FR2883680A1 - Transponder e.g. read only transponder, information reading device for article storage device, has detection units producing signal giving receiving antenna state changes from difference between reading antenna and compensation arm voltages - Google Patents

Abstract

The device has a reading antenna (110) permitting to generate an electromagnetic field for excitation of transponders (1) located in the field of the antenna. Detection units (150) are arranged to generate a useful signal representative of the changes of the state of the receiving antennas (6) of the transponders from a difference between respective voltages associated to the antenna (110) and a compensation arm. Each transponder has switching units (7) to modify the state of the antenna (6) and to transmit information to the device by modifying the coupling between the antennas (6, 110). The compensation arm includes fixed and variable resistors, an inductor, and fixed and variable capacitors. An independent claim is also included for a method for follow-up of contents of an article storage device, including a transponder information reading device, in a conveying device.

Description

The present invention relates generally to identification

  objects by means of transponders fixed on said objects, by means of a reading device for reading information stored in the transponders, or to exchange information with them.

  The invention more particularly relates to a reading device of the type comprising a reading antenna for generating an electromagnetic excitation field of at least one transponder located in the field of the antenna, this transponder comprising a receiving antenna and associated switching means for changing the state of the receiving antenna.

  The patent application FR-A-2 802 738 discloses a reading device comprising a reading antenna and detection means arranged to generate a useful signal from the evolution of the signal of the reading antenna relative to to a reference signal, this reference signal being representative of the signal of the reading antenna when the transponder receiving antenna is in a predetermined state, the useful signal being representative of the state changes of the receiving antenna .

  In this prior application, the reading antenna is excited by a low harmonic signal and the reading device comprises processing means arranged to perform an impedance demodulation.

  The reading device comprises a directional coupler arranged such that a modification of the coupling between the reading antenna and the receiving antenna gives rise to a useful signal representative of the disconnection of the reading antenna induced by the changes of the reading antenna. state of the receiving antenna.

  The reference signal is obtained by means of a compensation arm whose impedance is equal, to a known factor, notably different from 1, to that of the reading antenna when the receiving antenna is in a state predetermined. The aforementioned factor is for example between 2 and 10.

  The detection is carried out by means of a torus making it possible to detect a magnetic flux representative of the difference between the current in the reading antenna and a multiple of it in the compensation arm.

  A disadvantage of this known reading device is that the components of the compensation arm are brought to a high voltage, which can affect the life of the reading device, except to use more resistant but more expensive components.

  Another disadvantage is the sensitivity to the hand effect induced by the electric field in the compensation arm, which can generate a noise in the output signal.

  There is therefore a need to benefit from an improved reading device remedying all or part of these disadvantages.

  The invention thus has, according to one of its aspects, a reading device comprising a reading antenna for generating an electromagnetic excitation field of at least one transponder located in the field of the antenna; transponder comprising a reception antenna and associated switching means enabling it to modify the state of the reception antenna and thus transmit information to the reading device by modifying the coupling between the reading antenna and the antenna of reception, the reading device comprising: detecting means arranged to generate a useful signal representative of the state changes of the transponder receiving antenna from a difference between voltages respectively associated with a compensation arm and the reading antenna.

  Unlike the reading device described in FR 2 802 738, the invention makes it possible to avoid subjecting the components of the compensation arm to a high voltage.

  The device may comprise a first transformer and a second transformer, each of which comprises at least one primary winding and at least one secondary winding.

  In an exemplary implementation of the invention, the primary winding of the first transformer is in series with the reading antenna, the secondary winding of the second transformer is in series with the compensation arm, and the primary winding of the second transformer is in parallel with the reading antenna and the primary winding of the first transformer. The secondary winding of the first transformer is in parallel with the compensation arm and the secondary winding of the second transformer.

  The first transformer and the second transformer may be, in an exemplary embodiment, substantially identical. For example, they may have ratios of the number of primary turns to the number of inverse secondary turns.

  The first transformer, which acts as an intensity transformer, can work at zero flux.

  The ratio of the current in the compensation arm to the current in the reading antenna may be substantially equal to the ratio of the number of turns of the primary winding to the number of turns of the secondary winding of the first transformer.

  The second transformer can act as a voltage transformer.

  The voltage and / or the intensity in the compensation arm can be thanks to the invention lower than in the compensation arm described in FR 2 802 738.

  The components of the compensation arm may be chosen such that the impedance of the compensation arm is substantially equal to that of the read antenna, when the receiving antenna of the transponder is in a predetermined state.

  The device may comprise servo means for equalizing the resistive and reactive elements of the reading antenna and the compensation arm.

  The compensation arm thus comprises, for example, at least one variable resistive component and at least one variable capacitive or inductive component, and the reading device can comprise actuating means for acting on these variable components to ensure that the Real and imaginary values of the impedance of the compensation arm remain in a predefined relation, for example of equality, with those of the reading antenna. The actuating means comprise for example at least one drive motor of an adjusting member of a variable component, in particular a stepping motor.

  The reading antenna and the compensation arm may each comprise at least one inductance, a capacitor and a resistor connected in series. They may include, where appropriate, each a network of resistors, inductors and capacitors switched in series and / or in parallel so as to obtain the desired value.

  The reading antenna can be excited by a low harmonic signal, for example from a linear amplifier, for example class A, B or AB.

  The transmission frequency of the reading antenna is for example between 100 and 150 kHz.

  The reading device may comprise processing means arranged to perform an impedance demodulation.

  The reading device may comprise means for adjusting the phase shift of the reference voltage of a multiplier demodulator, in particular a variable phase bridge, as well as an automatic tuning device for the antenna measuring the phase difference. existing between the current in the antenna and the output voltage of the power amplifier.

  The reading antenna may be arranged to be placed in a box for receiving a plurality of articles each provided with a transponder.

  The transponders used may be of the read-only or read-write type, and the reading device may comprise switching means making it possible to modulate in all or nothing the power supply of the reading antenna so as to transmit information to the readers. transponders placed in the antenna field, in particular for recording information therein.

  The transponders can be powered electrically only by the electromagnetic energy from the reading antenna.

  Another subject of the invention, according to another of its aspects, independently of the reading device used, is a storage device intended to receive a plurality of articles each provided with a transponder, comprising at least one or two antennas, in particular three antennas, to receive information from transponders.

  The storage device advantageously comprises at least one reading device as defined above.

  The storage device may advantageously comprise at least three reading antennas formed by coils arranged so as to detect the transponders present in the field of the antennas.

  In an exemplary embodiment, a first antenna is disposed horizontally while a second and a third antenna are arranged vertically with an angle between them, for example an angle of between about 90 and about 120.

  In an exemplary embodiment, the horizontal antenna comprises several branches, in particular arranged at different heights in the storage device.

  The storage device may comprise a box comprising a metal wall, for example made of aluminum, of thickness for example greater than 2 mm, or even greater than 3 mm.

  The storage device may also include a battery for powering the reading device, the battery being for example fixed to the outside of the box, for example between the wheels of the storage device.

  The box for containing the articles may be sealed, and it may comprise a decompression system, for example at least one pellet of a gas-porous material, for example sintered bronze.

  The invention further relates, in one aspect, to a method of storing articles each provided with a transponder in a storage device, in which the articles are arranged so that the transponders are spaced apart. from each other by at least 6 mm, or even 8 mm, better by at least 10 mm.

  The invention further relates to a method of tracking the contents of an article storage device in a transport apparatus, comprising the following steps: - controlling by means of the reading device the contents of the storage device before departure , and control the contents of the storage device on arrival.

  For example, the information thus obtained can be compared with data concerning articles sold during transport.

  The invention will be better understood on reading the following detailed description of non-limiting exemplary embodiments of the invention and on examining the appended drawing, in which: FIG. 1 schematically represents and partially an example of a reading device according to the invention, - Figure 2 shows an example of a demodulator, - Figure 3 illustrates an alternative embodiment of the reading device of Figure 1, - Figures 4 to 6 illustrate schematically and partially another embodiment, - Figure 7 shows in perspective, schematically and partially, an article storage device according to the invention, - Figure 8 illustrates an example of arrangement of the antennas in the FIG. 9 is a schematic representation of a reading device that can be associated with the antennas of the storage device of FIGS. 7 and 8; FIG. Figure 10 schematically and partially illustrates the storage of articles in the storage device, and Figure 11 is a block diagram of a method of tracking the contents of a storage device.

  Reading device An exemplary embodiment of the reading device is described below, with reference to FIGS. 1 and 2.

  The reading device 100 comprises a reading antenna 110 making it possible to generate an electromagnetic excitation field of at least one transponder 1 situated in the field of the antenna 110, this transponder 1 comprising a reception antenna 6 and means for switching 7 associated to change the state of the receiving antenna 6 and thus transmit information to the reading device 100, by changing the coupling between the reading antenna 110 and the receiving antenna 6.

  The reading antenna 110 comprises, for example, in series a resistor 111, a fixed inductance 112, a variable inductance 114 and a capacitor 113.

  The following state changes of the receiving antenna 6 is determined by control means 9 internal to the transponder as a function of the information to be transmitted. The transponder 1 transmits information with a suitable code, for example a Manchester code known per se.

  The transponder 1 may be small, for example being encapsulated in a plastic pad having a diameter of about one centimeter. It is useful to refer to the European patent application EP-A-847 023 and to the patent application FR-A-2 772 164 which refer to the use of such transponders.

  Transponder 1 is for example read-only or read and write.

  The reading device 100 comprises a signal generator 101, of frequency for example between 100 and 150 kHz, for example equal to about 125 kHz, connected to a common mode power amplifier 102 preferably operating in class A, Bou AB .

  The reading device 100 also includes a compensating arm 120 configured to provide a reference signal for detecting the impedance changes of the read antenna 110 when the receiving antenna 6 of the transponder changes state.

  The compensation arm 120 comprises in the example considered a fixed resistor 121, a variable resistor 165, an inductance 122, a fixed capacitor 123 in parallel with a variable capacitor 166. The resistors 121 and 165, the inductor 122 and the capacitance 123 are connected in series, the resistor 121 being connected to ground. The inductance 122 of the compensation arm 120 may be a shielded inductor made without particular precautions with regard to the insulation between turns.

  In the example described, the reading antenna and the compensation arm each comprise an inductance, a capacitor and a resistor connected in series, but it is not beyond the scope of the present invention if it is otherwise. The reading antenna and the compensation arm may for example comprise several components of the inductive, capacitive or resistive type, connected in parallel or in series, so that the impedance of the reading antenna and that of the compensation arm are equal to the desired values, and in a particular embodiment, substantially equal.

  The primary 131 of a current transformer 130 is connected to the amplifier 102 and to the antenna 110 via the primary of another transformer 129 for detecting the phase shift of the current with respect to the voltage in the transformer. reading antenna 110, as will be detailed later.

  The transformer 130 comprises a secondary 132, one terminal of which is connected to the ground and the other to a resistor 128 which is itself connected to the ground, and comprises, for example, a number of turns n2 which is k times greater than the number of turns of the primary 131. k is in the example described equal to 10, the number of turns and the primary 131 being for example 10 and the number of turns n2 of the secondary 132 being 100.

  Thus, the current in the compensation arm is substantially k times lower than that in the antenna.

  The current from the power amplifier 102 is also fed into the primary 141 of a voltage transformer 140, which is similar in the example described to the current transformer 130. The voltage transformer 140 has a secondary winding 142 with k times less turns than the primary 141, especially 10 times less in the example described, the primary 141 comprising for example 100 turns and the secondary 142 having 10 turns.

  The secondary 142 of the transformer 140 is arranged in series with the compensation arm 120 and the primary 141 is connected in parallel with the reading antenna and the primary 131 of the transformer 130.

  The primary 141 and the secondary 142 are wound so that the polarity of the voltage across the secondary 142 is reversed relative to that of the voltage across the primary 141. Thus, the voltage across the secondary 142 tends to cancel that at the terminals of the compensation arm, the voltage developed across the secondary 132 being in phase with the intensity in the reading antenna 110 and that at the terminals of the secondary 142 being in phase opposition with the voltage across the terminals of the reading antenna 110.

  Current transformers 130 and voltage 140 are for example wound on torus or pot ferrite.

  The voltage across the resistor 128 may be substantially zero when the voltages across the secondary 142 and the terminals of the compensation arm are of equal amplitude when the receiving antenna 6 of the transponder is in a predetermined state. This voltage changes when the receiving antenna 6 of the transponder 1 changes state and can be demodulated by detection means 150 comprising a demodulator 151 connected to the resistor 128 and the amplifier 102.

  The advantages of such a reading device essentially due to the low voltages developed at the terminals of the compensation arm 120, which makes it possible to use less expensive components for its implementation and especially to avoid the strong electric fields generating effluvage in the capabilities of the compensation arm 120, and therefore the noises being manifested by sudden rips of the signal in the output voltage.

  The components of the read antenna 110 and the compensation arm 120 are preferably the same value, in order to have substantially the same quality factor and a good noise rejection in the bandwidth.

  In the foregoing, an exemplary embodiment has been described in which the impedances of the read antenna 110 and the compensation arm 120 are substantially equal and in which the secondary transformation ratios of the transformers 130 and 140 are equal.

  Of course, it is not beyond the scope of the present invention if it is otherwise.

  The impedances of the reading antenna and the compensation arm may be different, just as the ratios of the transformations may be different, being for example chosen as a function of the impedances of the reading antenna and of the compensation arm so that that the voltage across the compensation arm 120 is substantially proportional to the intensity of the current flowing in the reading antenna, that the voltage across the secondary 142 of the voltage transformer 140 is also substantially proportional to the voltage across the the reading antenna 110 and that the ratios of proportionality are substantially equal. Thus, a subtraction of these voltages can generate a signal of good signal / noise ratio, representative of the state changes of the receiving antenna 6 of the transponder 1 and substantially zero when the receiving antenna is in a predetermined state.

  The frequency with which the receiving antenna 6 of the transponder 1 changes state is for example less than 16 times, 32 times or even 64 times the frequency of the generator 101.

  In the exemplary embodiment considered, the reading device 100 comprises servocontrol means 160 of the variable components 165 and 166 of the compensation arm 120, so as to equalize at the beginning of the operation of the reading device, in the absence of transponder, the resistive and reactive elements of the reading antenna 110 and the compensation arm 120.

  These servocontrol means 160 comprise, for example, a microcontroller 161 for controlling a stepper motor 163 actuating the variable capacitor 166 and a microcontroller 162 for controlling a stepper motor 164 actuating the variable resistor 165. The signals controlling these two microcontrollers are from the demodulator 151.

  Of course, it is not beyond the scope of the present invention if the stepper motor 163 controls a variable inductance.

  A third microcontroller 167 can also be used to manage the automatic tuning of the reading antenna 110, for example by means of a stepper motor 171 acting on the variable inductor 114, after detection of the phase shift of the antenna through the transformer 129 and a phasemeter 170.

  Of course, it is not beyond the scope of the present invention if the microcontrollers are replaced by a more powerful computer, also performing other operations such as transponder interrogation management, collision avoidance and the processing of the addressed data. by transponders.

  This computer could for example be that, referenced 155, to which is sent the demodulated signal from the demodulator 151 via a double analog / digital converter 152.

  Referring to FIG. 2, it can be seen that the output voltage V of the transformer 140, received by the demodulator 151, is sent to a first multiplier 191 for synchronous demodulation of the useful signal representative of the state changes. of the receiving antenna of the transponder, and in a second multiplier 192 to perform a synchronous demodulation of the useful signal after phase shift of n / 2 of the carrier by means of a phase-shifter 293. Each of the multipliers also receives the phase reference of the power amplifier 102, as shown in Figure 2.

  The two signals from the two multipliers 191, 192 are amplified by respective amplifiers 195, 196 before being directed to the converter 152.

  The signal may also be integrated by respective integrators 197, 198, to constitute an error signal used to control the microcontrollers 161 and 162 used for the servocontrol of the compensation arm 120.

  In an alternative embodiment of the invention, illustrated in Figure 3, the transformer 140 comprises two additional windings 143 and 144 at the secondary. These two windings 143, 144 are connected in series, and are in phase opposition with respect to ground.

  A variable phase bridge 180 is formed by a resistor 181, a potentiometer 182, a capacitor 183 and a resistor 184.

  This device allows the adjustment of the phase of the reference voltage from the power amplifier 102 and sent to the demodulator 151. This setting may be particularly useful when mounting the device to balance the reactive and resistive parts of the impedance.

  FIGS. 4 to 6 illustrate another embodiment of the invention, in which a tosmeter 135 represented in FIG. 4 comprises the intensity transformers 130 and the voltage transformers 140. The compensation arm and its components, and the control unit of the compensation arm are detailed in Figure 5, as well as the electronic structure of the demodulator 151 in Figure 6.

  The references of the links of the tosmeter of FIG. 4 are shown in FIG.

  The circuit 193 is a zero centered comparator giving a rectangular voltage independent of the input level. It makes it possible to generate a reference voltage of the demodulator.

  The two circuits 191, 192 are analog Hilbert cell multipliers. The circuit 191 receives the reference signal of the power amplifier 102 in phase and demodulates the real ones. The circuit 192 receives the reference signal of the quadrature power amplifier and demodulates the imaginary. The inputs IN + and IN- are crossed and in parallel and receive the signal V to be demodulated.

  Two differential amplifiers 194 receive the differential outputs of the multipliers 191, 192.

  These two differential amplifiers 194 in turn each attack two different channels. First, the two integrators 197 and 198 generate the error voltages (real and imaginary) for the servocontrols of the compensation branch.

  On the other hand, the two amplifiers 195 and 196 generate the demodulated output signal for the reals and for the imaginary, which is then sent to the converter 152.

  The demodulated imaginary signal can be used for adjustment purposes when the system is first turned on. To this end, it must be canceled by adjusting the phase of the reference voltage by means of the variable-phase bridge constituted by the additional windings 143, 144 and by adjusting at resonance the transformer 199 attacked by the comparator 193.

  Storage device 7 will now be described with reference to FIGS. 7 to 10 a storage device 200 according to the invention, intended to receive a plurality of articles 250 each provided with a transponder 1, comprising at least one antenna for detecting the presence and / or location of the transponders 1, and possibly receiving information from the transponders 1.

  The storage device 200 may for example be mounted on rollers 202, to form a trolley. The storage device 200 may for example be used in a public transport device, for example an aircraft, a train or a boat, so as for example to allow a seller to circulate with articles 250 to offer for sale to travelers.

  In the storage device 200 are stored articles 250 on each of which is fixed a transponder.

  The storage device 200 is equipped with several wound antennas 220, 221, 222 and an associated reading device.

  The storage device 200 further comprises a box 210 receiving drawers 230 containing the articles 250 and a door 212.

  Preferably, the box 210 comprises a metal wall 211, for example made of aluminum, to prevent the antennas 220, 221, 222 from emitting a field outside the storage device 200, so for example to not disturb measurement instruments located nearby. The thickness of the metal wall 211 may for example be greater than or equal to 2 or 3 mm.

  The storage device 200 further comprises a battery for supplying the reading device 100, this battery 240 being for example stored outside the box 210. Preferably, the battery 240 is stored outside, for example between the wheels 202.

  A first antenna 220 is arranged horizontally around the storage volume while a second antenna 221 and a third antenna 222 are arranged vertically, also around the storage volume, with an angle between their axes, for example an angle between 90 and 120.

  The horizontal antenna 220 comprises several wound branches 220a, 220b, 220c arranged at different heights in the storage device 200, thus making it possible to improve the sensitivity of the reading device.

  For example, the number and quality of the articles contained in the storage device can be precisely determined, and the number and quality of the stored items can be monitored. It may be for example, in the case of an aircraft trolley, to determine the contents of the trolley at takeoff and landing.

  The outer metal structure of the storage device may provide sufficient shielding to attenuate the field generated by the internally located antennas significantly. However, it can be expected to insert in the door frame an electromagnetic seal.

  The latter may cause pneumatic sealing and it may be advantageous to provide in the storage device a decompression system 215, for example a sintered bronze pellet allowing the gases to escape, otherwise it will no longer be possible to open the storage device easily. because of the pressure differential due to the pressurization.

  The electronic structure of the reading device 100 of the storage device is illustrated in FIG. 9.

  The three antennas 220, 221 and 222 may each be tuned automatically, each comprising for example a stepping motor 171 driving a variable inductance controlled by signals from the computer 155.

  The single signal generator 101 feeds three power amplifiers 102 and three detection assemblies 104 each having two transformers 130, 140, a compensation arm 120 and the associated control device 160, arranged as described above.

  The signals are processed by three demodulators 151 before being received by the computer 155.

  The automatic chords 171 are preferably located closer to the reading antennas to have to use with the rest of the reading device that low impedance links, for example 80 ohms.

  Storage method The invention also relates to a method of storing articles each provided with a transponder in a storage device, in which the articles are arranged so that the transponders are spaced from each other more 6, 8 or 10 mm, as shown in Figure 10.

  Such storage facilitates the detection of articles.

  The operation of the reading device is improved if the transponders are not coupled.

  However, in the case where all the transponders are coupled two by two, the reading device is also able to detect them. The reading device can thus have two distinct modes of operation, the first in the case where the transponders are not coupled, and the second in the case where the transponders are coupled.

  The storage device may for example store more than 150 articles, for example between 180 and 200 articles.

  The object of the invention is also, as illustrated in FIG. 13, a method of tracking the contents of a device for storing articles for sale in a passenger transport apparatus, comprising the following steps: in step 300 the contents of the storage device before the departure of the device, and - check in step 310 the contents of the storage device at the arrival of the device.

  In step 320, information representative of the evolution of the contents of the storage device may be compared with data concerning the sale of articles during transport and check whether there is a match.

  The expression containing one must be understood as being synonymous with at least one, unless the opposite is specified.

Claims (16)

  1. Reading device (100) comprising a read antenna (110) for generating an electromagnetic field for exciting at least one transponder (1) located in the field of the antenna (110), said transponder (1) ) having a receiving antenna (6) and associated switching means (7) enabling it to change the state of the receiving antenna (6) and thereby transmit information to the reading device (100) by changing the coupling between the reading antenna (110) and the receiving antenna (6), the reading device comprising: detection means (150) arranged to generate a useful signal representative of the changes in state of the antenna receiving (6) the transponder (1) from a difference between voltages respectively associated with the read antenna and a compensation arm (120).   2. Device according to the preceding claim, comprising at least a first transformer (130) having a primary in series with the read antenna (110) and a secondary flow at least partially in the compensation arm (120).   3. Device according to one of the two preceding claims, comprising at least a second transformer (140) having a secondary (142) in series with the compensation arm (120) and a primary in parallel with the reading antenna (110). ).   4. Device according to claims 2 and 3, characterized in that the voltage transformers and intensity have the same transformation ratios.   5. Device according to any one of claims 1 to 4, wherein the first (130) and the second (140) transformer each comprise at least one primary winding (131; 141) and at least one secondary winding (132; ), the primary winding (131) of the first transformer (130) being in series with the read antenna, the secondary winding (142) of the second transformer (140) being in series with the compensation arm (120), the primary winding (141) of the second transformer (140) being in parallel with the read antenna (110) and the primary winding (131) of the first transformer (130), and the secondary winding (132) of the first transformer (130) being in parallel with the compensation arm (120) and the secondary winding (142) of the second transformer (140).   Apparatus according to any one of the preceding claims, wherein the impedance of the compensation arm (120) is substantially equal to the impedance of the read antenna (110) when the receiving antenna (6) is in a predetermined state.   7. Device according to the preceding claim, comprising servocontrol means (160) for equalizing the resistive (111; 121) and reactive (112, 113; 122, 123) components of the reading antenna (110) and the arm compensation (120).   8. Device according to the preceding claim, the servo means (161, 162) comprising at least one stepper motor (163; 164).   9. Device according to any one of the preceding claims, characterized in that the reading antenna (110) and the compensation arm (120) each comprise at least one inductor (112, 122), a capacitor (113, 123) and a resistor (111, 121) connected in series.   10. Device according to any one of the preceding claims, wherein the transmission frequency of the read antenna (110) is between 100 and 150 kHz.   A storage device (200) for receiving a plurality of items provided with transponders (1), comprising a reading device which may be as defined in any one of the preceding claims, the storage device comprising at least an antenna (110), in particular three antennas, for receiving information from the transponders.   12. Device according to the preceding claim, wherein a first antenna (220) is disposed horizontally, and a second (221) and a third (222) antenna are arranged vertically with an angle between them, including an angle between 90 and 120 .   13. Device according to the preceding claim, wherein the horizontal antenna (220) comprises a plurality of branches (220a, 220b, 220c), in particular arranged at different heights in the storage device.   14. Device according to any one of claims 11 to 13, comprising a box (210) having a metal wall (211).   15. Device according to any one of claims 11 to 14, characterized in that the articles are arranged in such a way that the transponders are spaced from each other by at least 6 mm, better still at least 8 mm. more preferably at least 10 mm.   A method of tracking the contents of an article storage device in a transport apparatus, comprising the steps of: (300) controlling the contents of the storage device prior to departure using the reading device as defined in any one of claims 1 to 13, - controlling (310) the contents of the storage device on arrival.