Electric Auxiliary Power Unit Based Electric Taxi System for Aircraft

When grounded, aircraft may taxi using thrust from the main aircraft engines, which can waste fuel and is often inefficient. This disclosure outlines an electric aircraft taxi system, or eTaxi system, that can operate without continuous power from the aircraft engines, allowing the engines to be turned off during taxi to save fuel. An electric auxiliary power unit, or eAPU, is equipped on the aircraft and powers electric motor-generators that can both drive landing gear wheels and regenerate power from the wheels during regenerative braking. When the eTaxi system is on, a drive controller and a taxi controller gather inputs from the aircraft controls and converts them into commands sent to the electric motor-generators, brakes, and steering devices.

BACKGROUND

The disclosed embodiments relate generally to the field of electric propulsion. More specifically, the disclosed embodiments related to aircraft propulsion, braking, and steering during ground maneuvers utilizing electrically driven wheels and a battery electric auxiliary power unit (eAPU).

2. Related Art

Aircraft ground maneuvers, or taxiing, have traditionally been performed using the aircraft's main propulsion system. By their nature, turbofan/jet engines are less efficient at low altitudes (on the ground) than they are at higher altitudes where they are designed for nominal performance. Due to these inefficiencies, the fuel consumption rate of aircraft during taxiing is high. Therefore, it is desirable to be able to taxi an aircraft with the main engines off by driving the main landing gear wheels with electric motors.

Multiple solutions have been provided to taxi an aircraft by means of electrically driven main landing gear wheels. U.S. Patent Publication No. 2021/0192964 to Van Deventer et al. discloses an aircraft taxiing system. In some examples, the energy storage locations include a gas turbine auxiliary power unit and battery, which could provide electric energy for powering a number of electric motors in taxiing. U.S. Patent Publication No. 2019/0375512 to Ribeiro et al. discloses hybrid electric taxi system (HETS) or full electric taxi system (FETS). During ground operations the core engine fuel supply is turned off and the engines are driven on electrical power only. U.S. Pat. No. 8,093,747 to Pearson et al. discloses an electrical power system architecture. In some examples, the electrical power system architecture may use a gas turbine auxiliary power unit (APU) as an electrical power source during taxi to drive electric motors in the main gear wheels. U.S. Pat. No. 8,727,270 to Burns et al. discloses a system for taxiing an aircraft without starting one or more main aircraft propulsion engines. In some examples, a hybrid gas turbine APU is configured to supply rotational power to both HP spool and LP spool to provide sufficient thrust to taxi aircraft without starting one or more engines. U.S. Pat. No. 9,849,849 to Vieillard et al. discloses a device for supplying electrical power to an aircraft on the ground. U.S. Pat. No. 9,567,100 to Jackson et al. discloses an electric taxi predictive performance system. In some examples, the electric taxi (eTaxi) system provides ground movement using a gas turbine auxiliary power unit generator (APUG) powering electric drive motor(s). U.S. Pat. No. 11,149,649 to Terwilliger et al. discloses a hybrid gas turbine engine system of a hybrid electric aircraft. The hybrid gas turbine engine system includes an electric motor operable to perform an electric taxiing of the hybrid electric aircraft.

Non-patent article “eTaxi Taxiing aircraft with engines stopped” to Nicolas discloses eTaxi systems in which one could taxi aircraft with engines stopped. Pages 6-7 of the article disclose a full eTaxi solution where one could get a full eTaxi performance with all engines stopped in every condition (e.g., taking in consideration the aircraft weight) with a modified gas turbine APU.FIG.6provides examples of control diagrams for implementing the disclosed eTaxi systems. Non-patent article “More Electric Aircraft: Review, Challenges, and Opportunities for Commercial Transport Aircraft” to Sarlioglu et al. discloses review, challenges, and opportunities for commercial transport aircraft based on the idea of a more electric aircraft.FIG.3(b)discloses a diagram of the main engine start system with electric APUs, consisting of a gas turbine engine driving an electrical generator to produce only electrical power.FIG.8discloses an electric taxi architecture with fuel cell electric power generation system and battery pack as additional energy storage implementations.

SUMMARY

In embodiments of the present disclosure, an eAPU-based aircraft taxi control system includes: an electric auxiliary power unit configured to provide electrical power; a drive controller configured to control a main gear electric motor-generator; an electric brake actuator controller configured for providing braking; and a taxi controller operatively coupled to the electric auxiliary power unit, the drive controller, the electric brake actuator controller and preexisting aircraft controls, wherein the taxi controller is configured to provide steering and drive control for taxiing the aircraft based on inputs received from the preexisting aircraft controls without receiving power from an aircraft engine.

In embodiments of the present disclosure, an aircraft taxi system includes: an electric power source configured to supply stored power installed on an aircraft configured to power aircraft and taxi system components; a plurality of main gear wheels each including: an electric motor-generator configured to drive a main gear wheel when powered by the electric power source and configured to provide regenerative braking; an electro-mechanical brake configured to provide a braking force on the main gear wheel; and a brake resistor configured to provide regenerative braking by converting electricity into heat; and a taxi controller configured to control the plurality of main gear wheels for performing forward and reverse driving, braking, and steering.

In embodiments of the present disclosure, a method for electric aircraft taxiing includes: providing electric power from an auxiliary power source configured onboard an aircraft, wherein the auxiliary power source provides electric power independent of aircraft engine power; and integrating a taxi controller with preexisting cockpit controls such that the cockpit controls are configured to control the aircraft via the taxi controller for performing the electric taxiing steps of; driving at least one main landing gear wheel powered by the electric power source for driving the aircraft; steering a nosewheel for steering the aircraft; and braking the at least one main landing gear wheel for braking the aircraft.

DETAILED DESCRIPTION

Aircraft taxiing is typically performed using thrust from the main aircraft engines to provide motion on wheels of the aircraft landing gear. This process can be inefficient and may waste fuel that could be burned more efficiently during flight.

Embodiments disclosed herein provide for an electric auxiliary-power-unit (eAPU)-based electric taxi system for aircraft. The eAPU-based eTaxi system provides an all-electric large, high energy-density battery that may replace a traditional gas turbine auxiliary power unit (APU) installed in an aircraft. The eAPU provides electrical power for the aircraft systems while the main engine generators are offline and enables crew to prepare the aircraft for flight without aircraft engine power and therefore without consuming any fuel. In an embodiment, the eAPU provides electrical power to a system that controls motor-generators and brakes housed within the main landing gear wheels, which allows the crew to taxi the aircraft on electrical power only.

There are several potential advantages provided by an eAPU-based eTaxi system for aircraft:The aircraft could save fuel by allowing the crew to start the engines only for the minimum time required before takeoff and stop the engines as soon as they have moved clear of the runway after landing, thus reducing engine run time and fuel consumption;By reducing the run time of the engines, there is a potential reduction of wear on the engines, which are generally the single most expensive maintenance item on the aircraft;In addition to conventional braking, the system would allow the use of regenerative braking, converting the kinetic energy of the aircraft into electrical energy to recharge the eAPU, reducing the turn-around time of the aircraft and reducing the maintenance costs associated with replacing traditional mechanical brakes;By converting to a brake-by-wire system, a hydraulic braking system can be eliminated from an aircraft, reducing aircraft weight and the number of flammable fluid zones in the aircraft;The system could be used to provide autonomous braking (or “auto-braking”), allowing the aircraft to reduce speed autonomously during the roll-out after landing so as to exit the runway at a pre-selected taxiway. By using the calculated ground speed of the aircraft at the touchdown point, the landing configuration of the aircraft (e.g., flaps, spoilers, thrust reverse) and the condition of the runway surface provided by the crew, the system could calculate the amount of braking force necessary for constant deceleration to arrive at the crew-selected taxiway at a safe runway exit speed. Said braking force can then be automatically applied to the aircraft via regenerative braking, charging the eAPU, or putting energy into the braking resistor, supplemented by the mechanical brakes of the aircraft;The eTaxi system for aircraft using an eAPU could provide the ability to decrease take-off distances by electrically driving the main landing gear wheels via the electric motor-generators during a Takeoff/Go-around thrust (TO/GA) takeoff. This would allow the aircraft to accelerate more quickly than relying on only the thrust from the engines, reducing the takeoff distance;The system could be used to drive the wheels on the main landing gear during final approach to landing in order to match the ground speed of the aircraft. By using the calculated ground speed of the aircraft during final approach, the landing configuration of the aircraft (e.g., flaps, spoilers, thrust reverse) and the condition of the runway surface provided by the crew, the system could calculate the speed at which to spin the main gear wheels to match ground speed at touchdown. This may reduce wear on the tires, reducing the need for replacement. This example could also be used in an off-airport landing package for special-missions aircraft that would be landing on unimproved (gravel or dirt) runway surfaces. This provides a safety feature and assists the crew in maintaining control of the aircraft after touchdown;In some embodiments, the system could decrease the turning radius of an aircraft by electrically driving one main gear wheel forward, and the other main gear wheel in reverse, improving ground maneuverability in confined spaces: and,The system may provide for the ability to vary the gain of the nosewheel steering systems based on the state of the motor-generator and drive speed improving controllability of the aircraft during ground maneuvers.

FIG.1is a schematic of an exemplary eAPU-based eTaxi system10for aircraft. System10is an electric aircraft taxi control system, or “eTaxi system” or “eTaxi,” suitable for performing taxi of an aircraft without relying on any engine thrust or power during the taxi process. For instance, an aircraft with dual turbine engines may have these engines offline while the aircraft is taxied with system10. In embodiments, system10may also be used to drive the aircraft landing gear wheels during takeoff and landing using electric power supplied from a battery.

Embodiments herein describe system10as it may be employed on aircraft equipped with an electric auxiliary power unit, hereinafter referred to as an “eAPU.” InFIG.1, an embodiment eAPU100comprises a set of high energy-density batteries configured to supply a direct current (hereinafter “DC”) that provide a power source to an aircraft when any engine-driven generators configured on aircraft engines, thrusters, turbines. propellers or other in-flight propulsion mechanisms (not shown) are not running. The use of eAPU100allows for purely electric operation of system10. In an embodiment, eAPU100may be installed in place of, or in addition to, a gas turbine APU, or in an aircraft that would otherwise not have a traditional APU installed. An example of an eAPU having battery modules is U.S. Pat. No. 10,864,995 to Chang et al., entitled Hybrid Auxiliary Power Unit for Aircraft, the disclosure of which is hereby incorporated by reference in its entirety.

eAPU100is electrically connected to an aircraft bus106by means of an eAPU contactor104. Contactor104is for example a relay used to switch on/off high voltage/current lines, and aircraft bus106comprises the main electrical system of an aircraft, which possibly includes gas turbine generators and power lines for air conditioning, avionics, and other electric devices typically outfitted on passenger aircraft. eAPU100is the power source for the eAPU-based eTaxi system10and may also power other components connected to aircraft bus106. eAPU100may be recharged from the main engine generators (not shown) via aircraft bus106or from an electric motor-generator206during regenerative braking, allowing for a bidirectional power supply between eAPU100and aircraft bus106. In an embodiment, gas turbine generators configured to provide electricity generated by the aircraft engines/thrusters may assist eAPU100in driving electric motor-generator206during a TO/GA takeoff. In other embodiments, such as with a low-speed taxi procedure, a lesser acceleration, or a light airplane, the TO/GA takeoff may be done relying solely on power from eAPU100.

A DC power junction110is electrically connected to eAPU100via an eTaxi contactor108, wherein eTaxi contactor108is a switch configured to be enabled or disabled by a crew member. A braking resistor214electrically connects with the DC power junction110via a braking resistor contactor212such that DC power may be diverted from eAPU100to braking resistor214via DC power junction110, for instance when eAPU is in a high state of charge. The braking resistor214may provide supplemental braking force during regenerative braking with the diverted DC power.

Cockpit controls700provide an interface for the crew to directly control the eTaxi features of system10. In embodiments, cockpit controls700comprise a preexisting set of cockpit input devices such as thrust levers; a yoke, joystick, control wheel, or control column; rudder/tiller; toe brakes; etc. that are configured to provide commands, inputs, or signals from the crew to the eTaxi system10when eTaxi system10is active In embodiments, cockpit controls700may comprise any preexisting aircraft controls or control scheme such that the preexisting aircraft controls may be configured to carry out functions of system10while still being configured to provide control for normal aircraft functions. No additional cockpit controls need be introduced to the aircraft to enable a fully functional embodiment system10as input signals from existing controls may be received and translated into commands for driving, steering, and braking by system10. For instance, when a throttle is increased while eTaxi system10is active and the aircraft engines are off, the aircraft wheels may be driven forward by power from eAPU100.

In embodiments, crew inputs are transmitted from cockpit controls700to an eTaxi controller500via inputs702and from cockpit controls700to an electric brake actuator controller200via a toe-brake angle sensor704; and in some embodiments, a nosewheel steering command506is transmitted from cockpit controls700to a nosewheel steering controller504. As part of cockpit controls700, the existing throttle levers are used to provide a speed input to the eTaxi system10while the engines are off. For example, a throttle position may be determined using one or more sensors, and a signal indicative of the throttle position such as a discrete or continuous electrical signal is provided to eTaxi controller500. In embodiments, inputs702comprise analog signals transmitted from cockpit controls700. Toe brakes angle sensors704mounted to the rudder pedals/toe brakes may be used, along with the eAPU status102, to determine the availability of regenerative braking and to compute how much, if any, mechanical braking may be required by the aircraft.

In embodiments, eTaxi controller500may compute and transmit outputs from algorithms configured to determine appropriate braking, wheel motor drive, and steering commands for components of system10based in part on inputs702. eTaxi controller500may comprise a computer with software installed, wherein the software is configured with algorithms that produce outputs which lead to smooth and predictable eTaxi behavior from system10. For the purposes of this disclosure, “smooth and predictable behavior” and similar phrases refer generally to a safe, expected, and responsive driving feel that remains consistent according to a current state of an aircraft. The behavior is predictable in the sense that a pilot or crewmember operating the aircraft may use eTaxi features of system10intuitively, or that the response of system10is similar to that of an aircraft performing a conventional taxi using aircraft thrusters. Steering the aircraft would not be expected to produce a different result between two steering inputs at the same speed with no other factors changed). The details of the control system and computer hardware/software are discussed alongsideFIGS.2and3. For steering a differential arc length of the main landing gear wheels during a turn, for example, rudder pedal inputs are provided to eTaxi controller500, which provides outputs to the wheel motor drive to drive the main landing gear wheels at different speeds through the turn.

An eDrive controller300is configured to drive one or more electric motor-generators206and to facilitate regenerative braking, and in embodiments eDrive controller300may assign each electric motor-generator206a “drive mode” and a “regeneration mode” for use when driving an electric motor-generator206and performing regenerative braking with an electric motor-generator206respectively. One or a plurality of electric motor-generators206may be configured on an aircraft, with an electric motor-generators206configured to drive each main gear wheel as an electric motor-generator. The function of a single electric motor-generator206is referred to for simplicity. Each electric motor-generator206may be configured with a wheel speed sensor222and a motor driveshaft sensor224for determining the speed of a landing gear wheel configured with electric motor-generator206. Wheel speed sensor222comprises a transducer that, when excited, provides a number of pulses per wheel revolution. Motor driveshaft sensor224also comprises a transducer configured to determine a driveshaft speed. Feedback from the sensors may be sent to eDrive controller300and eTaxi controller500for use in control logic and determining drive, steering, and braking commands.

In embodiments such as the embodiment depicted inFIG.4, electric motor-generators206are configured in one or more aircraft landing gear or landing gear wheels, such that each electric motor-generator206drives a wheel directly. Electricity from the eAPU is run directly to the landing gear in such embodiments. In other embodiments such as that depicted inFIG.5, one or more electric motor-generators206may drive one or more landing gear wheels via transmission through a driveshaft228through the landing gear. Such a configuration may simplify landing gear design by requiring fewer electrical components to be configured on and within the landing gear, and a single driveshaft may be configured to drive multiple landing gear wheels. Additionally, a configuration of electric motor-generators206with or without driveshafts may be preferable to adjust weight distribution or simplify construction around the aircraft.

An embodiment eDrive controller300may be configured to function as a bidirectional AC/DC converter while also communicating with eTaxi controller500and other components. During normal forward taxi (drive mode), eDrive controller300functions as an inverter and converts DC power from the eAPU100via DC power junction110to AC, n-phase, modulated power for the purpose of driving electric motor-generator206. Electric motor-generator206is electrically connected to the eDrive controller300by phase power connections208.

During taxi or TO/GA power configuration, the electric motor-generator206may function as a drive motor. During regenerative braking operations (regeneration mode), electric motor-generator206functions as a generator and produces n-phase alternating current (hereinafter “AC”) power while the eDrive controller300functions as a converter. This n-phase AC power is converted by eDrive controller300to DC power which travels along eTaxi contactor108to recharge eAPU100. If more braking force is necessary, or if eAPU100is already at a high state of charge, disconnected, or otherwise unavailable, the DC power is instead provided to the braking resistor214to provide additional braking.

The eTaxi controller500may comprise computer hardware and software that can reside in an independent controller housing, on a printed circuit board in a card cage with other controllers, or integrated onto a separate piece of computer hardware, as later discussed alongsideFIGS.2and3. The eTaxi controller500and associated subsystem controllers include algorithms stored in non-volatile memory for regenerative braking and eAPU charging; driving electric motor-generators206during taxi, TO/GA takeoff; or spinning electric motor-generators206to match ground speed prior to landing. During a TO/GA takeoff, traction control may be performed by eTaxi controller500to prevent the aircraft tires slipping on the runway surface, wherein a variable level of drive or braking may be applied to each electric motor-generator206to maintain predictable behavior of the aircraft.

eTaxi controller500operates in conjunction with eDrive controller300, electric brake actuator controller200, inputs702from cockpit controls700, and eAPU100. eTaxi controller500sends and receives information from multiple sources. It receives eAPU status102information from the eAPU100, inputs702from the cockpit controls700, sends and receives nosewheel steering command/position feedback502from the nosewheel steering controller504, and sends and receives information from an eDrive status and command302to and from eDrive controller300. eTaxi controller500may also send and receive information to and from avionics706.

Electric brake actuator controller200is used to provide braking inputs to an electro-mechanical brake actuator204. For example, the brake actuator controller200may receive inputs from the cockpit controls700via a toe-brake angle sensor704. From this input, the electric brake actuator controller200calculates a required electro-mechanical brake command202and compares that command to the calculated regenerative brake strength210sent from the eTaxi controller500. Comparing two inputs provides a level of independence and redundancy in calculating the mechanical brake command that may be used to provide for more predictable eTaxi braking behavior. Electric brake actuator controller200may also receive inputs from a brake pressure sensor226to inform commands sent to electric brake actuator controller200.

An electro-mechanical brake actuator204is a mechanical brake device driven by either an electric actuator or electro-hydraulic actuator as opposed to a purely hydraulic system. The electro-mechanical brake actuator204supplements the regenerative braking capability of the system in the case that purely regenerative braking supplied by electric motor-generators206is not sufficient to stop the aircraft. There may be one or many electro-mechanical brake actuators204installed within each main landing gear.

In certain embodiments, electric nosewheel steering and feedback may be incorporated into the system. In this embodiment, the nosewheel steering controller504receives steering commands in the form of a nosewheel steering command506from cockpit controls700and a digital command from eTaxi controller500. The commands are compared and converted by nosewheel steering controller504to a nosewheel steering actuator command508, which is then sent to the nosewheel steering actuator510. Closed-loop feedback is provided by a nosewheel steering angle sensor512back to the nosewheel steering controller504. The nosewheel steering controller504is a combination of electronic hardware and software that may reside in an independent controller housing, on a printed circuit board in a card cage with other controllers, or integrated onto a separate piece of electronic hardware.

FIG.2shows a block diagram of an example computing device2000that facilitates operation of an aircraft configured with an eAPU100and components of an embodiment system10, including components configured to send and receive commands such as eTaxi controller500or eDrive controller300as described with reference toFIGS.1and3. In some examples, the computing device2000is configured to perform functions of system10described with reference toFIGS.1and3. The computing device2000may include one or more chips, systems on a chip (SoCs), chipsets, packages, components or devices that individually or collectively constitute or comprise a processing system. The processing system may interface with other components of the computing device2000, and may generally process information (such as inputs or signals) received from such other components and output information (such as outputs or signals) to such other components. In some aspects, an example chip may include a processing system, a first interface to output or transmit information and a second interface to receive or obtain information. For example, the first interface may refer to an interface between the processing system of the chip and a transmission component, such that the computing device2000may transmit the information output from the chip. In such an example, the second interface may refer to an interface between the processing system of the chip and a reception component, such that the computing device2000may receive information that is then passed to the processing system. In some such examples, the first interface may obtain information, such as from the transmission component, and the second interface may also output information, such as to the reception component.

The processing system of the computing device2000includes processor (or “processing”) circuitry in the form of one or multiple processors, microprocessors, processing units (such as central processing units (CPUs), graphics processing units (GPUs) or digital signal processors (DSPs)), processing blocks, application-specific integrated circuits (ASICs), programmable logic devices (PLDs) (such as field programmable gate arrays (FPGAs)), or other discrete gate or transistor logic or circuitry (all of which may be generally referred to herein individually as “processors” or collectively as “the processor” or “the processor circuitry”). One or more of the processors may be individually or collectively configurable or configured to perform various functions or operations described herein. The processing system may further include memory circuitry in the form of one or more memory devices, memory blocks, memory elements or other discrete gate or transistor logic or circuitry, each of which may include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof (all of which may be generally referred to herein individually as “memories” or collectively as “the memory” or “the memory circuitry”). One or more of the memories may be coupled with one or more of the processors and may individually or collectively store processor-executable code that, when executed by one or more of the processors, may configure one or more of the processors to perform various functions or operations described herein. Additionally or alternatively, in some examples, one or more of the processors may be preconfigured to perform various functions or operations described herein without requiring configuration by software. The processing system may further include or be coupled with multiple radios (collectively “the radio”), multiple radio frequency (RF) chains or multiple transceivers, each of which may in turn be coupled with one or more of multiple antennas. In some implementations, one or more processors of the processing system include or implement one or more of the radios, RF chains or transceivers.

In some examples, the computing device2000can be configurable or configured for use in an aircraft eTaxi system, such as system10comprising eTaxi controller500or eDrive controller300as described with reference toFIGS.1and3. In some other examples, the computing device2000can be a microcontroller that includes such a processing system and other components such as eTaxi controller500or eDrive controller300with reference toFIGS.1and3.

The computing device2000is capable of transmitting and receiving wireless communications in the form of, for example, wireless packets or data elements. For example, the computing device2000can be configurable or configured to transmit and receive packets in the form of physical layer PPDUs and MPDUs conforming to one or more of the IEEE 802.11 family of wireless communication protocol standards. In some other examples, the computing device2000can be configurable or configured to transmit and receive signals and communications conforming to one or more 3GPP specifications including those for 4G NR or 6G.

In some examples, the computing device2000also includes or can be coupled with one or more application processors which may be further coupled with one or more other memories. In some examples, the computing device2000further includes at least one external network interface coupled with the processing system that enables communication with a core network or backhaul network that enables the computing device2000to gain access to external networks including the Internet.

The computing device2000may include a processor component2002, a memory component2004, a display component2006, a user interface component2008, a modem component2010, and a radio component2012. Portions of one or more of the components2006,2008, and2012may be implemented at least in part in hardware or firmware. In some examples, at least some of the components2006,2008, and2012of computing device2000are implemented at least in part by a processor and as software stored in a memory. For example, portions of one or more of display component2006, and the user interface component2008can be implemented as non-transitory instructions (or “code”) executable by processor2002to perform the functions or operations of the respective module.

In some implementations, processor2002may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, computing device2000). For example, a processing system of computing device2000may refer to a system including the various other components or subcomponents of computing device2000, such as the processor, or a transceiver, or a communications manager, or other components or combinations of components of computing device2000. The processing system of computing device2000may interface with other components of computing device2000and may process information received from other components (such as inputs or signals) or output information to other components. For example, a chip of computing device2000may include a processing system, a first interface to output information and a second interface to obtain information. In some implementations, the first interface may refer to an interface between the processing system of the chip and a transmitter, such that computing device2000may transmit information output from the chip. In some implementations, the second interface may refer to an interface between the processing system of the chip and a receiver, such that computing device2000may obtain information or signal inputs, and the information may be passed to the processing system. A person having ordinary skill in the art will readily recognize that the first interface also may obtain information or signal inputs, and the second interface also may output information or signal outputs.

Processor2002is capable of, configured to, or operable to processes information received through radio component2012, and processes information to be output through radio component2012for transmission through the wireless medium. Processor2002may perform logical and arithmetic operations using program instructions stored within memory2004. The instructions in memory2004may be executable (by processor2002, for example) to implement the methods described herein.

Memory2004is capable of, configured to, or operable to store and communicate instructions and data to and from processor2002.

User interface component2008may be any device that allows a user to interact with computing device2000, such as a microphone, dials, buttons, et cetera. In aspects, user interface component2008may be integrated with display component2006to present aircraft operational information and eTaxi statuses such as with control inputs and flight instruments comprised by cockpit controls700, with reference toFIGS.1and3.

Modem component2010may be any device configured to transmit data from computing device2000to another device on a common network such as via the Internet, a local area network, a wide area network, or another suitable network. In embodiments, computing device2000may not comprise modem component2010and may be interfaced via wired or wireless connection to an external modem for transmission of data on a network.

Radio component2012includes at least one radio frequency transmitter and at least one radio frequency receiver, which may be combined into one or more transceivers. The transmitter(s) and receiver(s) may be coupled to one or more antennas. In some aspects, processor2002, memory2004, and radio component2012may collectively facilitate the wireless communication of computing device2000with other wireless communication devices over multiple frequency bands (such as 2.4 GHz, 5 GHZ, or 6 GHz).

Now referring toFIG.3, system10relies on electric inputs, commands, or signals transmitted between eAPU100, eTaxi controller500, eDrive controller300, electric brake actuator controller200, cockpit controls700, and avionics706, wherein these signals enable communication between these components, and wherein these components may comprise computer hardware similar to computing device2000in embodiments with software installed that governs the resulting output of system10. The output from system10is a predetermined response in the sense that an algorithm determines the output in a consistent fashion from the gathered inputs. This leads to predictable taxi behavior when using system10such as smooth steering, smooth acceleration with a safe top speed, and more. Generally, inputs from avionics706, inputs702, eDrive status and command302, eAPU status102, and electric motor-generators206may be processed by computer hardware and software of eTaxi controller500and eDrive controller300to convert crew inputs sourced from cockpit controls700into smooth, predictable, and safe aircraft taxi behavior.

eTaxi controller500is configured to receive inputs directly from eAPU100, eDrive controller300, nosewheel steering controller504, cockpit controls700, and avionics706, in embodiments, and is configured to send outputs, commands, or signals to electric brake actuator controller200, eDrive controller300, nosewheel steering controller504, and avionics706. In embodiments where eTaxi controller500comprises a computing device2000, software installed in a memory component2004may be configured to process inputs from any of the aforementioned input components into output commands configured to create smooth, predictable, and safe aircraft taxi behavior.

In embodiments, eDrive controller300is configured to receive inputs directly from eAPU100, eDrive controller300, and electric brake actuator controller200, and is configured to send outputs, commands, or signals to eAPU100, eDrive controller300, and electric brake actuator controller200. In embodiments where eDrive controller300comprises a computing device2000, software installed in a memory component2004may be configured to process inputs from any of the aforementioned input components into output commands configured to create smooth, predictable, and safe aircraft taxi behavior.

System10may be configured to be enabled or disabled via a crew input to cockpit controls700, such that system10and taxi functionalities are not executed during flight when aircraft landing gear are not deployed. A user interface display such as a monitor configured in cockpit controls700may provide system information to crew about the status of the eTaxi system, such as eAPU status102or data gathered by avionics706. Moreover, crew may be able to interact with the user interface or another set of controls to adjust regenerative braking strength, calibrate auto-braking for exiting a runway at a preselected taxiway, or otherwise adjust the behavior of system10to provide for more predictable taxiing behavior or to provide for a preferred taxi feel, such as by increasing the gain on nosewheel steering controller504for a more responsive steering feel.

The operation of the eTaxi system may be broken into four sub-groups: sourcing power, providing steering control, providing taxi drive, and providing braking. eAPU100powers the system from battery charge or from power available from aircraft bus106, and system10is powered when eTaxi contactor108is engaged. Electrical power may also be sourced from any of electric motor-generators206during regenerative braking, and electrical power from eAPU100may be used for electric propulsion, electric steering, or electric braking of an aircraft.

To provide steering control, system10may employ nosewheel steering, traditional hydraulic steering, or differential driving/braking. In embodiments of the system where the nosewheel steering actuator510, the nosewheel steering angle sensor512, and the nosewheel steering controller504are installed, directional control during aircraft taxi is provided by system10. Cockpit controls700provides crew inputs to system10, and the crew inputs along with other inputs are processed by software installed on eTaxi controller500and eDrive controller300to provide stable, predictable steering. For instance, the aircraft's current taxi speed (sourced from avionics706or at least one wheel speed sensor222) is a control input to the nosewheel steering controller504. Using taxi speed data, the gain of the nosewheel steering may be increased at very low speeds and decreased at normal taxi speeds. This allows the aircraft to turn in a much tighter radius at low speed (i.e., on a ramp), but provide stable directional control at higher taxi speeds.

In embodiments of the system lacking active nosewheel steering (such as with free castering nosewheels) or comprising traditional hydraulic steering, the eTaxi controller500may be configured to provide differential braking commands to the two sides of the aircraft via the electric brake actuator controller200and differential drive commands to eDrive controller300. Crew inputs from cockpit controls700provide steering commands, and the resultant output to electric motor-generators206and electric brake actuator controller200may be modified by system10to mimic traditional steering controls. By providing differential drive and braking commands to the two sides of the aircraft, embodiments of the system may drive one wheel forward and the other backwards, allowing the aircraft to turn within its own radius.

To provide taxi drive, eTaxi controller500and eDrive controller300process signals from one another and from eAPU100, electric motor-generators206, and cockpit controls700into output signals that lead to smooth and predictable forward or reverse taxi motion for an aircraft. When eTaxi controller500receives crew input from cockpit controls700(such as a non-zero level of throttle) and an acceptable eAPU status102of the eAPU100. eTaxi controller500sends a command proportional to its received input to the eDrive controller300. eDrive controller300then functions as an inverter to convert DC power from the eAPU into n-phase AC power for driving the electric motor-generators206.

While taxiing, the maximum power provided to the electric motor-generators206is limited to a percentage of the maximum discharge rate of the eAPU100. This limitation prevents the aircraft from exceeding a safe forward taxi speed and becoming difficult to control. In embodiments, wheel speed sensors222and motor drive shaft sensors224may be configured to provide closed-loop feedback to eDrive controller300. Closed-loop feedback allows eDrive controller300to monitor the speed of the motor and adjust its output to closely match the real speed of the aircraft to a commanded taxi speed (for instance, a current taxi speed of 20 knots indicated to a crew member on a display of cockpit controls700), thereby providing for predictable operation of the aircraft during eTaxi.

In embodiments where TO/GA input is provided from the cockpit controls700to eTaxi controller500, eDrive controller300may apply a maximum power to electric motor-generators206to provide a maximum thrust from the landing gear wheels during takeoff to reduce the runway distance required for takeoff. When performing a reduced-distance takeoff, eDrive controller300will first drive electric motor-generators206at maximum torque. As the aircraft accelerates, eDrive controller300will begin reducing the torque demand from electric motor-generators206such that the torque delivered by the motors is approximately zero by the time the aircraft has reached rotation speed. This driving behavior during takeoff is configured to gently reduce aircraft acceleration from the wheels, preventing an abrupt and unexpected drop in acceleration during rotation while maintaining smooth and predictable behavior even during takeoff. During this initial acceleration, eDrive controller300may enact traction control based on feedback from wheel speed sensors222and motor drive shaft sensors224, wherein power to a given electric motor-generator206is reduced if wheelspin occurs to prevent inefficiency from wheelspin and to keep the aircraft moving forward in a controlled direction during takeoff.

In embodiments, during aircraft landing, airspeed or groundspeed data from avionics706may be input to eTaxi controller500and eDrive controller300and output as a command to drive electric motor-generators206, possibly to a maximum thrust. Electric motor-generators206may accelerate main gear wheels or other driven aircraft wheels until the wheel speed corresponds to the ground speed, thereby reducing tire wear upon touchdown.

In embodiments, when the eTaxi system is configured to allow electric motor-generators206to coast when no power is applied, the brake pedals must be engaged to slow the aircraft. As given by crew inputs to cockpit controls700, the angle of the toe brakes may correspond to the amount of braking action output to electric brake actuator controller200, braking resistor214, electric motor-generator206, or mechanical brakes disposed on the aircraft. The eTaxi controller500takes in inputs such as the level of charge of eAPU100and the temperature of braking resistor214to calculate how much regenerative braking is possible. This information is transmitted to electric brake actuator controller200. If additional mechanical braking is required, electric brake actuator controller200sends a command to electro-mechanical brake actuator204to supplement the regenerative braking with traditional mechanical braking.

Electro-mechanical brake actuator204mitigates the need for a large hydraulic brake system, and in embodiments system10may engage electro-mechanical brake actuator204to provide a clamping force to a mechanical brake when regenerative braking from electric motor-generator206is insufficient. In another embodiment, electro-mechanical brake actuator204is electro-hydraulic and comprises a small electric pump configured to create hydraulic pressure locally with a small amount of hydraulic fluid. At the same time, eDrive controller300sends a command to electric motor-generator206to perform regenerative braking and recharge eAPU100. If the eAPU100has a high state of charge, or is otherwise not able to accept the energy supplied from eDrive controller300, braking resistor214may be engaged to convert electrical energy to heat, thereby providing additional braking from the recovered energy on top of the regenerative braking performed by electric motor-generator206and, in embodiments, on top of the mechanical braking performed by electro-mechanical brake actuator204. In embodiments, eDrive controller300may optimize braking efficiency by calculating the total braking strength needed, supplying as much braking strength as possible using electric motor-generator206and braking resistor214, and supplementing this braking with any additional braking strength required to reduce the speed of the aircraft to a safe speed.

System10may also be used for autonomous braking. allowing the aircraft to reduce speed autonomously during roll-out after landing so as to exit the runway at a pre-selected taxiway. eDrive controller300may process data from avionics706, such as a calculated ground speed of the aircraft at the touchdown point, the landing configuration of the aircraft (e.g., flaps, spoilers, thrust reverse), and the condition of the runway surface, to calculate the amount of braking force necessary for constant deceleration to arrive at a preselected taxiway at a safe runway exit speed. Said braking force may then be automatically applied via instructions issued by eDrive controller300to the aircraft to perform regenerative braking with electric motor-generators206, braking resistor214, or electromechanical brake actuator204.

Referring now toFIG.4, a landing gear230comprises wheels232, an axle234a differential236, a light238, a landing gear shock strut240, a side strut242, and undercarriage doors246. A new or a preexisting landing gear230may be configured with an electric motor-generator206connected directly to axle234to drive wheels232or perform regenerative braking via wheels232. Brakes on the aircraft may comprise or be mechanically and/or electrically coupled to electromechanical brake actuator204, braking resistor214, and other methods for stopping an aircraft including purely mechanical brakes may be disposed directly on wheels232or axle234. In embodiments, braking resistor214may be mounted with the control electronics to assist with regenerative braking formed by electric motor-generator206.

An embodiment eDrive controller300is configured within the main body of an aircraft and may communicate and supply power to all electric motor-generators206configured on an aircraft with system10. A conduit244electrically connects electric motor-generator206and eDrive controller300to power and send commands to electric motor-generator206. Electric motor-generator206may also comprise or be configured with a differential236, a gearbox and clutch assembly, or other powertrain equipment.

Referring now toFIG.5, an aircraft may be configured with an electric motor-generator206connected to axle234or wheels232via a driveshaft228. Driveshaft228runs through or may run parallel to landing gear230, and in a specific embodiment within shock strut240, such that an electric motor-generator206may be mounted on the main body of the aircraft instead of landing gear230and still transmit power or perform regenerative braking with wheels232. In this case, differential236and other powertrain equipment may be configured at an end of driveshaft228opposite of electric motor-generator206. Otherwise, the assembly of landing gear230may be substantially similar to the embodiment shown inFIG.4.

Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of what is claimed herein. Embodiments have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from what is disclosed. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from what is claimed.