TECHNICAL FIELD

The present invention concerns equipment for identifying mobile objects, in particular, serving trolleys for aeroplanes.

BACKGROUND ART

As is known, the serving trolleys used on board aeroplanes belong to the airline companies and are used and managed by the company which distributes the food on board the aeroplanes (the catering company) . At the end of each flight, the serving trolleys are unloaded from the aeroplanes and taken to appropriate areas equipped for restocking with food (catering areas) where they are left until the next flight. Generally, these supply operations are effected without particular controls and it is therefore increasingly common that the airlines that own the serving trolleys do not know exactly how many trolleys are in their possession and in which airports they are to be found.

In addition, the serving trolleys require regular cleaning and maintenance and are therefore removed from the

catering areas and returned thereto without particular controls; as a consequence, losses of serving trolleys, and sometimes even theft, occur increasingly often.

Therefore, the need is increasingly felt by the airline companies for equipment which enables the identification of the serving trolleys so that they can be located anywhere in the world.

DISCLOSURE OF INVENTION

The object of the present invention is therefore to provide equipment which enables simple and economic identification of mobile objects, in particular, serving trolleys for aeroplanes.

According to the present invention there is provided equipment for identifying mobile objects, in particular serving trolleys for aeroplanes, characterised in that it includes a plurality of passive transponder means disposed, in use, on associated mobile objects, and at least one antenna module disposed, in use, along a route taken by the said mobile objects; the said antenna module comprising a plurality of antenna elements, and means for controlling the said antenna elements able to activate selectively the antenna elements themselves according to a predetermined scheme, and process signals detected by the said antenna elements for the identification of the said

transponder means; each of the said passive transponder means comprising transceiver means able to receive an activation signal sent by the said antenna elements, and first storage means attached to the said transceiver means which stores a transponder identification code, the said first storage means being activated by the said transceiver means on receiving the said activation signal, and providing the said transceiver means with the said identification code for the generation of an identification signal which is sent to the said antenna modules.

BRIEF DESCRIPTION OF DRAWINGS For a better understanding of the present invention there is now described a preferred embodiment, purely by way of non-limitative example and with reference to the accompanying drawings, in which;

- Figure 1 is a perspective view of a part of the equipment that is the subject of the present invention; - Figure 2 is a perspective view of a transponder of the equipment of Figure 1;

- Figure 3 is a view from below of a pair of serving trolleys provided with a transponder in a preferred mounting position; - Figure 4 is a view similar to Figure 2 in which the transponder is disposed in a different mounting position;

- Figure 5 is a side view of a detail of a serving trolley provided with a transponder;

- Figure 6 is a view similar to Figure 3 with a different serving trolley; - Figure 7 is a circuit diagram of an antenna module of the equipment according to the present invention; and

- Figure 8 is a connection diagram of several antenna modules of Figure 6.

BEST MODE FOR CARRYING OUT THE INVENTION

The equipment according to the present invention will now be described with specific reference to the identification of aeroplane serving trolleys, without by this losing its general application.

The identification equipment according to the invention identifies serving trolleys 1 of the standard type provided to airline companies comprising, as shown in Figure 1, an external casing 2 of a substantially rectangular parallelepipedal shape having a length of 40 or 80 cm, a width of 30 cm, and a height of 100 cm.

The external casing 2 includes a base 3 on the lower surface 4 of which, facing the ground, is fixed a pair of front wheels 5, a pair of rear wheels 6 and a pair of wheel locking/release control pedals 7 disposed between the two front wheels 5 and connected to the front and rear

wheels 5, 6 themselves by way of a transmission assembly, not shown.

The present equipment includes a plurality of transponders 10 disposed on associated serving trolleys 1, and a plurality of antenna modules 11 connected together to form at least one antenna and disposed along a path P taken by the serving trolleys 1 transversely of the path P itself; the object of the antenna modules 11, as described in detail below, is to activate the transponders 10 facing them, and receive the identification code transmitted thereby.

In particular, each transponder 10 is fixed to the lower surface 4 of the associated serving trolley 1, while the antenna modules 11 are disposed along the edge of a surface S on which the serving trolleys 1 travel along the path P; for example, the path P taken by the serving trolleys 1 could be the path between the aeroplane and the catering area, while the surface S could be the ground.

Each transponder 10 is of the passive type, that is, lacking supply batteries, not in anti-collision, and includes, as shown schematically in Figure 2 which shows transponders 10 which are in themselves known, a transceiver circuit 12 and a memory circuit 13 for storing

a transponder identification code connected to the transceiver circuit 12.

It is however stressed that when a serving trolley 1 passes over an antenna module 11, the module transmits an activation signal to the transponder 10 facing it, which signal is received by the transceiver circuit 12 of the transponder 10 itself, and provides this latter with the necessary energy to operate; the transceiver circuit 12 consequently activates the memory circuit 13 which provides the transceiver circuit 12 with a unique identification code for each transponder 10; the transceiver circuit 12 consequently generates an identification signal based on the aforesaid identification code and transmits it; this signal, received by the antenna module 11 facing the transponder 10 is decoded thereby for the identification of the transponder 10, and thus of the associated serving trolley 1.

In detail, the antenna modules 11 transmit an activation signal of a predetermined power, and the transponders 10 transmit the identification signal containing the identification code at a power 56 dB less than the power of the signal transmitted by the antenna modules 11.

The identification codes transmitted by the transponders

10 are encoded in 40 or 64 bit binary code, and therefore the number of different identification codes is 10 ¹² or 10 ¹⁹ respectively, and this number also represents the maximum number of identifiable serving trolleys 1. In addition, the transponders 10 have a working frequency of 125 kHz which can freely be used world-wide without specific approval for this type of use; the data transfer speed is

9600 bit/s; the operating temperature range is from -40° to +100° so as to withstand the different temperatures in the various airports; advantageously, the transponders 10 are highly resistant to impacts and other shocks and have a minimum life expectancy of more than 10 years.

Each transponder 10 is substantially cylindrical in shape with a diameter of 50 mm and a height of 1mm and is fixed, as shown in Figure 3, to the lower surface 4 of the serving trolley 1 along the longitudinal axis of symmetry A of the lower surface itself, preferably close to the centre of the lower surface 4, or below one of the wheel lock/release control pedals 7 disposed between the front wheels 5, as shown in broken outline.

Alternatively, as shown in Figure 4, each transponder 10 may be fixed to the lower surface 4 of the associated serving trolley 1 at a distance of at least 8 cm from a major edge 15 of the lower surface 4 itself.

In addition, if it is not fixed to one of the wheel lock/release control pedals 7, each transponder 10 is fixed, as shown in Figure 5, to the lower surface 4 of the associated serving trolley 1 at a predetermined distance from the lower surface 4 itself by a spacer 16. This distance is calculated by taking account both of the fact that the lower surface 4 of the serving trolley 1, being metal, acts as an insulating screen against the transponder 10 and interferes with its correct operation, and the fact that the power of the identification signal transmitted by the transponder 10 is 56dB less than that of the activation signal transmitted by the antenna modules 11, and therefore the electromagnetic path of the identification signal cannot to be too long.

In particular, the distance between the lower surface 4 of the serving trolleys 1 and the ground being 100 mm, laboratory tests have shown that the equipment functions correctly with transponders 10 spaced 45 mm away from the lower surface 4 of the associated serving trolley 1, and therefore 55 mm away from the antenna modules 11.

In some cases, as shown in Figure 6, boxes of sheet steel 17 having a depth of approximately 30 cm are fixed to the lower surface 4 of the serving trolleys 1; in this case, each transponder 10 is fixed to the associated box 17 by way of a 15 mm insulating spacer 18 so as to avoid

interference with the box 17 itself and a position too close to the surface S (the ground) .

Each antenna module 11 has different dimensions depending on whether the transponders 10 are disposed along the longitudinal axis A of the lower surface 4 or to the side.

In particular, where the transponders 10 are positioned along the longitudinal axis A of the lower surface 4, each antenna module 11 has a substantially rectangular shape, a length of lm, a width of 50 cm and a height of 2 cm, as shown in detail in Figures 6 and 7.

As shown in Figure 7, each antenna module 11 includes four substantially flat antenna elements 20 and a control circuit 21 for the four antenna elements 20. In particular, each antenna element 20 includes a substantially rectangular coil having sides of 30 and 23 cm, and a wire gauge of 5 mm; each coil 20 is also highly directional, that is, it has a radiation pattern having lobes that will not interfere with those of the adjacent coils 20.

The four coils 20 are coplanar and disposed so that they are partly side by side; in particular, the two central coils 20 are side by side ind are off-set with respect to the two lateral coils 20.

Specifically, the two central coils 20 have major sides 20a which are side by side, parallel and 20 mm apart, and minor sides 20b, side by side and parallel to a first major side 11a of the antenna module 11, and spaced from this latter by 10 mm.

On the other hand, the two lateral coils 20 have respective major sides 20a parallel to the minor sides lib, lie of the antenna module 11, and spaced from a respective minor side lib, lie by 10 mm, and aligned minor sides 20b parallel to a second major side lid of the antenna module 11 and separated therefrom by 10 mm; in addition, the central coils 20 are spaced 20 mm away from the adjacent lateral coils 20.

The control circuit 21 is disposed between the two lateral coils 20 close to the second major side lid of the antenna module 11, and has a substantially rectangular shape with a length of 183 mm, a width of 98 mm and a height of 10 mm, and major sides 21a parallel to the minor sides 20b of the central coils 20.

The control circuit 21 includes a control module stage 25 for activating selectively the four coils 20 according to a predetermined scheme; a filtering and decoding stage 26 for processing the identification signals received from the coils 20 and extracting the associated identification

code; and a memory stage 27 for storing the received and decoded identification code.

In particular, the control module stage 25, preferably realised by means of a microprocessor, is connected to the filtration and decoding stage 26 and the storage stage 27 in order to send the activation signals to the coils 20, to receive the identification codes from the filtering and decoding stage 26 and to store and read them, and has an input 28 for connection with a concentrator, not shown in Figure 7, connected to further antenna modules 11, as explained in more detail below.

The filtering and decoding stage 26 is preferably realised by means of analogue circuits of known type which are not described in detail.

In particular, the control module stage 25 activates alternatively, and at a predetermined frequency, two pairs of coils 20, each pair comprising two non-adjacent and alternating coils 20, so as to avoid the unwanted contemporaneous activation of two different transponders 10 disposed on adjacent serving trolleys 1, which would prevent the discrimination of the two identification codes and, therefore, the correct identification of the serving trolleys 1 thsmselves.

The dimensions of the coils 20, their electromagnetic characteristics, and their methods of activation enable the unambiguous identification of several contiguous serving trolleys 1 from each other when they are passing across one antenna module 11 at the same time.

In fact, in the case of two serving trolleys 1 which are perfectly aligned side by side and which cross a single antenna module 11 at the same time, and where the transponders 10 are disposed along the respective longitudinal axes A of the lower surfaces 4, the distance between the two transponders 10 is equal to 30 cm. Given that the width of each coil 20 is equal to 23 cm, and the coils 20 are activated alternately, only one of the coils 20 facing one of the transponders 10 is supplied at any time, while the coils 20 adjacent thereto are inactive. Given the high directionality of the coils 20, the adjacent transponder 10 is not activated and therefore, only one identification code is sent at a time; in addition, two adjacent coils 20 cannot activate a single transponder 10 at the same time, as they are never supplied with power at the same time.

From the description, it is clear that with the width of a serving trolley 1 being 30 cm, an antenna module 11 of a length of 1 m is able unambiguously to identify up to four

serving trolleys 1 passing across a single antenna module 11 at the same time.

As described above, the transponders 10 may also be disposed close to a major edge 15 of the lower surface 4, at a distance of at least 8 cm from the major edge 15 itself. In this case, the minimum distance between two transponders 10 is 16 cm, corresponding to a situation in which two serving trolleys 1 are perfectly aligned side by side but one of the two is rotated by 180° with respect to the other, or a situation in which the two serving trolleys 1 have associated transponders 10 mounted on opposite sides.

In this case, with antenna modules 11 having coils 20 of 23 cm in width, the contemporaneous identification of perfectly aligned serving trolleys 1 is not guaranteed and it is necessary to utilise the antenna modules 11 described above having a length of 50 cm, and including coils 20 of 11 cm in width.

With these dimensions, the unambiguous and error-free identification of adjacent serving trolleys 1 is guaranteed; in particular, by having a serving trolley 1 of 30 cm in width, each antenna module 11 is able to identify contemporaneously and unequivocally two serving trolleys 1.

As described above, the antenna modules 11 may be connected together to form one antenna which is disposed along the path P of the serving trolleys 1; in particular, where there are several different trolley identification areas in a single airport, one antenna is located in each of them. Where there are four trolley identification areas, as shown in Figure 8, each antenna, indicated 31, comprises a plurality of antenna modules 11 disposed side by side along respective minor sides, and connected to an associated concentrator indicated 30; by varying the number of flanking antenna modules 11, it is possible to vary the overall length of each antenna up to 10 m in order to adapt it to the transverse dimensions of the path P taken by the serving trolleys 1.

In detail, the concentrator 30 of each antenna 31 is connected to the inputs 28 of the control stages 25 of the individual antenna modules 11, and includes a module synchronisation stage 32, a memory 33 for receiving and storing the identification codes of the activated transponders 10 that are already stored in the individual control circuits 21, a marking stage 34 for associating date, time and location information identifying the serving trolleys 1 with the received identification codes to enable them to be located unambiguously world-wide, and a diagnostic stage 35 for the antenna modules 11.

The concentrators 30 are connected to a processing unit 40, for example, a personal computer which covers the entire airport, for managing the concentrators 30 themselves and receiving the information stored therein.

The processing unit 40 can also be connected to a telecommunications network, indicated 41 in Figure 8, for transmitting identification and location information for each serving trolley 1 to a remote processing unit 42, for example, remote personal computers provided to the various airline companies, which are therefore informed in real¬ time of the position and use of their own serving trolleys 1 in the various airports.

In addition, the processing units 40 at the airports may be provided with programs enabling instructions to be received from the remote processing unit 42 of the various airline companies concerning operations which are to be periodically carried out on each serving trolley 1. For example, each airline company could send a list of storage trolleys 1 on which programmed maintenance is due to the processing units 40 in all the airports in which they have flights; in this way, as soon as the presence of serving trolleys 1 has been indicated in a particular airport, corresponding, real-time messages can be generated to operate them.

Finally, it is clear that modifications and variations may be introduced to the identification equipment described and illustrated here without by this departing from the scope of protection of the present invention.