GB2176963A

GB2176963A - Locating power source for rail vehicle

Info

Publication number: GB2176963A
Application number: GB08514203A
Authority: GB
Inventors: John Philip Dakin; Charles Robert Batchellor
Original assignee: Plessey Co Ltd
Current assignee: Plessey Co Ltd
Priority date: 1985-06-05
Filing date: 1985-06-05
Publication date: 1987-01-07
Also published as: GB8514203D0

Abstract

In apparatus for locating a conductor rail or an overhead conductor wire 1 with respect to a track 2, 3 for vehicles 4 arranged to be supplied with motive power from the rail or wire 1, a pair of linear image sensors 5, 6 are spaced apart, a light source 10 illuminates the wire 1 or rail, and a signal processor 13 responds to signals 11, 12 received by the sensors 5, 6 as they are scanned which indicate the direction of reception of light reflected from the wire or rail 1 by their timing. The position of the wire or rail 1 with respect to the track 2, 3 is then determined by simple trigonometry. <IMAGE>

Description

SPECIFICATION Improvements relating to electric vehicle traction systems This invention relates to electric vehicle traction systems and relates more specifically to positiondetecting apparatus for use in such systems to determine the position of a power transmission conductor rail or overhead power transmission conductor wire relative to a track or other guidance means for vehicles supplied with motive power from the power transmission rail or conductor wire.

For the purpose of assessing the operational condition of overhead power line transmission systems it is necessary to survey the length of the overhead power conductor wire in order to detect any changes that may have occurred in the position of the conductor wire relative to the track for carrying the vehicle concerned. The surveying equipment concerned may itself be mounted on a train or other vehicle moving along the track or equivalent vehicle guidance means.

In order to measure any deviation of the conductor wire from a datum point (e.g. a position at a predetermined height above the mid-point of the vehicle track rails) it may be necessary not only to locate the conductor wire position relative to the vehicle but also to determine the position of the two track rails relative to the vehicle. This procedure will enable the surveying equipment to be mounted on a sprung vehicle chassis since changes in the position of the sprung vehicle chassis with the respect to the rails due to the suspension movement will be automatically compensated for.

Such conductor wire position surveying arrangements could use intrusive or non-intrusive techniques. An intrusive technique could involve measuring the position of an arm maintained in contact with the conductor wire and also measuring mechanically the position of the vehicle track relative to the vehicle. This intrusive technique would have the following disadvantages: a) To maintain contact between the arm and the conductor wire a force must be exerted on the latter which would displace it and thus prejudice the accuracy and repeatability of the position surveying measurements.

b) The contact arm would have to be manually located on the conductor wire at the start of the survey operation and re-located at the usual intersection conductor wire overlaps and at all conductor wire junctions.

c) The contact arm would be at high tension voltage causing electrical isolation problems.

d) Severe problems could be experienced in ensuring that the various components of the surveying apparatus have sufficient mechanical response times to allow measurements to be made at a reasonable train velocity.

A non-intrusive position surveying technique of measurement is clearly preferable since the conductor wire remains undisturbed. Consequently, there are no problems caused by passing conductor wire junctions or wire overlaps and contact with the high tension conductor wire is avoided. Of the possible methods of performing non-intrusive wire location techniques, optical measurement techniques have many advantages over electromagnetic or radar measurement techniques. Using optical measurement techniques the measurements made are totally unaffected by any electromagnetic interference from the high electrical power present in the conductor wire power supply system. The optical measurements can also be made in such a way as to circumvent the effects of support structures and other track-side equipment such as signal gantries.Moreover, the measurement system can respond extremely rapidly to any sudden changes in overhead cable wire position.

According the the present invention there is provided optical position-determining apparatus for sensing the location of a power conductor wire or rail relative to a vehicle or track for vehicles arranged to be supplied with motive power from the wire or rail, said apparatus comprising a light source for illuminating the conductor wire or rail the image of which is projected on to respective linear image sensors in pre-determined spaced apart locations relative to the track and signal processor means arranged to receive signals from the sensors indicative of the light reflected from the conductor wire or rail in response to scanning of the linear sensors at predetermined instants in time and the signal processor means providing data indicative of the location of the conductor wire or rail with respect to the vehicle or vehicle track.

In carrying out the present invention the linear image sensors may be located on the respective sides of the surveying vehicle's roof and the sensors may be arranged to produce in response to the scanning thereof video signals and suitable frame synchronisation pulses which are received by a video processor. The angular positions of the conductor wire relative to the respective image sensors are then determined by the video processor which compares the position of the conductor wire image pulse in the video signal with the position of the start of a scan synchronisation pulse. By peforming a triangulation computation between the image angles sensed by the image sensors and the known distance between the sensors the exact position of the conductor wire relative to the surveying vehicle travelling along the vehicle track can be determined.

If necessary the position of the surveying vehicle itself relative to the track may be accurately determined by imaging one or both of the polished track rails for the vehicle in the general manner set forth above. This may be necessary in cases where the optical sensing apparatus for determining the position of the conductor wire is mounted on a sprung vehicle chassis in which case compensation needs to be made for the lateral movement of the vehicle chassis relative to the track rails. Data from the apparatus for determining the position of the vehicle relative to the track rails may then be trans mitted to the aforesaid processor for the necessary compensatory adjustments to be made in calculating the location of the conductor wire relative to the vehicle track.

By way of example the present invention will now be described with reference to the accompanying single-figure drawing.

In the drawing there is shown a schematic arrangement for determining the exact position of an overhead conductor wire 1 relative to the track rails 2 and 3 for vehicles arranged to be supplied with motive power from the conductive wire 1 through a pantograph contact arm carried by the vehicle. As previously mentioned, the condition of the overhead conductor wire may be assessed by determining its precise position relative to the vehicle track rails.

The present invention provides an optical conductor wire position-determining apparatus carried by a surveying vehicle 4 travelling along the track rails 2 and 3 and preferably deriving its motive power from a diesel engine or other prime mover independent of the conductor wire power supplies.

This avoids the need for physical contact being made with the conductor wire 1 by a movable conductor arm which would produce displacement of the conductor wire and thereby give rise to difficulties in determining the true position of the conductor wire 1 relative to the vehicle track.

The apparatus comprises a pair of linear (i.e. one dimensional) opto-electric image sensors 5 and 6 which are located on opposite sides of the roof 7 of the vehicle 4. The sensors 5 and 6 having associated convex lenses 8 and 9 are angularly positioned for sensing light reflected from the conductor wire 1 when the latter is illuminated by a powerful light source 10 mounted on the vehicle roof 7 mid-way between the image sensors 5 and 6. Images of the conductor wire 1 falling within the field of view of the sensors will be received by the image sensors but the most reflective surface in the field of view of each sensor will be the lower surface of the conductor wire 1. Of the images received by each of the sensors 5 and 6 the image having the highest brightness will normaily be that of the conductor wire and, consequently, its position can be clearly identified.To this end the image sensors 5 and 6 are scanned simultaneously at regular predetermined intervals as the surveying vehicle travels along the track. In response to such scanning the sensors produce video signal outputs as shown in the drawing indicative of the conductor wire images received thereby and the angular positions of the conductor wire 1 relative to the sensors are represented by the positions of the conductor wire image pulses 11 relative to the start-of-scan synchronisation pulses 12.

This video signal data from the sensors 5 and 6 is processed by means of a video processor 13 which performs a triangulation computation on the received data and the known spacing between the sensors in order to provide an indication of the exact position of the conductor wire 1 relative to the surveying vehicle 4. In the case of a substantially rigid vehicle chassis mounting the measured position of the conductor wire will be relative to the track but in cases where the surveying vehicle body chassis is resiliently mounted it may be necessary to provide the video processor 13 with data to compensate for lateral movement of the vehicle chassis relative to the vehicle track. Such compensatory data may be provided by a further optical position-determining apparatus including a light source and associated image sensors similar to the sensors 5 and 6 for determining the position of one or both of the track rails relative the the vehicle chassis.

Claims

1. Optical position-determining apparatus for sensing the location of a power conductor wire or rail relative to a vehicle or track for vehicles arranged to be supplied with motive power from the wire or rail, said apparatus comprising a light source for illuminating the conductor wire or rail the image of which is projected on to respective linear image sensors in predetermined spacedapart locations relative to the track and signal processor means arranged to receive signals from the sensors indicative of the light reflected from the conductor wire or rail in response to scanning of the linear sensors at predetermined instants in time and the signal processor means providing data indicative of the location of the conductor wire or rail with respect to the vehicle or vehicle track.

2. Optical position-determining apparatus as claimed in claim 1, in which the linear image sensors are located on the respective sides of the surveying vehicle roof.

3. Optical position-determining apparatus as claimed in claim 1 or claim 2, in which the sensors are arranged to produce in response to the scanning thereof video signals and suitable frame synchronisation pulses which are received by a video processor, the angular positions of the conductor wire relative to the respective image sensors being determined by the video processor which compares the position of the conductor wire image pulse in the video signal with the position of the start of a scan synchronisation pulse so that by performing a triangulation computation between the image angles sensed by the image sensors and the known distance between the sensors and exact position of the conductor wire relative to the surveying vehicle travelling along the track can be determined.

4. Optical position-determining apparatus as claimed in any preceding claim, in which means are provided for producing on further optical sensors images of one or both of the track rails for the vehicle, these sensors being scanned and producing signals which are fed to further signal processor means which provides a data output which is fed to the first signal processor means so that adjustment of the conductor wire position data can be made according to the lateral position of the vehicle relative to the track.

5. Optical position-determining apparatus sub stantially as hereinbefore described with reference to the accompanying drawing.