An easy-to-use access control system

The invention relates to an access control system, in particular for vehicles, comprising an electronic control device at the access side, an identification device at the user side and antennas associated with the electronic control device at the access side and the identification device at the user side for a bidirectional wireless communication between the control device and the identification device.

An easy-to-use access control system of this type is used, for example, when it is a question of checking whether a respective person as the bearer of a respective identification device is authorized to pass the respective access control device. This can apply both to stationary access control devices to which only a selected circle of persons has access and to mobile access control devices, in particular in vehicles such as motor vehicles, ships or bicycles. Theft of the respective vehicle should in particular be countered here with the respective access control devices.

The respective easy-to-use access control system can in particular be provided as a so-called keyless entry system and/ or as a keyless starting system for vehicles. In this case, it includes an electronic control unit as the control device at the access side which is associated with the vehicle and which is as a rule permanently supplied with energy, and at least one mobile identification device which is intended to identify a respective authorized user. A respective identification device can itself be part of a vehicle key which is in a data exchange, preferably a bidirectional data exchange, with the control device in the region of the locking and/ or

starting system of the vehicle. The respective identification devices can in particular also be integrated in chip cards or the like and can be made, for example, as transponders. Transponders of this type do not have their own energy supply; they are rather supplied with energy in a wireless manner when the identification device approaches the control device and are addressed automatically in the further process for the transmission of the authentication response signals.

With the currently usual easy-to-use access control systems of the initially named kind, at least three antennas which generate magnetic fields clearly differing from one another are provided for the localization of the identification device inside or outside the monitored access region, i.e. for example inside or outside a vehicle, with the different magnetic fields resulting from the different positioning of the antennas inside or outside a vehicle, for example. The magnetic field is usually used, supported by a calculation of the relationships between the RSSI values of different antennas at those positions at which the magnetic field shape does not coincide with the outline of the vehicle, for the localization of an identification device inside the vehicle and/ or for the recognition of access to a vehicle door by a person. "RSSI" is the abbreviation of "received signal strength indication" and represents an indicator for the received field strength of wireless communication applications.

It is the underlying object of the invention to provide an improved easy-to- use access control system of the initially named kind with which in particular a more ideal localization of the identification device is possible.

This object is satisfied in accordance with the invention in that a plurality of transmission/ reception antennas are provided which are arranged at a plurality of different points inside the monitored access region and/ or

vehicle, which are connected to the electronic control device and via which a plurality of different part regions inside the monitored access region can be defined, with the control device including means for the evaluation of received signals of the transmission/ reception antennas to determine the different part regions in which the identification device is located, in the event that the identification device is located within the access region.

A localization of the identification device at the user side in a respective part region inside the monitored access region such as the inner space of a vehicle is now also possible due to this configuration with the easy-to- use access control system. Different part regions inside the monitored access region or the vehicle can be defined, for example via specific parameters, via settable magnetic fields generated by different transmission/ reception antennas arranged inside the monitored access region and/ or vehicle and via the relationship of said magnetic fields among one another. Such parameters are based, for example, on the relationships between different antenna pairs, on the spacing between a respective antenna and the identification device based on RSSI values and/or the like. A map of the respective magnetic field relationships can then be generated on the basis of at least one such parameter.

In an expedient practical embodiment of the easy-to-use access control system in accordance with the invention, the received signals of the transmission/ reception antennas are generated in response to the reception of signals which were transmitted by the identification device.

In this connection, the signals transmitted by the identification device are preferably response signals requested from the control device at the access side.

The received signals of different transmission/ reception antennas are advantageously compared with one another by the evaluation means for the determination of the part region containing the identification device.

It is in particular also of advantage if the received signals of the two transmission/ reception antennas of different antenna pairs are compared with one another by the evaluation means for the determination of the part region containing the identification device.

A further preferred practical embodiment of the easy-to-use access control system in accordance with the invention is characterized in that the spacing between the identification device and different transmission/ reception antennas is determined by the evaluation means and the spacings between the identification device and the different transmission/ reception antennas are compared with one. another for the determination of the part region containing the identification device.

In this connection, the spacings between the identification device and the respective transmission/ reception antennas are advantageously determined on the basis of RSSI values.

At least the horizontal position of the identification device is preferably determined by the evaluation means. It can therefore be determined, for example, whether the identification device is located inside a settable horizontal plane.

A further preferred embodiment of the easy-to-use access control system in accordance with the invention is characterized in that the different part regions defined via the transmission/ reception antennas are imaged on a display by means of the control device and the respectively determined

position of the identification device is marked in a field of the display corresponding to the respective part region.

In this connection, the fields corresponding to the different part regions are advantageously displayable on the display by means of the control device within an outline of the monitored access region reproduced on the display. As already mentioned, the monitored access region can, for example, be the interior space of a vehicle. In this case, the vehicle outline usually used on the display of the onboard vehicle computer to display open doors can be used for the presentation of the vehicle outline.

The respectively determined horizontal position of the identification device can preferably be projected by means of the control device into the region within the outline of the monitored access region and/ or vehicle reproduced on the display.

It is also in particular of advantage for the vertical position or the height of the identification device also to be determined by the evaluation means in addition to the horizontal position. In this connection, the vertical spacing of the identification device from the floor of the respective vehicle can therefore be determined, for example.

In accordance with an expedient practical embodiment of the easy-to-use access control system in accordance with the invention, the horizontal position and the vertical position of the identification device can be represented via a three-dimensional image by means of the control device or its evaluation means.

The vertical position of the identification device can advantageously also be represented on the display in addition to the horizontal position by means of the control device.

In this connection, the vertical position of the identification device can be able to be displayed alpha-numerically on the display, for example.

If the easy-to-use access control system is provided for a vehicle and the monitored access region is accordingly formed by the inner space of the vehicle, in accordance with a preferred practical embodiment, the control device is configured such that a respective engine start is only allowed when it has been found that the identification device is located in a settable part region of the inner space of the vehicle.

A respective engine start is advantageously only allowed in this connection if it was found that the identification device is located in the part region of the inner space of the vehicle including the driver's seat.

The invention can therefore be used, for example, in keyless easy-to-use access control systems, in particular for vehicles, with the feature of a localization of the identification device additionally being realized.

The calculation of the magnetic fields generated by different antennas arranged inside the vehicle is utilized in an ideal manner for this further localization function. Different part regions inside the vehicle can, for example, be defined via specific parameters via the relationship of the magnetic fields relative to one another. These parameters can be based, for example, on relationships between different antenna pairs, on the spacing between a specific antenna and the identification device based on

RSSI values and/ or the like. A map of the magnetic field relationships can be generated on the basis of at least one of the named parameters.

The vehicle outline normally generated on the display of the onboard vehicle computer and used for the display of open doors can also be used for the visualization of the determined or estimated position of the identification device. The calculated horizontal position of the identification device can be projected into the region inside this outline. The estimated or determined height of the identification device can also be represented, for example by text or alpha-numerically, in addition to the horizontal position.

A three-dimensional imaging of the respective positions of the identification device is possible. Starting in particular from such a three- dimensional image, depending on where the identification device was localized, for example, an engine start can then be allowed or prevented. An engine start is thus, for example, only allowed when the identification device is located in defined positions. An engine start can thus in particular be allowed if the identification device is located in the region of the driver's seat, whereas an engine start is prohibited if the identification device is detected in any other part region.