to slow the vehicle; determining if the speed sensor
is operative; when the speed sensor is operative, controlling the
brake according to a first routine in response to receiving the
control input; and when the speed sensor is inoperative,
controlling the brake according to a second routine in response to
receiving the control input, the second routine being different
than the first routine.
25. The method of claim 24 wherein controlling the brake according
to the second routine includes applying the brake to the wheel in
response to the control input.
26. The method of claim 24 wherein the wheel is a first wheel, the
brake is a first brake, and the speed sensor is a first speed
sensor, and wherein controlling the brake according to the first
routine includes: determining if a first speed of the first wheel
differs from a second speed of a second wheel by a preset amount;
and if the first speed differs from the second speed by the preset
amount, changing the application of at least one of the first and
second brakes.
27. The method of claim 24 wherein the wheel is a first wheel, the
brake is a first brake, and the speed sensor is a first speed
sensor, and wherein controlling the brake according to the first
routine includes: determining if a first speed of the first wheel
differs from a second speed of a second wheel by a preset amount;
and if the first speed differs from the second speed by the preset
amount, releasing at least one of the first and second brakes.
28. The method of claim 24 wherein controlling the brake according
to the first routine includes: determining if a first speed of the
wheel differs from a second speed associated with the speed of the
vehicle by a preset amount, the first speed being determined with
the speed sensor; and if the first speed differs from the second
speed by the preset amount, changing the application of the
brake.
29. The method of claim 24 wherein controlling the brake according
to the first routine includes: determining if a first speed of the
wheel differs from a second speed associated with the speed of the
vehicle by a preset amount, the first speed being determined with
the speed sensor; and if the first speed differs from the second
speed by the preset amount, releasing the brake.
30. A system for slowing a vehicle on the ground, the vehicle
having at least first and second wheels for supporting at least a
portion of the vehicle on the ground, the vehicle further having a
first brake and a first speed sensor associated with the first
wheel, and a second brake and a second speed sensor associated with
the second wheel, the system comprising: means for receiving a
first control input to slow the vehicle; means for applying the
first brake to the first wheel and the second brake to the second
wheel in response to receiving the first request; means for
determining if the first and second speed sensors are operative;
means for determining if a first speed of the first wheel differs
from a second speed of the second wheel by a preset amount when the
first and second speed sensors are operative; means for changing
the application of at least one of the first and second brakes if
the first speed differs from the second speed by the preset amount;
and means for continuing to apply the first brake to the first
wheel and the second brake to the second wheel while receiving the
first control input when at least one of the first and second speed
sensors is inoperative.
31. The system of claim 30 wherein the means for changing the
application of at least one of the first and second brakes includes
means for releasing at least one of the first and second brakes if
the first wheel speed differs from the second wheel speed by the
preset amount.
32. The system of claim 30 wherein: the means for changing the
application of at least one of the first and second brakes when the
first and second speed sensors are operative includes means for
releasing at least one of the first and second brakes if the first
wheel speed differs from the second wheel speed by the preset
amount; and the means for continuing to apply the first brake to
the first wheel and the second brake to the second wheel when at
least one of the first and second speed sensors is inoperative
includes means for continuing to apply the first and second brakes
if the first wheel speed differs from the second wheel speed by the
preset amount.
33. The system of claim 30 wherein the means for changing the
application of at least one of the first and second brakes includes
means for releasing the first brake if the speed of the first wheel
is slower than the speed of the second wheel by the preset
amount.
34. The system of claim 30 wherein the vehicle is an aircraft
having at least a first wheel truck and a second wheel truck, and
wherein the means for applying the first brake to the first wheel
and the second brake to the second wheel includes means for
applying the first and second brakes on the first wheel truck.
35. A system for slowing a vehicle on the ground, the vehicle
having a wheel for supporting a portion of the vehicle on the
ground, the vehicle further having a brake and a speed sensor
associated with the wheel, the system comprising: means for
receiving a control input to slow the vehicle; means for
determining if the speed sensor is operative; means for applying
the brake to the wheel according to a first routine in response to
receiving the control input when the speed sensor is operative; and
means for applying the brake to the wheel according to a second
routine in response to receiving the control input when the speed
sensor is inoperative, the second routine being different than the
first routine.
36. The system of claim 35 wherein the means for controlling the
brake according to the second routine includes means for applying
the brake to the wheel in response to the control input.
37. The system of claim 35 wherein the wheel is a first wheel, the
brake is a first brake, and the speed sensor is a first speed
sensor, and wherein the means for controlling the brake according
to the first routine includes: means for determining if a first
speed of the first wheel differs from a second speed of a second
wheel by a preset amount; and means for changing the application of
at least one of the first and second brakes if the first speed
differs from the second speed by the preset amount.
38. The system of claim 35 wherein the means for controlling the
brake according to the first routine includes: means for
determining if a first speed of the wheel differs from a second
speed associated with the speed of the vehicle by a preset amount,
the first speed being determined with the speed sensor; and means
for changing the application of the brake if the first speed
differs from the second speed by the preset amount.
39. An aircraft system comprising: a first landing wheel configured
to support at least a portion of an aircraft on the ground; at
least a second landing wheel configured to support at least a
portion of the aircraft on the ground; a first brake and a first
speed sensor associated with the first wheel; a second brake and a
second speed sensor associated with the second wheel; and a
processor operatively coupled to the first and second brakes and
the first and second speed sensors, wherein the processor is
configured to respond to a first control input to slow the aircraft
by: applying the first brake to the first wheel and the second
brake to the second wheel; determining if the first and second
speed sensors are operative; when the first and second speed
sensors are operative, determining if a first speed of the first
wheel differs from a second speed of the second wheel by a preset
amount; and if the first speed differs from the second speed by the
preset amount, changing the application of at least one of the
first and second brakes; when at least one of the first and second
speed sensors is inoperative, continuing to apply the first brake
to the first wheel and the second brake to the second wheel while
receiving the first control input.
40. The aircraft system of claim 39 wherein the processor is
further configured to release at least one of the first and second
brakes if the first wheel speed differs from the second wheel speed
by the preset amount when the first and second speed sensors are
operative.
41. The aircraft system of claim 39 wherein: the processor is
further configured to release at least one of the first and second
brakes if the first wheel speed differs from the second wheel speed
by the preset amount when the first and second speed sensors are
operative; and the processor is still further configured to
continue applying the first brake to the first wheel and the second
brake to the second wheel if the first wheel speed differs from the
second wheel speed by the preset amount when at least one of the
first and second speed sensors is inoperative.
42. The aircraft system of claim 39, further comprising: a first
wheel truck; and a second wheel truck spaced apart from the first
wheel truck, wherein the first and second landing wheels are
rotatably mounted to the first wheel truck.
43. The aircraft system of claim 39, further comprising: a first
wheel truck; and a second wheel truck spaced apart from the first
wheel truck, wherein the first and second landing wheels are
rotatably mounted to the first wheel truck in alignment with each
other.
44. The aircraft system of claim 39 wherein the processor includes
a bypass component configured to cause the processor to continue
applying the first brake to the first wheel and the second brake to
the second wheel while receiving the first control input when at
least one of the first and second speed sensors is inoperative.
Description
TECHNICAL FIELD
[0001] The following disclosure relates generally to wheel brake
systems and, more particularly, to wheel brake systems for aircraft
and other vehicles.
BACKGROUND
[0002] Conventional jet transport aircraft typically include
landing gears with anti-skid or anti-lock brake systems. One such
brake system is illustrated in FIG. 1, which shows a schematic top
view of an aircraft main landing gear system 100 configured in
accordance with the prior art. The prior art landing gear system
100 includes a left or first wheel truck 102a and a right or second
wheel truck 102b. On a typical aircraft, the first wheel truck 102a
can extend downwardly from a left wing (not shown), and the second
wheel truck 102b can extend downwardly from an opposite right wing
(also not shown). The first wheel truck 102a can include four
landing wheels 104 (shown as a first landing wheel 104a, a second
landing wheel 104b, a fifth landing wheel 104e, and a sixth landing
wheel 104f). Similarly, the second wheel truck 102b can also
include four landing wheels 104 (shown as a third landing wheel
104c, a fourth landing wheel 104d, a seventh landing wheel 104g,
and an eighth landing wheel 104h). Each wheel truck 102 can further
include four wheel brakes 106 (shown as brakes 106a-h) and four
wheel speed sensors 108 (shown as speed sensors 108a-h) operatively
associated with the wheels 104 in one-to-one correspondence.
[0003] The landing gear system 100 can further include a wheel
brake controller 110 and four processors 112 (shown as processors
112a-d). The controller 110 can be configured to receivebrake
control inputs from a pilot (not shown) and send corresponding
control signals to the brakes 106. Each of the processors 112 can
be associated with a pair of the wheels 104. For example, the first
processor 112a can be operatively connected to the speed sensors
108 of the first wheel 104a and the fifth wheel 104e. Similarly,
the second processor 112b can be operatively connected to the
second wheel 104b and the sixth wheel 104f. While four separate
processors 112 are depicted in FIG. 1 for purposes of illustration,
in practice two or more of the processors 112 may be combined into
a single processor that provides the same function as the two or
more processors. The landing gear system 100 can additionally
include an inertial reference unit 114 ("IRU 114") configured to
provide aircraft speed information to the processors 112.
[0004] In operation, the pilot initiates a brake control input from
the cockpit of the aircraft. The controller 110 receives this
control input, and in response sends a corresponding control signal
to one or more of the brakes 106. Although a single controller 110
is shown in FIG. 1 for purposes of illustration, in some brake
systems each wheel may have a dedicated controller, or conversely,
the controller may be omitted and each brake may receive the
control input directly from the pilot. The control input from the
pilot may be an electrical signal, or it may be transmitted by
actuator cable to a corresponding hydraulic valve associated with
the brake 106. The brakes 106 are applied to the wheels 104 in
response to the signals from the controller 110 to slow the
aircraft in accordance with the pilot's control input.
[0005] Each of the processors 112 can perform routines configured
to prevent the wheels 104 from locking up or skidding undesirably
when the pilot applies the brakes 106. These routines can include
an individual wheel anti-skid routine, a locked-wheel protection
routine, and a hydroplane/touchdown protection routine. The
individual wheel anti-skid routine can prevent a wheel from
skidding due to overly rapid deceleration. As the brake 106a, for
example, is applied to the first wheel 104a, the speed sensor 108a
measures wheel speed and transmits this information to the first
processor 112a. The first processor 112a monitors the deceleration
of the first wheel 104a, and compares this deceleration to a
maximum allowable deceleration. This maximum allowable deceleration
can equate to a threshold above which the first wheel 104a would
likely lock up and skid. If the deceleration of the first wheel
104a exceeds the maximum allowable deceleration, then the first
processor 112a transmits a signal to the brake 106a causing the
brake 106a to momentarily release. This release allows the wheel
104a to momentarily rotate freely, thus preventing wheel skid.
[0006] The locked-wheel protection routine can prevent wheel skid
by preventing gross disparity between wheel speeds in a group of
wheels. Referring to the first wheel 104a and the fifth wheel 104e
for purposes of illustration, as the brakes 106 are being applied,
the speed sensors 108 transmit wheel speed information to the first
processor 112a. The first processor 112a compares the speed of the
first wheel 104a to the speed of the fifth wheel 104e. If one of
the wheel speeds is less than the other wheel speed by a preset
amount or more, then the first processor 112a transmits a signal to
the brake 106 of the slower wheel 104, causing that particular
brake 106 to momentarily release. This momentary release allows the
slower wheel 104 to come up to speed and prevents the slower wheel
104 from going into a deep skid during heavy braking.
[0007] The hydroplane/touchdown protection routine applies to the
aft wheels 104 (i.e., the fifth wheel 104e, the sixth wheel 104f,
the seventh wheel 104g, and the eighth wheel 104h) to prevent
sustained hydroplane-induced wheel lockups during landing. This
protection is applied only to the aft wheels 104 because these
wheels touch down first during a typical landing. In this routine,
the IRU 114 determines a first speed based on the speed of the
aircraft and transmits this information to, for example, the first
processor 112a. The first processor 112a determines a second speed
based on the speed of the fifth wheel 104e as measured by the speed
sensor 108e. The first processor 112a then compares the first speed
from the IRU 114 to the second speed from the speed sensor 108e. If
the second speed is less than the first speed by a preset amount or
more, then the first processor 112a transmits a signal to the brake
106e causing the brake 106e to momentarily release. In this manner,
the hydroplane/touchdown routine pr vents the brake 106e from being
applied to the fifth wheel 104e until the fifth wheel 104e is
rotating at a speed commensurate with the aircraft speed, thus
preventing wheel skid.
SUMMARY
[0008] The present invention is directed generally toward methods
and systems for controlling wheel brakes on aircraft and other
vehicles. A method for slowing a vehicle on the ground in
accordance with one aspect of the invention can be used with a
vehicle having a wheel for supporting a portion of the vehicle on
the ground. The vehicle can further have a brake and a speed sensor
associated with the wheel. The method can include receiving a
control input to slow the vehicle, and determining if the speed
sensor is operative. When the speed sensor is operative, the method
can further include controlling the brake according to a first
routine in response to receiving the control input. Conversely,
when the speed sensor is inoperative, the method can further
include controlling the brake according to a second, different
routine in response to receiving the control input.
[0009] Another method for slowing a vehicle on the ground in
accordance with one aspect of the invention can be used with a
vehicle having at least first and second wheels for supporting a
portion of the vehicle on the ground. The vehicle can further have
a first brake and a first speed sensor operatively associated with
the first wheel, and a second brake and a second speed sensor
operatively associated with the second wheel. The method can
include receiving a first control input to slow the vehicle, and
applying the first brake to the first wheel and the second brake to
the second wheel in response to receiving the first control input.
The method can further include determining if the first and second
speed sensors are operative. When the first and second speed
sensors are operative, a first speed of the first wheel can be
compared to a second speed of the second wheel to determine if the
speeds differ by a preset amount. If the first sp ed differs from
the second speed by the preset amount, the application of at least
one of the first and second brakes can be changed. Conversely, when
at least one of the first and second speed sensors is inoperative,
the method can include continuing to apply the first brake to the
first wheel and the second brake to the second wheel while
receiving the first control input.
[0010] In another aspect of the invention, changing the application
of at least one of the first and second brakes when the first and
second speed sensors are operative can include releasing at least
one of the first and second brakes if the first wheel speed differs
from the second wheel speed by the preset amount. For example, in
one embodiment, the first brake can be released if the speed of the
first wheel is slower than the speed of the second wheel by the
preset amount. In a further aspect of the invention, continuing to
apply the first brake to the first wheel and the second brake to
the second wheel when at least one of the first and second speed
sensors is inoperative can include continuing to apply the first
and second brakes if the first wheel speed differs from the second
wheel speed by the preset amount.
[0011] An aircraft system configured in accordance with one aspect
of the invention can include a first landing wheel configured to
support at least a portion of an aircraft on the ground, and at
least a second landing wheel configured to support at least a
portion of the aircraft on the ground. The aircraft system can
further include a first brake and a first speed sensor associated
with the first wheel, a second brake and a second speed sensor
associated with the second wheel, and a processor operatively
coupled to the first and second brakes and the first and second
speed sensors. The processor can be configured to respond to a
first control input by applying the first brake to the first wheel
and the second brake to the second wheel to slow the aircraft. The
processor can be further configured to determine if the first and
second speed sensors are operative and, when the first and second
speed sensors are operative, determine if a first speed of the
first wheel differs from a second speed of the second wheel by a
preset amount. If the first speed differs from the second speed by
the preset amount, the processor can change the application of at
least one of the first and second brakes. Conversely, when at least
one of the first and second speed sensors is inoperative, the
processor can be configured to continue applying the first brake to
the first wheel and the second brake to the second wheel while
receiving the first control input.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic top view of an aircraft main landing
gear system configured in accordance with the prior art.
[0013] FIG. 2 is a schematic top view of an aircraft main landing
gear system configured in accordance with an embodiment of the
invention.
[0014] FIG. 3 is a flow diagram illustrating a routine for
bypassing locked-wheel protection in accordance with an embodiment
of the invention.
[0015] FIG. 4 is a flow diagram illustrating a routine for
bypassing hydroplane/touchdown protection in accordance with an
embodiment of the invention.
[0016] FIG. 5 is a flow diagram illustrating a routine for
implementing individual wheel anti-skid protection in accordance
with an embodiment of the invention.
[0017] FIG. 6 is a schematic top view of an aircraft main landing
gear system configured in accordance with another embodiment of the
invention.
[0018] FIG. 7 is a flow diagram illustrating a routine for
bypassing locked-wheel protection in accordance with a further
embodiment of the invention.
DETAILED DESCRIPTION
[0019] The following disclosure describes wheel brake systems for
aircraft and other vehicles, and associated methods for using such
systems to slow vehicles. Certain specific details are set forth in
the following description and in FIGS. 2-7 to provide a thorough
understanding of various embodiments of the invention. Other
details describing well-known structures and systems often
associated with aircraft and aircraft landing gear brake systems
are not set forth in the following description to avoid
unnecessarily obscuring the description of the various embodiments
of the invention.
[0020] Many of the details, dimensions, angles, and other
specifications shown in the Figures are merely illustrative of
particular embodiments of the invention. Accordingly, other
embodiments can have other details, dimensions, and specifications
without departing from the spirit or scope of the present
invention. In addition, other embodiments of the invention may be
practiced without several of the details described below.
[0021] In the Figures, identical reference numbers identify
identical or at least generally similar elements. To facilitate the
discussion of any particular element, the most significant digit or
digits of any reference number refer to the Figure in which that
element is first introduced. For example, element 210 is first
introduced and discussed with reference to FIG. 2.
[0022] FIG. 2 is a schematic top view of an aircraft main landing
gear system 200 configured in accordance with an embodiment of the
invention. In one aspect of this embodiment, the landing gear
system 200 includes a first wheel truck 202a and a second wheel
truck 202b. The first wheel truck 202a can include four landing
wheels 204 (shown as a first landing wheel 204a, a second landing
wheel 204b, a fifth landing wheel 204e, and a sixth landing wheel
204f). Similarly, the second wheel truck 202b can also include four
landing wheels 204 (shown as a third landing wheel 204c, a fourth
landing wheel 204d, a seventh landing wheel 204g, and an eighth
landing wheel 204h). Each wheel truck 202 can further include four
wheel brakes 206 (shown as brakes 206a-h) and four wheel speed
sensors 208 (shown as speed sensors 208a-h) operatively associated
with the wheels 204 in one-to-one correspondence. In other
embodiments, the landing gear system 200 can include more or fewer
wheel trucks 202 and/or more or fewer landing wheels 204. For
example, in one embodiment described in detail below, a landing
gear system configured in accordance with an embodiment of the
invention can include a wheel truck having six landing wheels.
Accordingly, aspects of the invention are not limited to the
particular landing gear configuration illustrated in FIG. 2.
Further, aspects of the invention are also not limited to aircraft.
For example, in another embodiment, a brake system configured in
accordance with aspects of the invention can be used with an
automobile.
[0023] In another aspect of this embodiment, the landing gear
system 200 further includes a wheel brake controller 210, an
inertial reference unit (IRU) 214, and four processors 212 (shown
as a first processor 212a, a second processor 212b, a third
processor 212c, and a fourth processor 212d). The controller 210,
the IRU 214, and the processors 212 can be at least generally
similar in structure and function to their counterparts described
above with reference to FIG. 1. Accordingly, the controller 210
receives brake control inputs from a pilot (not shown) and sends
corresponding control signals to one or more of the brakes 206. The
brakes 206 are applied to the wheels 204 in response to the control
signals. In addition, the processors 212 can implement individual
anti-skid routines, locked-wheel protection routines, and
hydroplane/touchdown protection routines as described above in
response to the information received from the speed sensors 208
and/or the IRU 214.
[0024] In a further aspect of this embodiment, the landing gear
system 200 additionally includes four bypass components 216 (shown
as a first bypass component 216a, a second bypass component 216b, a
third bypass component 216c, and a fourth bypass component 216d).
Each of the bypass components 216 can operatively associated with
one of the processors 212 in one-to-one correspondence. (In other
embodiments, one or more of the bypass components 216 can be
operatively associated with more than one of the processors 212,
thus allowing one or more of the bypass components 216 to be
omitted). As described in greater detail below, the bypass
components 216 can be configured to cause the processors 212 to
bypass one or more of the wheel anti-skid/anti-lock routines
described above if one of the speed sensors 208 is determined to be
inoperative. One advantage of this feature is that one of the
brakes 206 will not be released on the basis of an erroneous
indication (e.g., from the inoperative speed sensor 208) that the
corresponding wheel 204 has stopped rotating.
[0025] The landing gear system 200 of FIG. 2 includes a singl
controller 110 and four processors 112 for purposes of illustration
only. Accordingly, in other embodiments, the controller 210 may be
omitted, and pilot control inputs may go directly from the cockpit
to the brakes 206 (or to brake actuators) as either electrical or
mechanical control inputs or signals. Further, in other
embodiments, the functions of two or more of the processors 212, or
two or more of the bypass components 216, may be combined into a
single processor or bypass component, depending on the particular
situation.
[0026] FIG. 3 is a flow diagram illustrating a routine 300 for
bypassing locked-wheel protection in accordance with an embodiment
of the invention. For purposes of illustration, the routine 300 is
described below with reference to the landing gear system 200 of
FIG. 2. In other embodiments, the routine 300 can be implemented by
other brake systems for other vehicles, including land-based
vehicles such as automobiles and trucks. In block 302, the routine
300 receives a control input to apply the brakes 206 to the wheels
204. In block 304, the routine 300 applies the brakes 206 in
response to the control input. Referring to the first wheel 204a
and the fifth wheel 204e as a grouped wheel pair for purposes of
illustration, in decision block 306, the routine 300 determines if
the first speed sensor 208a is operative. If the first speed sensor
208a is inoperative, then the routine 300 bypasses locked-wheel
protection for the grouped wheel pair and proceeds to decision
block 308 to determine if a control input has been received to
release the brakes 206. If no such control input has been received,
then the routine 300 returns to block 304 and continues to apply
the brakes 206. Conversely, if a control input to release the
brakes 206 has been received, then in block 309 the routine 300
releases the brakes 206 and the routine 300 is complete.
[0027] Returning to decision block 306, if the first speed sensor
208a is operative, then the routine 300 proceeds to decision block
310 to determine if the fifth speed sensor 208e is also operative.
If the fifth speed sensor 208e is inoperative, then the routine 300
bypasses locked-wheel protection for the grouped wheel pair and
proceeds to decision block 308 as described above. Conversely, if
both the first speed sensor 208a and the fifth speed sensor 208e
are operative, then the routine 300 implements locked-wheel
protection for the grouped wheel pair by proceeding to decision
block 312.
[0028] In decision block 312, the routine 300 determines if the
difference in speed between the first wheel 204a and the fifth
wheel 204e exceeds a preset amount X. In one embodiment, the preset
amount X can correspond to a difference in speed that would result
in skidding of the slower wheel. For example, in one embodiment,
such a difference in speed can be equivalent to about 30% of the
speed of the faster wheel. In other embodiments, the difference in
speed for a particular application may include other values. If the
difference in speed between the first wheel 204a and the fifth
wheel 204e is not greater than the preset amount X, then the
routine 300 proceeds to decision block 308 and continues as
described above. Conversely, if the difference in wheel speeds is
greater than the preset amount X, then the routine 300 proceeds to
decision block 314 and determines which of the two wheels 204a or
204e is the slower wheel. If the first wheel 204a is the slower
wheel, then in block 316 the routine 300 releases the first brake
206a so that the first wheel 204a can come up to speed and not
skid. Conversely, if the fifth wheel 204e is the slower wheel, then
in block 318 the routine 300 releases the fifth brake 206e so that
the fifth wheel 204e can come up to speed. After releasing the
brake 206 on the slower wheel 204, the routine 300 returns to
decision block 312 to again determine if the difference in wheel
speeds exceeds the preset amount X.
[0029] When the difference in wheel speeds no longer exceeds the
preset amount X, the routine 300 proceeds to decision block 308 as
explained above. In decision block 308, if no control input has
been received to release the brakes 206, then the routine 300
proceeds to block 304 and applies the brakes 206. Conversely, if a
control input to release the brakes 206 has been received, then in
block 309 the routine 300 releases the brakes 206 and the routine
is complete
[0030] One feature of aspects of the embodiment described above
with reference to FIG. 3 is that if one or both of the first speed
sensor 208a or the fifth speed sensor 208e is inoperative, then the
first processor 212a will not erroneously release the corresponding
brake 206. One advantage of this feature is that the corresponding
wheel 204 will have braking capability even if the associated speed
sensor 208 is inoperative.
[0031] FIG. 4 is a flow diagram illustrating a routine 400 for
bypassing hydroplane/touchdown protection in accordance with an
embodiment of the invention. For purposes of illustration, the
routine 400 is described below with reference to the landing gear
system 200 of FIG. 2. In other embodiments, the routine 400 can be
implemented by other brake systems for other vehicles. In block
402, the routine 400 receives a control input to apply the brakes
206 to the wheels 204. In block 404, the routine 400 applies the
brakes 206 in response to the control input. Referring to an aft
landing gear wheel, such as the fifth wheel 204e, for purposes of
illustration, in decision block 406, the routine 400 determines if
the fifth speed sensor 208e is operative. If the fifth speed sensor
208e is inoperative, then the routine 400 bypasses
hydroplane/touchdown protection for the fifth wheel 204e and
proceeds to decision block 408 to determine if a control input has
been received to release the brakes 206. If no such control input
has been received, then the routine 400 returns to block 404 and
continues to apply the brakes 206. Conversely, if a control input
to release the brakes 206 has been received, then in block 409 the
routine 400 releases the brakes 206 and the routine 400 is
complete.
[0032] Returning to decision block 406, if the fifth speed sensor
208e is operative, then the routine 400 proceeds to decision block
410 to determine if a first speed as determined by the IRU 214
exceeds a second speed as determined by the fifth speed sensor 208e
by a preset amount Y. In one embodiment, the preset amount Y can
represent a difference in speed between the aircraft and the fifth
wheel 204e of such magnitude that the fifth wheel 204e is likely to
hydroplane or skid upon touchdown. For example, in one embodiment,
the difference in speed can be equivalent to about 50 knots. In
other embodiments, the difference in speed can have other values
depending on such factors as aircraft configuration. If the first
speed does not exceed the second speed by the preset amount Y, then
the routine 400 proceeds to decision block 408 and continues as
described above. Conversely, if the first speed does exceed the
second speed by the preset amount Y or more, then the routine 400
proceeds to block 412 and releases the fifth brake 206e allowing
the fifth wheel 204e to come up to speed at touchdown before the
fifth brake 206e is applied, thereby preventing skidding or
hydroplaning of the fifth wheel 204e at touchdown.
[0033] After releasing the fifth brake 206e, the routine 400
returns to decision block 410 to verify that the fifth wheel 204e
is now moving at a speed commensurate with the aircraft. If the two
speeds are commensurate such that the first speed does not exceed
the second speed by at least the preset amount Y, then the routine
400 returns to decision block 408 to determine if a command to
release the brakes has been received. If no such command has been
received, then the routine 400 returns to block 404 and applies the
fifth brake 206e to the fifth wheel 204e. Conversely, if a control
input to release the brakes 206 has been received, then in block
409 the routine 400 releases the brakes 206 and the routine 400 is
complete.
[0034] One feature of aspects of the embodiment described above
with reference to FIG. 4 is that if the fifth speed sensor 208e is
inoperative, then the first processor 212a will not erroneously
release the fifth brake 206e in accordance with the
hydroplane/touchdown routine. One advantage of this feature is that
the corresponding aft wheel 204e will have braking capability at
touchdown even if the associated speed sensor 208e is
inoperative.
[0035] FIG. 5 is a flow diagram illustrating a routine 500 for
implementing individual wheel anti-skid protection in accordance
with an embodiment of the invention. For purposes of illustration,
the routine 500 is described below with reference to the landing
gear system 200 of FIG. 2. In other embodiments, the routine 500
can be implemented by other brake systems for other vehicles,
including land-based vehicles such as automobiles and trucks. In
block 502, the routine 500 receives a control input to apply the
brakes 206 to the wheels 204. In block 504, the routine 500 applies
the brakes 206 in response to the control input. Referring to the
first wheel 204a for purposes of illustration, in decision block
506, the routine 500 determines if the first speed sensor 208a is
operative. If the first speed sensor 208a is operative, then the
routine 500 proceeds to decision block 510 to determine if the
deceleration of the first wheel 204a (i.e., the change in wheel
speed divided by the change in time) is greater than a preset
amount Z. In one embodiment, the preset amount Z can be a
deceleration that represents a maximum allowable deceleration
before wheel skid for the particular aircraft configuration is
likely to occur. If the deceleration of the first wheel 204a
exceeds the preset amount Z, then the routine 500 proceeds to block
512 and releases the first brake 206a so that the first wheel 204a
can come up to speed before the first brake 206a is applied.
[0036] After releasing the first brake 206a, the routine 500
returns to decision block 510 to again check the deceleration of
the first wheel 204a. If the deceleration of the first wheel 204a
does not exceed the preset amount Z, then the routine 500 proceeds
to decision block 508 to determine if a command to release the
brakes 206 has been received. If no such command has been received,
then the routine 500 returns to block 504 and applies the first
brake 206a. Conversely, if a command to release the brakes 206 has
been received, then the routine 500 proceeds to block 509 and
releases the brakes 206 and the routine 500 is complete.
[0037] Returning to decision block 506, if the first speed sensor
208a is inoperative, then in decision block 507, the routine 500
determines if the fifth speed sensor 208e is operative. If the
fifth speed sensor 208e is inoperative, then the routine 500
proceeds to decision block 508 and continues as described above.
Conversely, if the fifth speed sensor 208e is operative, then in
decision block 514 the routine 500 determines if the deceleration
of the fifth wheel 204e is greater than the preset amount Z. If the
deceleration of the fifth wheel 204e exceeds the preset amount Z,
then the routine 500 proceeds to block 516 and releases the first
brake 206a. In this manner, the routine 500 is providing anti-skid
protection for the first wheel 204a even though the first speed
sensor 208a is inoperative. This protection is provided by
utilizing wheel speed information from the fifth wheel 204e to
determine whether to release the first brake 206a of the first
wheel 204a. (Although not the focus of this particular discussion,
in another aspect of this embodiment, the fifth brake 206e can also
be released if the deceleration of the fifth wheel 204e is found to
exceed the preset amount Z). Returning to decision block 514, if,
conversely, the deceleration of the fifth wheel 204e does not
exceed the preset amount Z, then the routine proceeds to decision
block 508 and continues as described above.
[0038] One feature of aspects of the embodiment described above
with reference to FIG. 5 is that if the first speed sensor 208a is
inoperative, then the routine 500 can utilize wheel speed
information from the fifth speed sensor 208e to prevent skidding of
the first wheel 204a. One advantage of this feature is that the
first wheel 204a can have braking capability even if the associated
speed sensor 208a is inoperative. Although the foregoing
description has referred to the first wheel 204a and the fifth
wheel 204e for purposes of illustration, in other embodiments,
other wheel groups and/or wheel combinations can be used in
accordance with the present invention to provide the secondary
anti-skid protection described above.
[0039] FIG. 6 is a schematic top view of an aircraft main landing
gear system 600 configured in accordance with another embodiment of
the invention. In one aspect of this embodiment, the landing gear
system 600 includes a first wheel truck 602a and a second wheel
truck 602b. The wheel trucks 602 can be at least generally similar
in structure and function to the wheel trucks 202 described above
with reference to FIG. 2. In another aspect of this embodiment,
however, each of the wheel trucks 602 includes six landing wheels
(shown as landing wheels 604a-l) having associated wheel brakes 606
(brakes 606a-l) and associated wheel speed sensors 608 (speed
sensors 608a-l). In a further aspect of this embodiment, the
landing gear system 600 also includes a wheel brake controller 610,
an IRU 614, and four processors 612 (shown as processors 612a-d).
The controller 610, the IRU 614, and the processors 612 can be at
least generally similar in structure and function to their
counterparts described above with reference to FIG. 2.
[0040] In yet another aspect of this embodiment, the landing gear
system 600 additionally includes four bypass components 616 (shown
as bypass components 616a-d). Each of the bypass components 616 is
operatively associated with one of the processors 612 in one-to-one
correspondence. Each of the processors 612 is in turn operatively
associated with a separate wheel group. For example, the first
processor 612a is operatively associated with the first wheel 604a,
the fifth wheel 604e, and the ninth wheel 604i. As described in
greater detail below, the bypass components 616 can be configured
to cause the processors 612 to bypass one or more of the wheel
anti-skid/anti-lock routines described above if one of the
associated speed sensors 608 is determined to be inoperative. One
advantage of this feature is that one of the brakes 606 will not be
released based on an erroneous indication from the inoperative
speed sensor 608 that the corresponding wheel 604 has stopped
rotating.
[0041] FIG. 7 is a flow diagram illustrating a routine 700 for
bypassing locked-wheel protection in accordance with a further
embodiment of the invention. For purposes of illustration, the
routine 700 is described below with reference to the landing gear
system 600 of FIG. 6. In other embodiments, the routine 700 can be
implemented by other brake systems for other vehicles having wheel
groups with three or more wheels. In block 702, the routine 700
receives a control input to apply the brakes 606 to the wheels 604.
In block 704, the routine 700 applies the brakes 606 in response to
the control input. Referring to the first wheel 604a, the fifth
wheel 604e, and the ninth wheel 604i for purposes of illustration,
in decision block 706, the routine 700 determines if the first
speed sensor 608a, the fifth speed sensor 608e, and the ninth speed
sensor 608i are operative. If all of these speed sensors are
operative, then in decision block 710 the routine 700 implements a
locked-wheel protection routine by determining if the average speed
of the fifth wheel 604e and the ninth wheel 604i exceeds the speed
of the first wheel 604a by a preset amount X.
[0042] If the average speed of the fifth wheel 604e and the ninth
wheel 604i exceeds the speed of the first wheel 604a by the preset
amount X, then in block 712, the routine 700 releases the first
brake 606a so that the first wheel 604a can come up to speed with
the other two wheels in the group. Conversely, if the average speed
of the fifth wheel 604e and the ninth wheel 604i does not exceed
the speed of the first wheel 604a by the preset amount X, then in
decision block 714 the routine 700 determines if the average speed
of the first wheel 604a and the ninth wheel 604i exceeds the speed
of the fifth wheel 604e by the preset amount X. If so, then in
block 716 the routine 700 releases the fifth brake 606e.
Conversely, if the average speed of the first wheel 604a and the
ninth wheel 604i does not exceed the speed of the fifth wheel 604e
by the preset amount X, then the routine proceeds to decision block
718 to determine if the average speed of the first wheel 604a and
the fifth wheel 604e exceeds the speed of the ninth wheel 604i by
the preset amount X. If so, then in block 720 the routine 700
releases the ninth brake 606i. Conversely, if the average speed of
the first wheel 604a and the fifth wheel 604e does not exceed the
speed of the ninth wheel 604i by the preset amount X, then the
routine 700 proceeds to the decision block 708 to determine if a
command to release the brakes 606 has been received. If no such
command has been received, then the routine 700 returns to block
704 and continues to apply the brakes 606. Conversely, if such a
command has been received, then in block 709 the routine 700
releases the brakes 606 and the routine 700 is complete.
[0043] Returning to decision block 706, if at least one of the
speed sensors 608a, 608e, and 608i are inoperative, then the
routine 700 proceeds to decision block 722 to determine if the
first speed sensor 608a and the fifth speed sensor 608e are
operative. If these two speed sensors are operative, then the
routine 700 can perform the routine 300 described above with
reference to FIG. 3 for the first wheel 604a and the fifth wheel
604e. Conversely, if at least one of the first speed sensor 208a
and the fifth speed sensor 208e is inoperative, then the routine
700 proceeds to decision block 724 to determine if the first speed
sensor 208a and the ninth speed sensor 208i are operative.
[0044] If both the first speed sensor 208a and the ninth speed
sensor 208i are operative, then the routine 700 can perform the
routine 300 of FIG. 3 for the first wheel 604a and the ninth wheel
604i. Conversely, if at least one of the first speed sensors 608a
and the ninth speed sensor 608i is inoperative, then the routine
700 proceeds to decision block 726 to determine if both the fifth
speed sensor 608e and the ninth speed sensor 608i are operative. If
both of these speed sensors are operative, then the routine 700 can
perform the routine 300 of FIG. 3 for the fifth wheel 604e and the
ninth wheel 604i. Conversely, if at least one of the fifth speed
sensor 608e and the ninth speed sensor 608i is inoperative, then
the routine 700 proceeds to decision block 708 to determine if a
command to release the brakes 606 has been received. If no such
command has been received, then the routine 700 returns to block
704 and continues applying the brakes 606. Conversely, if a command
to release the brakes 606 has been received, then in block 709 the
routine 700 releases the brakes 606 and the routine 700 is
complete.
[0045] From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the spirit or scope of the invention.
Accordingly, the invention is not limited, except as by the
appended claims.
* * * * *