Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L23/00—Control, warning, or like safety means along the route or between vehicles or vehicle trains

Definitions

• the present invention relates to a method for determining quantities characteristic of a moving object, and an apparatus for implementing the method.
• Both the method and the apparatus are of general use, even though a particular application relates to the railway sector. In this respect, in this sector the constant increase in traffic and in the transit speed of trains together with ever increasing safety and quality standards demand constant and precise monitoring of a multiplicity of risk factors. Of these factors the most important relate to the overall dimensions of railway vehicles and, in the case of goods vehicles, of the goods transported thereby, their weight and the temperature of particular parts of them.
• the loads can undergo displacement from their original position and project beyond outline limits, risking collision with structures to the side of the track (poles, signals, cantilever roofs, tunnel walls).
• structures to the side of the track poles, signals, cantilever roofs, tunnel walls.
• certain mechanical parts, and in particular the brakes, the axle boxes or the pantograph trolleys can abnormally overheat.
• the load carried by goods carriages can in certain cases trigger fires.
• trucks and trailers carried on railway vehicles together with their load constitute a further risk factor, especially when loaded with fuel and not subject to control during the journey.
• An aim of the invention is to propose a method for determining the characteristic quantities of a railway vehicle, and an apparatus for implementing the method, however it should be noted that the method and apparatus can be generally used to determine the characteristic quantities of any moving object. This and other aims which will be apparent from the ensuing description are attained by a method for determining characteristic quantities of a moving object as described in claim 1. To implement the method of the invention, an apparatus is provided as described in claim 20.
• Figure 1 is a schematic front view of a portal equipped for determining the outline of a railway train
• Figure 2 illustrates schematically the operating principle of the apparatus for determining said outline
• Figure 3 is a schematic front view of the portal of Figure 1 also equipped for determining the thermal profile of the train
• Figure 4 is a schematic cross-section showing the principle of determining the train static load
• Figure 5 is a plan view of a track portion equipped for determining the dynamic load of the train
• Figure 6 is a schematic perspective view showing the train proximity and speed sensor
• Figure 7 is a general schematic view of a portal incorporating the various units connected to the processing and control units
• Figure 8 is a perspective view of variant of a device for measuring the static and dynamic load.
• the apparatus for implementing the method of the invention comprises an integral portal composed of two uprights 2 positioned on the two sides of a railway track 4 at any point of the track, for example before entering a particularly critical tunnel, or upstream of any portion of track to be monitored.
• a laser telemeter 6 positioned above the overall outline of the train 8, at least one traditional video camera 12 and a thermovisual video camera 10 for measuring the thermal profile of the train.
• a sensor 16 is positioned, which in cooperation with other similar sensors enables the static and dynamic load of the train 8 on the track 4 to be determined.
• the laser telemeter 6 installed on each upright 2 comprises a laser source 20 able to transmit an amplitude modulated laser signal 22 of predetermined frequency, onto a rotary mirror rotating at a predetermined speed, such as to deviate the signal 22, consisting of a laser beam, into a vertical plane perpendicular to the travel direction of the train 8, with an angular swing able to scan the train.
• amplitude modulated laser signal means a pulse modulated laser signal (pulsed laser signal) or modulated with a known waveform not of pulse type (modulated laser signal).
• a sensor 26 is provided consisting of a photomultiplier tube able to receive the laser pulses reflected from the surface of the train 8, to reconstruct its outline.
• a special narrow band optical interference filter 28 is provided set for the laser wavelength, to immunize the system against any interference from external light and hence enable it to fully operate in any light condition.
• the tube is controlled by an electronic unit 30 (using a time to digital converter) able to calculate the distance between each of the points on the train 8 struck by the pulsed laser beam 22 and the sensor 26.
• the device for measuring the train thermal profile installed on each upright 2, comprises a pair of thermovisual video cameras 10, positioned at each of the two ends of the upright 2 and disposed with their optical axis converging in order to completely frame the transiting train 8. They are sensitive to the infrared waves emitted by the various parts of the train 8 and are able to reconstruct its thermal map. Specifically, that thermovisual video camera 10 positioned at the lower end of the upright 2 is orientated upwards, to determine the temperature of the brakes and of the train moving parts, while that thermovisual video camera 10 positioned at the upper end of the upright 2 is orientated downwards, to determine the temperature of the loads, of the external surfaces and of the pantograph trolley.
• the video cameras 10 are controlled by the local processing unit 30, which besides synchronizing their operation is able to collect data for local processing, in addition to memorizing the data and activating the connection to a remote computer 32.
• the thermovisual video cameras 10 are connected to the local processing unit 30 by optical fibres, which provide high immunity to noise.
• the device for measuring the static and dynamic load of the train is a high precision system for monitoring the stresses exerted by the train 8 on the track 4. Its principle of operation is based on determining the elastic deformations induced on each rail 42 on passage of the train 8, and more precisely on determining the deformations involving the elastic layer 44 present between each rail 42 and the underlying sleeper 14.
• This device consists essentially of a sound-configured sensor '16 mounted on a robust bracket and fixed to the sleeper 14 just below the foot of the rail 42. With this sensor there is associated a wire turn forming part of an LC circuit connected to an electronic control circuit 43. As will be apparent hereinafter, passage of the train causes temporary compression of the elastic layer 44 and a consequent increase in the distance between the sensor 16 and the upper surface of the foot of the rail 42. Measuring the resonance frequency of the LC circuit enables that distance to be calculated and hence the extent of the elastic stress due to passage of the train 8.
• each sleeper 14 For a more complete determination of the train characteristics, and more particularly of any faceting of the wheels 46 due to braking, sliding or load unbalance, several pairs of sensors 16 are provided, installed on each sleeper 14 in correspondence with both the rails 42 and for a number of sleepers corresponding to a length of track 4 at least equal to the circumference of the wheels 46 of the train 8.
• each sensor 16 is connected to the local processing unit 30 via fibre optic connections, which ensure a very high transmission speed for the relevant data.
• the device of the invention also comprises a unit for determining passage of the train 8 and for calculating its speed. Its purpose is to activate the aforedescribed devices only as the train 8 approaches, so that they operate only when necessary, to reduce their maintenance to a minimum.
• the photoelectric cell devices 18 for sensing passage of the train 8 and its speed this latter being calculated from their distance apart and the time measured between passage of the train in front of them.
• the photoelectric cell devices 18 for sensing passage of the train 8 and its speed this latter being calculated from their distance apart and the time measured between passage of the train in front of them.
• other sensors in addition to this unit for determining train passage and calculating its speed, in that track portion between this unit and the constituent uprights 2 of the portal, other sensors
• the apparatus of the invention comprises a remote control unit to which measured data processed by the different local units are fed, in order to provide a complete picture of the characteristics of each train passing in front of the apparatus and to indicate any possible alarm situations due to differences between the measured parameters and the standard parameters beyond certain fixed thresholds.
• a pulsed laser beam 22 is directed onto the rotating mirror 24 to scan the train.
• Each laser pulse deviated by the rotating mirror 24 onto the surface of the train 8 is reflected thereby and sensed by the photomultiplier 26 positioned within the apparatus to the side of the laser source 20.
• the measurement system is able to adapt to the train speed, because of the ability to vary the rotational speed of the mirror 24.
• thermovisual video cameras 10 are sensitive to the infrared radiation emitted by those parts of the train 8 framed by the video cameras.
• the intensity of the infrared radiation emitted by a unit of surface is related to the temperature of that unit, hence by measuring this radiation at various points the thermal map of the moving train can be constructed.
• the surface of the railway train is totally measured by using four video cameras 10, two for each side of the train 8, one of which is for the lower part (for analyzing overheating of brakes and moving parts) and the other for the upper part (for analyzing the loads, the outer surface and the pantograph trolley).
• the first processing step take place directly on board the video camera assembly, by the processing card connected to it.
• a control card synchronizes the various video cameras 10 and collects the data.
• Final processing of the acquired images is done by the local data processing unit
• the processing system is able to analyze the thermal map determined by the video cameras 10. This analysis comprises verifying in continuous cycle the temperature at each point and comparing it with predetermined threshold values, to be able to immediately activate an alarm procedure should these values be exceeded.
• This alarm procedure comprises an automatic warning to the railway network and a simultaneous transmission to the central supervisory system of all information required to exactly identify the event which has caused the alarm, and in particular: - the type of alarm generated, - the reference number of the carriage involved, - the digital photograph of the overheated region with the thermal map overlying it, - the temperature level reached,
• the loads and stresses on the track 4 are calculated by measuring the elastic deformations induced in the track on passage of the train 8.
• the operating principle is based on the contactless inductive sensor 16 installed in proximity to the foot of the rail 42.
• a wire turn which, when current flows therethrough, generates on the forward lying rail foot a magnetic field which itself generates induced currents (Eddy currents) therein, which induce a magnetic counter-field in the original wire turn, of intensity related to the distance between the wire turn and the rail foot.
• This distance can be determined by an algorithm, by measuring the resonance frequency of the LC circuit comprising the wire turn.
• a pair of sensors 16 positioned on the same sleeper 14 in correspondence with the two rails 42 allows determination both of the weight supported by each train wheel axle and enables any load unbalance to be identified.
• the use of several pairs of sensors 16 covering a portion of track 4 equal to at least the wheel circumference enables any wheel facets to be detected. Such facets determine a non-uniformity of weight measured by the successive pairs of sensors 16.
• the data obtained by the sensors 16 are transmitted through the optical fibre connection to the local processing system 30, which verifies by continuous cycle the loads measured by the sensor, stores them in its internal memory, compares them with the predetermined threshold and analyzes them to determine the unbalance or the dynamic stresses.
• the device for measuring the static and dynamic load of the train consists of a rigid bar 17, which supports three sensors of the same type as that already described.
• the rigid bar 17 is fixed at its ends to two adjacent sleepers and is able to sense and measure, by comparison between the three response signals of the three sensors on train passage, the deformations of the rails 42 caused thereby.
• a traditional video camera As stated, on each upright 2 there is applied a traditional video camera
• a pulsed laser beam at a frequency of 1 MHz was used for each sensor directed on the octagonal mirror 24, which was rotated at a speed of 3750 r.p.m., to hence obtain scanning by the beam over an angle of about 80° at a frequency of 30,000 scans per second.
• the profile measurement accuracy obtained was ⁇ 1 cm with a horizontal resolution of 5 cm and a vertical resolution at 200 km/h (passenger train) of 10 cm and a vertical resolution at 80 km/h (goods train) of 3 cm.
• To determine the thermal profile of the train four video cameras were used able to acquire thermal images with a frequency of 20 Hz, i.e. 20 photographic images/second, with a resolution of 1 cm/pixel.
• the video cameras used by the measurement system were constructed using matrices of sensors based on Ga-As (gallium arsenide) technology which enable very high sensitivity, low noise and excellent thermal resolution to be obtained.
• This type of sensor is particularly rapid and hence has a very wide acquisition band (up to 20 GHz in the 8-12 ⁇ frequency spectrum.
• the standard matrix format of the pixels constituting the image plane of the sensor is 600x400.
• a measurement precision of ⁇ 2°C was obtained.
• the opening time for the shutter of the container housing each video camera is about 2 seconds.
• sensors were used having a measuring field of about 10 mm, with a maximum sensitivity to variations of about a few tens of microns. The minimum time required to obtain a measurement is about 10 ms, hence an acquisition frequency of about 100 Hertz can be obtained.
• a measurement precision of ⁇ 20 kg was obtained.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Train Traffic Observation, Control, And Security (AREA)
• Length Measuring Devices By Optical Means (AREA)

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• 2004
  • 2004-06-11 IT ITVE20040026 patent/ITVE20040026A1/it unknown
• 2005
  • 2005-06-09 EP EP05748315A patent/EP1753650B1/de not_active Not-in-force
  • 2005-06-09 WO PCT/EP2005/006191 patent/WO2005120923A1/en active IP Right Grant
  • 2005-06-09 DE DE602005003571T patent/DE602005003571T2/de active Active

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