SENSOR AND SENSOR SYSTEM FOR AIRCRAFT AND OTHER VEHICLE GROUND MANOEUVRES

Abstract: A vehicle visual aid system for ground manoeuvres employ­ ing a plurality of load sensors (10) disposed in or on the ground along a predetermined path to be followed by the vehicle. An illuminated display device (38) is disposed externally of the vehicle at a position forward of the vehicle when following the predetermined path. The display device (38) is coupled to the sensors (10) and is adapted to indicate visually to the person in control of the vehicle the prevailling position of the vehicle relative to the path. The invention also includes a load sensor unit for use in the visual aid system. The load sensor unit comprises en elongate trough-shaped base (14) for mounting in the ground and having an elongate loadreceiving member (28) of inverted trough-shape which is resiliently supported above the base (14) by means of mass (30) of solid, elastic compound disposed over a mass (34) of foam material. One or more proximity detectors are disposed in the unit for detecting and responding to predetermined downward displacement of the load-receiving member towards the base.

Description: DESCRIPTION SENSOR AND SENSOR SYSTEM FOR AIRCRAFT AND OTHER VEHICLE GROUND f4ANOEUVRES. The present invention relates to an aircraft and vehicle visual aid system for ground manoeuvres and to sensors for use in such systems. Aircraft, particularly larger aircraft, require very careful manoeuvring, when on the ground, in order to ensure that they are positioned correctly for take-off or for docking. This means that a high level of skill is required from the pilot who is situated in the cockpit many feet above the ground and who does not have a full view of the aircraft. This also applies to the driver of large vehicles such as articulated lorries. It is one object of the present invention to provide a visual aid system for aircraft and vehicles which eliminates much of the risk involved in manoeuvring such large vehicles into a desired position. It is a second object of the invention to provide a sensor which is specially adapted to use in such a system. In accordance with a first aspect of the present invention there is provided a vehicle visual aid system eor ground manoeuvres comprising a plurality of load sensors disposed in or on the ground along a predetermined path to be followed by said vehicle, and an illuiqinated display device disposed externally of the vehicle at a position forward of the vehicle when following said path, the display device being coupled eletrically.to said sensors and being adapted to indicate visually to the person in control of the vehicle his prevailing position relative to said path. Preferably, the load sensors are disposed in pairs, with the two sensprs in each pair disposed respectively one or. each side of said predetermined path to be followed by the vehicle, and in that said illuminated. display device is adapted to display to said person in control of the vehicle whether the vehicle is on said path, off said path to the right or off said path to the left, in accordance with signals received from the sensors. In accordance with a second aspect of the present invention, there is provided a sensor unit for detecting the presence of a load thereon, the sensor unit comprising a rigid elongate base for mounting in or on the ground, a rigid, elongate load-receiving member which is supported relative to the base by means of a mass of a solid, elastic compound disposed over a mass of a foam material, the elastic compound being of a nature which has substantially complete recovery after elastic deformation, and at least one proximity detector adapted to detect and respond to predetermined downward displacement of the load receiving member towards said base caused by the application of a downward load on the latter member. Preferably, the elastic compound encapsulates the load-receiving member so as to define between the latter member and the base a sealed space which contains said at least one detector. Advantageously, there are two of said proximity detectors in the sensing unit, one disposed adjacent each end of the unit, respectively. Any suitable form of proximity detector can be used, for example, an infra-red detector, Hall-effect device, inductive loop sensor, or even an hydraulically operating device, the requirement merely being to provide an output signal in response to said predetermined displacement of the load bearing member. The relative sizes of the masses of elastic compound and the foam are chosen to suit the anticipated minimum weight of the vehicle or aircraft to which the sensor.unit is to respond, the greater the proportion of foam, the lighter the vehicle or aircraft with which the unit can be used. When used in the visual aid system for vehicle ground manoeuvres, a plurality of said sensing units can be disposed in pairs, with the two units in each pair disposed one on each side of a predetermined path to be followed by an aircraft or other vehicle, the illuminated display device being coupled to the detectors within said sensing units and disposed externally of the vehicle in a position in front of the driver or pilot, the display device having means for indicating visually to the driver or pilot whether the vehicle is on said path, off said path to the right or off said path to the left, in accordance with the signals received from the detectors. The display can, for example, have three illuminated panels, possibly in the form of coloured arrows, corresponding to "left", "centre" and "right" which can be selectively activated (flashing or steady) to indicate the instantaneous position of the vehicle or aircraft. A centre-line indicator, either za complete or broken vertical line, preferably remains on all the time in order to enable the pilot to determine the position with respect to the centre-line by means of the white or coloured arrows updated as the pilot progresses towards the docking point. In the case of an aircraft, it is convenient for the sensing units to be arranged to respond to the passage of the aircraft nose wheel thereover, but other wheels or combination of wheels can be used to suit the circumstances. The invention will be described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig.l is a diagrammatic longitudinal section through one embodiment of a sensing unit of the present invention; Fig.2 is an enlarged diagrammatic, sectional end view on the line A-A of Fig.l; Fig.3 is a schematic diagram of a sensing unit in a fixed position in the ground; Fig.4 shows, schematically, possible positions of sensing units for use in aircraft manoeuvring; Fig.5 is a diagrammatic view of one embodiment of a display for a system in accordance with the present invention; and Fig.6 shows, schematically, possible positions of the front wheel of an aircraft on the sensing units of Fig.4. The present invention resides firstly in a system wherein a display is triggered to indicate to the pilot of an aircraft or driver of a vehicle, the position of the aircraft or vehicle on the ground, and secondly in the construction of special sensing devices for use in said system to detect the presence of an aircraft or vehicle as it passes over them. " Fig shows one embodiment of a sensing unit 10 which, in this case, contains two sensing devices 12. The sensing unit 10 has an outer, trough-shaped case 14 with closed ends, which is preferably manufactured -from a channel or box-section made of steel or any other suitable robust material. Inside the outer case 14 and welded thereto, as best seen in Fig.2, is a lower part 16 of an inner case which is also of channel-section with closed ends. One end of the outer case 14 and the adjacent end of the lower part 16 of the inner case both have a cable entry hole 18 therein to allow electrical access to the two sensing devices 12, which are disposed on the base of the part 16 adjacent its two ends respectively'. In this embodiment, the sensing devices 12 comprise infra red proximity detectors having associated electronic amplifiers (not shown) for amplifying the sensing signals and an associated electronic logic network. The associated electronic circuitry is indicated at 20. Each detector 2 is mounted on a small bracket 22 and is adjustable in height by means of an elongate slot 24 and a fixing screw 26. The inner case also includes an upper part 28, of inverted channel section and closed ends, which is mounted above the lower part 16 so that its underside surface 28a is normally spaced uniformly from the upstanding side walls of the lower part 16 by a predetermined distance X. The upper part 28 is supported above the lower part 16 by means of a mass of sealant compound 30 which is placed in the space between the upstanding walls of the lower part 16 of the inner case and the upstanding walls of the outer case 14, the sealant compound 30 being disposed on top of a foam base 34. The sealant 30 is extended over the upper surfaces of the part 28 so as to fully encapsulate the inner case in a fluid-tight manner. A sealed space 29 is thereby formed between the upper and lower parts 28,16 containing the sensing devices 12. Thus, as best seen in Fig.2, the side walls of the upper part 28 are inset in the sealant 30 to hold the upper part 28 above the lower part 16 by said predetermined distance X. If manufactured in metal, the casing parts are preferably zinc plated and gold passivated, with an epoxy finish. Attached to the underside of upper part 16 and situated directly above the detectors 12 are respective stainless steel mirrors 32 which preferably have a satin finish for efficient effect and which are used for reflecting infra red which is emitted by respective emitters fixed near to, or forming part of, the detectors 12 and which is then sensed by the detectors 12. The upper part 28 is positioned at said predetermined height X above the lower part 16 in order to give the required operational spacing between the mirrors 32 and the detectors 12. This spacing is chosen in dependence upon the weight of the aircraft or vehicle with which the sensing unit 10 is to be used and the sensitivity of the detectors 12. The amount of sealant 30 used and the amount of foam 34 used is governed by the load to displacement ratio required for each application. The more foam 34 and the less sealant 30 used the lighter the load which can be sensed. The sealant 30 is preferably a polyurethane based elastomeric compound which has uniform elasticity and ntust have complete recovery after movement and compression. In the event of having to sense extremely heavy loads, additional springs can be placed near the detectors 12 inside the inner case to take the extra weight. It will be appreciated that other kinds of proximity device may be used instead of the infra red devices, such as a Hall effect integrated circuit and k magnet which could be used in adverse climatic conditions which would otherwise affect the mirrors or the infra red detectors. The individual sensor units 10 can be powered from a common D.C. power supply. In each of the units 10 there is a 12 volt D.C. stabilised regulator. The infra red emitters) is supplied by a current-limiting resistor. The infra red detector senses a change in distance between the stainless-steel mirrors and itself, this being arranged to cause an operational amplifier to change state from logic 0 to logic 1. This logic change is used to change the display, as described hereinbelow, by way of a suitable interface (12 volt D.C. for COSMOS or 5 volt D.C for T.T.L. logic). The sensing units 10 are installed in a road or taxiway as shown in Fig.3 and can be disposed in many different configurations. One preferred arrangement for an aircraft taxiway is shown in Fig.4 wherein a plurality of sensor units 10 are connected to a display 38 via cables 40 (Fig.l) to enable the display to be changed by suitable electronic circuitry, to indicate to the pilot or driver the position of his vehicle. The display 38, which may be a zenon display of fibre optic or any other suitable illuminating device, is placed at the head of the sensing units 10 in good view of the pilot or driver, as shown, for example, in Fig.4. The particular display design shown diagrammatically in Fig.5. uses illuminated arrows as position indicators and is described further hereinbelow. For aircraft, it is preferable for each sensing unit 10 to contain two detectors 12, one at each end. The units 10 work in pairs for aircraft docking systems, as shown in Fig.4, with the two sensors of each pair installed on the two sides of a centre line 44, respectively. One extra unit 10 is installed at the start and finish of the docking way. The unit 42 at the start of the docking way first senses the aircraft nose wheel as it passes over it, compressing upper part 28 of the inner case which moves down and rests on the top of lower part 16 thereby closing the gaps between the detectors 12 and the mirrors 32. This triggers a signal which is then sent from the detectors 12 enabling the display and additional lighting such as the runway or taxiway centre lights at 44 shown in Fig.4. As the aircraft proceeds, each unit 10 produces one or two sensor signals depending upon the position of the nose wheel on each unit 10. These signals are sent to an electronic logic unit which then generates a signal which changes the display 38 in accordance with the position of the aircraft. As the aircraft triggers each consecutive unit 10, the electronic logic updates the display with the new information indicating to the pilot the new position of the nose wheel with respect to the centre line 44. When the aircraft reaches the end unit 46 a stop signal is displayed and the logic circuitry detects the presence of a docked aircraft after which it can switch off all the equipment such as taxiway lighting and the display 38. If an obstruction passes over the sensing units out of sequence, a stop indicator can be arranged to activate a warning to the pilot. The sequence of events relating the particular display of Fig.5 with the position of the nose wheel -t¯on the units 10 will now be explained in more detail with reference to Figs. 5 and 6. Fig.6 shows a plurality of different positions the nose wheel may occupy on the units 10. In position 48 both units 10 toe the pair are in use and the aircraft is centrally positioned. The central arrow indicator 62 of the display 38 then shows the aircraft nose wheel to be in a central position by remaining on or flashing on and off. In position 50 only the left-hand unit of the pair is actuated and the right-hand sensor of this unit switches on the left arrow indicator 64 on the display indicating steady left. In position 52, the left-hand unit of the pair has both detectors 12 operating together. This, again, switches on the left-hand arrow indicator 64 indicating steady left. In position 54, only the left-hand sensor of the lefthand unit is actuated and this switches the left-hand arrow indicator on so that it will flash and indicate to the pilot that he is extreme left. Positions 56, 58 and 60 provoke similar actions to positions 50, 52 and 54 respectively, but now switch on the right-hand arrow indicators 66. In this way, the pilot has a much easier job of steering into and following the correct path. The centre indicator can remain on continuously to assist the person in control of the aircrfat to determine his position with respect to the centre line by reference to the left and right indicators and whether these are activated or not. In an advantageous development, the sensing devices 12 can be placed in the sensing units 10 so as to position the aircraft slightly to one side of the centre line 44 in order to eliminate the bumping of the aircraft on the raised centre lights. As well as the docking application described above, the sensing units 10 can also be used to indicate that an aircraft is turning or changing to or from a taxiway, the information being sent to a control tower for checking. To reduce the number of accident, the sensing units 10 can also be placed at taxiway junctions and, in combination with air traffic control, can thus trigger the correct set of centre lights, thus preventing a pilot taking a wrong turning. Insofar as large road vehicles are concerned, it is sufficient to use just one column of sensing units. Also by using the sensing units in multiples placed so as to sense all four, six or more vehicle wheels, the system can be used for sensing overloading in commercial vehicles. In general, the sensor units 10 can be used singularly or in any multiple combination of such units. They can be disposed for sensing one wheel only of the vehicle or any numbers of such wheels in any combination. To improve on safety and docking of aircraft a radio link can be employed. One such system comprises a radio transmitter (TX) installed in each docking pad visual display. Each transmitter would have its own address code of transmission (TX). This could be derived by using five digit (or more) dual address monolithic devices, i.e. encoder and decoder. Each aircraft would have a receiver (RX) (possibly multi-channel) display unit, a miniaturised and similar display as installed at the docking pads, together with a numerical/alphanumeric or symbolised keyboard. The operation on approach would be as follows: The The pilot receives from air traffic control the type of docking e.g. 'Garrington's, and the address code of the docking pad where he is to park. He enters this code into his display via the keyboard; this is then stored in memory. After he lands he follows the taxiway (illuminated) and eventually activates the sensor in the ground. The transmitter (TX) then transmits the address which is recognized by the receiver (RX) in the aircraft. The aircraft miniature display is switched on to display the aircraft position as described hereinbefore. Each sensor in turn transmits the address again followed by another exclusive code which switches the correct display, e.g. left, centre, right. All codes are individual and exclusive. All addresses are individual and exclusive in order to eliminate errors and interference from other docking pad transmitters. Frequency spacing can also eliminate errors and TX's can be on various frequencies with air traffic control giving the correct channel to the pilot on approach, followed by the address.

Claims: CLAIMS 1. A vehicle visual aid system for ground manoeuvres characterised by a plurality of load sensors (10) disposed in or on the ground along a predetermined path to be followed by said vehicle, and an illuminated display device(38) disposed externally of the vehicle at a position forward of the vehicle when following said path, the display device (38) being coupled electrically to said sensors (10) and being adapted to indicate visually to the person in control of the vehicle his prevailing position relative to said path. 2. A vehicle visual aid system according to claim 1, characterised in that said load sensors (10) are disposed in pairs, with the two sensors in each pair disposed respectively one on each side of said predetermined path to be followed by the vehicle, and in that said illuminated display device (38) is adapted to display to said person in control of the vehicle whether the vehicle is on said path, off said path to t:he right or off said path to the left, in accordance with signals received from the sensors (10). 3. A vehicle visual aid system according to claim 2, characterised in that the-display includes three illuminated panels (64, 62, 66), in the form of white or coloured indicators, corresponding to "left", "centre1,, and "right", which can be selectively activated in accordance with signals received from said sensors to indicate the instantaneous position of the vehicle on said path. 4. A vehicle visual aid system according to claim 1, 2 or 3, wherein the actuation by said vehicle of a loading sensor (42) at the upstream end of said path is used as a trigger for the enablement of the visual display (38) and/or a plurality of lights (44) illuminating the path itself. 5. A load sensor unit for detecting the presence of a load thereon, characterised in that the sensor unit comprises a rigid, elongate base (14) for mounting in or on the ground, a rigid, elongate loadreceiving member (28) which is supported relative to the base by means of a mass (30) of a solid, elastic compound disposed over a mass (34) of a foam material, the elastic compound (30) being of a nature which has substantially complete recovery after elastic deformation and at least one proximity detector means (12) adapted to detect and respond to predetermined downward displacement of the load-receiving member (28) towards the base (14). 6. A sensor unit according to claim 2, characterised in that the elastic compound (30) encapsulates the load-receiving member (28) to define between the latter member and the base (14) a sealed space (29), said detector means being disposed within said sealed space. 7. A sensor unit according to cLaim 5 or 6, characterised in that the base comprises an elongate, trough-shaped member (14) having upstanding side and end walls, the load-receiving member (28) is o inverted trough-shape, and the inverted trough-shaped load-receiving member (28) is resiliently supported above the base (14) by said solid elastic compound and said mass of foam so that its side and end walls extend downwardly towards said base. 8. A sensor unit according to claim 7, characterised in that the depending side and end walls of the load-receiving member (28) are received within the trough-shaped base (14) and are at least partially enveloped by said mass (30) of solid elastic compound. 9. A sensor unit according to claim 8, further characterised by a further elongate, trough-shaped member (16) having upstanding side and end walls and disposed on the base (14) so that, normally the upper edges of its side walls are spaced from the underside of the base of the trough-shaped load-bearing member (28) by a predetermined uniform gap (X), the resilient support for the load bearing member provided by the solid elastic material (30) and the foam material (34) permitting said gap to be reduced in dependence upon the load applied to the load bearing member (28) and said proximity detector means being adapted to respond td the magnitude of said gap. 10. A sensor unit according to any of claims 5 to 9, characterised in that the proximity detector means includes two individual proximity detector devices (12), one disposed ajacent each end of the unit respectively, whereby when a load is applied at one end only of the load-receiving member (28), only that one of the two detectors disposed adjacent that one end of the load-receiving member is actuated, when a load is applied at, the other end only of the load-receiving member only that one of the two detectors disposed adjacent that other end of the load-receiving member is actuated, and when a load is ¯applied adjacent the centre of the load-receiving member both detectors are actuated.

Inventors: GARRINGTON, BARRY
Applicants: GARRINGTON, BARRY
Application year: 1984
Main classification: B64F1
IPC codes: B64F1, G08G5