Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G1/00—Traffic control systems for road vehicles
  • G08G1/01—Detecting movement of traffic to be counted or controlled
  • G08G1/042—Detecting movement of traffic to be counted or controlled using inductive or magnetic detectors

Definitions

• the invention relates to a device for detecting vehicles, with at least one current-carrying conductor loop, preferably installed in the floor, and an evaluation unit connected to it for detecting changes in the current in the conductor loop, which are caused by the presence of metallic vehicle components above the conductor loop - the.
• the object of the invention is to provide a device for detecting vehicles of the type mentioned at the beginning, with which it is also possible, in addition to detecting the mere presence of a vehicle, to obtain further information about the vehicle or the vehicle owner.
• the device should have a construction that is as simple as possible and advantageous for existing systems with loops installed in the floor can be retrofitted without major structural interventions.
• a receiving device is provided for contactless acquisition of the data of an identification unit arranged in or on the vehicle, the conductor loop being used as the antenna of the receiving device.
• the measure according to the invention makes it possible, without major structural interventions, to supplement a previous system with a conductor loop for the mere detection of the presence of metallic vehicle components in order to record vehicle-specific or driver-specific data which are stored in the identification unit.
• This system can be used, for example, when entering a parking garage or an underground car park. Normal vehicles with metallic vehicle components are only detected when they are present. A parking ticket is then issued, for example, and a barrier is subsequently opened.
• the presence of the vehicle can also first be detected on the basis of its metallic components.
• such vehicles have an identification unit which is advantageously arranged on the outside on the underside of the vehicle and which can be read by the receiving device according to the invention.
• identification units on vehicles per se is already known.
• An essential aspect of the invention is to use the same conductor loop for the conventional detection of the mere presence of metallic vehicle components on the one hand and for communication with an identification unit which may be present.
• the evaluation unit and the receiving device which may be supplemented by a transmitting device, from the same hardware components (electronic components) and then to operate these hardware components in a first operating mode as an evaluation device for the presence detection of metallic vehicle components and in a second operating mode as a transmitting and receiving device for communication with the identification unit on the vehicle.
• a microprocessor it is possible for a microprocessor to automatically operate the entire device initially in the first operating mode in order to detect the presence of metallic vehicle components. As soon as this presence is recognized, a microprocessor, for example, automatically switches to the second operating mode and tries to read the identification unit. If an identification unit is attached to the vehicle, the data can then be processed further, for example compared with an authorization database. After passing this vehicle, the microprocessor can then switch back to the first operating mode.
• FIG. 1 schematically shows the barrier and parking ticket issuing unit at the entrance of a parking garage or an underground car park with three conductor loops laid one behind the other,
• FIG. 2 shows a vertical section through a conductor loop laid in the ground with an approaching vehicle and equipped with an identification unit
• FIG. 3 schematically shows a simple exemplary embodiment for realizing the idea according to the invention
• FIG. 4 shows a schematic block diagram of an exemplary embodiment of the device according to the invention, as well as an associated identification unit
• 5 shows the current profile in one of the glider loops of FIG. 4 in different vehicle positions or different operating modes of the device according to the invention.
• FIG. 1 shows the arrangement customary in multi-storey car parks or underground garages.
• Three conductor loops S1, S2, S3 are laid in the floor. These record the presence of metallic vehicle components above the conductor loops S1, S2, S3 via an evaluation unit 3 shown schematically in the column 2. If a vehicle moves over the loops S1, S2, a parking ticket is issued and the barriers 4 open, via the loop S3 it can be detected whether the vehicle has left the area of the barrier in order to prevent it from being blocked by the barrier Vehicle collides when closing, the loops S1, S2, S3 and the evaluation unit essentially only detect the presence of metallic vehicle components and their structure only to a limited extent. It is therefore not possible to actually identify individual guest vehicles.
• the invention provides that an identification unit 6 is provided on vehicles 5, in which vehicle and / or driver-specific data are stored.
• the conductor loop S1 is also used as an antenna of a receiving device for reading the data of the identification unit 6 (FIG. 2).
• the conductor loop (or, in the case of several conductor loops, at least one of them) is therefore used twice, once - in order, as was previously the case - only to detect the presence of metallic vehicle components and additionally borrowed as an antenna for reading the identification unit 6 on a vehicle 5.
• FIG. 3 A simple exemplary embodiment of the device according to the invention is shown in FIG. 3. It is a current-carrying conductor loop S1 installed in the floor with an evaluation unit 3 connected to it. This is used to detect changes in the current in the conductor loop S1, which are caused by the presence of metallic vehicle components above the conductor loop. It can thus be detected whether a vehicle is above the conductor loop S1.
• a changeover switch 7 is now provided, which of course can also be implemented electronically.
• This changeover switch 7 is controlled via a control line 8 when the evaluation unit determines that a vehicle is on the loop S1. Then the switch 7 moves to the position shown in FIG. 3 in a position in which it connects the loop S1 to the receiving device for reading the identification unit 6 on the vehicle 5. In this position, the conductor loop Sl thus acts as an antenna for the Empfangsein ⁇ direction "9.
• the changeover switch 7 can then return to the position shown in Fig. 3. In the embodiment shown in Fig.
• Receiving device for communication with the identification unit essentially consist of the same hardware components.
• the same hardware components which advantageously comprise a microprocessor, can then simply be used in a first operating mode as an evaluation unit for the presence detection of metallic vehicle components and in a second operating mode as a (transmitting and) receiving device for communication with the identification unit 6 am Use vehicle.
• FIGS. 4 and 5 Such an embodiment is shown in FIGS. 4 and 5.
• the device shown there thus works both as an evaluation unit 3 for the mere presence detection of metallic vehicle components and as a receiving device for reading the data stored in the identification unit 6.
• the device shown in FIG. 4 has an oscillator 10, which is connected via a power amplifier 11 the loops S1, S2, S3 shown schematically in the floor are supplied with alternating current of fixed frequency f Q. In the exemplary embodiment, this frequency is typically in the range of approximately 100-150 kHz.
• the conductor loops S1 to S3 can be operated in time-division multiplex operation in order to obtain more precise information about the vehicle position. In principle, however, the device would also work with a conductor loop S1, which is why only the conductor loop S1 is referred to below.
• the inductance of the loop S1 and the capacitance of the capacitor device designated overall by 14 form a series resonant circuit which is matched to the driver frequency f Q from the oscillator 10.
• the oscillator 10 in the embodiment shown in FIG. 4 definitely specifies a fixed frequency. If the series resonant circuit S1, 14 is ideally matched to this frequency f 0 , a current with the maximum current intensity flows through the conductor loop S1 and the current detection device 15. Any detuning of the series resonant circuit S1, 14 with respect to the frequency f Q brings about a reduction in the current intensity (amplitude of the alternating current).
• FIG. 5 shows an example of the temporal course of the current intensity detected by the detection device 15.
• the maximum current (amplitude AI) is present in area A. In this time segment there is no metallic vehicle component in the area of the loop S1. Together with the capacitor device 14, this is ideally matched to the fundamental frequency f Q of the oscillator 10.
• the identification device has an antenna 21 and a capacitor 22.
• the switch 23 When the switch 23 is closed, it is possible via this circuit to provide the necessary supply voltage for the electronic logic circuit 25 after rectification in a rectifier 24.
• the identification unit 6 is thus “woken up” by the transmitter pulses from the conductor loop S1.
• Such battery-free identification units are fundamentally already known to the person skilled in the art and therefore need not be described in detail here.
• After "waking up” it is now a matter of the identification unit 6 sending back vehicle-specific or driver-specific data as a response, which are stored, for example, in an E 2 PROM 26.
• the logic circuit 25 receives this stored data and controls the switch 23 via the control line 27 in order to transmit the binary (0/1) -coded data.
• the receiving device 9 determines that it is not receiving any data, the vehicle is not equipped with any (or a non-functioning) identification unit 6.
• the microprocessor 19 opens the barriers 29 via the amplifier unit 28 after it has issued a parking ticket via a parking machine (not shown). If the vehicle is equipped with a functioning data carrier (identification unit 6), the microprocessor 19 can check the read data for authorization with internally or externally stored data in a database and, in the event of a positive result, immediately issue the barrier without issuing a parking ticket 29 open. This means that vehicles with a valid identification unit can pass control stations quickly and easily, in particular barriers at the entrance to a parking garage or underground car park. A particularly advantageous automatic adjustment of the resonant circuit consisting of the conductor loop S1 and the capacitor device 14 to the driver frequency f Q would have to be added . It has been shown that due to external influences or
• Moisture varies the inductance of the conductor loop S1.
• the microprocessor can selectively switch on and off the schematically represented switches of the individual capacitors C1 to C5 via the control line 30 until the digital current value on line 18 becomes maximum.
• the resonant circuit S1, 14 formed is then ideally matched to the oscillator frequency f Q.
• the invention is of course not limited to the exemplary embodiments shown.
• the most diverse types of data carriers (identification units 6) are particularly suitable. For example, those can be used that continuously send out the information contained in them, and indeed without any external query. In a motor vehicle there is always a DC voltage available, the one could supply such a mere transmission identification unit continuously. In this case, the conductor loop S1 does not need to have a transmitting antenna effect, but rather only has a receiving antenna effect.
• other types of data carriers are also conceivable and possible.
• a capacitor device the total capacitance of which can be selectively switched on and off, can also be used in other fields of application and is therefore not tied to use in a vehicle detection device.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Near-Field Transmission Systems (AREA)
• Traffic Control Systems (AREA)
• Geophysics And Detection Of Objects (AREA)

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• 1995
  • 1995-06-30 AT AT95923115T patent/ATE175798T1/de not_active IP Right Cessation
  • 1995-06-30 EP EP95923115A patent/EP0767946B1/fr not_active Expired - Lifetime
  • 1995-06-30 WO PCT/AT1995/000141 patent/WO1996000958A1/fr active IP Right Grant
  • 1995-06-30 DE DE59504829T patent/DE59504829D1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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