Moving vehicle identification system

What is claimed is:

1. A system for the exchange of information via electromagnetic transmission and reception between a fixed location interrogator comprising a data signal processing means and a transponder moving in the vicinity of said interrogator, said system comprising:

means at said interrogator for periodically transmitting trigger pulses;

means, comprising storage means at said transponder, responsive to a first received one of said trigger pulses for transmitting a first data message derived from data contained by said storage means at the time that said first trigger pulse is received;

means at said interrogator for receiving said first data message and responsive to the receipt thereof for generating and transmitting a second data message;

means at said transponder for receiving said second data message and for storing data derived from said second data message in said storage means;

means at said interrogator for transmitting a second trigger pulse a predetermined period of time after said first trigger pulse, the predetermined period of time being of sufficient length to permit the storage in said storage means of data derived from said second message; and

means at said transponder for transmitting a third data message responsive to said second trigger pulse, said third data message comprising data derived from the data contained by said storage means at the time of said second trigger pulse.

2. The system of claim 1 comprising means for analyzing said third data message to determine the proper operation by said transponder in response to said second data message.

3. The system of claim 2 wherein said interrogator comprises means for deriving said second data message from said first data message.

4. The system of claim 3 wherein said interrogator comprises means for deriving said second data message from said first data message and data from weigh in motion apparatus.

5. The system of claim 3 wherein said interrogator comprises means for deriving said second data message from said first data message and data relating to roadway use tolls.

6. A fixed location interrogator for exchanging information with a transponder, comprising a storage means, moving in the vicinity of said interrogator, said interrogator comprising:

antenna means for transmitting and receiving signals conveyed by electromagnetic radiation;

means for periodically transmitting a first trigger pulse via said antenna means;

means for receiving a first data message from said transponder and responsive to the receipt thereof for generating and transmitting a second data message via said antenna means;

means for transmitting a second trigger pulse via said antenna means a predetermined period of time after the transmission of said second data message; and

means for receiving a third data message via said antenna means and for determining from the content of said third data message the proper operation by said transponder in response to said second data message.

7. A transponder for exchanging information with a fixed location interrogator, said transponder moving in the vicinity of said interrogator and comprising:

storage means for containing transponder data;

antenna means for transmitting and receiving signals conveyed by electromagnetic radiation;

means responsive to a first trigger pulse received via said antenna means for transmitting via said antenna means a first data message derived from data contained by said storage means at the time that said first trigger pulse is received;

means for receiving a second data message from said interrogator via said antenna means and for storing data derived from said second data message in said storage means; and

means responsive to a second trigger pulse received from said interrogator via said antenna means a predetermined period of time after said first trigger pulse for transmitting a third data message comprising data derived from the data contained by said storage means at the time of said second trigger signal.

8. A method of exchanging information between a fixed position interrogator and a transponder, comprising storage means for storing data, and moving in the vicinity of said interrogator, said method comprising:

periodically transmitting trigger pulses by said interrogator;

receiving at said transponder a first one of said trigger pulses transmitting by said transponder first data message derived from data contained by said storage means, in response to said first received trigger pulse;

receiving said first data message by said interrogator;

transmitting by said interrogator a second data message derived from said received first data message;

receiving said second data message at said transponder;

storing in said storage means data derived from said received second data message;

transmitting by said interrogator a second trigger pulse a predetermined period of time after said first trigger pulse, said predetermined period of time being of sufficient length to permit the completion of the preceding storing step; and

transmitting by said transponder in response to said second trigger pulse, a third data message derived from the data contained by said storage means at the time of said second trigger pulse.

9. The method of claim 8 comprising analyzing by said interrogator said third data message to assure proper operation by said transponder in response to said second data message.

10. The method of claim 9 comprising deriving by said interrogator, said second data message from said first data message.

11. The method of claim 9 comprising deriving, by said interrogator, said second data message from said first data message and data from weigh in motion apparatus.

12. The method of claim 9 comprising deriving, by said interrogator, said second data message from said first data message and data relating to roadway use tolls.

13. In a system for exchanging information between a fixed position interrogator and a transponder moving in the vicinity of said interrogator, a method of operating said interrogator comprising:

periodically transmitting trigger pulses;

receiving a first data message from said transponder within a predetermined period of time after a first of said trigger pulses;

transmitting a second data message responsive to the receipt of said first data message;

transmitting a second trigger pulse a predetermined period of time after the transmission of said second data message;

receiving a third data message from said transponder after the second trigger pulse transmission step; and

determining from the content of said third data message the proper operation of said transponder.

14. In a system for exchanging information between a fixed position interrogator and a transponder comprising storage means and moving in the vicinity of said interrogator, a method of operating said transponder comprising:

receiving a first trigger pulse from said interrogator;

transmitting, in response to said received first trigger pulse, a first data message derived from data contained by said storage means at the time said first trigger pulse is received;

receiving a second data message from said interrogator;

storing in said storage means data derived from said second data message;

receiving a second trigger pulse from said interrogator after said storing step; and

transmitting a third data message comprising data derived from data contained by said storage means at the time that said second trigger pulse is received.

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BACKGROUND OF THE INVENTION

This invention relates to automatic vehicle identification systems and particularly to such systems which include the ability to accurately modify data stored in a vehicle transponder while the vehicle is in motion.

There is a need for an identification system wherein moving objects such as railroad cars and motor vehicles, passing an interrogation station, identify themselves for both accounting and control purposes. Such a system would also be applicable to boats, trucks, shipping containers, mail bags, pallets, etc. In addition to the above uses the ability to read, write, delete or modify data in a digital form makes the system applicable to a variety of uses, an example of which is a credit card. In this case, the system serves as a portable interrogable memory for information such as a credit balance.

The complexity of modern transportation systems has increased to the point where automated traffic management has become essential for efficient operation. This is true of railways, highway truck transportation, and urban transit systems. Early attempts to meet these needs followed the premise that all that was necessary was to identify the individual vehicles automatically and all other management functions could then be carried out in a central computer. This notion belies the fact that a vast amount of data communications with a central data base are then required. In many cases, particularly when operations cover a large geographic area, this approach is both expensive and impractical. In addition, initial encoding of earlier devices was not satisfactory. The device was either factory-programmed, requiring a cross-reference table to relate the arbitrary number to that of the vehicle, or it was field-programmed by physical and/or electric contact, requiring sealing in the field to ensure package integrity.

An alternative to the centralized storage of vehicle data is to store data in the vehicle itself. This requires a system which includes data storage in the vehicle and the ability to change that information. Such systems are disclosed, for example in Baldwin, et al., U.S. Pat. No. 4,870,419 and Cardullo, et al., U.S. Pat. No. 3,713,148. Although these known systems are capable of changing data stored in a moving vehicle, both transmit signals specifying data change, then do nothing to assure that accurate data change actually occurs. Data modification without assured accuracy can result in many vehicles containing inaccurate data to the detriment of both the operators of those vehicles and the traffic control and regulation systems relying on such data.

A need exists for an automatic vehicle identification system having the ability to change the content of memory of a moving vehicle and which provides assurances that such changes are accurately completed.

Also needed is a reader-transponder system which utilizes a multi-function transponder. More specifically a multi-function transponder can cooperate with a reader or an interrogator to perform the following functions with the vehicle in motion:

1) Transmit vehicle identification and other basic data;

2) Accept programming of input data from the interrogator;

3) Communicate with other equipment on board of the vehicle such as a visual display, speed alarm and road advisories; and

4) Work with additional input from the vehicle such as weight on the road as measured by a vehicle road sensor such as disclosed and claimed in C. M. Tromp U.S. Pat. No. 4,799,381 ("Vehicle Road Sensor").

SUMMARY OF THE INVENTION

The present invention provides an electronic identification system that can store both fixed and changing information on a moving object, such as a railroad car, without physical contact and while the object is moving at relatively high speeds. Furthermore, a portion of the information stored on the object can be protected from accidental erasure so that portion cannot be changed without further steps being taken. After a change of non-protected data is requested, an additional read of the data is initiated by the device requesting the change so that the data actually stored in the vehicle can be checked to make certain that the requested change was actually made.

In the case of a highway vehicle, the system provides the vehicle's identity and other pertinent information relating to the vehicle. Some of the information is protected from erasure, such as the identification number, the type of vehicle and loading limits. Other information, such as a toll credit balance and weight as measured by weigh in motion apparatus can be reprogrammed remotely by an interrogation station.

To provide for high speed transmission of information, a memory that can be read and changed and has a number of separate pages to store information is located on the object. Different interrogation stations can then be placed to send encoded interrogation signals to read individual pages of information. Some pages may be protected from erasure as they contain fixed information, while other pages may be remotely changed as desired. By utilizing separate pages in the memory, and more than one interrogation station, more information can be gathered in a shorter space of time, thus allowing higher relative speeds between the object and the interrogation station. The information gathered by the interrogation stations may be transmitted in a computer-compatible format for storage and transmission by existing data communication systems.

Another use for the system is to place electronic identification devices along the path, such as a railroad track, road or highway, and install an interrogation station on a moving vehicle, such as a railroad train, automobile or truck. The electronic identification system of the present invention has an information and identity storage device including a logic circuit and memory, trigger circuit and a transmitter located on the object, with the trigger circuit operating on low power. Upon being triggered by a signal from a remote interrogation station, the transmitter transmits the data into memory in a short series of transmissions. Power for the transmitter is provided by battery but can include other sources of power, such as an inertial generator, electromagnetic generation, induction, visible or infrared light, or by combinations of these power sources. Moving objects can generate power for the transmitter from movement or vibration in a gravitational field. This technique can also be used to extend the life of the battery.

The interrogation station, as well as sending a signal to trigger the trigger circuit, also has a pulse sequence generator to program the memory on the object, a receiver to receive the data from the memory on the object, and an arrangement for checking the accuracy of data received by requesting a readout thereof.

The use of an absolute time source in the information and identity storage device provides for synchronization between the transmitter and the receiver and allows the use of a non-return to zero (NRZ) code format. Alternatively, a free running clock can be used in the system and synchronization can be effected by choice of a suitable code format and appropriate processing in the decoding unit.

This system has the additional advantage of allowing the clock oscillator to be gated off between interrogations with further savings in quiescent power consumption. The data transfer rate for the transmitter should be sufficient to allow for the relative velocity between the object to be identified and the interrogation station.

The information and identity storage devices of automatic vehicle identification systems have to be suitably packaged for protection against weather and environmental conditions and have antennas to allow transmission and receipt of coded signals in suitable locations. In a disclosed embodiment, the vehicle transponder is mounted behind the vehicle license plate to provide secure, easy mounting in a location having good RF exposure to roadway mounted antennas.

The present invention provides an electronic identification system for remotely storing information on an object, and remotely retrieving information from the object. The electronic identification system includes, in combination, an information and identity storage device located on the object, and at least one interrogation station located remotely from the object. The interrogation station is adapted to read data from the information and identity storage device as well as to program it without physical contact. After programming, the data of the vehicle is read to check the accuracy of the reprogramming.

The information and identity storage device comprises memory means for storing information and identity data, and protect means for protecting a portion of the memory means against accidental erasure. Logic circuit means for producing a predetermined coded signal representing the information and identity data stored in the memory means has a remote non-contact means for programming the portion of the memory means not protected by the protect means. Transmitter means for transmitting the coded signal is coupled to trigger circuit means which, when triggered, causes the coded signal to be transmitted. A battery power source energizes the other portions of the information and identity storage device.

The interrogation station comprises interrogation signal means for triggering the logic circuit means in the information and identity storage device and pulse sequence generating means for programming the portion of the memory means on the information and identity storage device not protected by the protect means. The interrogation station also has receiver means for receiving the coded signal from the information and identity storage device and synchronization means between the information and identity storage device, and the receiver means. Decoder means for decoding the coded signal, verifies the accuracy of the coded signal, and recovers the information and identity data stored in the memory means of the information and identity storage device and transmitted to the interrogation station. The interrogation station further requests re-transmission of data after a reprogramming request so that the accuracy of reprogramming can be ascertained.

An absolute time source is provided integral with the information and identity storage device, together with synchronization means between this time source and the receiver means. In another embodiment, the memory means has the ability to store a plurality of pages representing the information and identity data, and the logic circuit means can select data from the plurality of pages upon receipt of predetermined timed interrogation pulses from the interrogation station. In yet a further embodiment, the decoder means verifies the accuracy of the coded signal by including an integral count of the number of zeros in the coded signal.

An additional embodiment of the vehicular identification system and the equipment disclosed herein is monitoring highway vehicles' motion on multi-lane highways such as toll roads and expressways. In particular, states of the United States have found it necessary to control heavy truck traffic on interstate highways within their borders. In order to effectively maintain traffic control, in particular, it is necessary and desirable to weigh, identify and accurately communicate with vehicles as they traverse bi-directionally on multi-lane highways. In keeping with the present and future highway speed limit, it is necessary to do this at speeds such as 70 m.p.h. Typically, in order to describe the systems disclosed herein, 120 ft./sec. or 72 m.p.h. will be used, although higher speeds can be accommodated at increased data rates. The use of radio frequency signals from the road surface to high speed vehicles, such as trucks travelling along bidirectional multi-lane highways, presents appreciable application difficulties. As those skilled in the art will recognize, it is necessary to transmit and receive signals from the road surface to each lane of the highway and individually identify each vehicle, although they may be closely spaced, as they travel over a transmitting and receiving antenna located at the highway surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an electronic identity system having an information and identity storage device and an interrogation station and embodying the present invention;

FIG. 2 is a schematic diagram illustrating one embodiment of a vibrationally driven power source for the information and identity storage device of FIG. 1;

FIG. 3 is a block diagram of a logic circuit in the information and identity storage device of FIG. 1;

FIG. 4 is a schematic diagram of a microwave triggered circuit of the information and identity storage device of FIG. 1;

FIG. 5 is a block diagram of the interrogation station of FIG. 1;

FIG. 6 is a block diagram showing the coded signal receiver of the interrogation station of FIG. 5;

FIG. 7 is a diagram of the identification system of the invention as installed on a bidirectional, four lane highway, particularly showing the location of individual lane triggering and receiver antennas;

FIG. 8A shows a single lane portion of the four lane highway of the type shown in FIG. 7 having positioned therein a 130 kHz. triggering loop and a 2450 MHz. leaky coax antenna;

FIG. 8B shows another single lane portion of the four lane highway of the type shown in FIG. 7 having positioned therein a 130 kHz. triggering loop antenna and a 915 MHz. colinear array receiving antenna;

FIG. 8C shows a single lane portion of the four lane highway of the type shown in FIG. 7 having positioned therein a 915 MHz. colinear array, triggering pulse transmitting and a 915 MHz. colinear array data receiving antenna;

FIG. 8D shows a single lane portion of the four lane highway of the type shown in FIG. 7 having positioned therein a single 915 MHz. colinear array antenna for interrogation, transponder triggering, and transponder signal receiving through the use of a directional coupler;

FIG. 9 is an isometric view of the antenna and a reflective shield or channel housing embodying the present invention, showing details of the positioning of the channel in a roadway of a highway and the position of the antenna in the channel;

FIG. 9A is an isometric view of the colinear array antenna of FIG. 9, showing further details of its construction;

FIG. 9B is an additional depiction of a portion of the colinear array of FIG. 9A, showing two complete elements and a partial element constructed from coaxial cable;

FIG. 9C is a graphic depiction of the current distribution in the center conductor of the coaxial cable elements of the array of FIG. 9B; FIG. 9D is a further graphic depiction of the current distribution in the sheath of the coaxial cable elements of the antenna of FIG. 9B;

FIG. 10 is a sectional view taken substantially along line 10--10 of FIG. 9, showing details of the colinear array antenna and the reflecting shield;

FIG. 10A is a partly sectional view of the colinear array antenna of FIG. 8D, in an operative position showing details of the radiation signal pattern of the colinear array antenna in a direction parallel with the colinear array;

FIG. 10B is an elevational view of the roadway of FIG. 9, showing the pattern of radiated energy from the colinear array antenna and reflecting shield of FIG. 9;

FIG. 11 is a diagrammatic representation of the sequence of triggering and data pulses transmitted and received by an interrogation station positioned adjacent a fourth lane of a four lane highway;

FIG. 12 is an isometric view of one form of a leaky coax radiating element;

FIG. 13 is a timing diagram of information exchange between an interrogator and transponder of an embodiment;

FIG. 14 is a bock diagram of a logic circuit in the information and identity storage device for use with a single transmit and receive antenna;

FIG. 15 is a flow diagram of functions performed by an embodiment of the interrogation station of FIG. 1;

FIG. 16 is a flow diagram of the functions performed by information and identity storage device (transponder) of FIG. 14;

FIG. 17 illustrates an embodiment the advantageous placement of the vehicle antenna on the vehicle license plate; and

FIG. 18 is a diagrammatic representation of the use of trigger pulses to convey data.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, an electronic identification system 8 includes a transponder or identification and identity storage device 10 and a fixed transponder or interrogation station 11. The information and identity storage device 10 includes a power source 12, a logic circuit and a memory 13, a receiver and trigger circuit 14 with a first antenna 15, a radio frequency transmitter 16 and a second antenna 17. The interrogation station 11 includes a receiver 18 with an antenna 19 of an antenna array, a decoder 20, a data processor 21, which provides data format memory and control functions, and a trigger interrogation pulse sequence generator and a transmitter 22 with an antenna 23. The data processor 21 aids in the decoding process, formats the data for communication with a central data processing unit (not shown) and generally controls the functions of the interrogation station 11. In general, the complexity of the data processor 21 depends on the particular function which the electronic identification system 8 is required to perform.

The power from the power source 12 for data retention in the memory of the information and identity storage device 10 must be present at all times unless an EEROM is used and so a battery is required. However, the battery could be supplemented by other power sources including energy transfer from inductive or radio frequency energy fields, of which several examples exist in prior art, or inertial field generation as described herein. In many embodiments, of which railroad cars are one example, the power requirements are such that available batteries could provide up to a 20 year operational lifetime without supplemental sources of energy. For those applications where additional energy is required, and where the object requiring data storage is in motion, a means for producing power for data transmission is from the inertial field.

FIG. 2 illustrates an inertial energy generator where electric power is derived from the vibration or vertical movement of the moving object. A small mass 30 is shown mounted in a frame 31 on one end of a resilient strip 32. Piezoelectric material 33 is bonded to each side of the strip 32, and a movement of the mass 30, causing deflection of the strip 32, generates an alternating voltage. Leads 34 from the piezoelectric material 33 feed to a circuit where rectification and doubling of the voltage is performed by the diodes 35, 36 and the energy storage capacitors 37, 38. Alternatively, an ordinary full-wave or half-wave rectifier may be used if the higher voltage is not required. The direct current energy either can be stored in the capacitors 37, 38 or in a rechargeable battery 39. A means for limiting the maximum voltage is provided in the form of a Zener diode 40, by a number of diodes in series, or by a voltage regulator circuit.

The contents of the memory are maintained by the battery power source 12 which provides sufficient energy to the transmitter 16 so that the coded signal is completely transmitted before the stored power drops low enough to stop the data transmission. The transmitter 16 draws little power from the power source 12, in its quiescent state, allowing excess generated energy from the power source 12 to be stored for later transmission. The data to be transmitted from the information and identity storage device 10 must be formatted in such a way that the desired information is conveyed accurately. While the following scheme is the preferred embodiment for marking railroad cars, a number of variations are possible. In general, the data will contain coded information to designate the owner of the car and the car's serial number in a protected portion of the memory.

Data bits can be coded in various ways. For North American rail