GB2542395A

GB2542395A - Automated docking of an aircraft mover and aircraft

Info

Publication number: GB2542395A
Application number: GB1516540.0A
Authority: GB
Inventors: Kulkarni Tushar
Original assignee: Textron Ground Support Equipment UK Ltd
Current assignee: Textron Ground Support Equipment UK Ltd
Priority date: 2015-09-18
Filing date: 2015-09-18
Publication date: 2017-03-22
Anticipated expiration: 2035-09-18
Also published as: GB2542395B; GB201516540D0

Abstract

An aircraft mover 10 has a wheeled chassis 12 and a drive generation means 20 mounted to the wheeled chassis 12 which is arranged to provide a motive force to the aircraft mover. The mover includes an aircraft engagement mechanism 22 for releasably engaging an aircraft 28 for manoeuvring. An aircraft position locator 46 is arranged to determine a relative position and/or orientation of the said aircraft 28 relative to the aircraft mover 10 and a processor 44 in communication with the aircraft position locator 46 is arranged to calculate an optimum or preferred trajectory 54 for the aircraft mover to engage the aircraft engagement mechanism with a nose landing gear 26 of the said aircraft 28. Methods of calculating and using the optimum or preferred trajectory 54, and a system for assisting with the transit of grounded aircraft 28 are also provided.

Description

Automated Docking of an Aircraft Mover and Aircraft

The present invention relates to an aircraft mover for transporting grounded aircraft. The invention further relates to a method of calculating an optimum trajectory of an aircraft mover for engagement with a nose landing gear of an aircraft, to a method of docking an aircraft mover with a nose landing gear of an aircraft using an optimum trajectory, and also to a system for assisting with the transit of grounded aircraft.

Modem aircraft movers or tractors generally have an aircraft engagement mechanism which utilises a series of clamps to engage with the nose landing gear of aircraft, in order to tow the aircraft when landed. Typically, the driver of the aircraft mover will be required to reverse the aircraft mover up to the front end of the undercarriage of the aircraft, and position the clamps around the nose landing gear in the correct manner, so as to provide an even clamping force.

Unfortunately, there is little room for error with this process. If the aircraft mover approaches the nose landing gear offset from the centreline of the landing gear, then the operator ought to re-approach in order to correctly align the clamps of the aircraft engagement mechanism with the landing gear. If the operator decides not to re-approach, then there is a risk of collision between the aircraft mover and the nose landing gear, which can lead to damage of either.

Landing gear of an aircraft is designed to support large weights along the vertical axis, that is, to bear the load of the aircraft. As a result, the landing gear is relatively weak or brittle in the plane perpendicular to this vertical axis, and a collision between the aircraft mover and the nose landing gear has the potential to be very damaging to the nose landing gear and therefore to the airworthiness of the aircraft.

Operator error is the leading cause of damage to the nose landing gear, either by incorrect operation of the clamps of the aircraft engagement mechanism or by operator-induced collision of the aircraft mover with other objects.

It is an object of the present invention to provide an aircraft mover which is capable of automatically docking with the landing gear of an aircraft.

According to a first aspect of the present invention, there is provided an aircraft mover comprising: a wheeled chassis; drive generation means mounted to the wheeled chassis and arranged to provide a motive force to the aircraft mover; an aircraft engagement mechanism for releasably engaging an aircraft for manoeuvring; an aircraft position locator arranged to determine a relative position and/or orientation of the said aircraft relative to the aircraft mover; and a processor in communication with the aircraft position locator and arranged to calculate an optimum or preferred trajectory for the aircraft mover to engage the aircraft engagement mechanism with a nose landing gear of the said aircraft.

By providing a means of determining an optimum trajectory for an aircraft mover to follow in order to engage with an aircraft to be manoeuvred, the possibility for collision of the aircraft mover with the aircraft, obstacles and/or pedestrians as a result of operator error is greatly reduced. Furthermore, the likelihood of an approach towards an aircraft by an aircraft mover being aborted due to an incorrect orientation of the aircraft mover is advantageously reduced. These benefits serve to reduce the prospect of damage occurring, whilst also reducing the amount of time wasted when approaching an aircraft with an aircraft mover, improving the efficiency of the manoeuvring procedure.

Preferably, the aircraft mover may further comprise an obstacle detector arranged to detect obstacles between the aircraft mover and the aircraft, information about present obstacles being transmissible to the processor for optimum or preferred trajectory calculation.

By providing an obstacle detector, the optimum or preferred trajectory can be analysed and determined such that the aircraft mover avoids any collision with said obstacle, further improving the efficiency benefits herebefore mentioned.

Optionally, there may be further provided an aircraft-mover control override in communication with the processor and a control means of the aircraft mover, the aircraft-mover control override taking automatic control of the control means in order to follow the optimum or preferred trajectory calculated by the processor. Said control means may include a steering control of the aircraft mover, and/or a velocity control of the aircraft mover.

The provision of an override mechanism to allow the processor to control the steering and/or velocity of the aircraft mover beneficially allows the control of the trajectory to be freed from manual intervention; in effect, the docking of the aircraft mover about the nose landing gear can be automated as the aircraft mover automatically follows the calculated optimum or preferred trajectory.

Additionally or alternatively, there may further comprise an aircraft-engagement control override in communication with the processor and an aircraft-engagement control means of the aircraft mover, the aircraft-engagement control override taking automatic control of the aircraft-engagement control means after the optimum or preferred trajectory as calculated by the processor has been followed.

The aircraft engagement mechanism can also be automated in a similar manner to the overriding of the steering and/or velocity control, thereby allowing the engagement and lifting of the nose landing gear to be automatically operated. This further removes the potential for operator error to cause damage, primarily due to activation of the aircraft engagement mechanism when the aircraft mover is incorrectly positioned with respect to the nose landing gear.

The aircraft position locator may update in real-time. A real-time aircraft position locator allows the optimum or preferred trajectory to also be recalculated in real-time by the processor, which advantageously allows the aircraft mover to adapt in response to changing circumstances; for instance, were the aircraft itself to move, or obstacles to appear between the aircraft mover and nose landing gear.

Preferably, there may be provided an operator display located at or adjacent to an operator location of the aircraft mover, the operator display being in communication with the processor to display the calculated optimum or preferred trajectory to an operator. The processor may be arranged to display aircraft-mover control instructions to the operator via the display.

If an operator display is provided, and if the entire docking process is not fully automated, then the progress of the docking process can be visualised for the operator, allowing them to follow the optimum or preferred trajectory if necessary, or activate automatic sequences for docking if required. Commands may also beneficially be relayed to the operator, if appropriate, to encourage them to avoid mistakes.

The aircraft position locator may include an optical scanner, an ultrasonic scanner, an infra-red scanner, or a combination thereof.

Various different methods of detecting relative position of objects are available; in particular, the provision of an optical scanner such as a video camera permits a live feed to be transmitted to the operator of the aircraft mover.

According to a second aspect of the invention, there is provided a method of calculating an optimum or preferred trajectory of an aircraft mover for engagement with a nose landing gear of an aircraft, the method comprising the steps of: a] providing an aircraft mover, preferably in accordance with the first aspect of the invention; b] positioning the aircraft mover near to the nose landing gear of the aircraft; c] determining a relative position and/or orientation of the nose landing gear of the aircraft relative to the aircraft mover; and d] calculating an optimum or preferred trajectory for the aircraft mover such that the aircraft engagement mechanism would engage with the nose landing gear of the aircraft.

There may further comprise a step prior to step d] of detecting the presence or absence of obstacles between the aircraft mover and aircraft, and, if one or more obstacles are detected, factoring the presence of the or each obstacle into the calculation of the optimum or preferred trajectory during step d]. Step d] may be repeated as the aircraft mover approaches the nose landing gear of the aircraft.

According to a third aspect of the invention, there is provided a method of docking an aircraft mover with a nose landing gear of an aircraft using an optimum or preferred trajectory calculated preferably using a method in accordance with the second aspect of the invention, the method comprising the step of: the processor providing a control signal to override a steering and/or velocity control of the aircraft mover such that the aircraft mover automatically follows the calculated optimum or preferred trajectory.

There may further comprise a step of the processor reactively altering the control signal in real-time as the optimum or preferred trajectory is recalculated.

Furthermore, the method may comprise the step of the processor providing a further control signal subsequent to the completion of the optimum or preferred trajectory, the further control signal overriding an aircraft-engagement control of the aircraft mover such that the aircraft engagement mechanism of the aircraft mover automatically engages with a nose landing gear of the aircraft.

According to a fourth aspect of the invention, there is provided a system for assisting with the transit of grounded aircraft, the system comprising: an aircraft mover having a wheeled chassis, a drive generation means mounted to the wheeled chassis and arranged to provide a motive force to the aircraft mover, and an aircraft engagement mechanism for releasably engaging an aircraft for manoeuvring; a scanning means for determining a relative position and or orientation of the aircraft mover with respect to the said aircraft; and a processor in communication with the scanning means and arranged to calculate an optimum or preferred trajectory for aircraft mover for engagement of the aircraft engagement mechanism with a nose landing gear of the said aircraft.

Whilst it may be beneficial to provide the aircraft position locator as part of the aircraft mover, it, and indeed the processor, could be provided separately, which may potentially offer a way or means for a single locator and processor to concurrently monitor the location of a plurality of aircraft movers and aircraft.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a perspective representation of one embodiment of an aircraft mover in accordance with the first aspect of the invention, in the process of docking with the nose landing gear of an aircraft;

Figure 2 shows a perspective representation of the rear of the aircraft mover of Figure 1 as it approaches the nose landing gear of the aircraft, as viewed from a cab of the aircraft mover towards the rear end thereof;

Figure 3 shows a representation of the view from the cockpit inside the cab of the aircraft mover of Figure 1, as viewed in a direction away from the aircraft with which the aircraft mover is to dock, including a display screen showing the approach of the aircraft mover shown in Figure 2, as viewed through a rear-mounted camera;

Figure 4 shows a diagrammatic representation of a method of calculating an optimum or preferred trajectory of an aircraft mover for engagement with a nose landing gear of an aircraft, in accordance with the second aspect of the invention; and

Figure 5 shows a diagrammatic representation of a method of docking an aircraft mover with a nose landing gear of an aircraft using an optimum or preferred trajectory.

Referring firstly to Figure 1, there is illustrated an aircraft mover 10, specifically an aircraft tractor, which has a chassis 12 having a plurality of wheels 14 attached thereto, a cab 16 mounted to the chassis 12 from which an operator 18 may control the aircraft mover 10, a drive generation means, here illustrated as an electric motor 20 engaged with one of the wheels 14, to provide motive force to the aircraft mover 10, and an aircraft engagement mechanism, here formed as or including a cradle 22 having a plurality of aircraft wheel-contacting components 24 engagable with a nose landing gear 26 of an aircraft 28. The cradle 22 is preferably positioned between two elongate rear chassis portions 30 of the aircraft mover 10, between which a nose landing gear 26 of an aircraft 28 can be accepted. Such an approach towards the aircraft is illustrated in Figure 2.

Aircraft movers 10 are typically constructed with the cab 16 being positioned towards a forward end 32 of the chassis 12, with an appropriately positioned windscreen 34 to allow the operator 18 to readily drive the aircraft mover 10, but rearwardly-mounting cabs 16 are also known. Similarly, the drive generation means of the aircraft mover 10 can be provided in many different forms; compression-ignition combustion engines are common, as are hybrid-powered vehicles.

The aircraft mover 10 also includes a steering control 36 mounted within the cab 16, here illustrated as a steering wheel, which allows the operator 18 to manually control the steering of the aircraft mover 10, in addition to a velocity control means, typically an acceleration pedal 38 and brake pedal 40, as can be seen in Figure 3. A user-operable control panel 42 may also preferably be provided for manual operation of the cradle 22. It will be appreciated that the engagement cradle 22 is only one means by which an aircraft mover 10 may couple to the nose landing gear 26, and other aircraft engagement mechanisms, typically involving mutually co-operable clamps, are available within the field.

The aircraft mover 10 also includes a processor 44, which is here in communication with the steering control 36, the velocity control means 38, 40, and the aircraft-engagement control of the cradle 22, allowing the processor 44 to send command signals to each. It will be appreciated that the processor 44 could be coupled to any or all of these various controls, however. An aircraft position locator 46 is also provided, here mounted at or adjacent to one of the rear chassis portions 30 of the chassis 12. This aircraft position locator 46 is arranged to scan, image or otherwise detect the surrounding area to determine the location and/or orientation of the nose landing gear 26. This could be achieved in any number of ways: an optical camera; an infra-red scanner; and/or ultrasound scanner; or a combination thereof. Other means of detecting the relative position and/or orientation of the aircraft 28 with respect to the aircraft mover 10 will be apparent to the skilled reader. An obstacle detector 48 may also preferably be provided, which is able to detect the presence of obstacles 50, such as debris or pedestrians, which are positioned in between the aircraft mover 10 and the aircraft 28. The obstacle detector 48 could readily be combined with the aircraft position locator 46 if, for example, an optical camera were utilised.

Also preferably provided within the cab 16 in a position which is visible to the operator 18 is a display screen 52, as illustrated in Figure 3, which is in communication with the processor 44 and is arranged to display information to the operator 18 whilst the aircraft tractor 10 is operational.

In use, and as illustrated in the methodological representation of Figure 4 at S100, the aircraft mover 10 is positioned in step SI 10 close to the nose landing gear 26 of the aircraft 28. The aircraft position locator 46 then determines in step S120 the relative position and/or orientation of the aircraft mover 10 and aircraft 28, relaying the information to the processor 44. The processor 44 then analyses the information to calculate in step S130 an optimum or preferred trajectory 54 for the aircraft mover 10 for engagement of the cradle 22 with the nose landing gear 26. The processor 44 may receive information in step S140 from the obstacle detector 48 in order to determine this optimum or preferred trajectory 54.

As illustrated in methodological representation S150, shown in Figure 5, the processor 44 may use the calculated optimum or preferred trajectory 54 to provide in step S160 a control signal to operate the steering control 36 to control the steering of the aircraft mover 10, such that the aircraft mover 10 will follow the optimum or preferred trajectory 54 at a speed determined by the velocity control means 38, 40, which may also preferably be automatically controlled by the processor 44. Subsequently, the aircraft engagement mechanism can also be overridden in step S170 using a control signal from the processor 44, in order to effect engagement and lifting of the aircraft 28 via the cradle 48.

By positioning the aircraft mover 10 near to the nose landing gear 26 of the aircraft 28, scanning the relative location and/or orientation of the nose landing gear 26 using the aircraft position locator 46, which is then transferred to the processor 44, an optimum or preferred trajectory for the aircraft mover can be calculated. By analysing the aircraft position, and accounting for any obstacles which may have been detected by the obstacle detector 48, the processor 44 can calculate the optimum or preferred trajectory 54 for the aircraft mover 10 so as to engage the cradle 22 with the nose landing gear 26.

At present, to engage an aircraft mover with the nose landing gear 26 of aircraft 28, the operator must manually steer the tractor into position in order to align a cradle or clamps of the aircraft engagement mechanism with the nose landing gear 26. Therefore, operator error can pose a risk of collision between the aircraft mover and the nose landing gear 26, which could lead to damage of the aircraft 28.

In the present embodiment of the invention, the optimum or preferred trajectory 54 for the aircraft mover 10 to follow to ensure perfect alignment of the cradle 22 and the nose landing gear 26 can be calculated, thus minimising the risk of damage. This is most easily achieved by scanning of the nose landing gear 26 to provide information about its location and/or orientation to the processor 44 on the aircraft mover 10.

The calculation of the optimum or preferred trajectory 54 may factor in some obstacle recognition to ensure a smooth approach of the aircraft mover 10 towards the aircraft 28.

It is advantageous to provide some form of obstacle recognition, so as to avoid collision between the aircraft mover 10 and any obstacle 50, for instance, which may be on the runway 56. The information collected by the obstacle detector 48 can be relayed to the processor 44 in order to effect this calculation of the optimum or preferred trajectory 54. The optimum or preferred trajectory 54 can be visualised from Figure 2. As illustrated, the optimum or preferred trajectory 54 is unlikely to be a direct straight line, due to the need to align the nose landing gear 26 within the rear chassis portions 30 such that the cradle 22 can be correctly engaged. A curved trajectory will likely be most appropriate in order to accommodate this need for correct alignment of the rear chassis portions 30 of the aircraft mover 10.

The calculated optimum or preferred trajectory 54 could feasibly be utilised by the processor 44 in order to automatically control the motion of the aircraft mover 10 in order to effect a measure of automated docking with an aircraft 28. This can be achieved by allowing the processor 44 to transmit a control signal to any or all of the steering control 36, the velocity control means 38, 40, and/or the cradle 22. The control signal sent to the steering control 36 can therefore override the steering of the aircraft mover 10 such that the direction of the optimum or preferred trajectory 54 can be followed, and the velocity control means 38, 40 being controlled to propel the aircraft mover 10 at a constant speed. Either of these could feasibly be achieved manually, for example, the steering control 36 could be overridden by the processor 44, whilst the operator 18 controlled the speed of the aircraft mover 10 towards the nose landing gear 26.

In doing so, it is therefore possible to minimise or even eliminate misalignment of the cradle 22 and the nose landing gear 26 due to operator error, by forcing the aircraft mover 10 to follow the optimum or preferred trajectory 54 as calculated. Doing so will limit the possibility of a collision between the aircraft mover 10 and the aircraft 28.

The optimum or preferred trajectory 54 of the aircraft mover 10 may be continually updated as the aircraft mover 10 approaches the nose landing gear 26 of the aircraft 28. The processor 44 may reactively alter the steering control 36 and/or velocity control means 38, 40 of the aircraft mover 10 in response to an updated optimum or preferred trajectory 54, for instance, if a new obstacle 50 is detected by the obstacle detector 48.

If, for any reason, the aircraft mover 10 were to deviate from the optimum or preferred trajectory 54, it is then also possible for the trajectory to be reactively modified as the aircraft mover 10 moves, to recalibrate an optimum or preferred trajectory 54. For instance, imperfections in the surface of the runway 56, such as potholes, may require deviation from the optimum or preferred trajectory 54.

As an alternative to the automatic control of the steering and/or velocity of the aircraft mover 10, it may also be possible for the processor 44 to simply relay information to the operator 18 in order to instruct a manual approach towards the aircraft 28. This can be achieved by presenting real-time video and/or audio information on the display screen 52, for example, by providing a video feed of the approach towards the aircraft 28 with an overlay of the optimum or preferred trajectory 54 shown for the operator 18 to follow. This is best illustrated in Figure 3.

Instructions may also be provided on the display screen 52 which contain information for the operator 18, for example, about the distance to engagement of the cradle 22 of the aircraft mover 10 with the nose landing gear 26 of the aircraft 28, or about the speed of the aircraft mover 10. Furthermore, a warning could be shown or sounded if, for example, the obstacle detector 48 registered an obstacle 50 interrupting or near the optimum or preferred trajectory 54 and that imminent collision might be likely.

Once the aircraft mover 10 has correctly approached the nose landing gear 26, such that the wheel-contacting components 24 of the cradle 22 contact the nose landing gear 26 in the correct orientation, the process of engagement and lifting the aircraft 28 can begin by locking the wheel-contacting components 24 of the cradle 22 into the correct position about the nose landing gear 26.

By allowing the processor 44 to send a control signal to override the control of the aircraft engagement mechanism, such that the cradle 22 is automatically engaged with the nose landing gear 26 once the optimum or preferred trajectory has been followed, automated docking of the aircraft mover 10 with an aircraft 28 can be achieved. The engagement of the cradle 22 can be achieved by relative displacement of the wheelcontacting components 24 so as to securely grip a wheel of the nose landing gear 26.

It will be appreciated that the final step of engagement between the cradle 48 and the nose landing gear 28 need not necessarily be automated. For instance, the operator 18 of the aircraft mover 10 could activate the aircraft engagement mechanism using the user-operable control panel 42 to effect the necessary repositioning of the wheel-contacting components 24. This could also be visualised via the display screen 52.

Whilst the aircraft mover has hereto been described engaging with a single aircraft, it will be apparent that the principles are applicable regardless of the type of aircraft to be lifted. Indeed, a single aircraft mover could feasibly be adapted to engage with a plurality of different types and/or sizes of aircraft, potentially the aircraft mover having an adaptable aircraft engagement means.

It will be apparent that although the above-described embodiment of the invention includes the aircraft position locator affixed to the aircraft mover, that in fact, there is only a requirement to know the relative positions and/or orientations of the aircraft mover with respect to the aircraft and in particular to the nose landing gear. As such, there is no specific need for the aircraft position locator to be affixed to the aircraft mover, and could indeed be mounted to the aircraft, or could be a device external to both the aircraft and aircraft mover, such as an infra-red emitter and detector system which was mounted to the runway.

It is therefore possible to provide an aircraft mover which can be at least in part automatically docked with an aircraft, either by determining and following an optimum or preferred trajectory for the aircraft mover to follow in order to avoid collision with obstacles and/or the aircraft, or by providing a means for automatic engagement of the aircraft engagement mechanism of the aircraft mover with the aircraft once such a trajectory has been followed.

The words ‘comprises/comprising’ and the words ‘having/including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.

Claims

1. An aircraft mover comprising: a wheeled chassis; drive generation means mounted to the wheeled chassis and arranged to provide a motive force to the aircraft mover; an aircraft engagement mechanism for releasably engaging an aircraft for manoeuvring; an aircraft position locator arranged to determine a relative position and/or orientation of the said aircraft relative to the aircraft mover; and a processor in communication with the aircraft position locator and arranged to calculate an optimum or preferred trajectory for the aircraft mover to engage the aircraft engagement mechanism with a nose landing gear of the said aircraft.

2. An aircraft mover as claimed in claim 1, further comprising an obstacle detector arranged to detect obstacles between the aircraft mover and the aircraft, information about present obstacles being transmissible to the processor for optimum or preferred trajectory calculation.

3. An aircraft mover as claimed in claim 1 or claim 2, further comprising an aircraft-mover control override in communication with the processor and a control means of the aircraft mover, the aircraft-mover control override taking automatic control of the control means in order to follow the optimum or preferred trajectory calculated by the processor.

4. An aircraft mover as claimed in claim 3, wherein the control means includes a steering control of the aircraft mover.

5. An aircraft mover as claimed in claim 3 or claim 4, wherein the control means includes a velocity control of the aircraft mover.

6. An aircraft mover as claimed in any one of the preceding claims, further comprising an aircraft-engagement control override in communication with the processor and an aircraft-engagement control means of the aircraft mover, the aircraft-engagement control override taking automatic control of the aircraft-engagement control means after the optimum or preferred trajectory as calculated by the processor has been followed.

7. An aircraft mover as claimed in any one of the preceding claims, wherein the aircraft position locator updates in real-time.

8. An aircraft mover as claimed in any one of the preceding claims, further comprising an operator display located at or adjacent to an operator location of the aircraft mover, the operator display being in communication with the processor to display the calculated optimum or preferred trajectory to an operator.

9. An aircraft mover as claimed in claim 8, wherein the processor is arranged to display aircraft-mover control instmetions to the operator via the display.

10. An aircraft mover as claimed in any one of the preceding claims, wherein the aircraft position locator includes an optical scanner.

11. An aircraft mover as claimed in any one of the preceding claims, wherein the aircraft position locator includes an ultrasonic scanner.

12. An aircraft mover as claimed in any one of the preceding claims, wherein the aircraft position locator includes an infra-red scanner.

13. An aircraft mover substantially as hereinbefore described, with reference to Figures 1 to 3 of the accompanying drawings.

14. A method of calculating an optimum or preferred trajectory of an aircraft mover for engagement with a nose landing gear of an aircraft, the method comprising the steps of: a] providing an aircraft mover as claimed in any one of the preceding claims; b] positioning the aircraft mover near to the nose landing gear of the aircraft; c] determining a relative position and/or orientation of the nose landing gear of the aircraft relative to the aircraft mover; and d] calculating an optimum or preferred trajectory for the aircraft mover such that the aircraft engagement mechanism would engage with the nose landing gear of the aircraft.

15. A method as claimed in claim 14, further comprising a step prior to step d] of detecting the presence or absence of obstacles between the aircraft mover and aircraft, and, if one or more obstacles are detected, factoring the presence of the or each obstacle into the calculation of the optimum or preferred trajectory during step d].

16. A method as claimed in claim 15 or claim 16, wherein step d] is repeated as the aircraft mover approaches the nose landing gear of the aircraft.

17. A method of docking an aircraft mover with a nose landing gear of an aircraft using an optimum or preferred trajectory calculated using a method as claimed in any one of claims 14 to 16, the method comprising the step of: the processor providing a control signal to override a steering and/or velocity control of the aircraft mover such that the aircraft mover automatically follows the calculated optimum or preferred trajectory.

18. A method as claimed in claim 17, further comprising the step of the processor reactively altering the control signal in real-time as the optimum or preferred trajectory is recalculated.

19. A method as claimed in claim 17 or claim 18, further comprising the step of the processor providing a further control signal subsequent to the completion of the optimum or preferred trajectory, the further control signal overriding an aircraft-engagement control of the aircraft mover such that the aircraft engagement mechanism of the aircraft mover automatically engages with a nose landing gear of the aircraft.

20. A system for assisting with the transit of grounded aircraft, the system comprising: an aircraft mover having a wheeled chassis, a drive generation means mounted to the wheeled chassis and arranged to provide a motive force to the aircraft mover, and an aircraft engagement mechanism for releasably engaging an aircraft for manoeuvring; a scanning means for determining a relative position and or orientation of the aircraft mover with respect to the said aircraft; and a processor in communication with the scanning means and arranged to calculate an optimum or preferred trajectory for aircraft mover for engagement of the aircraft engagement mechanism with a nose landing gear of the said aircraft.