CA1179040A - Device for the contact-less measuring of the velocity of and/or the distance covered by a vehicle and a method for carrying out measurements with the device - Google Patents

Device for the contact-less measuring of the velocity of and/or the distance covered by a vehicle and a method for carrying out measurements with the device

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Publication number
CA1179040A
CA1179040A CA000386843A CA386843A CA1179040A CA 1179040 A CA1179040 A CA 1179040A CA 000386843 A CA000386843 A CA 000386843A CA 386843 A CA386843 A CA 386843A CA 1179040 A CA1179040 A CA 1179040A
Authority
CA
Canada
Prior art keywords
frequency
vehicle
frequencies
track
velocity
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
Application number
CA000386843A
Other languages
French (fr)
Inventor
Ole Snedkerud
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BBC Brown Boveri AG Switzerland
Original Assignee
BBC Brown Boveri AG Switzerland
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by BBC Brown Boveri AG Switzerland filed Critical BBC Brown Boveri AG Switzerland
Application granted granted Critical
Publication of CA1179040A publication Critical patent/CA1179040A/en
Expired legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S11/00Systems for determining distance or velocity not using reflection or reradiation
    • G01S11/02Systems for determining distance or velocity not using reflection or reradiation using radio waves

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Train Traffic Observation, Control, And Security (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

A b s t r a c t A device for the contact-less measuring of the velocity of and/or the distance covered by a vehicle (W) with the aid of three transmitters (F1, F2, F3;
F?, F?, F?), arranged along and/or at the ends of a track (J), which generate two so-called standing waves running in opposite directions. These standing waves are detected and analysed by means of a measuring device (Q) which is located in a vehicle (W). The frequencies (f1, f2, f3) are different, frequency multi-pliers (M2, M3) being advantageously used in two transmitters (F2, F3; F?, F?). The method of measuring by means of this device makes it possible to detect the velocity and/or the distance covered much more accurately and is also suitable for vehicles without wheels, that is to say, for example, for suspension railways and air-cushion vehicles.

Description

- 3 ~7.~

The present invention relates to a device and method for determining both the distance covered and the speed of a vehicle by contact-less measurement.
With railways systems whlch depend on wheels, conventional velocity measuring instruments generally obtain their measuring signal from the wheel axles in the form of pulses. This makes it possible to follow the wheel rotation accurately. In modern locomotives all wheel axles are driven in order to be able to exert the maximum traction power corresponding to the weight of the locomotive. Since the value of the friction between wheel and rail fluctuates depending on the charac-teristics of the wheel and of the rail, protective devices are necessary against short~term slipping or dragging of the wheels with respect to the rail. The spinning increases the wear of locomotive components and decreases the tractive force exerted. However, the spinning also increases the error of the distance measurement. If a maximum distance error of 1/oo is tolerated, the wheel must not move by more than 1/oo with respect to the rail.
Vehicles without wheels such as suspension railways and air-cushion vehicles do not have wheel axles from which the pulses for the velocity or distance measurement could be picked up.
In Swiss Patent 598,597 a method for measuring the velocity of vehicles with the aid of a track conductor is described. The track conductor is fed from both ends by means of two transmitters which have a certain reference relationship to one another and the vehicle velocity is measured by means of a computing device on ~' the vehicle by comparing the waves of the two trans-mitters which are received on the vehicle. This Swiss patent also describes the operation of this type of velocity measurement and supports it with a discussion of the theory involved.
It has been shown, however, that under certain circumstances this method described in the Swiss patent also displays greater distance errors than are permissible.
The solution according to Swiss patent 598,597 can be used to generate a standing wave on a track conductor with the aid of two transmitters if fl = f2.
One wave moves at a low velocity from one end of the fl > f2- The velocity is then c (fl f2) vl fl ~ f2 km/s where c designates the velocity of light. The time interval between the zero transitions is t = f If it is intended to determine the velocity of the vehicle at each second, the frequency difference must be 1 Hz. It is also possible to work with harmonics or subharmonics of the frequencies fl and f~. If c = 300,000 km/s and with a velocity vl of the so-called standing wave of 500 km/h, the factor vl/c = 0.46 10 6 .

Thus, the frequencies fl and f2 must be in the MHz region if the corresponding difference is to be 1 Hz~
A so~called standing wave has a natural velocity even if the vehicle is stationaryO

~ ~9~'~0 The present invention eliminates the disadvantages of the known methods and devices and creates a device of the type mentioned initially which displays only very small distance errors even under unfavorable circumstances and which also is suitable for vehicles which move without wheels.
Accordingly one feature of the present invention is to overcome these disadvantages and thus problems in the determination of the zero velocity. The device according to the invention is used to generate two standing waves running in the opposite directions by introducing a third frequency f3 ~ fl which is transmitted by a third transmitter. The result is that the difference is also clearly zero in the stationary vehicle.
If the vehicle is moving at a velocity vw, the following equations are obtained for the velocities v'l and v'2 of the two standing waves relative to the moving vehicle: v'l= vl + VW and V'2 = V2 -- V
where c (f3 fl) V2 fl + f3 If the frequencies fl, f2, and f3 are selected to give /vl/ = iv2/, then the velocity of the vehicle is Vll-- v12 v = 2 ---Thus, the difficulty in determining the zero velocityis also eliminated.

~7~

One embodiment according to the present invention is advantageous particularly if a conductor already exists along the track.
Another embodiment is most suitable in the case where no conductor exists and the track essentially extends in a straight line.
The frequency multipliers according to the present invention make it possible to separate the frequencies more easily or to shift the frequencies into the frequency bands permitted, for example, for the railways. If the frequencies are within a range of one hundred kHz and only have a difference of 1 Hz, they can be separated from one another only with difficulty. The multiplying of two frequencies facilitates the mutual separation.
The mixing stages of the measuring device accord ing to the present invention facilitate the analysis of the values measured.
A further development according to the present invention makes it possible, with a conductor running along the track, to use the device according to the invention even for long distances. Another object according to the present invention is to make it possible to bridge gaps in the conductor. Also the method of the present invention describessuitable possibilities in the selection of the frequencies and their further processing.
A more complete appreciation of the lnvention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when 1 ~9~

considered in connection with the accompanying drawings, wherein:
FIGURE 1 shows an overall arrangement with the device according to the invention;
FIGURE 2 shows a more detailed illustration of the measuring device A from Figure 1, FIGURE 3 shows a more detailed illustration of intermediate amplifier B from Figure 1, and FIGURE 4 shows a more detailed illustration of the passive intermediate station C from Figure 1.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to Figure 1 thereof, wherein both a conductor L and a radio path JF are arranged along a track J. At one end of the track J a transmitter Fl and F*l is located and at the other end two transmitters F2, E'3 and F*2 ~ F*3 .
The * designates the parts intended only for the radio path JF. The conductor L is, for example, a conductor of a continuous automatic train running control system known in itself or a conductor for feeding power to the vehicle or another conductor extending in the di.rection of travelling. Two transmitters F2, F3 are provided with frequency multipliers N2, N3. The frequencies of the transmitters Fl, F2, F3 are designated by f1, f2, f3.
The frequencies f2, f3 are multiplied by the frequency multipliers N2, N3. In the example shown, the multiply-ing factor of the frequency multiplier N2 is equal to 3 and that of the frequency multiplier N3 is equal to 2.
The multiplied frequencies are designated by f'2, f'3 ~

~7~

The arrows indicate the two posslbilities for the velocity Vw of the vehicle W. The measuring device Q
of the vehicle W is of course arranged to be stationary in this vehicle W. The conductor L is broken by an intermediate amplifier B and bridged by a passive intermediate station C at a point of interruption~
K designates a frequency control device. E and E*
indicate receivers.
If no conductor exists, the radio path JF can be used to handle the same function. This alternative has also been shown in Figure 1 for reasons of clarity.
The ends of the radio path JF are formed by aerials A*.
The vehicle W is provided with a measuring device Q
which carries an aerial A for working in conjunction with the transmitters Fl, F2, F3 and an aerial A* for working in conjunction with the transmitters F*l, F*2 ~ F*3 q Figure 2 shows the measuring device Q from Figure 1 in greater detail. In the vicinity of the conductor L or in the radio path JF an aerial A or A*, respectively, is located which is connected to three receivers El, E2, E3 which are connected in parallel.
The receivers E2, E3 are provided with frequency multi-pliers N'2 , N'3 having reciprocal multiplying factors to the multipliers N2 and N3 r Thus, in this example the multiplying factor of the frequency multiplier N'2 = 3 and the multiplying factor of the frequency multiplier N'3 = 2 ~ In this way the original frequencies f2, f3 are obtained from the multiplied frequencies f'2, f'3-L ~

The frequencies fl~ f2, ~3 are mixed in pairs in the mixing stages Ml, M2, fed to filters T which filter out the fundamental frequencies and the higher frequencies and are processed in a difference detection device D which can also be equipped with a counter. The time base derived from the output of the mixing stages Ml and M2 by means of a third multiplier N'l is designated by t.
In this example, both a velocity measuring instrument G
and two direction-of-travel detectors Ul, U2, which are connected via integrators I to a distance measuring instrument Sv for the forward direction and a distance measuring instrument SR for the reverse direction, are used for analysis purposes.
Figure 3 shows an illustrative embodiment of the intermediate amplifier B from Figure 1. Such an intermediate amplifier B can be installed, for example, into the conductor L after each 10 km. Filters Hl, H2 and H3 are connected in parallel and provided for the frequencies fl~ f'2 and f'3 and the former are equipped with terminating resistances Z which ensure for relatively good matching. Phase shifting elements P are also connected in series with the amplifier stages Vl, V2 and V3. The operation of the amplifiers Vl, V2 and V3 makes it possible to bridge even very long distances in stages. The phase shifting elements P
prevent any phase shifts which could have an unfavorable effect on the measuring process~
Figure 4 shows the same elements as Figure 3 but without the amplifiers Vl, V2 and V3 and the termi-nating resistances Z. This passive intermediate station 9~

C is used if a gap exists in the conductor L for other purposes or if signals transmitted via the conductor L
for other services are coupled in at other locations.
Obviously, numerous (additional) modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifi-cally described herein.

o L i s t o f d e s i g n a t i o n s . . . _ _ .
J Track L Conductor JF Radio path W Vehicle Q Measuring device of the vehicle W
Fl~ F2, F3 Transmitter 2~ N3 Frequency multipliers with multiplying factors n2~ n3 ~1~ f2~ f3 Frequencies of the transmitters Fl, F29 3' ~
f2, f3 Multiplied frequencies VW Velocity of the vehicle W
K Frequency control device B Intermediate amplifier C Passive intermediate station A, A~ Aerials ~ Transmitter for the radio ~.ath JF
E, E~ Receiver at the end of the conductor L
or the radio path JF
El, E29 E3 Receiver of the measuring device Q
N2, N' Frequency multipliers with reciprocal 3 factors n2g n3 Ml, M2 Mixing stages T Filter Nl Frequency multiplier with factor nl~ 1 t Time base D Difference detection device - counter U Direction-of-travel detec-tor for the 1 forward direction U2 Direction-of-travel detector for the reverse direction I Integrator G Velocity measuring instrumen-t SV Distance measuring instrumen-t for the forward direction SR Distance measuring instrument for the reverse direction Hl, H2, H3 Filter for frequencies fl~ f2~ f3 1~79~
- 1~ - 84/80 : L i s t o f d e s i g n a t i o n s (continued) .. . _ . . . . _ Z Terminating resistances Vl, V2, V3 Amplifier stages P Phase shifting elements

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method for the contact-less measuring of the velocity of a vehicle along a track comprising the steps of:
generating at least two standing waves propagating along the track with propagation velocities of equal amount and opposite direction;
determining at the vehicle the propagation velocities of said standing waves relative to the velocity of the vehicle;
subtracting said relative propagation velocities from each other and dividing the difference by two; and taking the result of said division as the velocity of the vehicle.
2. A method according to claim 1 further comprising the steps of:
providing a first transmitter at one end of the track and at least two transmitters at the other end of the track whereby each of said transmitters operate at a different frequency;
operating said first transmitter at a frequency greater than the frequency of one of said transmitters at the other end of the track and lower than the frequency of the other of said transmitters at the other end of the track;
choosing said frequencies so that by pairwise combination of said frequencies at least two standing waves are established which propagate alone the track with propagation velocities of equal amount and opposite direction;

transmitting said frequencies along the track on a transmission path, receiving at the vehicle said frequencies; and determining from said received frequencies the propagation velocities of said standing waves relative to the velocity of the vehicle.
3. A method according to claim 1 further comprising the steps of:
providing a first transmitter a-t one end of the track and at least two transmitters at the other end of the track whereby each of said transmitters operate at a different frequency;
operating said first transmitter at a frequency greater than the frequency of one of said transmitters at the other end of the track and lower than the frequency of the other of said transmitters at the other end of the track;
choosing said frequencies so that by pairwise combination of said frequencies at least two standing waves are established which propagate along the track with propa-gation velocities of equal amount and opposite direction, converting prior to transmission at least two of said frequencies into frequency bands differing from each other and from the frequency band of the third frequency, transmitting said converted and non-converted frequencies along the track on a transmission path, receiving at the vehicle said transmitted frequencies;
recovering from said received frequencies the original frequencies of said transmitters; and determining from said recovered frequencies the propagation velocities of said standing waves relative to the velocity of the vehicle.
4. A method according to one of the claims 2 or 3 further comprising the steps of:
pairwise mixing at the vehicle the frequencies which establish one of said standing waves;
filtering out the basic difference frequencies contained in said frequency mix;
deriving from one of said transmitter frequencies a time base; and deriving from said basic difference frequencies and said time base the propagation velocities of said standing waves relative to the velocity of the vehicle.
5. A method according to one of the claims 1, 2 or 3 further comprising the step of:
integrating the measured vehicle velocity in time to get the distance covered by the moving vehicle.
6. A device for the contact-less measuring of the velocity of a vehicle along a track comprising:
a transmission path extending along the track;
a first transmitter operating at a first frequency at one end of said transmission path;
a second and third transmitter operating at a second and third frequency at the other end of said transmission path whereby said second frequency is lower than said first frequency and said third frequency is greater than said first frequency so that two standing waves with propagation velocities of equal amount and opposite direction are generated along the track;

a first, second and third receiver located at said vehicle tuned to the respective frequencies of said transmitters;
a first and second mixing stage mixing the output signals of said first and second receiver and said first and third receiver, respectively;
a first and second filter connected to the output of said first and second mixing stage, respectively and tuned to the basic difference frequencies delivered by said mixing stages;
a frequency divider deriving a time base from the output signal of one of said vehicle receivers;
a difference detection device deriving from said basic difference frequencies and said time base the difference of the propagation velocities of said standing waves relative to the velocity of the vehicle;
a fourth receiver at the other end of the trans-mission path tuned to said first frequency; and a frequency control device connected to the output of said fourth receiver and controlling the frequencies of said second and third transmitter.
7. A device for the contact-less measuring of the velocity of a vehicle along a track comprising:
a transmission path extending along the track;
a first transmitter operating at a first frequency at one end of said transmission path;
a second and third transmitter operating at a second and third frequency at the other end of said trans-mission path whereby said second frequency is lower than said first frequency and said third frequency is greater than said first frequency so that two standing waves with Propagation velocities of equal amount and opposite direction are established along the track;
means located at the other end of said transmission path for converting prior to transmission said second and third frequency into frequency bands differing from each other and from the frequency band of said first frequency;
a first, second and third receiver located at said vehicle tuned to the respective transmitted frequencies;
means connected to the output of said receivers for recovering the frequencies of said transmitters;
a first and second mixing stage mixing said first and second frequency and said first and third frequency delivered by said recovering means;
a first and second filter connected to the output of said first and second mixing stage respectively and tuned to the basic difference frequencies delivered by said mixing stages;
a frequency divider deriving a time base from the output signal of one of said vehicle receivers;
a difference detection device deriving from said basic difference frequencies and said time base the difference of the propagation velocities of said standing waves relative to the velocity of the vehicle, a frequency control device connected to the output of said fourth receiver and controlling the frequencies of said second and third receiver.
8. A device according to one of the claims 6 or 7 further comprising:
an integrator located at said vehicle connected to the output of said difference detection device.
9. A device for the contact-less measuring of the velocity of a vehicle along a track comprising:
means for generating a transmission path extending along the track, means for generating at least two standing waves propagating along the track with propagation velocities of equal amount and opposite direction;
means for measuring at said vehicle the propagation velocities of said standing waves relative to the velocity of the vehicle; and means for deriving from said relative propagation velocities the velocity of the vehicle.
CA000386843A 1980-10-20 1981-09-28 Device for the contact-less measuring of the velocity of and/or the distance covered by a vehicle and a method for carrying out measurements with the device Expired CA1179040A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH780380 1980-10-20
CH7803/80-1 1980-10-20

Publications (1)

Publication Number Publication Date
CA1179040A true CA1179040A (en) 1984-12-04

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CA000386843A Expired CA1179040A (en) 1980-10-20 1981-09-28 Device for the contact-less measuring of the velocity of and/or the distance covered by a vehicle and a method for carrying out measurements with the device

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Country Link
CA (1) CA1179040A (en)
DE (1) DE3135354A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4327385A1 (en) * 1993-08-14 1995-02-16 Horst Dr Baehring System for recording the distance traveled by a motor vehicle
AUPN437395A0 (en) * 1995-07-24 1995-08-17 D & E Consulting Pty Ltd System and method for determining the distance travelled by a vehicle

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Publication number Publication date
DE3135354A1 (en) 1982-09-02

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