Smart electric taxi path control

An aircraft taxi control system may include a motor connected to drive a landing gear wheel of the aircraft. A motor controller may be connected to control speed of the motor. The system may also include an aircraft taxi route database, an aircraft position determination unit; an aircraft performance database and a processor configured to a) integrate signals from the aircraft taxi route database, the aircraft position determination unit and aircraft performance database, and b) produce a motor deceleration signal to the motor controller when the aircraft arrives at a predetermined distance from a predetermined location so that the aircraft arrives at the location traveling at a desired speed.

BACKGROUND OF THE INVENTION

The present invention generally controlling taxi speeds of an aircraft during ground-based operations. More particularly, the invention relates to automated taxi speed control and guidance systems that may be readily retrofitted into existing aircraft.

Traditional aircraft taxi systems utilize the primary thrust engines (running at idle) and the braking system of the aircraft to regulate the speed of the aircraft during taxi. Such use of the primary thrust engines, however, is inefficient and wastes fuel. For this reason, electric taxi systems (i.e., traction drive systems that employ electric motors) have been developed for use with aircraft. Electric taxi systems are more efficient than traditional engine-based taxi systems because they can be powered by an auxiliary power unit (APU) of the aircraft rather than the primary thrust engines.

In its simplest form, a crew member may manually steer the aircraft during an electric taxi maneuver using a flight deck controller (e.g. a tiller) while looking out a window. In this case, the crew member utilizes his or her best judgment regarding execution of a taxi maneuver. An improvement over this process is provided by a visual guidance system wherein a crew member enters airport parameters such as airport congestion, the visual guidance system determines the best taxi path, subject to airport terminal control (ATC) clearance, and presents it on a cockpit display along with instructions as to the best way to navigate the aircraft along the suggested taxi path; e.g. speed, steering, when to turn thrust engines off and turn electric drive motors on, etc. ATC clearance can include taxi route, assigned take-off or landing runway, hold points etc. and is considered in the calculated path.

While effective, the above described visual guidance system exhibits certain inefficiencies. For example, variations in complying with display guidance instructions, even in the neighborhood of a few seconds, may decrease fuel savings; e.g. a pilot waits a short time before turning thrust engines off. The pilot may execute faster turns than necessary resulting in increased tire wear, or brake more often than necessary causing unnecessary wear and tear on the braking system. In addition, some actions that would increase efficiency are too subtle for the crew to recognize and manage; e.g. optimum acceleration of the aircraft during taxi.

Some automated taxi control systems have been proposed and described in the prior art. Typically such prior art systems include features for control of steering and braking of an aircraft during ground operations. While implementation of such systems may be practical when constructing a newly designed aircraft, they have limited applicability for existing aircraft. If such a prior art system were to be retrofitted into an existing aircraft, there would be a need to re-design and modify all of the braking and steering systems of the aircraft. Such a retrofitting would be very costly.

As can be seen, there is a need for an automated taxi speed control and guidance system that may be readily retrofitted into existing aircraft. More particularly, there is a need for such a system that may perform automatic speed control while leaving a pilot to steer the aircraft while at the same time providing display guidance.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an aircraft taxi control system may comprise: at least one motor connected to drive at least one landing gear wheel of the aircraft; a motor controller connected to control speed of the at least one motor; an aircraft taxi route database; an aircraft position determination unit; an aircraft performance database; a processor configured to a) integrate signals from the aircraft taxi route database, the aircraft position determination unit and aircraft performance database, and b) produce a motor deceleration signal to the motor controller when the aircraft arrives at a predetermined distance from a predetermined location so that the aircraft arrives at the location traveling at a desired speed.

In another aspect of the present invention, apparatus for retrofitting an automated taxi control system onto an aircraft with a pre-existing friction brake system, the apparatus may comprise: at least one motor connected to drive at least one landing gear wheel of the aircraft; a motor controller connected to control speed of the at least one motor and the aircraft without employment of a pre-existing friction braking system; an aircraft taxi route database; an aircraft position determination unit; an aircraft performance database; a processor configured to, a) integrate signals from the aircraft taxi route database, the aircraft position determination unit and aircraft performance database, and b) produce a motor deceleration signal to the motor controller when the aircraft arrives at a predetermined distance from a predetermined location so that the aircraft arrives at the location traveling at a desired speed without use of the pre-existing friction brake system.

In still another aspect of the present invention, a method for guiding an aircraft during ground based operation may comprise the steps: propelling the aircraft with at least one motor connected to drive at least one landing gear wheel of the aircraft; controlling speed of the motor with a motor controller; providing information to a processor from; a) an aircraft taxi route database, b) an aircraft position determination unit. and c) an aircraft performance database; integrating signals in the processor from the aircraft taxi route database, the aircraft position determination unit and aircraft performance database, and producing a motor deceleration signal from the processor to the motor controller when the aircraft arrives at a predetermined distance from a turning location so that the aircraft arrives at the turning location traveling at a desired turning speed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides an automated taxi control system that may be readily retrofitted into existing aircraft. The system may provide display guidance to a pilot and perform automatic speed control while leaving a pilot to manually steer the aircraft. More particularly, the system may relieve the pilot from a need to continuously perform manual speed adjusting of the aircraft.

Referring now toFIG. 1, a schematic block diagram illustrates an exemplary embodiment of an automated taxi control system100for an aircraft (not shown) equipped with or retrofitted with an electric taxi system (ETS) (not shown). One or more electric motors102of the ETS may be provided with speed regulation through a motor controller104and a processor106. The one or more motors102may be selectively coupled to drive landing gear wheels176(seeFIG. 4) of the aircraft.

The processor106may be configured to receive an aircraft ground position signal108from a position determination unit110. Additionally, the processor106may receive an aircraft performance signal112from an aircraft performance database114and a taxi route signal116from a taxi route database118. The processor may be configured to continuously integrate the aircraft ground position signal108, the aircraft performance signal112and the taxi route signal116and to provide a desired-speed signal120to the motor controller104. The motor controller104may produce controlled power122to the one or more motors102so that the motors102may operate at a speed that corresponds to the desired-speed signal120.

During taxing movement of the aircraft, the position determination unit110may continuously obtain ground-position data from one or more conventional sources, e.g., GPS data. The position determination unit110may be configured to include an interactive map of the airport in which the aircraft may be operating.

The taxi route database118may be configured with routing instructions124transmitted from an airport terminal control center (ATC)126. The taxi route database118may include, among other things, information such as gate assignments, taxiways to be used to reach assigned gate, maximum permitted speeds at various ground locations. The taxi route database118may be re-configured each time that the aircraft arrives at a particular airport. In an exemplary embodiment, the taxi route database118may be adjusted or further reconfigured by a pilot of the aircraft through use of an input device128such as a keyboard, touch screen or cursor device.

The aircraft performance database114may be configured to include data such as available electrical power from auxiliary power unit (APU), weight of aircraft and maximum acceleration rates based on power availability and weight. Some relevant data may be provided to the aircraft performance database form various sensors130, for example sensor that may indicate remaining fuel in tanks. Some data may be pre-loaded into the database114and other data may be provided through a pilot input device132. For example, a pilot may enter a number of passengers and a weight of cargo and fuel into the database after an aircraft is loaded.

Referring now toFIG. 2as well asFIG. 1, an exemplary embodiment of a display unit or screen140is illustrated. The screen140may be positioned in a flight deck of the subject aircraft, visible to the pilot, and may be continuously updated as the subject aircraft engages in ground movement under control of the automated taxi control system100. The screen140may continuously provide the pilot with information relating to relative position of the subject aircraft on the ground and also predictive information relating to expected future behavior of the subject aircraft in response to being controlled by the automated taxi control system100. For example, real-time aircraft position142may be shown. An indicator line144may show how far the subject aircraft may travel forward from the position142if the pilot were to disengage the ETS or manually set a desired speed to zero. Another indicator line144may show how far the subject aircraft may travel from the position142at the current speed and setting after a predetermined lapse of time (e.g., 20 seconds). An indicator line146may show how far the subject aircraft may travel from the position142at a maximum speed setting after a predetermined lapse of time (e.g., 20 seconds).

A deceleration-point symbol150may show a location at which the aircraft may begin decelerating in order to bring its speed to a desired limit so that a particular maneuver may be carried out safely. For example, the subject aircraft may be required to stop or hold before crossing a runway160. In that case the subject aircraft must come to a complete stop before reaching the runway160because another aircraft, shown by a symbol151may be landing. Alternatively, the taxi route database118may dictate that the aircraft should turn onto the runway160. In that case, the aircraft may be required to decelerate to a reduced speed, but not a complete stop, prior to making the turn. In these cases, the processor106may produce a reduced desired-speed signals120(i.e., a deceleration signal) to the motor controller104

Referring now toFIG. 3, there are shown some additional features of the automated taxi control system100that, for purposes of simplicity, were not shown inFIG. 1. In the exemplary embodiment ofFIG. 3, the system100may include a nose-wheel angle sensor152, an obstacle sensor154and a regenerative braking command unit156.

The processor106may be configured to produce a regenerative braking command158, on an as needed basis, so that the aircraft may arrive at a turning location traveling at the desired turning speed. Additionally, the processor106may be configured to produce a reduced desired-speed signal120(i.e., a motor deceleration signal) to the motor controller104if the speed of the aircraft, during a turn, exceeds a safe speed for a sensed nose wheel angle. The processor106may also produce the regenerative braking command158on an as needed basis so that, during a turn, the aircraft does not exceed a safe speed for a sensed nose wheel angle.

The automated taxi control system100may employ the obstacle sensor154to control a speed of the aircraft so that a predetermined distance is maintained between the subject aircraft and an obstacle such as another aircraft that may be in front of the subject aircraft. In that context the processor106may receive an obstacle-present signal155from the obstacle sensor154and produce a reduced desired-speed signal120prior to reaching the predetermined minimum separation distance.

Referring now toFIG. 4, a block diagram illustrates some pilot operated control features of the automated taxi control system100ofFIG. 1. A switch170may be actuated by the pilot to engage or disengage the ETS. Upon operation by the pilot, an ETS engagement or disengagement signal172may be transmitted to clutch174so that the clutch174may couple or uncouple the motor102from a landing gear wheel176.

Two brake switches may also be provided for actuation by the pilot. A first-stage brake switch178may be actuated when a pilot lightly presses, or presses briefly, on one or more brake pedals (not shown) to coast or to prepare to operate friction brakes (not shown) of the aircraft. Such light pressure actuation may provide an automation-suspension signal180to the processor106. In that case, the processor106may produce a signal120with a zero-speed value to the motor controller104. In that context, the clutch174may continue maintaining a coupling between the motor102and the landing gear wheel176. In the event that the pilot elects to return the aircraft to automated speed control, he or she may actuate a resume switch182.

A second-stage brake switch184may be actuated when a pilot presses heavily on the brake pedal to operate the friction brakes. Such heavy pressure actuation may result in an ETS disengagement signal186being transmitted to the clutch174. In that case, the clutch174may uncouple the motor102from the landing gear wheel176.

Referring now toFIG. 5, a flow chart illustrates an exemplary embodiment of a method500for guiding and controlling speed of an aircraft during ground based operation. In a step502the aircraft may be propelled with a motor coupled to a landing gear wheel (e.g., the motor102may drive a clutch174that couples the landing gear wheel176to the motor102). In a step514speed of the motor may be controlled by a motor controller (e.g., the motor controller104may control speed of the motor102). In a step504, a processor may be provided with a signal from an aircraft taxi route database, (e.g., the processor106may be provided with the signal116from the database118). In a step506, a processor may be provided with a signal from an aircraft position determination unit (e.g., the processor106may be provided with the signal112from the database114). In a step508, a processor may be provided with a signal from an aircraft performance database (e.g., the processor106may be provided with the signal108from the unit110).

In a step510, a processor may integrate signals from the aircraft taxi route database, the aircraft position determination unit and aircraft performance database (e.g., the processor106may integrate the signals108,112and116). In a step512, a processor may produce a motor deceleration signal when the aircraft arrives at a predetermined distance from a predetermined location so that the aircraft arrives at the location traveling at a desired speed (e.g., the processor106may produce the signal120in a deceleration mode when the aircraft arrives at the point150). In the step514, the motor controller may control the speed of the motor at a reduced speed that corresponds to the signal produced in step512. In a step516, the aircraft may be propelled in a deceleration mode until reaching the speed that corresponds to the signal produced in step512. Likewise the system may produce acceleration control speeds such as when completing the deceleration into a turn.