WO2005017853A1

WO2005017853A1 - Classification of vehicles

Info

Publication number: WO2005017853A1
Application number: PCT/IB2004/002624
Authority: WO
Inventors: Petrus Paulus Haasbroek
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-08-13
Filing date: 2004-08-12
Publication date: 2005-02-24
Anticipated expiration: 2006-02-13

Abstract

A vehicle classifying system (10) includes a sensor arrangement (14) for sensing the number of wheels on a vehicle axle. The system (10) further includes a sensor (16) for sensing the presence of a vehicle. In addition it includes an axle counting sensing arrangement (18). The sensor arrangements (14, 16 and 18) are connected to a processor and from signals generated by the sensor arrangements (14, 16 and 18) the processor is able to determine when a vehicle is present, the number of axles the vehicle has and the number of wheels on each axle. This permits the vehicle to be classified to determine the toll fee payable at a toll collection point.

Description

CLASSIFICATION OF VEHICLES

THIS INVENTION relates to the classification of vehicles. More particularly it relates to a method of automatically classifying a vehicle and to an automatic vehicle classifying system. Various systems are used to monitor vehicular traffic. These include induction loop sensors, treadles, optical sensing arrangements and the like.

In certain applications e.g. at a toll booth, it is important not only to detect the presence of a vehicle but also, in an automatic fashion, to be able to classify the vehicle as belonging to a particular vehicle class since the toll fee payable may vary depending on the class into which a vehicle falls. One criterion which is used to classify vehicles is the number of wheels per axle. In the context of this specification a "single-wheel axle" is to be understood as an axle which has a single wheel at each side such as that on motor cars, light delivery vehicles and the like. The term "multiple-wheel axle" is to be understood as an axle having two or more closely spaced wheels on each side such as that on heavy vehicles. However, prior art automated systems of which the Inventor is aware encountered difficulties in reliably classifying a vehicle as having single-wheel axles and/or multiple-wheel axles. It is an object of this invention to provide means which the Inventor believes will at least alleviate this problem.

According to one aspect of the invention there is provided a method of automatically classifying a vehicle at a classification station which includes the steps of monitoring a plurality of distinct zones in a lane through which the vehicle is to move, the zones being arranged transversely to the intended direction of travel of the vehicle; and generating an output signal which is indicative of the width of a wheel and/or the number of wheels on an axle of the vehicle.

Monitoring the zones may include providing at least one vehicle wheel detecting sensor associated with each zone, the sensor being configured to sense whether or not a vehicle wheel is present in that particular zone.

According to another aspect of the invention there is provided an automatic vehicle classifying system which includes at least one sensor arrangement having a plurality of vehicle wheel detecting sensors arranged at a plurality of transversely spaced positions across a lane through which vehicles are to move, each sensor being arranged to sense whether or not a vehicle wheel is present in a predetermined zone associated with the sensor. Hence, in use, depending upon the number of wheels sensed by the sensor arrangement a vehicle can be classified as having a single- wheel axle or a multiple-wheel axle or a combination of the two.

It will be appreciated that, depending on the width of the zone being monitored by each sensor, a vehicle wheel may activate two or more sensors. Accordingly, the width of each zone will typically be selected to be less than the spacing between the wheels of a multiple-wheel axle such that when a vehicle with a multiple-wheel axle passes through the classification station, at least two sensors or sets of sensors will sense the presence of the two wheels and be activated with at least one sensor, positioned between the activated sensors or sets of sensors, remaining unactivated.

Each zone will typically have a width which is less than half of the spacing between the wheels on a multiple-wheel axle. Typically the zones will have a width of from 20 mm to 40 mm. Preferably, each zone has a width of about 40 mm.

Each sensor may include a transmitter and a complementary receiver, the signal between which is altered by the presence of a vehicle wheel in the zone being monitored In one embodiment of the invention, the transmitter is capable of generating a beam of electromagnetic, typically infra-red, radiation which, in the absence of a vehicle wheel in the associated zone, is received by the receiver and is interrupted by the presence of a vehicle wheel in the associated zone.

The transmitters and receivers may be positioned on opposite sides of a transversely extending recess which extends at least partway across the lane.

The automatic vehicle classification system may also include a processor for receiving signals generated by the at least one sensor arrangement and classifying a vehicle axle as being a single- or multiple- wheel axle according to the signal generated.

The automatic vehicle classification system may include at least one further sensor arrangement which is linked to the processor.

The automatic vehicle classification system may include a sensor arrangement for sensing the presence of an object in a predetermined region, the at least one sensor arrangement being positioned within the predetermined region. This sensor arrangement may be in the form of an induction loop sensor.

The automatic vehicle classification system may include an axle' counting sensor arrangement. The axle counting sensor arrangement may include a pair of longitudinally spaced transversely extending sensors. The sensors may be in-road sensors such as contact treadles, piezo elements or the like. Instead, they may be electromagnetic, e.g. infra red beams or the like. The automatic vehicle classification system may include a bonnet sensing arrangement. The bonnet sensing arrangement may include an electromagnetic, e.g. infra-red, beam sensor.

The automatic vehicle classification system may include a vehicle profile sensing arrangement. The vehicle profile sensing arrangement may include a plurality of transverse beam sensors arranged at different heights above the road surface thereby permitting a profile of a vehicle to be determined.

The invention extends also to a sensor arrangement for use in an automatic vehicle classifying system as described above.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings: Figure 1 shows a schematic three-dimensional view of part of an automatic vehicle classifying system in accordance with the invention; Figure 2 shows a three-dimensional view of part of a sensor arrangement forming part of the automatic vehicle classifying system of Figure 1 ; Figure 3 shows a cross-sectional view taken at III - III in Figure 2; and Figure 4 shows a three-dimensional view of part of another sensor arrangement suitable for use in a vehicle classifying system. In the drawings, reference numeral 10 refers generally to part of an automatic vehicle classifying system in accordance with the invention. The system 10 is provided at a vehicle classification station which is generally indicated by reference numeral 12 which could be at any suitable location. In a preferred embodiment of the invention, the system 10 is provided at a toll fee collection station and is used to classify a vehicle passing through the station 12 to ensure that the correct toll is in fact paid as described in more detail below. The system 10 includes a sensor arrangement, generally indicated by reference numeral 14, the purpose of which is to determine the number of wheels on an axle of a vehicle passing through the station 12. The system 10 further includes a sensor arrangement, generally indicated by reference numeral 16 for sensing the presence of a vehicle in the station 12.

In addition, the system 10 includes an axle counting sensor arrangement, generally indicated by reference numeral 18, for counting the axles on a vehicle passing through the station 12.

The sensor arrangement 16 is in the form of an induction loop sensor and includes at least one coil 20 which is embedded in a surface, e.g. the surface of the road 22, along which vehicles passing through the vehicle classification station have to travel.

The axle counting sensor arrangement 18 includes a pair of infrared beam sensors 24, 26, which are longitudinally spaced relative to the direction of travel indicated by arrow 28. The beam sensor 24 includes a transmitter 30 positioned on one side of the road 22 and a complementary receiver 32 positioned on the other side of the road. Similarly, the beam sensor 26 includes a complementary transmitter 34 and receiver 36 positioned on opposite sides of the road 22. Hence, the sensors 24, 26 define transversely extending longitudinally spaced beams 38, 40 which are at a height such that the beams are broken or interrupted by the wheels on each axle of a vehicle passing through the station 12. Hence, by counting the number of times the beams are broken the number of axles on a vehicle can be determined.

The sensor arrangement 14 is positioned within the coil 20 and comprises a plurality of distinct transversely spaced zones 42. The arrangement 14 further includes, associated with each zone 42 at least one vehicle wheel detecting sensor configured to determine whether or not a vehicle wheel is present in the associated zone 42. In one embodiment of the invention, the sensor arrangement 14 may be in the form of a strip sensor such as that which is available from Mikros (Proprietary) Limited.

In another embodiment of the invention, as can best be seen in Figures 2 and 3 of the drawings, the sensor arrangement 14 includes a transverse recess 44 in the surface of the road, the recess 44 having opposed longitudinally spaced sides 46. A plurality of transversely spaced transmitters 48 is provided in one of the sides 48 with corresponding complementary receivers 50 being provided on the opposite side 46. The transmitters 48 are configured to generate a narrow beam of electromagnetic, typically infra-red, radiation. At least one transmitter 48 and complementary receiver 50 are associated with each pf the zones 42. The width of the recess 44 is selected such that a tyre of a vehicle wheel passing over the sensor arrangement 14 will protrude sufficiently far into the recess 44 so as to be positioned between the transmitter 48 and its complementary receiver 50 thereby blocking the transmission from the transmitter to the receiver.

It will be appreciated that, in order to reduce the risk of incorrect readings, the spacing between the transmitters 48 must be small enough that a vehicle wheel is not receivable therebetween without blocking the transmission form at least one transmitter to its complementary receiver. It is accordingly possible that a vehicle wheel may then interrupt the transmission from two or more transmitters 48 to their complementary receivers 50. In order to permit the sensor arrangement 14 to be able to determine the number of wheels on a vehicle axle, the spacing between the transmitters 48 is selected to be less than half of the spacing between the wheels on multiple axles. As a result, when two wheels of a multiple wheel axle are positioned in the recess 44 the signals from at least two transmitters 48 or sets of transmitters 48 to their associated receivers 50 will be interrupted, however, the transmission from at least one transmitter 48 positioned between the transmitters or sets of transmitters will not be interrupted thereby indicating that multiple wheels are positioned on the sensor arrangement 14.

With reference now to Figure 4 of the drawings, reference numeral 60 refers generally to another sensor arrangement 14 in accordance with the invention. In this embodiment of the invention, the transmitter 48 and complementary receiver 50 are not directed towards one another. Instead, the transmitter 48 and receiver 50 are directed upwardly and inwardly such that when a vehicle tyre is positioned on top of the transmitter and receiver, the signal received by the receiver 50 is different to that when no vehicle tyre is present. In other respects the sensor arrangement 60 functions in a similar fashion to the sensor arrangement 14.

In use, the sensor arrangements 14, 16, 18 are connected to a processor and from the signals generated, the processor is able to determine when a vehicle is present in the station 12, the number of axles that the vehicle has, and the number of wheels on each axle.

More particularly, when a vehicle (not shown) enters the vehicle classification station its presence is detected by the induction loop sensor 16. The induction loop sensor 16 generates a signal which indicates to the processor that a vehicle has entered the station. As the vehicle continues to travel in the direction of arrow 28 the front wheels of the vehicle interrupt the beam 38 resulting in a signal being transmitted from the sensor 24 to the processor. Subsequently, the front wheels interrupt the beam 40 resulting in a signal being transmitted from the sensor 26 to the processor. As the wheel passes, the beam 38 is re-established and subsequently the beam 40 is re-established with corresponding signals being sent to the processor. Each time the beams 38, 40 are interrupted will correspond to an axle of the vehicle passing through the station 12. In addition, the signals from these sensors can be used to determine the direction of travel of the vehicle. Further, the signals can be used to calculate the speed of an axle and by comparing the different axle speeds for a vehicle, the average acceleration of a vehicle. As the vehicle axle moves over the sensor arrangement 14, signals are received from the sensors associated with each of the zones 42 in which the presence of a vehicle is detected. The sensor arrangement is used physically to measure the width and separation of a double wheel on the one side of an axle. The sensor arrangement also provides outputs which include an indication of the presence of an axle/wheel, a profile of the wheel footprint, the estimated width of the wheel, the duration of occupancy and whether the axle consists of single or dual wheels per side.

Optionally, the vehicle classification system 10 includes another sensor arrangement, generally indicated by reference numeral 70. In the embodiment shown, the sensor arrangement 70 is a vehicle profile sensing arrangement which includes on one side of the road 22 a post 72 on which a plurality of electromagnetic beam, typically infra-red, vertically spaced transmitters 74 is provided. The sensor arrangement 70 further includes a post 76 positioned on the other side of the road 22 on which, complementary receivers (not shown) are provided. Instead, or in addition, the system 10 may include a variable height measurement sensor (not shown) which is used to indicate whether a vehicle has a bonnet or not.

In South Africa, vehicles with a mass of less than 3 tonnes and with single road wheels all round are classified as light vehicles. Light vehicles are classified in various sub-classes, namely: Class 2L - Light vehicle with two axles Class 3L - Light vehicles with three axles Class 4L - Light vehicles with four axles Class 5L - Light vehicles with five axles Class 6L - Light vehicle with six axles.

A heavy vehicle is a vehicle having double wheels on an axle. Once again, heavy vehicles are divided into various sub-classes namely: Class 2H - Heavy vehicle with two axles Class 3H - Heavy vehicle with three axles Class 4H - Heavy vehicle with four axles Class 5H - Heavy vehicles with five axles Class 6H - Heavy vehicles with six axles Class 7H - Heavy vehicles with seven axles Class 8H - Heavy vehicles with eight axles.

The Inventor believes that the system 10 will be suitable for use in classifying vehicles at any desired location. In this regard it is envisaged that the system 10 may be portable. However, the Inventor believes that the system 10 will find application particularly at a toll collection point. In this application, when a vehicle approaches a toll collection point, an operator visually classifies the vehicle and the toll payable is determined by this classification. Typically, the collector will input the classification to a toll collecting computer system e.g. by means of a key board. The toll collecting computer will capture the classification, and transmit a message to a toll display unit indicating to the driver of the vehicle the toll payable. Once the toll has been paid the vehicle moves in the direction of arrow 28 and passes through the station 12 in which, as described above, the vehicle is classified according to its number of axles as well as the number of wheels per axle. Further, by making use of the sensor arrangement 70 as well as the speed measurement determined by the sensor arrangement 18, a side profile of the vehicle can be determined. In this way, the system 10 automatically classifies the vehicle and this classification is compared with that inputted by the toll collector. If the classification inputted by the toll collector and that determined by the sensor 10 correspond, then the transaction is considered as being completed and the next transaction can be processed. If, however, the classification does not correspond then the discrepancy is recorded for further processing in terms of one or more auditing mechanisms.

In the present case the system is used to classify the vehicle as it leaves the station 12. However, it will be appreciated that it could be used to classify a vehicle approaching the station, so that the toll fee payable could be determined by this classification.

The Inventor believes that one advantage with the vehicle classification system in accordance with the invention is that the provision of the sensor arrangement 14 enables the system 10 accurately and reliably to determine the number of wheels on a vehicle axle thereby improving the accuracy of the classification of the vehicle over prior art systems of which the Inventor is aware.

A further advantage of the system 10 is that it is particularly compact. More specifically, the footprint of the system 10 can have a width measured in the direction of travel of the vehicle, i.e. in the direction of arrow 26, of as little as 500 mm. This compares with prior art systems of which the Inventor is aware which have a footprint of between 3 m and 6 m. In view of the fact that a toll transaction cannot be considered complete until the vehicle has passed through the classification system 10, this reduction in the size of the footprint substantially reduces the time associated with the classification of the vehicle thereby increasing the lane processing time. This in turn results in a higher throughput of vehicles per lane.

Claims

1. A method of automatically classifying a vehicle at a classification station which includes the steps of monitoring a plurality of distinct zones in a lane through which the vehicle is to move, the zones being arranged transversely to the intended direction of travel of the vehicle; and generating an output signal which is indicative of the width of a wheel and/or the number of wheels on an axle of the vehicle.

2. A method as claimed in claim 1 , in which monitoring the zones includes providing at least one vehicle wheel detecting sensor associated with each zone, the sensor being configured to sense whether or not a vehicle wheel is present in that particular zone.

3. An automatic vehicle classifying system which includes at least one sensor arrangement having a plurality of vehicle wheel detecting sensors arranged at a plurality of transversely spaced positions across a lane through which the vehicles are to move, each sensor being arranged to sense whether or not a vehicle wheel is present in a predetermined zone associated with the sensor.

4. A system as claimed in claim 3, in which the width of each zone will typically be selected to be less than the spacing between the wheels of a multiple-wheel axle such that when a vehicle with a multiple-wheel axle passes through the classification station, at least two sensors or sets of sensors will sense the presence of the two wheels and be activated with at least one sensor, positioned between the activated sensors or sets of sensors, remaining unactivated.

5. A system as claimed in claim 4, in which the zone has a width which is less than half of the spacing between the wheels on a multiple- wheel axle.

6. A system as claimed in claim 4 or claim 5, in which the zones each have a width of from 20 mm to 40 mm.

7. A system as claimed in claim 5 or claim 6, in which each zone has a width of 30 mm.

8. A system as claimed in any one of claims 3 to 7, inclusive, in which each sensor includes a transmitter for transmitting a signal and a complementary receiver for receiving the signal, which signal is altered by the presence of a vehicle wheel in the zone being monitored

9. A system as claimed in claim 8, in which the transmitter is capable of generating a beam of electromagnetic radiation which, in the absence of a vehicle wheel in the associated zone, is received by the receiver and is interrupted by the presence of a vehicle wheel in the associated zone.

10. A system as claimed in claim 8 or claim 9, in which the transmitters and receivers are positioned on opposite sides of a transversely extending recess which extends at least partway across the lane.

11. A system as claimed in any one of claims 3 to 10, inclusive, which includes a processor for receiving signals generated by the at least one sensor arrangement and classifying a vehicle axle as being a single- or multiple- wheel axle according to the signal generated.

12. A system as claimed in claim 11 , which includes at least one further sensor arrangement which is linked to the processor.

13. A system as claimed in claim 12, which includes at least one object sensing sensor arrangement for sensing the presence of an object.

14. A system as claimed in claim 13, in which the object sensing sensor arrangement is in the form of an induction loop sensor for sensing the presence of an object in a predetermined region the at least one sensor arrangement being positioned in the predetermined region.

15. A system as claimed in any one of claims 11 to 13, inclusive, which includes an axle counting sensor arrangement.

16. A system as claimed in claim 15, in which the axle counting sensor arrangement includes a pair of longitudinally spaced transversely extending sensors.

17. A system as claimed in claim 16, in which the sensors are in-road sensors.

18. A system as claimed in claim 16, in which the sensors are electromagnetic beam sensors.

19. A system as claimed in any one of claims 12 to 18, inclusive, which includes a bonnet sensing arrangement.

20. A system as claimed in claim 19, in which the bonnet sensing arrangement includes an electromagnetic beam sensor.

21. A system as claimed in any one of claims 12 to 20, inclusive, which includes a vehicle profile sensing arrangement.

22. A system as claimed in claim 21 , in which the vehicle profile sensing arrangement includes a plurality of transverse beam sensors arranged at different heights above the road surface thereby permitting a profile of a vehicle to be determined.

23. A sensor arrangement for use in an automatic vehicle classifying system as claimed in any one of claims 3 to 22 inclusive.