Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02851869 2014-05-14
REDUNDANT CURRENT-SUM FEEDBACK ACTUATOR
FIELD
Embodiments of the present disclosure relate generally to suppression of
failure
in electrical-mechanical control systems. More particularly, embodiments of
the present
disclosure relate to suppression of failure in actuation systems.
BACKGROUND
A flight path of an airplane is controlled by a deflection of flight control
surfaces.
In many modern airplanes, flight control surfaces are deflected by
actuator(s). Such flight
control surfaces may include elevators for pitch control, ailerons and
flaperons for roll
control, and a rudder for yaw control. In many cases, electric current
controls output of
the actuator. In some cases, an electromagnetic effect of the electric current
directly
produces a mechanical output for Electro-Mechanical Actuator (EMA), or Electro-
Hydrostatic Actuator (EHA), while in other cases, it is amplified by some
other means,
such as through controlling the hydraulic flow through a servo valve such as a
Direct-
Drive Valve (DDV), or Electrohydraulic Servo Valve (EHSV) in single or
multiple
stages.
Electric current flows through a coil (or coils) and is converted to a
magnetically
induced useable force to actuate the actuator. A non-optimality causing an
erroneous
level of current could cause the actuator to move to an un-commanded position
or output
an un-commanded force. Such a non-optimality may cause an airplane to deviate
from a
commanded path and/or cause structural anomaly to the airplane, particularly
if the non-
optimality is oscillatory or cyclic.
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SUMMARY
A system and methods for redundant current-sum feedback control of an actuator
system is presented. An actuator comprises actuation coils configured to
actuate the
actuator, and an actuation coil current sensor senses a measured total coil
current
comprising a sum of coil currents of each of the actuation coils. Actuator
coil controllers
control the actuation coils based on a commanded total coil current and the
measured
total coil current.
In this manner, an effect of electrical non-optimality is suppressed to a
negligible
level. Embodiments architecturally suppress an effect of electrical non-
optimality in one
of redundant control loops, regardless of characteristics of the non-
optimality. Therefore,
the architecture alleviates a need for tasks such as custom analysis/tuning of
elaborate
monitors, and avoids effects to schedule and certification. Furthermore,
application of
less costly devices becomes possible.
In an embodiment, there is provided a redundant current-sum feedback actuator
system comprising: an actuator comprising a plurality of actuation coils
configured to
actuate the actuator; an actuation coil current sensor configured to sense a
measured total
coil current comprising a sum of coil currents of each of the actuation coils;
and a
plurality of actuator coil controllers configured to control the actuation
coils based on a
current-sum difference between a commanded total coil current and the measured
total
coil current, wherein the actuation coil current sensor comprises: a plurality
of sensor
coils configured to receive an actuator current that actuates one of the
actuation coils
respectively, a magnetic core configured to receive a magnetic flux from the
sensor coils,
and at least one sensor coupled to the magnetic core and configured to measure
the
measured total coil current.
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In another embodiment, there is provided a method for suppressing non-
optimality
in an actuator control system, the method comprising: sensing a measured total
coil
current comprising a sum of coil currents of each of a plurality of actuation
coils of an
actuator with an actuation coil current sensor; controlling the actuation
coils with a
plurality of actuator coil controllers based on a current-sum difference
between a
commanded total coil current and the measured total coil current; receiving at
each of a
plurality of sensor coils an actuator current that actuates one of the
actuation coils
respectively; receiving a magnetic flux from the sensor coils in a magnetic
core; and
measuring the measured total coil current by at least one sensor coupled to
the magnetic
core.
In a further embodiment, there is provided a redundant current-sum feedback
actuator controller comprising: an inner feedback control loop configured to:
receive a
desired total coil current and a measured total coil current comprising a sum
of coil
currents of each of a plurality of actuation coils of an actuator, and control
the actuation
coils based on a current-sum difference between the desired total coil current
and the
measured total coil current; and an actuation coil current sensor configured
to sense the
measured total coil current, and comprising: a plurality of sensor coils
configured to
receive an actuator current that actuates one of the actuation coils
respectively, a magnetic
core configured to receive a magnetic flux from the sensor coils, and at least
one sensor
coupled to the magnetic core and configured to measure the measured total coil
current.
In a further embodiment, there is provided a redundant current-sum feedback
actuator controller comprising: an inner feedback control loop configured to:
receive a
desired total coil current and a measured total coil current comprising a sum
of coil
currents of each of a plurality of actuation coils of an actuator as a
feedback parameter in
each of a plurality of controllers, wherein the actuation coils are configured
to actuate the
actuator, and control the actuation coils based on a current-sum difference
between the
desired total coil current and the measured total coil current, wherein the
measured total
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coil current is measured by magnetically summing magnetic flux generated by
sensor
coils of each of the controllers.
In a further embodiment, there is provided a redundant current-sum feedback
actuator controller comprising: an inner feedback control loop configured to:
receive a
desired total coil current and a measured total coil current comprising a sum
of coil
currents of each of a plurality of actuation coils of an actuator as a
feedback parameter in
each of a plurality of controllers, wherein the actuation coils are configured
to actuate the
actuator, and control the actuation coils based on a current-sum difference
between the
desired total coil current and the measured total coil current, wherein each
of the
controllers measure each other's actuator coil current through an electrically
independent
means to measure a respective adjacent coil current and sums the respective
adjacent coil
current with a respective local coil current to create the measured total coil
current as the
feedback parameter.
In a further embodiment, there is provided a redundant current-sum feedback
actuator controller comprising: an inner feedback control loop configured to:
receive a
desired total coil current and a measured total coil current comprising a sum
of coil
currents of each of a plurality of actuation coils of an actuator as a
feedback parameter in
each of a plurality of controllers, wherein the actuation coils are configured
to actuate the
actuator, and control the actuation coils based on a current-sum difference
between the
desired total coil current and the measured total coil current, wherein an
erroneous current
through one of the actuation coils causes a current to flow in other actuation
coils among
the actuation coils and creates a magnetic flux opposing the erroneous
current, thereby
reducing force fight between actuators on a same surface.
This summary is provided to introduce a selection of concepts in a simplified
form that are further described below in the detailed description. This
summary is not
intended to identify key features or essential features of the claimed subject
matter, nor is
it intended to be used as an aid in determining the scope of the claimed
subject matter.
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BRIEF DESCRIPTION OF DRAWINGS
A more complete understanding of embodiments of the present disclosure may be
derived by referring to the detailed description and claims when considered in
conjunction with the following figures, wherein like reference numbers refer
to similar
elements throughout the figures. The figures are provided to facilitate
understanding of
the disclosure without limiting the breadth, scope, scale, or applicability of
the disclosure.
The drawings are not necessarily made to scale.
Figure 1 is an illustration of a flow diagram of an exemplary aircraft
production
and service methodology.
Figure 2 is an illustration of an exemplary block diagram of an aircraft.
Figure 3 is an illustration of an existing actuator.
Figure 4 is an illustration of an exemplary parallel dual actuator controller
with
total current inner loop according to an embodiment of the disclosure.
Figure 5 is an illustration of an exemplary parallel triplex actuator
controller with
total current inner loop according to an embodiment of the disclosure.
Figure 6 is an illustration of an exemplary time-history plot showing piston
position (in) plot, differential pressure (psi) plot, and current (mA) plot
for a simulated
fault in the conventional actuator of Figure 3.
Figure 7 is an illustration of an exemplary time-history plot showing piston
position (in) plot, differential pressure (psi) plot, and current (mA) plot
for a simulated
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fault suppression in the triplex actuator system of Figure 5 according to an
embodiment of
the disclosure.
Figure 8 is an illustration of an independent current measurement according to
an
embodiment of the disclosure.
Figure 9 is an illustration of total current derivation in the independent
current
measurement of Figure 8 according to an embodiment of the disclosure.
Figure 10 is an illustration of a total current measurement according to an
embodiment of the disclosure.
Figure 11 is an illustration of an exemplary flowchart showing a process for
fault
suppression in an actuator controller according to an embodiment of the
disclosure.
DETAILED DESCRIPTION
The following detailed description is exemplary in nature and is not intended
to
limit the disclosure or the application and uses of the embodiments of the
disclosure.
Descriptions of specific devices, techniques, and applications are provided
only as
examples. Modifications to the examples described herein will be readily
apparent to
those of ordinary skill in the art, and the general principles defined herein
may be applied
to other examples and applications without departing from the spirit and scope
of the
disclosure. The present disclosure should be accorded scope consistent with
the claims,
and not limited to the examples described and shown herein.
Embodiments of the disclosure may be described herein in terms of functional
and/or logical block components and various processing steps. It should be
appreciated
that such block components may be realized by any number of hardware,
software, and/or
firmware components configured to perform the specified functions. For the
sake of
brevity, conventional techniques and components related to control laws,
control systems,
measurement techniques, measurement sensors, actuators, data transmission,
signaling,
network control, and other functional aspects of the systems (and the
individual operating
components of the systems) may not be described in detail herein. In addition,
those
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skilled in the art will appreciate that embodiments of the present disclosure
may be
practiced in conjunction with a variety of hardware and software, and that the
embodiments described herein are merely example embodiments of the disclosure.
Embodiments of the disclosure are described herein in the context of a
practical
non-limiting application, namely, suppressing fault in an actuator for an
aircraft flight
control surface. Embodiments of the disclosure, however, are not limited to
such aircraft
structure, and the techniques described herein may also be utilized in other
applications.
For example but without limitation, embodiments may be applicable to manned
and
unmanned ground, air, space, water and underwater vehicles, windmills, or
other
machinery.
As would be apparent to one of ordinary skill in the art after reading this
description, the following are examples and embodiments of the disclosure and
are not
limited to operating in accordance with these examples. Other embodiments may
be
utilized and structural changes may be made without departing from the scope
of the
exemplary embodiments of the present disclosure.
Referring more particularly to the drawings, embodiments of the disclosure may
be described in the context of an exemplary aircraft manufacturing and service
method
100 (method 100) as shown in Figure 1 and an aircraft 200 as shown in Figure
2. During
pre-production, the method 100 may comprise specification and design 104 of
the aircraft
200, and material procurement 106. During production, component and
subassembly
manufacturing process 108 (production stage 108) and system integration 110
(production
stage 110) of the aircraft 200 takes place. Thereafter, the aircraft 200 may
go through
certification and delivery 112 in order to be placed in service 114. While in
service by a
customer, the aircraft 200 is scheduled for routine maintenance and service
116 (which
may also comprise modification, reconfiguration, refurbishment, and so on).
Each of the processes of method 100 may be performed or carried out by a
system integrator, a third party, and/or an operator (e.g., a customer). For
the purposes of
this description, a system integrator may comprise, for example but without
limitation,
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any number of aircraft manufacturers and major-system subcontractors; a third
party may
comprise, for example but without limitation, any number of vendors,
subcontractors, and
suppliers; and an operator may comprise, for example but without limitation,
an airline,
leasing company, military entity, service organization, and the like.
As shown in Figure 2, the aircraft 200 (aircraft 200) produced by the method
100
may comprise an airframe 218 with a plurality of systems 220 and an interior
222.
Examples of high-level systems of the systems 220 comprise one or more of a
propulsion
system 224, an electrical system 226, a hydraulic system 228, an environmental
system
230, and a redundant current-sum feedback actuator system 232. Any number of
other
systems may also be included. Although an aerospace example is shown, the
embodiments of the disclosure may be applied to other industries.
Apparatus and methods embodied herein may be employed during any one or
more of the stages of the method 100. For example, components or subassemblies
corresponding to production stage 108 may be fabricated or manufactured in a
manner
similar to components or subassemblies produced while the aircraft 200 is in
service.
In addition, one or more apparatus embodiments, method embodiments, or a
combination
thereof may be utilized during production stages 108 and 110, for example, by
substantially expediting assembly of or reducing the cost of an aircraft 200.
Similarly, one
or more of apparatus embodiments, method embodiments, or a combination thereof
may
be utilized while the aircraft 200 is in service, for example and without
limitation, to
maintenance and service 116.
Flight control surfaces are deflected by actuator(s) (hydraulically or
electrically
powered) to ultimately control a flight path. Such flight control surfaces may
comprise,
for example but without limitation, elevators for pitch control, ailerons and
flaperons for
roll control, rudder for yaw control, or other flight control surface. There
are often
multiple actuators attached to a single flight control surface in parallel,
and in many cases,
they may all be activated in normal conditions. There are control mechanisms
(e.g.,
electronic, mechanical) that control a deflection to which each actuator
positions the
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flight control surface. In normal conditions, the actuators on a single/same
surface work
in unison to deflect the flight control surface to the commanded position.
However, an
anomaly in an actuator or its controller may cause the affected actuator ("non-
optimal
actuator") to try to deflect the flight control surface to a position other
than the
commanded position.
Embodiments of the disclosure provide a system and methods wherein flux
summing in a servo valve and a current-sum feedback loop (the "current sum" or
the total
current flowing through multiple coils) is used as a feedback parameter in
each of
multiple actuator controllers to achieve a near-perfect fault suppression
capability.
**current sum- may refer to a sum of currents, and thus current sum, sum of
currents and
total current may be used interchangeably in this document.
Figure 3 is an illustration of an existing actuator controller 300. An
actuator
output 310 of a conventional actuator 302 is controlled by a difference 308
between a
desired output 306 (command 306) and a measured output 304 (feedback 304).
Piston
position 310 is one example of the actuator output 310 that may be controlled
in this way.
The difference 308 between the command 306 and the feedback 304 is used to
determine
an appropriate control electric current 314 to drive the feedback 304 closer
to the
command 306. The actuator controller 316 shows a case in which the control
electric
current 314 output is set proportional to the difference 308, but there are
many other
control methods available. The control electric current 314 is converted to
mechanical
output in a variety of ways as discussed above.
Figure 4 is an illustration of an exemplary parallel dual actuator controller
system
400 with total current inner loop according to an embodiment of the
disclosure. As with
the conventional actuator 302, an output of an actuator 402 is controlled
through feedback
control, where a measured output 410/412 (feedback 410/412) is compared
against a
desired output 414/416 (command 414/416) respectively. In this case, a
feedback control
loop 418 and 420 are referred to as the "outer feedback control loop 418 and
outer
feedback control loop 420" and are electrically independent outer control
loops 418/420.
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In this document, a measured output and a measured actuator position may be
used
interchangeably. Similarly, in this document, a desired output, a command, and
a desired
actuator position may be used interchangeably.
The system 400 comprises the actuator 402, an actuator coil controller 1
(406), an
actuator coil controller 2 (408), an actuation coil current sensor 460, and an
outer loop
feedback sensor 458.
The actuator 402 comprises a plurality of actuation coils such as an actuation
coil
1 (422) and an actuation coil 2 (424) configured to actuate the actuator 402.
The
actuation coils 422/424 comprise a common actuation power.
The actuation coil current sensor 460 is configured to sense a measured total
coil
current 462 comprising a sum of coil currents 426 and 428 of the actuation
coil 1 (422)
and the actuation coil 2 (424). The actuation coil current sensor 460 is
explained in more
detail in the context of discussion of Figures 8-10 below.
The actuator coil controller 1 (406) and the actuator coil controller 2 (408)
are
configured to control the actuation coil 1 (422) and an actuation coil 2 (424)
respectively
based on a commanded total coil current 436/438 and the measured total coil
current 462.
One difference in the control system 400 compared to the existing actuator
controller 300 is that there are multiple independently driven actuation coils
namely the
actuation coil 1 (422) and the actuation coil 2 (424), and the coil current
426 through the
actuation coil 422 and the coil current 428 through the actuation coil 424 are
controlled
independently by the actuator coil controller 1 (406) and the actuator coil
controller 2
(408) respectively.
Another difference is that each control path comprises, an inner feedback
control
loop 430 and an inner feedback control loop 432 respectively, in addition to
their
respective outer feedback control loop 418 and outer feedback control loop
420. A
control parameter for the inner feedback control loop 430/432 is the measured
total coil
current 462. The measured total coil current 462 is a sum of the coil currents
426 and 428
or a "current sum" or a total current flowing through the multiple actuation
coils 422/424
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as the feedback parameter in each of the multiple actuator coil controllers
406/408. Thus,
measured total coil current, measured total current sum, current sum value,
and current-
sum feedback value may be used interchangeably in this document.
The outer feedback control loop 418 determines the desired current sum 436
(commanded total coil current 436, or a desired value 436) based on a
difference 442
between the desired actuator output 414 and the measured actuator output 410.
The inner
feedback control loop 430 (fed back through the actuation coil current sensor
460 and
through the sum of coil currents 462) determines an appropriate command 446
(command
output 446) to its current amplifier 450 based on a current-sum difference
between the
commanded total coil current 436 (desired total coil current 436, or desired
value 436)
and the measured total coil current 462 and generates the command output 446
to control
the actuator 402.
Similarly, the outer feedback control loop 420 determines the commanded total
coil current 438 (desired total coil current 438) based on a difference 444
between the
desired actuator output 416 and the measured actuator output 412. The inner
feedback
control loop 432 (fed back through the actuation coil current sensor 460 and
through the
sum of coil currents 462) determines an appropriate command 448 (command
output 448)
to its current amplifier 452 based on a current-sum difference between the
commanded
total coil current 438 and the measured total coil current 462 and generates
the command
output 448 to control the actuator 402.
The desired total coil current 436/438 comprises an output current difference
454/456 between a desired actuator current output 414/416 and a measured
actuator
current output 418/420, and the command output 446/448 comprises a difference
between
the desired total coil current 436/438 and the measured total coil current
462.
The system 400 suppresses electrical non-optimality effects. An erroneous
level
of current may be output from one actuator coil controller 406/408 as a result
of any of
various anomaly modes and any number of anomaly modes, comprising those in
actuator
coil controller electronics, sensor, or devices within or external to the two
control loops.
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Regardless of an origin of an anomaly, a current anomaly in one coil 422/424
directly
affects the measured total coil current 462 that is applied as the inner loop
feedback
parameter in the other actuator coil controller 406/408. The actuator coil
controller
406/408 then adjusts its current output in order to drive the current sum
value 462
towards the desired value 436/438, and therefore, suppressing an effect on an
actuator
output 464. Because the actuator output 464 is dictated by the sum of the coil
currents
namely the measured total coil current 462, the system 400 architecturally
suppresses an
effect of electrical non-optimality anywhere in one of the redundant control
loops
418/420 and 430/432, regardless of characteristics of the non-optimality.
While a dual-redundant architecture has been discussed above, any redundancy
(e.g., triple, quadruple, etc.) would suppress an effect of the non-
optimality, with a degree
of efficacy increasing with a level of redundancy.
Figure 5 is an illustration of an exemplary parallel triplex actuator coil
controller
system 500 (system 500) with total current inner loop according to an
embodiment of the
disclosure. System 500 is described herein in conjunction with system 400.
System 500
may have functions, material, and structures that are similar to the system
400. Therefore
common features, functions, and elements may not be redundantly described
here.
The actuation coil current sensor 528 is configured to sense a measured total
coil
current 524 comprising a sum of coil currents 426, 428 and 526 of the
actuation coil 1
(422), the actuation coil 2 (424), and the actuation coil 3 (530). The
actuation coil current
sensor 528 is explained in more detail in the context of discussion of Figures
8-10 below.
The outer feedback control loop 418/420/508 determines a desired current sum
436/438/512 (commanded total coil current 436/438/512) based on a difference
442/444/514 between the desired actuator output 414/416/516 and the measured
actuator
output 410/412/518. The inner feedback control loop 430/432/506 determines an
appropriate command 446/448/520 to its current amplifier 450/452/522 based on
a
difference between the commanded total coil current 436/438/512 and the
measured total
current sum 524 (measured total coil current 524). The measured total coil
current 524 is
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the sum of the coil currents 426, 428, 526 or the "current sum" or the total
current
flowing through the multiple actuation coils 422/424/530 as the feedback
parameter in
each of the multiple actuator coil controllers 406/408/504.
Figure 6 is an illustration of an exemplary time-history plot 600 showing
piston
position (in) plot 602, differential pressure (psi) plot 604, and current (mA)
plot 606 for a
simulated fault in the conventional actuator 302 of Figure 3. As shown by the
plot 606,
an erroneous current 610 through the actuation coil 312 of the conventional
actuator 302
of Figure 3 causes a large force fight between inboard and outboard actuators
on a same
aerodynamic surface as shown by the difference between the differential
pressures 612
and 614 shown in the plot 604, as well as by the piston position displacement
616 and 618
shown in the plot 602 represented by a deviation from a desired sinusoidal
command
profile as shown in plot 702 of Figure 7.
By the outer feedback control loop 418/420/508 determining a desired current
sum 436/438/512 (commanded total coil current 436/438/512) based on the
difference
442/444/514 between the desired actuator output 414/416/516 and the measured
actuator
output 410/412/518, and the inner feedback control loop 430/432/506
determining an
appropriate command 446/448/520 to its current amplifier 450/452/522 based on
a
difference between the commanded total coil current 436/438/512 and the
measured total
coil current 524, system 500 provides unprecedented non-optimality suppression
capability that is near-perfect. An example of this is shown in the time-
history plot 700
below.
Figure 7 is an illustration of an exemplary time-history plot 700 showing
piston
position (in) plot 702, differential pressure (psi) plot 704, and current (mA)
plot 706 for a
simulated fault suppression in the parallel triplex actuator coil controller
system 500 of
Figure 5 according to an embodiment of the disclosure. When an erroneous level
of
control current 708 (erroneous current 708) flows through one actuator coil
422/424/530
within a servo valve a slight change in the measured total coil current 524 is
sensed by the
actuation coil current sensor 528 and the other two actuator coil controllers
work to
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actively generate currents that immediately oppose the erroneous current 708
to keep the
measured total coil current 524 at the commanded total coil current
436/438/512.
In this way, the effects of the erroneous current 708 is kept to negligible
levels, as
shown by a force fight represented by the difference between the differential
pressures
714 and 716 shown in the plot 704, as well as by a piston position
displacement 718 and
720 represented by the deviation from the desired sinusoidal command profile
shown in
the plot 702. This is contrasted to the extreme effects seen with
"Conventional" actuators
such as the conventional actuator 302 shown in Figure 6.
More specifically in this example, the erroneous current 708 through the
actuation coil 422 is substantially immediately opposed by the currents 710
and 712
through other two actuation coils, e.g., the actuation coil 2 (424) and the
actuation coil 3
(530) respectively. Thus, the force fight as well as the piston position
displacement
between the inboard and the outboard actuators on the same aerodynamic surface
are
reduced to negligible levels.
Feedback control loop, puts into place a feature in which each control current
directly affects the other control currents electromagnetically, such that an
erroneous
control current is actively and immediately opposed by the other control
currents. Thus,
when an anomaly in one or more of signals in one of lines of either feedback
loops or in a
device generating a signal such as the desired actuator output 414
representing the desired
piston position causes the erroneous current 708 to flow through an actuation
coil such as
the actuation coils 422, the resulting magnetic flux 818/820 is sensed by the
magnetic
flux sensor 802/812 (Figure 8, actuation coil current sensor 460/528 in
Figures 4 and 5) in
the other two lines of the position control loops. This, in turn, causes a
current to flow in
the other two actuation coils 424/526 and creates a magnetic flux 818/820
opposing that
which is created by the erroneous current 708.
A difference in hydraulic pressure between two sides of cylindrical pistons,
"differential pressure" may be substantially proportional to a load applied on
or output by
the actuator 402. This differential pressure is measured and monitored by a
force sensor.
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The force sensor monitors at least two measured actuator forces. The system
400/500
may comprise other types of actuators such as an electro-mechanical actuator
where a
"differential pressure" may not be used to measure a force. In this case,
other means of
force measurement might be used such as, but without limitation, a strain
gage, or other
force measurement means.
Figure 8 is an illustration of an independent current measurement 800
according
to an embodiment of the disclosure. Figure 9 is an illustration of total
current derivation
900 in the independent current measurement of Figure 8 according to an
embodiment of
the disclosure.
A plurality of sensor coils 804/814 are configured to receive an actuation
current
426/428 that actuates one of the actuation coils 422/424 respectively. The
sensor coils
804/814 may be electrically independent from circuitry generating current the
sensor coils
804/814 are measuring, so that a common electrical anomaly does not cause an
erroneous
current such as the erroneous current 708, in parallel with corrupting a
measurement
applied as a feedback parameter to another actuator coil controller.
A magnetic core 808/816 is configured to receive the magnetic flux 818/820
from the sensor coils 804/814 respectively.
At least one magnetic flux sensor 802/812 is coupled to the magnetic core
808/816 and is configured to measure the measured total coil current 462. The
at least
one magnetic flux sensor 802/812 may comprise, for example but without
limitation, a
Hall-effect sensor, or other sensor. The measured total coil current 462
(current-sum
feedback value) may be derived in a number of ways. The measured total coil
current
462 should be measured in a way that is electrically independent from the
devices and
circuitry that are controlling the current (unless another separate means of
protection is
provided to address the anomaly of that common device or circuitry).
As explained above, this is so that a common electrical anomaly does not cause
erroneous current, in parallel with corrupting the measurement applied as the
feedback
parameter to the other actuator coil controller. For example, the system 400
should avoid
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an anomaly that causes erroneous current to flow through the actuation coil 1
(422) and
corrupts the total current measurement used in the actuator coil controller 2
(408).
In Figures 8 and 9, each of the multiple controllers such as the actuator coil
controllers 406 and 408 (see Figure 4) measure each other's actuator coil
current through
an electrically independent means to measure a respective adjacent coil
current and sums
the respective adjacent coil current with a respective local coil current to
create the
measured total coil current 462 as the feedback parameter.
For example, the actuator coil controller 406 measures its own local coil
current
(measured coil current 826) such as the coil current 426 of the actuator coil
422, measures
an adjacent coil current (measured coil current 828) such the coil current 428
of the
actuator coil 424, and sums the coil current 428/828 with the coil current
426/826 to
create the measured total coil current 902/462 as the feedback parameter.
Similarly, the actuator coil controller 408 measures its own local coil
current
(measured coil current 828) such as the coil current 428 of the actuator coil
424, measures
an adjacent coil current (measured coil current 826) such the coil current 426
of the
actuator coil 422, and sums the coil current 428/828 with the coil current
426/826 to
create the measured total coil current 904/462 as the feedback parameter.
An independent measurement is accomplished in this example by the magnetic
flux sensors 802/812 in which the current 426/428 flows through the sensor
coils 804/814
respectively and generate respective magnetic flux 818/820 which is measured
in
respective gap 806/810 in the respective magnetic core 808/816.
In addition, depending on a type of the actuator 502, embodiments may
independently measure or derive the measured total coil current 462 (or a
close
approximation) using the actuation coils 422/424 directly, rather than
installing external
sensor coils 804/814 dedicated for measurement purposes, as shown in Figure
10.
Figure 10 is an illustration of a total current measurement 1000 according to
an
embodiment of the disclosure. Figure 10 shows another example, in which the
measured
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total coil current 462 is measured by magnetically summing the magnetic flux
818/820
(Figure 8) generated by two sensor coils 804/814.
The two actuator coil controllers 406 and 408 (Figure 4) measure the total
coil
current 462 by magnetically summing the magnetic flux 818/820 generated by the
two
sensor coils 804/814. An independent measurement is accomplished in this
example by
the magnetic flux sensor 802/812 in which the current 426/428 flows through
the sensor
coil 804/814 and generates the magnetic flux 818/820, a sum (1004/462 and
1006/462) of
which is measured respectively in the gap 806 and 810 in the core 1002.
The methods in Figures 8-11 may be expanded to derive the measured total coil
current 462 for other levels of redundancy (e.g., triple, quadruple, etc.).
Figure 11 is an illustration of an exemplary flowchart showing a process 1100
for
suppression of a non-optimality in an actuator coil controller according to an
embodiment
of the disclosure. The various tasks performed in connection with process 1100
may be
performed mechanically, by software, hardware, firmware, a computer-readable
medium
having computer executable instructions for performing the process method, or
any
combination thereof. It should be appreciated that process 1100 may include
any number
of additional or alternative tasks, the tasks shown in Figure 11 need not be
performed in
the illustrated order, and process 1100 may be incorporated into a more
comprehensive
procedure or process having additional functionality not described in detail
herein.
For illustrative purposes, the following description of process 1100 may refer
to
elements mentioned above in connection with Figures 4-5, and 7-10. In some
embodiments, portions of the process 1100 may be performed by different
elements of the
system 400-500 such as: outer feedback control loop 418/420/508, the inner
feedback
control loop 430/432/506, the current amplifier 450/452/522, the actuation
coils
422/424/526, the sensor coils 804/814, the magnetic flux sensor 802/812, etc.
Process
1100 may have functions, material, and structures that are similar to the
embodiments
shown in Figure 4-5 and 7-10. Therefore common features, functions, and
elements may
not be redundantly described here.
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Process 1100 may begin by sensing a measured total coil current such as the
measured total coil current 462 comprising a sum of coil currents of each of a
plurality of
actuation coils such as the actuation coils 422/424 of an actuator such as the
actuator 402
with an actuation coil current sensor such as the actuation coil current
sensor 460 (task
1102).
Process 1100 may then continue by controlling the actuation coils 422/424 with
a
plurality of actuator coil controllers such as the actuator coil controllers
406/408 based on
a commanded total coil current such as the commanded total coil current
436/438 and the
measured total coil current 462 (task 1104). Controlling the actuation coils
422/424 with
the actuator coil controllers 406/408 may be based on a difference (current-
sum
difference) between the commanded total coil current 436/438 and the measured
total coil
current 462.
Process 1100 may then continue by actuating the actuator 402 via the actuation
coils 422/424 (task 1106).
Process 1100 may continue by receiving a desired actuator position such as the
desired output 414/416 and a measured actuator position such as the measured
output
410/412 (task 1108).
Process 1100 may continue by generating the commanded total coil current
436/438 based on the desired actuator position such as the desired output
414/416 and the
measured actuator position such as the measured output 410/412 (task 1110).
Process 1100 may continue by receiving at each of a plurality of sensor coils
such as sensor coils 804/814 an actuator current such as the actuator current
426/428 that
actuates one of the actuation coils 422/424 respectively (task 1112).
Process 1100 may continue by receiving a magnetic flux such as the magnetic
flux 818/820 from the sensor coils 804/814 in a magnetic core such as the
magnetic core
808/816 (task 1114).
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Process 1100 may continue by measuring the measured total coil current 462 by
at least one sensor such as the magnetic flux sensor 802/812 coupled to the
magnetic core
808/816 (task 1116).
In this way, a system and methods are provided for suppressing anomaly in an
actuator.
The above description refers to elements or nodes or features being
"connected"
or "coupled" together. As used herein, unless expressly stated otherwise,
"connected"
means that one element/node/feature is directly joined to (or directly
communicates with)
another element/node/feature, and not necessarily mechanically.
Likewise, unless
expressly stated otherwise, -coupled" means that one element/node/feature is
directly or
indirectly joined to (or directly or indirectly communicates with) another
element/node/feature, and not necessarily mechanically. Thus, although Figures
4-5 and
8-10 depict example arrangements of elements, additional intervening elements,
devices,
features, or components may be present in an embodiment of the disclosure.
Terms and phrases used in this document, and variations thereof, unless
otherwise expressly stated, should be construed as open ended as opposed to
limiting. As
examples of the foregoing: the term -including" should be read as meaning
"including,
without limitation" or the like; the term "example" is used to provide
exemplary instances
of the item in discussion, not an exhaustive or limiting list thereof; and
adjectives such as
"conventional," "traditional," "normal," "standard," "known," and terms of
similar
meaning should not be construed as limiting the item described to a given time
period or
to an item available as of a given time, but instead should be read to
encompass
conventional, traditional, normal, or standard technologies that may be
available or
known now or at any time in the future.
Likewise, a group of items linked with the conjunction "and" should not be
read
as requiring that each and every one of those items be present in the
grouping, but rather
should be read as "and/or" unless expressly stated otherwise. Similarly, a
group of items
linked with the conjunction "or" should not be read as requiring mutual
exclusivity
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CA 02851869 2014-05-14
among that group, but rather should also be read as "and/or" unless expressly
stated
otherwise.
Furthermore, although items, elements or components of the disclosure may be
described or claimed in the singular, the plural is contemplated to be within
the scope
thereof unless limitation to the singular is explicitly stated. The presence
of broadening
words and phrases such as "one or more," "at least,- "but not limited to" or
other like
phrases in some instances shall not be read to mean that the narrower case is
intended or
required in instances where such broadening phrases may be absent. The term
"about"
when referring to a numerical value or range is intended to encompass values
resulting
from experimental error that can occur when taking measurements.
According to an aspect of the present disclosure there is provided a redundant
current-sum feedback actuator system comprising an actuator comprising a
plurality of
actuation coils configured to actuate the actuator; an actuation coil current
sensor
configured to sense a measured total coil current comprising a sum of coil
currents of
each. of the actuation coils; and a plurality of actuator coil controllers
configured to
control the actuation coils based on a current-sum difference between a
commanded total
coil current and the measured total coil current.
The system is one further comprising an actuation coil current sensor
configured
to sense the measured total coil current, and comprising a plurality of sensor
coils
configured to receive an actuator current that actuates one of the actuation
coils
respectively; a magnetic core configured to receive a magnetic flux from the
sensor coils;
and at least one sensor coupled to the magnetic core and configured to measure
the
measured total coil current.
The system is one further comprising an outer feedback control loop comprising
a
plurality of electrically independent outer control loops each configured to
receive a
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desired actuator position and a measured actuator position; and generate the
commanded
total coil current based on the desired actuator position and the measured
actuator
position.
The system is one wherein the actuation coils comprise a common actuation
power.
According to an aspect of the present disclosure there is provided a method
for
suppressing non-optimality in an actuator control system, the method
comprising sensing
a measured total coil current comprising a sum of coil currents of each of a
plurality of
actuation coils of an actuator with an actuation coil current sensor; and
controlling the
actuation coils with a plurality of actuator coil controllers based on a
current-sum
difference between a commanded total coil current and the measured total coil
current.
The method is one further comprising actuating the actuator via the actuation
coils.
The method is one further comprising receiving a desired actuator position and
a
measured actuator position; and generating the commanded total coil current
based on the
desired actuator position and the measured actuator position.
The method is one further comprising receiving at each of a plurality of
sensor
coils an actuator current that actuates one of the actuation coils
respectively; receiving a
magnetic flux from the sensor coils in a magnetic core; and measuring the
measured total
coil current by at least one sensor coupled to the magnetic core.
According to an aspect of the present disclosure there is provided a redundant
current-sum feedback actuator controller comprising an inner feedback control
loop
configured to receive a desired total coil current and a measured total coil
current
comprising a sum of coil currents of each of a plurality of actuation coils of
an actuator;
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and control the actuation coils based on a current-sum difference between the
desired
total coil current and the measured total coil current.
The redundant current-sum feedback actuator controller is one further
comprising
an actuation coil current sensor configured to sense the measured total coil
current, and
comprising a plurality of sensor coils configured to receive an actuator
current that
actuates one of the actuation coils respectively; a magnetic core configured
to receive a
magnetic flux from the sensor coils; and at least one sensor coupled to the
magnetic core
and configured to measure the measured total coil current.
The redundant current-sum feedback actuator controller is one further
comprising
an outer feedback control loop comprising a plurality of electrically
independent outer
control loops each configured to receive a desired actuator position and a
measured
actuator position; and generate the desired total coil current based on the
desired actuator
position and the measured actuator position.
The redundant current-sum feedback actuator controller is one wherein the
actuation coils comprise a common actuation power.
The redundant current-sum feedback actuator controller is one wherein the
redundant current-sum feedback actuator controller controls an aircraft flight
control
surface.
The redundant current-sum feedback actuator controller is one further
comprising
a current amplifier operable to receive the current-sum difference between the
desired
total coil current and the measured total coil current and generate a command
output to
control an actuator.
The redundant current-sum feedback actuator controller is one wherein the
desired
total coil current comprises an output-current difference between a desired
actuator
current output and a measured actuator current output.
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The redundant current-sum feedback actuator controller is one wherein the
actuation coils are configured to actuate an actuator.
The redundant current-sum feedback actuator controller is one wherein the
measured total coil current comprises the sum of coil currents of the
actuation coils of the
actuator as a feedback parameter in each of a plurality of controllers.
The redundant current-sum feedback actuator controller is one wherein the
measured total coil current is measured by magnetically summing magnetic flux
generated by sensor coils of each of the controllers.
The redundant current-sum feedback actuator controller is one wherein each of
the
controllers measure each other's actuator coil current through an electrically
independent
means to measure a respective adjacent coil current and sums the respective
adjacent coil
current with a respective local coil current to create the measured total coil
current as the
feedback parameter.
The redundant current-sum feedback actuator controller is one wherein an
erroneous current through one of the actuation coils causes a current to flow
in other
actuation coils among the actuation coils and creates a magnetic flux opposing
the
erroneous current, thereby reducing force fight between actuators on a same
surface.
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