NZ754150B2 - Distributed flight control system - Google Patents
Distributed flight control system Download PDFInfo
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- NZ754150B2 NZ754150B2 NZ754150A NZ75415016A NZ754150B2 NZ 754150 B2 NZ754150 B2 NZ 754150B2 NZ 754150 A NZ754150 A NZ 754150A NZ 75415016 A NZ75415016 A NZ 75415016A NZ 754150 B2 NZ754150 B2 NZ 754150B2
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Abstract
set of commands for each of a plurality of actuators to alter an aircraft's state responsive to one or more inputs is produced. The set of commands is provided to fewer than all actuators comprising the plurality of actuators.
Description
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DISTRIBUTED FLIGHT CONTROL SYSTEM
BACKGROUND
Automated flight control is indispensable in flying some aircraft. Safety of
an automated flight control or autopilot program is critical. An automated flight control
system may require a form of redundancy to safeguard against failures. Building
redundancy in automated flight control systems may be complex or costly.
SUMMARY
[0001A] According to a first aspect of the present invention there is provided a flight
control system for an aircraft which includes actuators and rotors, the system comprising a
flight computer, which comprises a processor configured to produce a set of commands
for fewer than all of said actuators to alter a state of the aircraft responsive to one or more
inputs, the input(s) comprising a desired attitude of the aircraft or a desired rate of change
of attitude of the aircraft, and to provide the set of commands to the actuator(s) for which
the set of commands is produced, wherein at least one of the commands comprises a
command to adjust a speed of a motor of the aircraft to achieve the desired attitude or the
desired rate of change of attitude.
[0001B] According to a second aspect of the present invention there is provided an
aircraft provided with the system according to the first aspect, the aircraft including said
actuators and rotors.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described, by way of
non-limiting example only, with reference to the accompanying drawings briefly
described as follows.
Figure 1 is a diagram illustrating an embodiment of a non-redundant flight
control system.
Figure 2 is a diagram illustrating an embodiment of a triplex redundant
flight control system.
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Figure 3A is a diagram illustrating an embodiment of a multicopter that
utilizes a distributed flight control system.
Figure 3B is a diagram illustrating an embodiment of a multicopter that
utilizes a distributed flight control system.
Figure 4 is a diagram illustrating an embodiment of a distributed flight
control system.
Figure 5 is a diagram illustrating an embodiment of connection in a
distributed flight control system.
Figure 6 is a diagram illustrating an embodiment of a distributed flight
control system.
Figure 7 is a diagram illustrating an embodiment of a mode-switch
mechanism of a distributed flight control system.
Figure 8 is a flow diagram illustrating an embodiment of a mode switch
decision process.
Figure 9 is a diagram illustrating an embodiment of a distributed flight
control system in an aircraft.
Figure 10 is a flow diagram illustrating a distributed flight control system
process.
Figure 11 is a diagram illustrating an embodiment of flight computer of a
distributed flight control system.
Figure 12 is a diagram illustrating an embodiment of distributed flight
control system flow.
DETAILED DESCRIPTION
Teachings herein can be implemented in numerous ways, including as a
process; an apparatus; a system; a composition of matter; a computer program product
embodied on a computer readable storage medium; and/or a processor, such as a processor
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configured to execute instructions stored on and/or provided by a memory coupled to the
processor. In general, the order of the steps of disclosed processes may be altered within
the scope of the disclosure. Unless stated otherwise, a component such as a processor or a
memory described as being configured to perform a task may be implemented as a general
component that is temporarily configured to perform the task at a given time or a specific
component that is manufactured to perform the task. As used herein, the term ‘processor’
refers to one or more devices, circuits, and/or processing cores configured to process data,
such as computer program instructions.
A detailed description of one or more embodiments of the invention is
provided below along with accompanying figures that illustrate the principles of the
invention. The invention is described in connection with such embodiments, but the
invention is not limited to any embodiment. The scope of the invention is limited only by
the claims and the invention encompasses numerous alternatives, modifications and
equivalents. Numerous specific details are set forth in the following description in order
to provide a thorough understanding of the invention. These details are provided for the
purpose of example and the invention may be practiced according to the claims without
some or all of these specific details. For the purpose of clarity, technical material that is
known in the technical fields related to the invention has not been described in detail so
that the invention is not unnecessarily obscured.
A distributed flight control system is described. The flight control system
comprises a processor configured to produce a set of commands for each of a plurality of
actuators to alter the state of an aircraft responsive to one or more inputs. The inputs may
comprise a desired attitude or rate of attitude change. In some embodiments, the flight
control system comprises a set of sensors, and the set of commands are produced
responsive to sensor readings. The processor is configured to provide the set of commands
to fewer than all actuators comprising the plurality of actuators. In some embodiments, the
aircraft comprises a plurality of actuators configured to enable flight in an aircraft in the
event zero or one actuators of the multitude of actuators are inactive. The system may
comprise a plurality of processors. The system may comprise an equal number of
processors and actuators. The processors and actuators may comprise a one to one
relationship wherein each actuator receives instructions from a corresponding processor.
An aircraft may be controlled with a degree of automation. A distributed
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flight control system may comprise one or more flight computers. A flight computer of the
one or more flight computers may run auto-pilot software. The flight computer may
comprise a processor and a set of sensors. The distributed flight control system may
comprise elements of redundancy for safety reasons. For example, the system may be
required to be free of any single points of failure. The distributed flight control system
may be utilized in an over-actuated aircraft, wherein redundancy is physically built into
the aircraft. For example, the aircraft may comprise more actuators than it requires for
controllable flight. The distributed flight control system may take advantage of the over-
actuated aircraft. The aircraft’s physical redundancy may be used to implement flight
control system redundancy. Each actuator may be controlled by a separate processor. In
some embodiments, each processor considers all actuators and calculates instructions for
all actuators but controls only one actuator. The processor may be physically connected to
only one actuator. In the event a processor malfunctions, only one actuator of the aircraft
may be affected. The distributed flight control system may comprise a simple to
implement and redundant autopilot hardware set-up.
Figure 1 is a diagram illustrating an embodiment of a non-redundant flight
control system. The flight computer and actuators depicted may be positioned on a same
aircraft. In the example shown, inputs are provided to flight computer 100. Inputs may
comprise information collected from instruments on the aircraft. Inputs may comprise
signals delivered by a pilot via controls or via an interface. Flight computer 100 may
process the inputs and determine instructions for actuators of the aircraft that will put the
aircraft on a desired flight trajectory based on the inputs. Flight computer 100 may provide
instructions to actuator_1 102, actuator_2 104, actuator_3 106, and actuator_4 108. The
actuators may comprise a physical component of the aircraft that affects the aircraft’s
trajectory. An actuator may comprise a motor, a flap, a pushrod, a control surface, a
mechanism, a component that interacts with the physical world, or any appropriate object.
Flight computer 100 may produce instructions for all the actuators. The
actuators may be coordinated in order to achieve desired flight. For example, a rotor on a
left side of an aircraft and a rotor on a right side of an aircraft may be instructed to rotate
in opposite directions in order to prevent rotation of the aircraft. While a non-redundant
flight control system is simple to build, it may raise safety concerns. In the event flight
computer 100 malfunctions, no back-up system is shown. A single error in flight computer
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100 may cause the aircraft to crash.
Figure 2 is a diagram illustrating an embodiment of a triplex redundant
flight control system. A triplex redundant flight control system uses three flight computers
to provide redundancy. In the example shown, inputs are provided to flight computer_1
200, flight computer_2 202, and flight computer_3 204. The flight computers provide
information to decision unit 206. The flight computers may each separately determine
instructions for all actuators of the aircraft. Decision unit 206 may be used to determine
which instructions to provide to the actuators. Decision unit 206 may use a voting scheme.
For example, in the event flight computer_1 200 and flight computer_2 202 produced a
same instruction for actuator_1 208 but flight computer_3 204 did not, decision unit 206
may pass on the instruction that a majority of the flight computers agreed upon. In the
example shown, decision unit 206 provides instructions to actuator_1 208, actuator_2 210,
actuator_3 212, and actuator_4 214.
The triplex redundant flight control system may provide redundancy in the
aircraft’s autopilot and eliminate single points of failure. However, the system may be
complex or costly to implement. Decision unit 206 may comprise complex hardware or
software. Decision unit 206 may require redundant elements in its hardware or software.
The system’s hardware or software may be required to be designed from beginning to end
with redundancy in mind.
For some aircraft, a non-redundant or a triplex redundant flight control
system is not feasible due to cost, complexity, or safety concerns. Some aircraft may
exhibit specific characteristics that suit a flight control system based on those
characteristics. A distributed flight control system may efficiently utilize physically
redundant aircraft.
Figure 3A is a diagram illustrating an embodiment of a multicopter that
utilizes a distributed flight control system. In some embodiments, a multicopter is
inherently unstable. The multicopter may require active control or an autopilot to prevent
the multicopter from flipping. The multicopter may require electronics in its control
system opposed to solely mechanical pilot controls. A distributed flight control system
may provide a minimum level of autopilot functionality required to allow a pilot to
manually fly the multicopter. The system may provide a basic level of autopilot
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functionality required for the multicopter, comprising attitude control or attitude rate
control. With a minimum amount of inputs provided, the distributed flight control system
may prevent an aircraft from creating uncontrolled rolling, pitching, or yawing torques.
The distributed flight control system may generate proper body torques to keep the
multicopter stable. The system may be easily and elegantly utilized in an aircraft such as a
multicopter where all actuators are the same (e.g. motors).
The aircraft shown comprises fuselage 300, with five rotors on either side
of the fuselage. Rotors 302, 306, 310 and rotors 312, 316, and 320 are positioned adjacent
to fuselage 300 on left and right sides of the fuselage, respectively. Rotors 304 and 308 are
positioned adjacent to rotors 302, 306, and 310. Rotors 314 and 318 are positioned
adjacent to rotors 312, 316, and 320. Outer rotors 304, 308, 314, and 318 may be
positioned between two inner rotors, e.g. rotors adjacent to the fuselage. The rotor
configuration may allow the multicopter to have a wide wingspan.
Actuators of the multicopter may comprise the rotors. The multicopter may
be over-actuated. More rotors than are strictly required to maintain desired flight of the
aircraft may be present. For example, the multicopter may achieve acceptable flight
performance in the event one of the ten rotors is inactive. The aircraft may be physically
redundant such that in the event one rotor is active but is not operating as desired, the
aircraft is still able to maintain desired flight. For example, the aircraft will not flip over in
the event one rotor is rotating in an undesired direction or at an undesired speed. A
physically redundant aircraft may be well-suited for a distributed flight control system.
In some embodiments, in the event one rotor fails, the aircraft is able to
detect the failure and turn off an opposite rotor in order to balance torque. In some
embodiments, the rotors are not in communication. In some embodiments, cross coupling
at the output of the flight computers does not occur. Feedback control algorithms in the
flight computers of the distributed flight control system may resolve a rotor failure. The
flight computers may detect a position or full attitude of the vehicle. They may determine
appropriate motor speeds to achieve a desired attitude. In the event a motor is
malfunctioning and a desired position is not achieved, the system may continue to adjust
speed or thrust until a correct state is achieved.
The multicopter of Figure 3A may be designed to have a small form-factor.
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The multicopter may be flown at low altitudes and low speeds. The multicopter may be
designed to be low-cost. In some embodiments, a distributed flight control system is a
simple solution made with low-cost parts. The system may be designed for low-cost
aircraft.
In some embodiments, the distributed flight control system is used in an
unmanned aircraft. For example, the multicopter shown may be fully autonomous. In
some embodiments, the distributed flight control system is used in a manned aircraft.
Figure 3B is a diagram illustrating an embodiment of a multicopter that
utilizes a distributed flight control system. In the example shown, the multicopter
comprises fuselage 350 and rotors 352, 354, 356, 358, 360, 362, 364 and 366. The eight
rotors are arranged around fuselage 350. The rotors may be attached via booms or beams.
The distributed flight control system may be used in a standard multicopter. The
distributed flight control system may be used in a standard aircraft. For example, the
system may be used in an aircraft that comprises two wings.
Figure 4 is a diagram illustrating an embodiment of a distributed flight
control system. In the example shown, inputs are provided to flight computer_1 400, flight
computer_2 404, flight computer_3 408, and flight computer_4 412. Inputs may comprise
desired attitudes or desired attitude rates. The inputs may be sourced from pilot controls or
from a higher level flight computer.
Flight computer_1 400 provides inputs to actuator_1 402. Flight
computer_2 404 provides inputs to actuator_2 406. Flight computer_3 408 provides inputs
to actuator_3 410. Flight computer_4 412 provides inputs to actuator_4 414. In some
embodiments, a flight computer exists for each actuator of the aircraft. Each flight
computer may be unaware of other flight computers. Each flight computer may act as
though it is the only flight computer present in the system. The flight computers may be
decoupled from each other, with no communication among them. All flight computers of
the system may be identical. They may comprise identical hardware and software. The
flight computers may comprise a processor, a set of sensors, and computer algorithms.
The set of sensors may comprise a rate gyro, accelerometer, or magnetometer. In some
embodiments, the flight computer is a board comprising several integrated circuits. For
example, one integrated circuit may function as a microprocessor, whereas another
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functions as an accelerometer. Each flight computer may determine instructions for all
actuators of the aircraft. The flight computer may determine instructions based on its
inputs (e.g. desired attitude or desired attitude rate) and collected sensor data. The flight
computer may determine instructions for the actuators to achieve the desired attitude or
attitude rate while keeping the aircraft balanced. For example, a multicopter may be
inherently unstable and require a torque control loop that the flight computer puts into
place. Each flight computer may run a feedback control loop.
In some embodiments, each flight computer is physically connected to only
one actuator. An actuator corresponding to the flight computer may receive only the
instruction applying to said actuator. In some embodiments, an actuator of the aircraft is
decoupled from other actuators. The actuators may not be in communication. In some
embodiments, a flight computer provides instructions for all actuators to the actuator it is
physically connected to. The actuator may utilize the correct instruction based on the
actuator’s position.
In some embodiments, the distributed flight control system enables use of
flight computers that are simple to build or program. The computers may comprise low
cost processors. Wiring of the distributed flight control system may be simple due to
decoupled flight computers. In the event an error occurs in a single flight computer, only
its singular corresponding actuator may be affected. Due to a physically redundant aircraft,
a flight trajectory of the aircraft may proceed as desired in the event an actuator
malfunctions. Using a separate flight computer for each actuator may allow a failure in the
flight computer to percolate to the actuator level, where it is resolved. An error occurring
in a flight computer or speed controller may result in undesired behavior in a singular
corresponding actuator of an aircraft. In an over-actuated aircraft, the undesired behavior
of the actuator does not significantly affect the aircraft’s flight trajectory.
Figure 5 is a diagram illustrating an embodiment of connection in a
distributed flight control system. In some embodiments, the wiring or wiring harness used
in the flight control system causes a flight computer to provide instructions to a subset of
actuators available in the aircraft. In the example shown, four actuators are present. The
distributed flight control system may be positioned on an aircraft with four actuators. In
the example shown, flight computer_1 500, flight computer_2 504, flight computer_3 508,
and flight computer_4 512 each produce four outputs. The outputs may be instructions for
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each actuator in the aircraft. Each flight computer may determine instructions for all
actuators, wherein each actuator’s instructions are provided on a different wire. Each flight
computer may have one or more wires that are not connected to actuators and the outputs
are not used. For example, each flight computer has one actuator instruction output wire
that is connected to an actuator while all other actuator instruction output wires from the
flight computer are not connected to any actuator. As shown, flight computer_1 500 is
physically connected to actuator_1 502 and no other actuators. Flight computer_2 504 is
physically connected to actuator_2 506 and no other actuators. Flight computer_3 508 is
physically connected to actuator_3 510 and no other actuators. Flight computer_4 512 is
physically connected to actuator_4 514 and no other actuators.
Figure 6 is a diagram illustrating an embodiment of a distributed flight
control system. In some embodiments, the distributed flight control system has multiple
levels of flight computers. Higher level flight computers may reduce complex instructions
into a set of simple commands that are then provided to lower level flight computers. The
higher level flight computer may control the position and velocity of the aircraft while
lower level flight computers control the attitude of the aircraft. The actuators may receive
instruction from lower level flight computers. In the example shown, inputs are provided
to higher level flight computer 600.
Inputs may comprise an input from a user interface. For example, a pilot
may enter a latitude and longitude. Inputs may comprise conditions, such as a stipulation
to avoid locations with bad weather, fly over areas of low population density, or to take
the shortest path. The inputs may comprise an instruction to execute a complex flight
trajectory. The higher level flight computer may determine an appropriate velocity or
position for the aircraft based on the inputs. The higher level flight computer may
automatically navigate or control the aircraft to achieve the desired velocity or position.
The higher level flight computer may determine a desired attitude or desired rate of
attitude change based on the inputs and provide the desired attitude or desired rate of
attitude change to lower level flight computers. Higher level flight computer 600
determines instructions given to lower level flight computer_1 602, lower level flight
computer_2 604, lower level flight computer_3 608, and lower level flight computer_4
610.
Lower level flight computer_1 602 as shown provides inputs to actuator_1
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612. Lower level flight computer_2 604 provides inputs to actuator_2 614. Lower level
flight computer_3 608 provides inputs to actuator_3 616. Lower level flight computer_4
610 provides inputs to actuator_4 618. The lower level flight computers may determine a
speed for a rotor, a tilt angle of a flap, an amount of thrust used, or any other appropriate
factor. The lower level flight computers may perform full feedback control. For example,
the lower level flight computer may determine an actual attitude or attitude rate of the
aircraft and compare to a desired attitude or attitude rate of the aircraft. The lower level
flight computer may then determine instructions to lower the difference between the two
values, if one exists. An aircraft may comprise 2, 10, 22, or any appropriate number of
actuators. The aircraft may comprise an equal number of lower level flight computers.
Figure 7 is a diagram illustrating an embodiment of a mode-switch
mechanism of a distributed flight control system. In some embodiments, lower level flight
computers have an option to be controlled by a higher level flight computer or to be
controlled manually, e.g. by a pilot. The lower level flight computers may constantly
calculate actuator actions in order to maintain a base level of flight. They may further
factor in instructions given by a higher level flight computer or pilot directing the
aircraft’s flight trajectory. The flight computers may each comprise independent code or
hardware to determine when to switch from listening to a higher level flight computer to
listening to manual control. Control may be desired to switch over to a manual mode in
the event a malfunction is detected in the higher level flight computer or an irregularity is
detected. In some embodiments, the aircraft’s actual state is tracked and compared to the
aircraft’s desired state. In the event the actual state does not track the desired state
appropriately, the system may signal that a malfunction is detected. A pilot’s controls may
comprise a switch, button, application, or other mechanism to select a mode.
In some embodiments, lower level flight computers of the system are
identical. However, each lower level flight computer may comprise its own set of sensors.
The computer may use sensor data to determine whether a mode switch is required.
Different lower level flight computers may comprise sensors of different specifications.
The lower level flight computers may be positioned in varying places on the aircraft,
causing sensor data to vary. Without linking the flight computers, they may determine to
switch modes at different times.
In the event one lower level flight computer switches from listening to a
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higher level computer to listening to a pilot line, all flight computers may be switched at
once. Maintaining the same mode for all flight computers may allow actuators of the
aircraft to fly the aircraft effectively. In some embodiments, the flight computers of a
distributed flight control system are in communication. The flight computers and pilot line
may communicate over a bus or communication network to coordinate switching. The
flight computers and pilot line may be electrically connected via logic gates. In the
example shown, flight computer_1, flight computer_2, flight computer_3, flight
computer_4, and a pilot are inputs to an OR gate. In some embodiments, the flight
computers and pilot are inputs to a series of OR gates wherein each OR gate has two
inputs. In some embodiments, the communication line reads as “low” or is below a
predetermined voltage threshold when the aircraft is in one mode. In the event a flight
computer or the pilot switches modes, the flight computer or pilot’s signal may go “high”
or be above a predetermined voltage threshold. Pulling one of the signals high may cause
the entire communication line to be pulled high, changing the mode for all flight
computers and the pilot.
Figure 8 is a flow diagram illustrating an embodiment of a mode switch
decision process. In 800, it is determined whether a flight computer has switched modes.
The process may check to see if any flight computer of the system’s lower level flight
computers has switched modes. In the event no flight computers have switched modes, the
process repeats 800. In some embodiments, the process pauses for a predetermined period
of time before repeating 800. In the event a flight computer has switched modes, in 802
modes of all the flight computers are switched.
In some embodiments, in 800 it is determined whether a flight computer
has switched modes or if an indication to switch modes is received. An indication to
switch modes may be received by a pilot or a higher level flight computer. For example, a
higher level flight computer may automatically switch the lower level flight computers
from automatic to manual mode in the event the higher level flight computer detects that
the higher level flight computer is compromised. The mode may be automatically
switched from manual to higher level flight computer mode in the event no signals are
received from a pilot’s aircraft controls for a period of time.
Figure 9 is a diagram illustrating an embodiment of a distributed flight
control system in an aircraft. In some embodiments, the system may be utilized by an
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aircraft that comprises two booms and a fuselage. The system may be used on a
multicopter compromising rotors that are installed on the two booms. The multicopter of
Figure 3 may be positioned over two booms or pontoons. The booms may be inflatable or
lightweight and enable the aircraft to land on water. A pilot may be situated in the
fuselage.
In the example shown, major elements of the distributed flight control
system are stored on fuselage 975. Masterboard 974 is situated on fuselage 975.
Masterboard 974 may act as a backplane. Lower level flight computers of the system may
be laid out on a shared circuit board. Lower level flight computers may plug into the
masterboard. In the example shown, lower level flight computers 950, 954, 958, 962, 966,
952, 956, 960, 964, and 968 are installed on masterboard 974. The lower level flight
computers may be electrically isolated from each other. They may plug into separate
power sources. The lower level flight computers may be microcontrollers with a set of
sensors. The sensors may comprise typical smart phone sensors, such as a magnetometer,
rate gyro, or accelerometer. The lower level flight computers may be installed in a center
of the aircraft in the fuselage in order to collect accurate data from their sensors. Higher
level flight computer 970 is also installed on masterboard 974. Global positioning system
971, radar 972, and camera 973 are also installed on masterboard 974 and provide data to
higher level flight computer 970. Camera 973 may comprise a stereo camera or infrared
camera. Other sensors such as lidar or sonar may also provide data to the masterboard.
In the example shown, display 942 is present on the fuselage. The display
may provide flight information to a pilot of the aircraft. The display may enable the pilot
to control the aircraft, for example via a touch screen. Mode switch 944, pilot controls
946, and kill switch 948 are also present on the fuselage. Mode switch 944 may comprise
a button, switch, or other control that enables a pilot to switch between manual mode and
higher level flight computer automatic mode. Kill switch 948 may allow the pilot to
disable power to all actuators of the aircraft, such as all the rotors. Pilot controls 946 may
comprise one or more physical objects the pilot manipulates to adjust the aircraft’s
position. For example, a joystick, steering wheel, pedal, lever, or any other appropriate
control may be used. In some embodiments, a boot button may exist. The boot button may
be used to power on the system. The power up and power down mechanisms may be
physically separate in order to decrease chances of triggering the incorrect action.
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In the example shown, higher level flight computer 970 receives inputs
from pilot controls and sensors. The higher level flight computer may provide instruction
to the lower flight computer based on the pilot controls and sensor information. For
example, in the event a pilot abruptly changes a direction of the aircraft while it is engaged
in automatic mode, the higher level flight computer may immediately allow the pilot
control input to override a prior path of the aircraft.
In some embodiments, a lower level flight computer is connected to a rotor.
The lower level flight computer may be powered by a battery that also powers the rotor.
The battery may be isolated from other rotors or flight computers. In the example shown,
lower flight computer 952 provides inputs to electronic speed controller 978. Electronic
speed controller 978 is connected to rotor 979. The electronic speed controller may
determine how fast the rotor spins. Electronic speed controller 978 may be in
communication with battery management system 976 which manages battery 977. The
controller and battery management system may share an analog connection. Increasing
rotor speed may comprise using more battery power.
In the example shown, lower flight computers 952, 956, 960, 964, and 968
control five rotors positioned on right boom 998. Lower flight computer 956 controls
electronic speed controller 982, which controls rotor 983. Battery 981 is managed by
battery management system 980. Battery 981 powers rotor 983 and lower flight computer
956. Lower flight computer 960 corresponds to electronic speed controller 986, rotor 988,
battery management system 984, and battery 985. Lower flight computer 964 corresponds
to electronic speed controller 992, rotor 993, battery management system 990, and battery
991. Lower flight computer 968 corresponds to electronic speed controller 996, rotor 997,
battery management system 994, and battery 995.
In the example shown, lower flight computers 950, 954, 958, 962, and 966
control five rotors positioned on left boom 940. Lower flight computer 950 controls
electronic speed controller 906, which controls rotor 904. Battery 900 is managed by
battery management system 902. Battery 900 powers rotor 904 and lower flight computer
950. Lower flight computer 954 corresponds to electronic speed controller 914, rotor 912,
battery management system 910, and battery 908. Lower flight computer 958 corresponds
to electronic speed controller 922, rotor 920, battery management system 918, and battery
916. Lower flight computer 966 corresponds to electronic speed controller 930, rotor 928,
C:\Users\gw\AppData\Roaming\iManage\Work\Recent\35527837NZ Distributed flight control system\35527837 - Amendments Response to 2ER(20818251.1).docx-10/27/2020
battery management system 926, and battery 924. Lower flight computer 966 corresponds
to electronic speed controller 938, rotor 936, battery management system 934, and battery
932.
In some embodiments, each lower level flight computer is connected to an
electronic speed controller via a serial connection. Each lower level flight computer may
have a separate serial connection that is isolated from other connections in the flight
control system. For example, a short in one serial connection between one lower level
flight computer and one electronic speed controller may have no effect on other lower
level flight computers or other electronic speed controllers in the flight control system.
Pilot controls 946 may be connected to higher level flight computer 970 via
an analog connection. In some embodiments, pilot control inputs may be first inputted to
the higher level flight computer while in manual mode. The higher level flight computer
may enhance the pilot instructions before commands are given to the lower level flight
computers. For example, a pilot may let go of all pilot controls when the aircraft is desired
to remain motionless in its current position. The higher level flight controller may perform
altitude control and prevent the aircraft from drifting in position. Using the higher level
flight controller during manual mode may allow the aircraft’s position to be more
accurately controlled. However, the distributed flight control may enable pilot inputs to be
directly provided to lower level flight computers. As shown, the pilot controls are
additionally separately connected to the lower level flight computers. In the event the
higher level flight computer fails, a pilot is able to directly provide inputs to the lower
level flight computers.
Electronic speed controllers and battery management systems of the
distributed flight control system may be connected via Ethernet. In some embodiments,
the electronic speed controllers and battery management systems provide information over
the Ethernet network regarding a state of a battery, an amount of heat being produced, or
any other appropriate information. The lower level flight computers may also be part of
the network. The components may plug into an Ethernet switch. A Wi-Fi radio may be
connected to the Ethernet network and provide information on components of the
distributed flight control system to the pilot or to ground.
Figure 10 is a flow diagram illustrating a distributed flight control system
C:\Users\gw\AppData\Roaming\iManage\Work\Recent\35527837NZ Distributed flight control system\35527837 - Amendments Response to 2ER(20818251.1).docx-10/27/2020
process. The process may be performed by a single lower level flight computer of the
system. In 1000, pilot or upper level flight computer inputs are received. In 1002,
corresponding instructions for all actuators are determined. The lower level flight
computer may determine a position or action for all actuators of the aircraft to accomplish
instructions received and also maintain desired base levels of flight. In 1004, actuator
instructions are provided to a single actuator. The lower level flight computer may be
physically connected to only one actuator.
Figure 11 is a diagram illustrating an embodiment of flight computer of a
distributed flight control system. Lower-level flight computer 1116 comprises a set of
sensors and processor 1114. In the example shown, rate gyro 1100, accelerometer 1102,
magnetometer 1104, and barometer 1106 provide sensor data to processor 1114. The
processor may comprise a microcontroller. Processor 1114 comprises attitude estimator
1108, attitude controller 1110, and state machine 112. As shown, sensor data is provided
to attitude estimator 1108.
The attitude estimator may determine an approximate actual attitude of the
aircraft based on the sensor data provided. The attitude estimate is provided to attitude
controller 1110. As shown, attitude controller 1110 receives a desired attitude from state
machine 1112. Attitude controller 1110 may determine whether a difference exists
between the desired attitude and the attitude estimate. The attitude controller may
determine actuator commands intended to change the actual attitude of the aircraft to
match the desired attitude. Attitude controller 1110 provides actuator commands to state
machine 1112.
State machine 1112 receives a desired attitude and actuator commands. The
desired attitude may be provided by a pilot or a higher level flight computer. The state
machine may determine which desired attitude to provide to the attitude controller. For
example, the state machine may ignore inputs from a pilot in the event the flight control
system to set to an automatic mode wherein the higher level flight computer is in control.
State machine 1112 outputs actuator commands for the aircraft. In some embodiments,
state machine 1112 acts as a process control mechanism. For example, the state machine
may prevent actuator commands from being sent in the event the aircraft is on land and
flight control should not be engaged. Commands provided may vary for different types of
actuators based on the aircraft. For example, motor commands may be provided for a
C:\Users\gw\AppData\Roaming\iManage\Work\Recent\35527837NZ Distributed flight control system\35527837 - Amendments Response to 2ER(20818251.1).docx-10/27/2020
multicopter.
In some embodiments, data is collected by processor 1114 and provided to
a higher level flight computer. The data may comprise sensor data or position data. The
data may be used for logging. In some embodiments, an actuator of the aircraft may be in
communication with a higher level flight computer of the system. The actuator may report
on its health. The system may use actuator health information to compensate for a disabled
or malfunctioning actuator with other actuators. Reporting back a status may enable the
aircraft to adjust to a failure faster than a default tactic of iterating. By default, the system
may iterate and continually adjust instructions to the actuators until a desired flight
position or trajectory is achieved.
Figure 12 is a diagram illustrating an embodiment of distributed flight
control system flow. In the example shown, switch 1200 receives a higher level flight
computer desired attitude and a pilot desired attitude. Switch 1200 may determine on
desired attitude to pass on to summation block 1202 based on whether the flight control
system is in manual mode or automatic mode. Summation block 1220 may receive a
desired attitude and an attitude estimate and determine an attitude error, or difference
between the two. The attitude estimate may be an estimate of the aircraft’s actual attitude.
Attitude controller 1204 as shown receives the attitude error and produces actuator
commands for the aircraft based on the attitude error. The commands may be determined
to eliminate the attitude error. Actuator commands are provided to safety block 1206.
Safety block 1206 may prevent commands from being sent to actuators in the event the
aircraft is already landed, in a take-off sequence, or in a landing sequence. In the event the
aircraft is prepared to receive actuator commands, actuator commands are provided by the
safety block to aircraft 1208. The aircraft’s actuators may provide information on their
state to sensors 1210. For example, a signal may be sent that the actuators changed
position. In some embodiments, the aircraft’s actuators change position based on received
commands and the sensors detect the change in position. Information may not be
explicitly sent from the aircraft to sensors. Sensors 1210 provide sensor data to attitude
estimator 1212. Attitude estimator 1212 may process the sensor data received. For
example, the attitude estimator may disregard signal noise. Attitude estimator 1212 may
determine an estimate of the aircraft’s attitude based on the sensor data. Attitude estimator
1212 may provide an attitude estimate to 1202. In some embodiments, switch 1200 and
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safety block 1206 are executed by one software block, for example, a state machine.
In some embodiments, the number of lower level flight computers may be
less than the number of actuators. For example, each lower level flight computer may
control two rotors of a multicopter. The two rotors may be opposite each other. In the
event a lower level flight computer fails, the aircraft may experience negligible negative
effects because the aircraft remains balanced.
Although the foregoing embodiments have been described in some detail
for purposes of clarity of understanding, the invention is not limited to the details
provided. There are many alternative ways of implementing the invention. It will be
apparent to a person skilled in the relevant art that various changes in form and detail can
be made therein without departing from the spirit and scope of the invention. The
disclosed embodiments are illustrative and not restrictive. Thus, the present invention
should not be limited by any of the above described exemplary embodiments.
Throughout this specification and the claims which follow, unless the
context requires otherwise, the word "comprise", and variations such as "comprises" and
"comprising", will be understood to imply the inclusion of a stated integer or step or group
of integers or steps but not the exclusion of any other integer or step or group of integers
or steps.
The reference in this specification to any prior publication (or information
derived from it), or to any matter which is known, is not, and should not be taken as an
acknowledgment or admission or any form of suggestion that that prior publication (or
information derived from it) or known matter forms part of the common general
knowledge in the field of endeavour to which this specification relates.
C:\Users\gw\AppData\Roaming\iManage\Work\Recent\35527837NZ Distributed flight control system\35527837 - Amendments Response to 2ER(20818251.1).docx-10/27/2020
Claims (11)
1. A flight control system for an aircraft which includes actuators and rotors, the system comprising a flight computer, which comprises a processor configured to produce a set of commands for fewer than all of said actuators to alter a state of the aircraft responsive to one or more inputs, the input(s) comprising a desired attitude of the aircraft or a desired rate of change of attitude of the aircraft, and to provide the set of commands to the actuator(s) for which the set of commands is produced, wherein at least one of the commands comprises a command to adjust a speed of a motor of the aircraft to achieve the desired attitude or the desired rate of change of attitude.
2. The system of claim 1, comprising a set of sensors corresponding to the processor.
3. The system of claim 1, comprising a set of sensors corresponding to the processor and the set of commands is produced responsive to sensor data from the set of sensors.
4. The system of claim 1, comprising a set of sensors corresponding to the processor, the set of sensors comprising a rate gyro, accelerometer, magnetometer or barometer.
5. The system of any one of claims 1 to 4, wherein the actuators are configured to enable flight in the aircraft in the event that none or one of the actuators is inactive.
6. The system of any one of claims 1 to 5, wherein the processor is physically connected to only one actuator.
7. The system of any one of claims 1 to 6, comprising one or more additional processors configured to produce a set of commands for fewer than all of the actuators and to provide the set of commands to the actuator(s) for which that set of commands is produced.
8. The system of claim 7, comprising an equal number of processors and actuators.
9. The system of any one of claims 1 to 8, wherein one of the actuators receives commands from only one corresponding processor.
10. The system of any one of claims 1 to 9, wherein the processor of said flight computer provides basic autopilot capabilities.
11. The system of any one of claims 1 to 10, wherein the processor of said flight computer receives inputs from a pilot. C:\Users\gw\AppData\Roaming\iManage\Work\Recent\35527837NZ Distributed flight control system\35527837 - Amendments Response to 2ER(20818251.1).docx-
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2016/068377 WO2018118070A1 (en) | 2016-12-22 | 2016-12-22 | Distributed flight control system |
US15/388,627 | 2016-12-22 | ||
US15/388,627 US9977432B1 (en) | 2016-12-22 | 2016-12-22 | Distributed flight control system |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ754150A NZ754150A (en) | 2021-01-29 |
NZ754150B2 true NZ754150B2 (en) | 2021-04-30 |
Family
ID=
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