EP2517146A1

EP2517146A1 - Mobile reading device, and method for locating an object that is marked with an active transponder

Info

Publication number: EP2517146A1
Application number: EP10790399A
Authority: EP
Inventors: Andreas Bohnenberger; Daniel Evers; Martin Glänzer; Ulrike Heim; Fabian Kurz
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2010-02-05
Filing date: 2010-12-07
Publication date: 2012-10-31
Also published as: DE102010006982A1; CN102725764A; CN102725764B; WO2011095244A1; US20130194078A1

Abstract

The invention relates to a mobile reading device for locating an object that is marked with a transponder. The reading device has an antenna device (110) for receiving a signal transmitted by the transponder, said antenna device having a main radiation direction. Furthermore, an electronic assembly is provided for calculating a direction from the reading device to the transponder using the received signal. The reading device further has an orientation detector, an electronic compass for example, with which an absolute orientation of the reading device with respect to an exterior region can be detected. While the main radiation direction of the antenna is pivoted in the region and the signal strength is measured, the orientation in the region is simultaneously detected. A correlation of the orientation that is detected at a point in time t to the signal strength that is measured at the same point in time allows the determination of the direction to the transponder because it can be assumed that the signal has a maximum when the main radiation direction points in the direction of the transponder.

Description

description

Mobile reading device and method for finding an object tagged with an active transponder

The invention relates to a mobile direction finding device for finding an object marked with an active transponder. The retrieval of an object eg. In industrial

Large bearings represents a significant cost factor, as the search for the object is often an enormous amount of time it requests ^¬. The use of the RFID technology known per se ("radio frequency identification" or "radio frequency identification", analogously: identification with the aid of electromagnetic waves) can accelerate the finding. A corresponding RFID system typically includes at least ^¬ a transponder and a reader. Of the

Transponder, which can also be referred to as a "tag" is attached to an object, which, for example, stored in a warehouse and later found again. To find the object or the transponder again, the reader is used. This sends out a RF request signal which is received by the transponder is modulated and either flexed or re- actively transmitted again, wherein the modu lation ^¬ those data is carried out in accordance to be transmitted to the Le ^¬ segerät. The modulation is usually selected such that it is at least suitable for unambiguously identifying the transponder. If the transponder has, for example, an additional sensor, then the modulation can also take place as a function of the measured values recorded by the sensor. Additionally or alternatively, any data may be stored in a corresponding memory of the transponder, for example. Information about the object to which the transponder is attached. Accordingly, these data would also be included in the modulation. Especially when active RFID transponders are known active method to the above purpose. Used, which does not reflect the light emitted from the Lesege ^¬ advises signal after modulation but actively transmitted. This allows a higher range to be achieved, but at the cost of a more complex design of the transponder. For example. it is not ^¬ manoeuvrable in this case to provide a power supply. Here, too, are known different ways, starting with Batte ^¬ RIE or battery power to self-powered transponders countries that relate to the energy required to run from the vicinity of the transponder.

Basically, the searched, with an active

Transponder marked object are in read range of the reader to be found and identified. Furthermore, there must be no interfering obstacles between the reader and transponder that shield the transponder signal. Depending on the required positioning accuracy, different complex location methods can be used, for example, time-based or field strength-based location combined with appropriate algorithm. Accuracies of 1-5m can be achieved with such methods. All these methods have in common recently, ob- tain that a comparatively complex infrastructure for their realization of positioning stations (= readers) is required which may have to be even more complicated po sitioned ^¬, calibrated or possibly synchronized in time. For this reason, such a location with high accuracy, especially for dynamic storage unsuitable because, for example. Under certain circumstances, no power supply is available (eg outdoor campsites) and / or because the permanent construction of an infrastructure can often not be guaranteed. In addition, a dense infrastructure, as required for accurate location, is so costly that the economic advantage of accelerated object retrieval is relativized. In principle, it is also possible to locate the active transponder solely on the basis of a field-strength-based measurement by assuming that the transponder must be located in the direction in which the strongest signal is measured. For this purpose, a measurement of the field strength is carried out with the reader while it is being swiveled in space. The reading device or the antenna is at least as long ge ^¬ pivots until it detects a maximum signal level. In the appropriate direction then the searched transponder would have to be. However, this procedure requires a trained staff.

It is the object of the present invention to specify a mobile reading device and a method for locating a transponder.

This object is achieved by the inventions specified in the independent claims. Advantageous embodiments emerge from the dependent claims.

In the solution according to the invention, the problem of complex and cost-intensive positioning infrastructure is solved in that the locating function is fully integrated into a single mobile reader, which is able to indicate the direction to the searched, marked with a transponder object without the current position of

Transponder and / or the reader itself must be known. A warehouse operator can thus navigate with the aid of this reader to the respective active transponder and thus to the searched object.

A mobile reader according to the invention has:

an antenna device for receiving one of

Transponder transmittable signal S, wherein the antenna device has a main beam direction,

an electronic module for calculating a direction from the reading device to the transponder on the basis of the received signal S, a display device, on which the calculated direction can be displayed,

in which

the reading device has an orientation detector, with which an orientation or an orientation change of the

Reading device with respect to an outer space associated coordinate system K _R can be determined.

Advantageously, the electronic assembly is adapted to from a signal strength of the signal received with the antenna means signal and from the same time as the signal ^¬ strength determined orientation R or change in orientation to calculate AR of the reader on the display device anzuzei ^¬ constricting direction to the transponder.

The orientation detector is in particular designed to indicate an absolute orientation R in the outer space.

In addition, a relative sensor system can be provided which quantitatively detects a change in the orientation of the reading device in the outer space.

Alternatively, the orientation detector is designed to indicate a relative orientation with respect to a specific starting position of the reading device, in particular a change in orientation AR relative to the starting position, in the outer space.

The main beam direction of the antenna device is pivotable relative to the reader. In particular, the

Antenna device itself be pivotable relative to the reader. Alternatively, the main radiation direction of the

Antenna device be electronically pivotable.

An inventive method for determining a direction from a mobile reading device to a transponder, wherein the reading device comprises an antenna device with a

Main beam direction, comprises the following steps: the antenna device receives a signal from the transponder,

the main beam direction is swung while receiving bezüg ^¬ Lich an external space, at the same time the measured strength of the received signal during the pivoting, and an orientation or a Orientierungsände ^¬ tion of the reader with respect to the outer space is determined,

these records comprising the ge during pivoting ^¬-measured signal strength and at the same time determined Orien ^¬ orientation or change in orientation are associated with each other, wherein the one orientation or Orientierungsände ^¬ tion, which was determined at the maximum measured signal strength than the desired direction to the transponder identifi ed ^¬ is ,

The main beam direction is pivoted by

the reading device is moved relative to the outer space,

- The antenna device is moved relative to the reader or

- An electronic panning is used.

The transponder is a passive transponder and the signal S emitted by the transponder is a first from

Reader emitted and reflected on the transponder signal.

Alternatively, the transponder is an active transponder that actively transmits the signal.

Preferably, an absolute orientation with respect to the outer space is determined and in addition, in particular after the direction to the transponder has been determined,

Changes in the orientation of the reading device detected quantitatively, these changes are used to improve the Er ^¬ result of direction determination or correct. With the aid of the mobile reading device according to the invention and the method according to the invention, for example, a warehouse operator can navigate through an automated bearing of an active transponder to the destination. This can be supported by a corresponding display on the reader. The reader fully ^¬ constantly replaced each location infrastructure such as locating base stations or GPS satellites. Even without this infrastructure, objects can be found quickly. All, for example, objects marked by active RFID tags within reach can be used as navigation targets. By using an electronic compass in the reader specified boresight is inde pendent ^¬ correct the orientation of the warehouse staff or of the reader in the room. If the warehouse operator follows the directional information of the reader, it guides him on the direct route to the destination.

Further advantages, features and details of the invention will become apparent from the ^exemplary embodiment described below and from the drawings. Showing:

FIG. 1 shows a bearing

Figure 2 shows a reader in a schematic representation. 1 shows a bearing 1, in which a user B, for example. A Lagerist, with the aid of a reading device 100 scans the object 0, which is located in a shelf 10 of the bearing and is labeled with NEM ei ^¬ active transponders 200th The bearing 1 is assigned a coordinate system K _R. To find the transponder DERS 200, the reader 100 is, or, more generally, a main beam direction ^¬ H an antenna (only indicated in Figure 1) of the reading device 100, pivoted in space.

A commercially available reading device 100 typically has at least the following components (see FIG.

an antenna device 110, which receives the signal S emitted by the active transponder 200, a display device 120, on which the determined direction is displayed by the reading device 100 to the transponder 200, and

an electronic module 130, in which at least all processes for data processing, including the calculation of the direction to the transponder 200, take place using the received transponder signal S and the activation of the display device 120 and possibly the antenna device 110.

Various approaches are possible for determining the direction from the reading device 100 to the transponder 200: a) The reading device 100 is pivoted in different directions, the transponder signal S being measured during the swiveling. The term "panning" includes both a mere back-and-forth rotation about the vertical, as well as a full 360 ° rotation of the main beam direction about the vertical. An evaluation of the signal strength of the empfange- NEN signal S depending on the pivoting direction results in the desired direction in which the transponder is 200, wherein the direction in which the maximum signal strength is measured ^¬ corresponds to the desired direction.

Ideally, the antenna device 110 is a directional antenna 110 whose directional characteristic has a maximum that corresponds to a main beam direction of the antenna device 110 or the directional antenna 110. b) In order to simplify the handling of the reader 100, the antenna 110 of the reader 100 may also be implemented as steu ^¬ newable directional antenna 110th The main ^beam direction of such a directional antenna 110 can be made rotatable or pivotable relative to the reading device 100 in order to be able to dispense with manual pivoting of the antenna device 110 or the reading device 100.

Such a pivoting can be achieved by an internal mechanical pivoting device 140, with which the directional antenna 110 itself is pivoted relative to the reading device 100, and / or by an ne electrical, phase and amplitude correct control of a multi-element directional antenna 110 realize, such as in a so-called. "Phased Array Antenna". The latter option can be referred to as electronic pivoting of the main beam direction.

Such a multi-element directional antenna 110 has at least two individual antennas (not shown). The control of the multi-element directional antenna and / or the pivot mechanism would take place via the electronics assembly 130. c) Alternatively, a SAR algorithm ("synthetic aperture radar") can be used. Again, a pan is performed while measuring the signal strength. In the SAR algorithm, it is necessary to know very accurately the course of the panning with respect to speed and direction, i. the reader 100 must still have a corresponding sensor 150. From the data recorded in this way, the direction in which the transponder is located can be reconstructed.

The approaches a) and b) has in common that the antenna device 110 must be formed as a directional antenna whose main ^¬ beam direction is mechanically or electronically pivoted. At the same time, the dependence of the signal strength on the current direction is measured. In addition to the signal strength of the incident transponder signal S depending on the mo ^¬ mentanen orientation of the main direction of the beam, and a phase measurement allows conclusions as to the direction to the

Transponder 200. If the antenna device 110 has, for example, two (or more) individual antennas which receive the transponder signal S, then the two phases of the signals received at the individual antennas are dependent on the direction to the transponder 200: The phase difference is zero if the distances of the two antennas to the transponder are the same. This applies to a uniqueness range of 2π. If the antenna arrangement were to be rotated, the phase position would also change, the change depending on the wavelength of the signal and on the antenna arrangement. So it turns out determine the direction by comparing the phases at the individual antennas. Of course, the phase measurement method can be combined with the Mes ^¬ solution of signal strength to increase the accuracy of the direction determination.

In the known method according to a) and b), the user B observed during pivoting an indication of the receive ^¬ NEN signal strength at the reader and determines so, in which direction the transponder is located about. However drive this comparison is inaccurate and requires a certain skill ^¬ friendliness and experience in dealing with the reader.

In approach c), in contrast to a) and b) does not require Richtan ^¬ antenna, that is, the antenna device 110 is here WE niger consuming. In return, in the approach c) higher processing power or signal processing in the electronic assembly 130 is needed.

The reader 100 according to the invention has, in addition to the above-mentioned typical components, an orientation device 160 which serves to simplify the determination of the direction to the transponder 200.

Orientation detector 160, in a first embodiment, permits the absolute determination of the orientation of reading device 100 in space. The orientation detector 160 may be formed, for example, as an electronic compass 160. The compass 160 is integrated in the reading device 100 and connected to the electric ^¬ nikbaugruppe 130th While the main beam direction of the antenna device 110 is pivoted in space, as explained in connection with the method a) or b), and the signal strength received by the transponder 200 is measured, the orientation R of the reading device 100 in the space is determined simultaneously with the compass. These two data sets are supplied to the electronic module 130, where they are matched with one another or assigned to one another. This adjustment can, for example, consist in that the signal strength S (tl) measured at a time t 1 corresponds to the same Time tl determined orientation R (tl) is assigned. Thus, it is possible to automatically determine in which direction the largest field strength was measured. Since it is made ^¬ sure that the received signal has a maximum level when the main beam direction in the direction of

Transponder points, so the direction to the transponder can be determined.

As an alternative to the use of the electronic compass, with which a determination of the absolute orientation of the reading device in space is possible, in a second embodiment an orientation detector 160 can be used, which only allows the determination of a relative orientation or the determination of an orientation change. This relative orientation refers to a specific starting position of the reading device. The initial position can, for example, the orientation of the reader at the time of turning on the Lesegerä ^¬ tes or at the time of activating a search mode or similar. be. For example. could at the reader, a switch may be provided (not ones shown, asserted), the starting position Festge than the current orientation of the reader when actuated ^¬ is inserted.

Such an orientation detector 160 for determining a relative orientation relative to a starting position may be a relative sensor system, such as a gyro 160.

Accordingly, in the second embodiment, the orientation detector 160 of the reader 100 does not allow an absolute determination of the orientation, but only the detection of a change in orientation. However, this is completely sufficient for the purpose of determining the direction to the transponder 200. Also in the second embodiment, the main beam direction of the antenna device 110 of the reader 100 is pivoted in space and in this case measured from the received transponder 200 Sig ^¬ nalstärke. At the same time, the gyro 160 determines the change in the orientation R of the reading device 100 in the room. These two records will be electronic Subassembly 130 is supplied, where they are compared with each other ^¬ .

Both embodiments have in common that automatically can be displayed in the direction in which the transponder is based on the simultaneous determination of the signal strength and the absolute or relative orientation. Thus, the determination of the direction is significantly simplified because the user of the reader no longer has to manually search for the maximum signal.

With regard to the first embodiment, it would be conceivable, an additional relative sensors 170, for example. To provide an acceleration sensor ^¬. After determining the direction to

Transponder 200 are using the relative sensor 170 at least changes in the orientation of the reading device 100 quantitatively ^¬ tively detected, ie in particular rotations about the vertical. In addition, changes in position could also be detected. These data are supplied to the electronic module 130. There they are used, for example, to improve the result of the directional estimation described above or, for example, during or after a movement of the reading device 100 in the room to verify or correct. Alternatively or additionally, with the aid of the output data of the relative sensor system 170, for example in the case that the

Transponder signal S is shielded by an obstacle and therefore no longer received, the previously determined and displayed on the display device 120 direction to the transponder 200 corrected and displayed accordingly. If, for example, prior to a change in the orientation of the reading device, it would be determined that the relative direction from the reading device 100 to the transponder 200 is at an angle of w = + 30 ° to the longitudinal direction of the reading device, and would then, after no more transponder signal S has been received the Relativsen ^¬ sensor system 170 determines that the orientation about Aw = + 10 ° is changed, the electronic module would be calculated 130, the corrected relative direction w 'to the transponder 200 must now be at an angle of w '= w-Aw = + 20 ° to the longitudinal direction of the reader 100 must. Corresponding calculation ^¬ calculations could be made, if the position of the reader 100 changes.

The various assemblies of the reader 100, i. the antenna device 110, the display 120, the pivot 140, the sensor 150, the electronic compass 160, and the optional relative sensor 170 are all connected to the electronics assembly 130 (not shown).

In addition to the direction determination, for example, the distance from the reading device 100 to the transponder 200 can also be estimated on the basis of the measured signal strength and displayed on the display device 120. Relative sensor system 170 can also be used to determine the distance between reader 100 and transponder 200: Relative sensor system 170 determines a distance traveled or a change in position of reader 100, while at the same time the signal strength of transponder signal S is measured. These data are supplied to the electronic module 130. Since the signal strength weakens with the distance to the transponder 200, it is possible to deduce the course of the signal strength in the direction in which the transponder 200 is located. For example. If the signal strength decreases, it can be assumed that you are moving away from the transponder 200 and vice versa. Based on the Ge ^¬ speed with which the measured signal strength changed ^¬ changed, one can estimate the direction accurately and not only whether one example away from the transponder 200. The transponder 200 is in the direction in which the Signal strength increases or decreases fastest. A directional antenna is not required for this purpose.

The invention has been described in connection with an active

Transponder described. In principle, however, it is not absolutely necessary for the functionality that it is an active transponder, ie, in principle, passive transponders can also be used, which can be used, for example. received signal from the reader, modulate if necessary and send out again.

The reading device can be designed, for example, in the manner of a PDA (Personal Digital Assistant).

Claims

claims

1. Mobile Reader (100) with

an antenna device (110) for receiving a signal S that can be transmitted by a transponder (200), the antenna device (110) having a main beam direction,

an electronic module (130) for calculating a direction from the reading device (100) to the transponder (200) on the basis of the received signal S,

- a display device (120) on which the calculated

Direction is displayed,

in which

- The reader (100) an orientation detector (160), on ^¬ points, with an orientation or a orientation change of the reading device (100) with respect to an outer space (1) associated coordinate system K _R can be determined.

2. Mobile reading device according to claim 1, characterized in that the electronic assembly (130) is formed to from a signal strength of the antenna device (110) received signal and from the same time with the Signalstär ^¬ ke determined orientation R or orientation change AR of the reading device (100) calculate the direction to be displayed on the display device (120) to the transponder (200).

3. Mobile reader according to claim 1 or 2, characterized

characterized in that the orientation detector (160)

is formed to indicate an absolute orientation R in the outer space (1).

4. Mobile reading device according to claim 3, characterized in that in addition a relative sensor (170) is provided which detects a change in the orientation of the reading device (100) in the outer space (1) quantitatively.

5. Mobile reader according to claim 1 or 2, characterized

characterized in that the orientation detector (160) is adapted to a relative orientation with respect to a certain initial position of the reading device (100),

in particular a change in orientation AR relative to the starting position, to be specified in the outer space (1).

6. Mobile reading device according to one of the preceding claims, characterized in that the main beam direction of the antenna device (110) relative to the reading device (100)

is pivotable.

7. A mobile reading device according to claim 6, characterized in that the antenna device (110) relative to the reading device (100) is pivotable.

8. A mobile reading device according to claim 6, characterized in that the main radiation direction of the antenna device (110) is electronically pivotable.

9. A method for determining a direction from a mobile reading device (100) to a transponder (200), wherein the

Reader (100) has an antenna device (110) with a main radiation direction, wherein in the method

the antenna device (110) receives a signal from the transponder (200),

- the main beam direction is swung during the reception with respect to an outer space (1), wherein simultaneously measured during the pivoting of the strength of the received signal, and an orientation or a Orientierungsände ^¬ tion of the reader (100) relative to the outer space ER- averages is

- these records the ge during pivoting ^¬-measured signal strength and at the same time determined Orien ^¬ orientation or change in orientation are associated with each other comprising, wherein the one orientation or change in orientation, which was determined at the maximum measured signal strength than the desired direction to the transponder (200) is identified.

10. The method according to claim 9, characterized in that the main radiation direction is pivoted by

the reading device is moved relative to the outer space,

- The antenna device is moved relative to the reader or

- An electronic panning is used.

11. The method according to claim 9 or 10, characterized

characterized in that the transponder is a passive transponder and the signal S emitted by the transponder

first emitted by the reader and the transponder reflected signal is.

12. The method according to claim 9 or 10, characterized

in that the transponder is an active transponder and actively transmits the signal.

13. The method according to any one of claims 9 to 12, characterized in that an absolute orientation with respect to the outer space is determined and in addition, in particular after the direction was determined to the transponder,

Changes in the orientation of the reader are detected quantitatively, these changes are used to improve the result of the direction determination or correct.