CA1108294A - Measuring systems - Google Patents
Measuring systemsInfo
- Publication number
- CA1108294A CA1108294A CA316,891A CA316891A CA1108294A CA 1108294 A CA1108294 A CA 1108294A CA 316891 A CA316891 A CA 316891A CA 1108294 A CA1108294 A CA 1108294A
- Authority
- CA
- Canada
- Prior art keywords
- vehicle
- detector
- radiation
- measuring system
- emitters
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Length Measuring Devices By Optical Means (AREA)
- Traffic Control Systems (AREA)
Abstract
ABSTRACT
A measuring system particularly for measuring the length of a moving vehicle comprises a pair of detector stations spaced a known distance apart along a path of vehicle movement each detector station comprising a vertically extending series of electromagnetic radiation beam-emitters disposed on one side of the path and at least one detector disposed on the other, The beams from the emitters are aimed at the detector so that each part of the vehicle when disposed between the emitters and detector will interrupt some of the beams to produce a characteristic quantity of incident electro-magnetic radiation on the detector which will serve to identify that part of the vehicle. Data processing means are provided for processing the outputs from the detectors at the two stations to provide a velocity related vehicle measurement.
A measuring system particularly for measuring the length of a moving vehicle comprises a pair of detector stations spaced a known distance apart along a path of vehicle movement each detector station comprising a vertically extending series of electromagnetic radiation beam-emitters disposed on one side of the path and at least one detector disposed on the other, The beams from the emitters are aimed at the detector so that each part of the vehicle when disposed between the emitters and detector will interrupt some of the beams to produce a characteristic quantity of incident electro-magnetic radiation on the detector which will serve to identify that part of the vehicle. Data processing means are provided for processing the outputs from the detectors at the two stations to provide a velocity related vehicle measurement.
Description
8~
l`his invention relates to measuring systems and has pa-rticular, but not exclusive, application to the measurement o~ the lengtll of moving vehicles.
In the txansportation oE commercial road vehicles by sea ferries, the tariEf charged is based, inter alia, on vehicle length. The tarife is normally expressed as a charge per metre with a gradation down to 0.1 metre which is charged proportianally. At the present time the declared lengths of vehicles are checked on a random basis to discourage under-declarations of length. This checking is carried out by inspectors using tape-measures or the like and has to be carried out while the vehicles are stationary; it is thereEore time-~onsuming and labour intensive.
The main object Oe the present invention is to provide a measuring system which enables the length of a vehicle to be measured automatically while the vehicle is moving.
Accordingly the present invention provides a measuring system comprising:-(a) a pair of detector stations spaced a predetermined distance apart along a path of movement for a vehicle, each detector station comprising a vertically extending series of electromagnetic radiation emitters disposed on one side of said path, each emitter producing a clirectional beam of radiation, and at least one electromagnetic radiation detector ~hich is designed to produce an electrical output signal related to the quantity or intensity ot radiation incident upon it, said detector being disposed on the other side of said path and said emitters or a group of said emitters being arranged to direct their l~eams at it, whereby the said quantity or intensity of incident electromagnetic radiation re~istered by said detector is dependent upon the number of said beams interceptecl by a passing ~ehicle, and ,., : . :
:: : :: ::
32~L
(b) data processing mean.s for processing the output signals from said detectors on a time basis and utilising the Icnown predetermined spacing of said detector stations to provide a velocity related vehicle measurement.
Said electromagnetic radiation is advantageous,ly infra-red radiation.
Thus the measuring systèm of the invention can be used to measure vehicle length and/or vehicle velocity.
As will be explained the measurement of vehicle length is a function of vehicle velocity, which in turn is a function of the time taken for an identifiable point on the vehicle to cover the known distance between the two detector stations.
With the above defined emitter and detector arrangements at the two detector stations, a vehicle as it passes each detector station will produce on the d~tector a radiation lntensity or quantity pattern determined by the number of said radiation beams which are interrupted by each cross-section of the vehicle passsing through that station, From these patterns certain characteristic points along the vehicle are readily identiflable. Hence a measurement of the time taken for a number of identifiable points to move between the two stations can be made and an average transit time arrived at, which will compensate within limits for variation in vehicle velocity as it i9 moving between the two stations.
One of the characteristic points which is iderltifiable by pattern recognition are vehicle axles. The system can therefore additionally be used to count the number of vehicle axles, and this in combination with a weight measurement can provide information regarding axle loading.
'rhe measuring system of the present invention can readily be incorporated into a comprehensive vehicle data system. Thus the measuxing system can be , ;
, ~ . .. .
.. . ...
:: : . ,.: . . . :
:: . . .
. ' : ' . `` : , ~
... . .
. -- ~
installed adjacent a dynamic weighbridge system and the infor~llation provided by the two systems can be fed to a data base where it is combined with other relevant ~rehicle data, to provide a composite read-out of all this data.
One embodiment of the measuring system Oe the invention as applied to vehicle length measurement will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:-Figure 1 shows the measuring system in association with a dynamic weighbridge, Figure 2 shows a view of one of the detector stations as seen by the vehiclemoving along its path of travel, ~ igure 3 shows a block circuit diagram of tlle data processing means for processing the output signals from the detector stations, Figure 4 shows radiation intensity or (luantity patterns on a time base as a vehicle moves past the detector stations, and Figure 5 shows a view similar to Figure 2 of a modified detector station.
Referring to the drawings, the measuring system comprises two detector stations 1 and 2, which in effect form gateways at either end of a dynamic weighbridge 3 so that a vehicle ~ passing over the weighbridge 3 also passes through the two detector stations 1 and 2. As will be described the two detector stations 1 and 2 pro~ide electrical outputs to data processing means 5 which provides as its output a signal representative of overall ~ehicle length. This output together with an output from the weighbridge data unit 6 representative of gross vehicle weight is fed to a data base 7 in a freight office and from which a print-out of these items of information together with other vehicle data can be obtained. The data base may have provision for feeding its information to a central computer.
;
:~: .: ; . : ., The detector stations 1 and 2 are spaced a predetermined distance apart (e. g. 2 metres). Each station comprises a pair of posts 8 and 9 disposed on opposite sides of the patlh of vehicle travel. The posts 8 each carry a vertical series of infra-red radiation emitting diodes 10 spaced for example 0. 2 metres apart and each producing a constant radiation intensity output. Each of the diodes 10 incorporates a lens system so that it produces a conically diverging beam of infra-red radiation, the cone angle being for example 10 . The posts 9 each carry a sing.~e infra-red detector diode 11, whose vertical posi~ion on the post 9 is adjustable for convenience in setting up the system. The diodes 10 are oriented so that their optical axes are directed at the detector diode 11 of the associated detector station. Thus a triangular curtain of infra-red radiation extends across the path of vehicle travel at each station as shown in Figures 1 and 2.
Each of the detector diodes 11 produces an electrical output representative of the intensity or quamity of the infra-red radiation incident upon it so that as long as any part of a vehicle is interrupting one of the radiation curtains the output from the associated diode 11 will be a "less than maximum intensity or quantity" signal. If therefore the data processing means fundamentally has the facility for measuring the time taken for output signals from each of the detectors 11 to move from "maximum intensity or quantity" back to "maximum intensity or , quantity" through a continuous range of "less than maximum intensity or quantity", the length of a vehicle can be measured using the following two equations:
L = (tlR ~ tl~')V (1) D
( 2F lE~ ) (2)
l`his invention relates to measuring systems and has pa-rticular, but not exclusive, application to the measurement o~ the lengtll of moving vehicles.
In the txansportation oE commercial road vehicles by sea ferries, the tariEf charged is based, inter alia, on vehicle length. The tarife is normally expressed as a charge per metre with a gradation down to 0.1 metre which is charged proportianally. At the present time the declared lengths of vehicles are checked on a random basis to discourage under-declarations of length. This checking is carried out by inspectors using tape-measures or the like and has to be carried out while the vehicles are stationary; it is thereEore time-~onsuming and labour intensive.
The main object Oe the present invention is to provide a measuring system which enables the length of a vehicle to be measured automatically while the vehicle is moving.
Accordingly the present invention provides a measuring system comprising:-(a) a pair of detector stations spaced a predetermined distance apart along a path of movement for a vehicle, each detector station comprising a vertically extending series of electromagnetic radiation emitters disposed on one side of said path, each emitter producing a clirectional beam of radiation, and at least one electromagnetic radiation detector ~hich is designed to produce an electrical output signal related to the quantity or intensity ot radiation incident upon it, said detector being disposed on the other side of said path and said emitters or a group of said emitters being arranged to direct their l~eams at it, whereby the said quantity or intensity of incident electromagnetic radiation re~istered by said detector is dependent upon the number of said beams interceptecl by a passing ~ehicle, and ,., : . :
:: : :: ::
32~L
(b) data processing mean.s for processing the output signals from said detectors on a time basis and utilising the Icnown predetermined spacing of said detector stations to provide a velocity related vehicle measurement.
Said electromagnetic radiation is advantageous,ly infra-red radiation.
Thus the measuring systèm of the invention can be used to measure vehicle length and/or vehicle velocity.
As will be explained the measurement of vehicle length is a function of vehicle velocity, which in turn is a function of the time taken for an identifiable point on the vehicle to cover the known distance between the two detector stations.
With the above defined emitter and detector arrangements at the two detector stations, a vehicle as it passes each detector station will produce on the d~tector a radiation lntensity or quantity pattern determined by the number of said radiation beams which are interrupted by each cross-section of the vehicle passsing through that station, From these patterns certain characteristic points along the vehicle are readily identiflable. Hence a measurement of the time taken for a number of identifiable points to move between the two stations can be made and an average transit time arrived at, which will compensate within limits for variation in vehicle velocity as it i9 moving between the two stations.
One of the characteristic points which is iderltifiable by pattern recognition are vehicle axles. The system can therefore additionally be used to count the number of vehicle axles, and this in combination with a weight measurement can provide information regarding axle loading.
'rhe measuring system of the present invention can readily be incorporated into a comprehensive vehicle data system. Thus the measuxing system can be , ;
, ~ . .. .
.. . ...
:: : . ,.: . . . :
:: . . .
. ' : ' . `` : , ~
... . .
. -- ~
installed adjacent a dynamic weighbridge system and the infor~llation provided by the two systems can be fed to a data base where it is combined with other relevant ~rehicle data, to provide a composite read-out of all this data.
One embodiment of the measuring system Oe the invention as applied to vehicle length measurement will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:-Figure 1 shows the measuring system in association with a dynamic weighbridge, Figure 2 shows a view of one of the detector stations as seen by the vehiclemoving along its path of travel, ~ igure 3 shows a block circuit diagram of tlle data processing means for processing the output signals from the detector stations, Figure 4 shows radiation intensity or (luantity patterns on a time base as a vehicle moves past the detector stations, and Figure 5 shows a view similar to Figure 2 of a modified detector station.
Referring to the drawings, the measuring system comprises two detector stations 1 and 2, which in effect form gateways at either end of a dynamic weighbridge 3 so that a vehicle ~ passing over the weighbridge 3 also passes through the two detector stations 1 and 2. As will be described the two detector stations 1 and 2 pro~ide electrical outputs to data processing means 5 which provides as its output a signal representative of overall ~ehicle length. This output together with an output from the weighbridge data unit 6 representative of gross vehicle weight is fed to a data base 7 in a freight office and from which a print-out of these items of information together with other vehicle data can be obtained. The data base may have provision for feeding its information to a central computer.
;
:~: .: ; . : ., The detector stations 1 and 2 are spaced a predetermined distance apart (e. g. 2 metres). Each station comprises a pair of posts 8 and 9 disposed on opposite sides of the patlh of vehicle travel. The posts 8 each carry a vertical series of infra-red radiation emitting diodes 10 spaced for example 0. 2 metres apart and each producing a constant radiation intensity output. Each of the diodes 10 incorporates a lens system so that it produces a conically diverging beam of infra-red radiation, the cone angle being for example 10 . The posts 9 each carry a sing.~e infra-red detector diode 11, whose vertical posi~ion on the post 9 is adjustable for convenience in setting up the system. The diodes 10 are oriented so that their optical axes are directed at the detector diode 11 of the associated detector station. Thus a triangular curtain of infra-red radiation extends across the path of vehicle travel at each station as shown in Figures 1 and 2.
Each of the detector diodes 11 produces an electrical output representative of the intensity or quamity of the infra-red radiation incident upon it so that as long as any part of a vehicle is interrupting one of the radiation curtains the output from the associated diode 11 will be a "less than maximum intensity or quantity" signal. If therefore the data processing means fundamentally has the facility for measuring the time taken for output signals from each of the detectors 11 to move from "maximum intensity or quantity" back to "maximum intensity or , quantity" through a continuous range of "less than maximum intensity or quantity", the length of a vehicle can be measured using the following two equations:
L = (tlR ~ tl~')V (1) D
( 2F lE~ ) (2)
2~9L
from which two equations:-~t - t ) D
~ 2F lF ) ( ) where tlF i9 the time in absolute terms at which the front of the vehicle interrupts the detector station 1, t2F is the time at which the front of the vehicle interrupts the detector station 2, tlR is the time at which the rear of the vehicle clears the detector ~t~tion 1, t2R is the time at which the rear o~ the vehicle clears the detector station 2, L is the length of the vehicle, V is the velocity of the vehicle, D is the distance between the detector stations.
It will be appreciated from equation ~3) that there is no need for an indication of vehicle velocity to be given. However a constant vehicle velocity has been assumed and this fact could introduce unacceptable errors into the length measurement if in fact the vehicle velocity does vary as it passes between the two detector stations 1 and 2. As will now be described the measuring system has an inbuilt facility for deternnining, in eEfect an average vehicle velocity of transit so that, within limits changes in vehicle velocity oL transit are compensated for in the length measurement.
As a vehicle passes through each ot the radiation curtains each ~ross-section of the vehicle will interrupt a certain number of infra-red~beafns so that on a time base a radiation ~intensity or quantity pattern will be produced on the associated detector diode 11 nnd this will be rellected in the Olltput from the ~ ~ _ detector diode. Such intensity or ~luantity patterns from the two detector stations are shown superimposed in Figure 4. Using pattern recognition tecllnklues therefore certain ~eatures of the vehicle can be recognised, for example as annotated on Figure 4 where the front of the vehicle cab 100, the cab body 101, the wheels 102, 104 and 105 and the trailer bodyAare indicated. ~lence a number of velocitymeasurements can be made for different points along the vehicle length and an average velocity derived for use in equation (3). Thus the general equation for vehicle velocity corresponding to equation (2) is V = D (4) (t ~ t Where tlX is the time in absolute terms at which a given point in the length of the vehicle interrupts the detector station 1 and t2X is lhe time at which said given point interrupts detector station 2.
Figure 3 shows a block diagram of the data processing means 5 in which the outputs of the two detector diodes 11 are fed to an interface unit 12 which includes an analogue-to-digital converter for converting the analogue output signals fro-m the diodes 11 to equivalent digital values. Under the control of the micro-computer 13 either of these digital values can be fed into the micro-computer store. The operator's console 14 has a keyboard and display which enable the operator to initiate the measuring process, to select which measurements are re~luired (e. g. "length", "num~er of axles"), and to supply data such as the vehicle registration, With this information, the micro-computer receives and stores the sequence of radiation intensity or quantity values from the detectors 11, computes the desired measurements using the quoted equatior6 and causes these measurements to be printed by the printer on the operator's console 14, and transmitted to the Freight Office data base 7.
.
; :
.:
32~
With the lengtll measurement system descril)ed above a narrow band optical filter is advantageously placed in front of each Oe the detector diodes 11 to block radiation other than that in the infra-red zone of the spectrum. ~ny problems with reflected light can be overcome by time modulating the output of the radiation emitting diodes at a fixed frequency and tuning the detectors to this frequency. Such modulation can conveniently be achie~red by switching a d. c, supply to one station's light-emitting diodes for alternate half cycl~s of said predetermined frequency and to the seconcl station's light-emitting diodes for the other half cycles.
In the above described æystem a single detector 11 is used at each detector station. In a modif i cation two or more detectors may be used, a respective group of the infra-red emitting diodes 10 having their optical axes directed at each of the detectors. ~igure 5 shows one such arrangement in which two detectoræ
referenced 11 and 11 are used, one at the same level as in Figure 2 and the other at a relatively low level. The upper group of diodes referenced 10 have their optical axes directed at the detector 11 and the lower group of diodes referenced 10 have their optical axes directed at the detector 11 .
The quantity of radiation falling on the two detectors 11 and 11 is summed and produces a pattern for the ~ehicle similar to that shown in Figure 4. 'rhe advantage of having a plural detector arrangement as shown in Figure 5, is that it enables recognition of the lower part of the vehicle more accurately and thus for example provides a more reliable axle count arrangement. In fact the detect 11 and its associated group of electrodes 10 could be used ~lone for axle counting.
. :.,, :. .; . ~ . : , ~
from which two equations:-~t - t ) D
~ 2F lF ) ( ) where tlF i9 the time in absolute terms at which the front of the vehicle interrupts the detector station 1, t2F is the time at which the front of the vehicle interrupts the detector station 2, tlR is the time at which the rear of the vehicle clears the detector ~t~tion 1, t2R is the time at which the rear o~ the vehicle clears the detector station 2, L is the length of the vehicle, V is the velocity of the vehicle, D is the distance between the detector stations.
It will be appreciated from equation ~3) that there is no need for an indication of vehicle velocity to be given. However a constant vehicle velocity has been assumed and this fact could introduce unacceptable errors into the length measurement if in fact the vehicle velocity does vary as it passes between the two detector stations 1 and 2. As will now be described the measuring system has an inbuilt facility for deternnining, in eEfect an average vehicle velocity of transit so that, within limits changes in vehicle velocity oL transit are compensated for in the length measurement.
As a vehicle passes through each ot the radiation curtains each ~ross-section of the vehicle will interrupt a certain number of infra-red~beafns so that on a time base a radiation ~intensity or quantity pattern will be produced on the associated detector diode 11 nnd this will be rellected in the Olltput from the ~ ~ _ detector diode. Such intensity or ~luantity patterns from the two detector stations are shown superimposed in Figure 4. Using pattern recognition tecllnklues therefore certain ~eatures of the vehicle can be recognised, for example as annotated on Figure 4 where the front of the vehicle cab 100, the cab body 101, the wheels 102, 104 and 105 and the trailer bodyAare indicated. ~lence a number of velocitymeasurements can be made for different points along the vehicle length and an average velocity derived for use in equation (3). Thus the general equation for vehicle velocity corresponding to equation (2) is V = D (4) (t ~ t Where tlX is the time in absolute terms at which a given point in the length of the vehicle interrupts the detector station 1 and t2X is lhe time at which said given point interrupts detector station 2.
Figure 3 shows a block diagram of the data processing means 5 in which the outputs of the two detector diodes 11 are fed to an interface unit 12 which includes an analogue-to-digital converter for converting the analogue output signals fro-m the diodes 11 to equivalent digital values. Under the control of the micro-computer 13 either of these digital values can be fed into the micro-computer store. The operator's console 14 has a keyboard and display which enable the operator to initiate the measuring process, to select which measurements are re~luired (e. g. "length", "num~er of axles"), and to supply data such as the vehicle registration, With this information, the micro-computer receives and stores the sequence of radiation intensity or quantity values from the detectors 11, computes the desired measurements using the quoted equatior6 and causes these measurements to be printed by the printer on the operator's console 14, and transmitted to the Freight Office data base 7.
.
; :
.:
32~
With the lengtll measurement system descril)ed above a narrow band optical filter is advantageously placed in front of each Oe the detector diodes 11 to block radiation other than that in the infra-red zone of the spectrum. ~ny problems with reflected light can be overcome by time modulating the output of the radiation emitting diodes at a fixed frequency and tuning the detectors to this frequency. Such modulation can conveniently be achie~red by switching a d. c, supply to one station's light-emitting diodes for alternate half cycl~s of said predetermined frequency and to the seconcl station's light-emitting diodes for the other half cycles.
In the above described æystem a single detector 11 is used at each detector station. In a modif i cation two or more detectors may be used, a respective group of the infra-red emitting diodes 10 having their optical axes directed at each of the detectors. ~igure 5 shows one such arrangement in which two detectoræ
referenced 11 and 11 are used, one at the same level as in Figure 2 and the other at a relatively low level. The upper group of diodes referenced 10 have their optical axes directed at the detector 11 and the lower group of diodes referenced 10 have their optical axes directed at the detector 11 .
The quantity of radiation falling on the two detectors 11 and 11 is summed and produces a pattern for the ~ehicle similar to that shown in Figure 4. 'rhe advantage of having a plural detector arrangement as shown in Figure 5, is that it enables recognition of the lower part of the vehicle more accurately and thus for example provides a more reliable axle count arrangement. In fact the detect 11 and its associated group of electrodes 10 could be used ~lone for axle counting.
. :.,, :. .; . ~ . : , ~
Claims (7)
1. A measuring system comprising:-(a) a pair of detector stations spaced a predetermined distance apart along a path of movement for a vehicle, each detector station comprising a vertically extending series of electromagnetic radiation emitters disposed on one side of said path, each emitter producing a directional beam of radiation, and at least one electromagnetic radiation detector which is designed to produce an electrical output signal related to the quantity or intensity of radiation incident upon it, said detector being disposed on the other side of said path and said emitters or a group of said emitters being arranged to direct their beams at it, whereby the said quantity or intensity of incident electromagnetic radiation registered by said detector is dependent upon the number of said beams intercepted by a passing vehicle, and (b) data processing means for processing the output signals from said detectors on a time basis and ulilising the known predetermined spacing of said detector stations to provide a velocity related vehicle measurement.
2. A measuring system according to claim 1 wherein each emitter produces a directional beam of infra-red radiation.
3. A measuring system according to claim 2 wherein each emitter produces a conically diverging beam of electromagnetic radiation, the cone angle being about 10°.
4. A measuring system according to Claim 1, wherein each detector station has a plurality of vertically spaced electromagnetic radiation detectors and the electromagnetic radiation emitters are divided into a number of groups equal to the number of detectors, the emitters of each said group being arranged to direct their beams of radiation at a respective detector.
5. A measuring system according to any claim 1 wherein said data processing means calculates vehicle length using the time taken for the vehicle to pass one of said detector stations and the vehicle velocity as calculated by the time taken for a given point on the vehicle to move the predetermined distance between said two detector stations.
6. A measuring system according to claim 5, wherein a vehicle velocity for each of a plurality of points on said vehicle is derived and an average of the derived vehicle velocities used in the calculation of vehicle length.
7. A measuring system according to claim 6, wherein said given points are recognised by the characteristic radiation quantity or intensity which they cause to be registered on said detectors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA316,891A CA1108294A (en) | 1978-11-27 | 1978-11-27 | Measuring systems |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA316,891A CA1108294A (en) | 1978-11-27 | 1978-11-27 | Measuring systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108294A true CA1108294A (en) | 1981-09-01 |
Family
ID=4113026
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA316,891A Expired CA1108294A (en) | 1978-11-27 | 1978-11-27 | Measuring systems |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108294A (en) |
-
1978
- 1978-11-27 CA CA316,891A patent/CA1108294A/en not_active Expired
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Legal Events
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|---|---|---|---|
| MKEX | Expiry |