Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L25/00—Recording or indicating positions or identities of vehicles or trains or setting of track apparatus
  • B61L25/02—Indicating or recording positions or identities of vehicles or trains
  • B61L25/021—Measuring and recording of train speed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L25/00—Recording or indicating positions or identities of vehicles or trains or setting of track apparatus
  • B61L25/02—Indicating or recording positions or identities of vehicles or trains
  • B61L25/025—Absolute localisation, e.g. providing geodetic coordinates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L25/00—Recording or indicating positions or identities of vehicles or trains or setting of track apparatus
  • B61L25/02—Indicating or recording positions or identities of vehicles or trains
  • B61L25/026—Relative localisation, e.g. using odometer

Definitions

• the present invention relates to a device for measuring the displacement of a self-guided vehicle according to the preamble of claim 1.
• Inertial units combining accelerometers, gyrometers and terrestrial positioning systems such as GPS. These, however, remain very expensive because of their high-level technology, most often for applications to aeronautical systems;
• the accelerometer comprises two measurement axes for respectively determining an acceleration along a direction of trajectory of the vehicle as well as for determining and therefore taking into account in the calculation of displacement a slope of the vehicle with respect to port to a horizontal plane.
• Measurement signal values of the accelerometer and the tachometer are also compared with speed threshold values which, if a threshold is exceeded, make it possible to indicate a presence of loss of adhesion (packing / jamming) of the vehicle.
• a rail transport unit most often has an elongated geometry along which a single accelerometer and a tachometer placed upstream of the vehicle can not provide a measuring means revealing the effects acting on the complete whole of the vehicle, such as, for example, curvature or lateral acceleration effects.
• An object of the present invention is to propose a device for measuring the displacement of a self-guided vehicle having an increased measuring robustness, in particular during a loss of adhesion and whatever the profile of the path of the vehicle in terms of slope, curve and slope.
• a device for measuring the movement of a self-guided vehicle comprising on board two accelerometers, each having two measuring axes and whose measurement signals are coupled to a displacement calculator is proposed according to claim 1.
• At least one tachometer can be mounted on one of the axles of the vehicle and also be coupled with the computer data processing issues and all sensors (accelerometers and tachometer).
• the measurement signals delivered by the tachometer can be used to improve the accuracy of the device.
• the device according to the invention delivers, from the accelerations measured on the measurement axes, velocity data and longitudinal displacement of the vehicle (for example along a railway track). It can be associated with any type of on-board device that may need a precise and continuous measurement of the speed and the displacement of the vehicle, independently of the raill / wheel adhesion conditions and whatever the profile of the path in term slope, curve and slope.
• the accelerometers and their measurement axes are arranged in such a way that they make it possible, from the measurements made on the various measurement axes, to calculate a longitudinal acceleration, a lateral acceleration and a slope acceleration of the vehicle. determine by time integration the acceleration values, the speed and the longitudinal displacement of the vehicle.
• the device according to the invention also advantageously makes it possible to detect in a safe manner an immobilization of the vehicle on its path and produces for this purpose a zero velocity information from the information delivered by the sensors.
• the device comprises a self - calibration and self - test means which makes it possible, when the vehicle is stationary, to check the correct functioning of the sensors and consequently to guarantee with great confidence the data made available by other embedded systems.
• a suitable use of the device according to the invention covers the field of guided vehicles whatever their type of guidance (mechanical or intangible that is to say without mechanical link between the ground and the vehicle), including trains, subways, tramway or bus, and whatever the type of bearing (axles, bogies) with wheels iron or tire. It should be noted that for this category of vehicle with a geometry / longitudinal frame, the effects of curvature and slope are not negligible depending on the position (or the offset) of the accelerometers on board the vehicle. The invention then makes it possible to overcome these effects advantageously in order to determine the movement of the vehicle more precisely.
• the device according to the invention thus makes it possible to calculate the movement of a guided vehicle, having no axles free of any braking and traction force, traveling on any profile track, maintaining a precision equivalent to that of a free-axle system, while avoiding adhesion losses (slippage and skidding induced by traction / braking forces) and errors induced by lateral (curvature) and vertical (slope) acceleration.
• a set of subclaims also has advantages of the invention.
• FIG. 1 a vehicle equipped with a device for measuring the movement of the self-guided vehicle according to the invention
• FIG. 2 a diagram of definition of the planes related to the moving vehicle
• FIG. 3 a diagram for taking into account the effect of slope on the device
• Figure 4 a diagram for taking into account the curvature effect on the device.
• FIG. 1 represents a vehicle VEH equipped with a device for measuring the movement of the self-guided vehicle according to the invention and possibly associated with FIG. 2, clarifying how plans related to the moving vehicle are defined in agreement with the acceleration experienced by the vehicle and measured by two accelerometers 101, 102.
• Figures 3 and 4 show the arrangement of measurement axes Acc1, Acc2, Acc3, Acc4 accelerometers according to the plans chosen according to the type of acceleration Gx, Glat, Gpes ( longitudinal displacement, curvature effect and / or slope) undergone by the vehicle in an orthonormal reference [X, Y, Z] centered on the accelerometers and whose X axis indicates the direction of longitudinal trajectory of the vehicle.
• the displacement measuring device (instantaneous position Dx) of the self-guided vehicle VEH comprises on board:
• an accelerometer 101 provided with two measuring axes Accl, Acc2 in a longitudinal plane Py defined by a first longitudinal axis X along a main displacement VEx assumed to be straight of the vehicle and of a second axis Z perpendicular to the floor of the vehicle;
• each output signal Sl, S2 comprises an orthogonal projection measurement Gac1c, Gacc2 of a resultant of global acceleration of the vehicle on the associated measurement axis Accl, Acc2,
• a second accelerometer 102 being provided with at least two measurement axes Acc3, Acc4 in a horizontal plane Pz defined by the first axis X and a third axis Y perpendicular to the first and second axis X, Z,
• each output signal S3, S4 comprises a measurement in projection
• the set of measurement axes Accl, Acc2; Acc3, Acc4 of the first and second accelerometer 101, 102 have in their respective plane Py, Pz a relative angle A1 + A2, A3 + A4 being adjustable so adjusted, so that the computer 103 delivers from the four measurements of projection Gaccl, Gacc2, Gacc3, Gacc4 at least one instantaneous value of longitudinal acceleration Gx of the vehicle at each point of a path including slope and curve.
• the value of longitudinal acceleration Gx is an exact value of acceleration taking into account the effects of slope and curvature.
• a loss of adhesion leading to distorting a measurement of acceleration that would be deduced from the rotation of the axles can here be ideally compensated.
• the device according to the invention therefore uses two accelerometers 101, 102 bi-axes fixed on the vehicle body and intended to measure a longitudinal acceleration and a lateral acceleration of the vehicle.
• the vehicle is subjected to three forces producing a longitudinal acceleration Gx (displacement of the vehicle subjected to the traction / braking forces), a lateral acceleration Glat (the curvature of the trajectory induces a centrifugal acceleration) and a vertical acceleration Gpes due to the gravity which is exercised in the presence of a slope (the slope of the trajectory).
• the first accelerometer 101 whose two axes Accl, Acc2 are located in the vertical plane Py and the second accelerometer 102 whose two axes Acc3, Acc4 are located in the horizontal plane Pz, will make it possible to measure a resultant of the accelerations (longitudinal, lateral, gravity) projected on each of the four measurement axes.
• the angles between the different axes of measurement of the accelerometers are known and fixed after adjustment.
• the computer 103 solves a system composed of four equations in order to determine four unknowns at the vehicle position Dx, namely an angle of slope Ave of trajectory, a lateral acceleration angle Ay (resulting from the centripetal force due to the speed of the vehicle.
• the computer 103 determines the longitudinal speed Vx and the longitudinal displacement Dx of the vehicle VEH on its path for any slope and curve CURB.
• the device according to the invention is completed by a tachometer 108 to improve the previous measurement accuracy of the speed Vx and the distance traveled Dx.
• the tachometer 108 is fixed on one of the axles RIa, R2a, RIb, R2b of the vehicle VEH and its output signal STb is transmitted to the computer 103.
• the computer 103 evaluates a displacement DxT and a speed VxT from the signal (s). tachometer measurement.
• the computer makes a comparison between the measurement results of displacement from the tachometer and those from the accelerometers. When, for these measured values, a measurement deviation is below a threshold, the measured values are adjusted to those from the tem- perometer. In the opposite case (value greater than a threshold), there is no correction of the results coming from measurement of the accelerometers.
• information of zero speed Op can also be safely delivered by the calibration.
• culator 103 from information Im from an apparatus of the vehicle (immobilization signal, zero speed indicator, etc. ..) or be determined by the device according to the invention itself. For this determination, calculator 103 processes the information from the tachometer and accelerometers.
• the device When the device determines a zero speed and, thanks to the peculiarities of the proposed assembly of accelerometers, the device also has the advantageous ability to implement a self-test function.
• This self - test function makes it possible to evaluate the necessary corrections to be made to the accelerometer measurements (after auto - calibration) and to identify operating faults of the accelerometers.
• the multiplicity of measurement axes provides a very advantageous redundancy of several measurements (due to the two bi-axis accelerometers) and allows periodic verification of the reliability of the accelerometers (for example at each station stop) to guarantee test measurements. (and therefore of subsequent displacement) with a very low probability of error, making them compatible with the safety requirements of a safe system as required in the railway field.
• the components of the projection measurements Gac1c, Gacc2 by addition of projections accelerations Gx, Glat, Gpes on each axis Acc1, Acc2 of the accelerometer 101 are:
• Gaccl projection (Gx) - projection (Gpes) - projection (Glat) (1)
• Gac1c Gx cos (Ay) cos (Al) + Gpas sin (Al-Ax) - Glat sin (Ay) cos (Al)
• Gacc2 Gx cos (Ay) cos (A2) - Gp sin (A2 + Ax) - Glat sin (Ay) cos (A2)
• the components of the projection measurements Gacc3, Gacc4 by adding projections accelerations Gx, Glat, Gpes on each of the axes Acc3, Acc4 of the accelerometer 102 are:
• Gacc3 projection (Gx) - projection (Glat) - projection (Gpes)
• Gacc4 projection (Gx) - projection (Glat) - projection (Gpes)
• the angle Ay is calculated by Arctg (Lx / R), thus at first approximation Lx / R since the value of the radius of curvature R is usually higher than the offset distance Lx.
• the resolution of the system formed by the four equations (1) to (4) is based on mathematical techniques which are not described here and whose purpose is to calculate the four variables Gx, Glat, Ax and Ay according to the measurements of acceleration values Gaccl, Gacc2, Gacc3, Gacc4 available to the computer 103.
• the resolution of the system is advantageously simplified in certain particular hypotheses of arrangement of the accelerometers 101, 102.
• the device according to the invention can provide that at least one of the relative angles A1 + A2, A3 + A4 is orthogonal.
• each relative angle A1 + A2, A3 + A4 is in fact subdivided (or subdivided) into a first and a second angle A1, A2 and respectively A3, A4 corresponding to angles of projection between the four axes of measurement Acc1, Acc2, Acc3, Acc4 of the first and second accelerometer 101, 102 and the first axis X (longitudinal axis according to a moving principal). supposedly rectilinear of the vehicle).
• Gac1c Gx cos (Ay) cos (Al) + Gpas sin (Al-Ax) - Glat sin (Ay) cos (Al)
• Vx J (Gx dt)
• Dx j (Vx dt)
• the device according to the invention thus allows the computer 103 to deliver a slope angle value Ax, of an angle Ay of lateral acceleration (that is to say representing the rotation of the lateral acceleration at the point of mounting the accelerometer assembly relative to what it would be in the center of the vehicle for the radius of curvature R) at each point of the path including slope and curve.
• the computer 103 delivers a speed Vx and a position Dx at each point of the path including slope and curve by successively integrating the longitudinal acceleration value Gx of the vehicle.
• the device can also include:
• a tachometer 104 disposed on at least one axle of the vehicle and delivering a speed tachometer value VxT and position DxT of the vehicle,
• the tachometric values VxT, DxT and the speed and position values Vx, Dx obtained and respectively delivered by the computer 103 are supplied to a comparator 106 included in the computer 103,
• the comparator 106 determines differences between categories of speed values and position, and if these are below a predefined threshold, a resetting of the speed and position values Vx, Dx delivered by the computer 103 to each point of the path including slope and curve is performed on the tachometric values VxT, DxT. If the deviations are below the threshold, the registration is inhibited.
• the device according to the invention may also comprise a zero velocity detection means 107 of the vehicle being included or coupled to the computer 103 and to the tachometer 104.
• the latter comprises at least one correlator of the speed and position values Vx, Dx delivered by the computer 103 and corresponding tachometric values VxT, DxT.
• a very safe zero velocity detection function is performed either: by taking into account information external to the device made available by one of the vehicle devices (for example by means of an immobilized vehicle internal signal, ...)
• the device Following these treatments, if the vehicle is really guaranteed to be stopped, the device provides information called zero speed.
• a function called autotest can then advantageously uti ⁇ Liser information called zero speed.
• uti ⁇ Liser information called zero speed.
• the associated test thus consists in verifying that the measurement values delivered by the accelerometers 101, 102 satisfy the previously given system of equations (1), (2), (3), (4) which then reduces to:
• a second chosen threshold higher than the first threshold can also be defined to declare the device according to the invention out of operation.
• the device according to the invention comprises:
• a self-calibration means 105 for the accelerometers 101, 102 that can be activated if the zero speed detection means confirms a stopping of the vehicle
• the self-calibration means processing measurements from the accelerometers 101, 102 and given by an accelerations calculation unit 104 (itself receiving the measurements from the accelerometers 101, 102 and being included in the computer 103),
• the self-calibration means calibrates the measurements in correspondence with zero values of the longitudinal acceleration Gx and lateral Glat of the vehicle.
• the self-calibration means 105 has a first control mode for verifying the equality of the measurement values Gacc3, Gacc4 on the second accelerometer 102 and a means for re-calculating the slope angle ⁇ x from which the values measurement Gaccl, Gacc2 of the first accelerometer 101 are verified by means of a second control mode.
• the verification is made very reliable and even more so if the slope angle can be evaluated and confirmed in redundancy by known information external to the device.
• correction factors from the self-calibration means 105 are then forwarded to the computing unit 104 (more generally the displacement calculator 103).
• an on-board measurement failure indicator is activated.
• a simplified model for evaluating a probability of failure of the so-called self-test function can thus be achieved by considering that, at the end of the vehicle, measurements made on the accl, acc2, acc3, acc4 measurement axes Accelerometers 101, 102 are obtained in redundancy.
• the device makes it possible to guarantee a level of confidence in the measured data which is required for the safety required in the railway field.
• the device according to the invention can then comprise a probability of failure evaluation means activatable between two stops of the vehicle and employing a redundancy measurement on the axes measurements of accelerometers.
• This evaluation means can be integrated into the self-calibration means 105 previously described.
• the device according to the invention may also optionally comprise a vehicle adhesion loss detector (in case of slipping or skidding) coupled to at least one of the first and second accelerometers 101, 102 bi-axes for which displacement measurements can be associated with external values (slope, curvature of a databank or data of a path marker system, etc.).
• a risk of loss of adhesion of the vehicle can be detected and by extension complement the information provided by the zero speed detection system (locked wheel, but moving vehicle).
• the vehicle adhesion loss detector may also, where appropriate, be coupled to at least one vehicle axle tachometer 108 in addition to one of the first and second accelerometers 101, 102 so as to compare their measurement data. angular movement and respectively longitudinal displacement. In this way, the zero speed detection function can then be made even safer.
• Y axis perpendicular to the X axis and in the floor plan of the vehicle
• Z axis perpendicular to the vehicle floor
• Px plane orthogonal to the X axis and determined by the Y
• Z Py axes plane orthogonal to the Y axis and determined by the X
• Z Pz axes plane orthogonal to the axis Z and determined by the X
• Gx longitudinal acceleration of the vehicle along the X axis
• Glat lateral acceleration of the vehicle at the point of accelerometers in the vehicle
• Vx longitudinal speed along the X axis
• Dx position / longitudinal displacement along the X axis
• VxT longitudinal speed given by the tachometer
• DxT longitudinal displacement given by the tachometer
• Accl first axis of measurement of the accelerometer 101 Acc2: second measuring axis of accelerometer 101 Acc3: first axis of measurement of accelerometer 102 Acc4: second axis 2 of measuring of accelerometer 102
• Al angle in plane Py between axis X and axis Accl
• A2 angle in plane Py between axis X and axis Acc2
• A3 angle in plane Pz between axis X and axis Acc3
• A4 angle in plane Pz between axis X and axis Acc4
• Ax vehicle trajectory angle in plane Py (ie angle between horizontal and X axis)
• Lx distance of offset between the center of the vehicle and the point of attachment of accelerometers 101, 102
• Ay angle related to the radius of curvature in the plane Py.
• Ay is cabled by Arctg (Lx / R), so in first approximation Lx / R
• Vx longitudinal speed of the vehicle along the X axis

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)
• Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
• Navigation (AREA)
• Steering Controls (AREA)
• Control Of Driving Devices And Active Controlling Of Vehicle (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2007
  • 2007-12-10 EP EP07871826A patent/EP2219931B1/de active Active
  • 2007-12-10 DK DK07871826.9T patent/DK2219931T3/da active
  • 2007-12-10 US US12/747,371 patent/US8571741B2/en active Active
  • 2007-12-10 ES ES07871826T patent/ES2366148T3/es active Active
  • 2007-12-10 BR BRPI0722245A patent/BRPI0722245B1/pt active IP Right Grant
  • 2007-12-10 CN CN2007801023121A patent/CN101939203B/zh not_active Expired - Fee Related
  • 2007-12-10 AT AT07871826T patent/ATE510747T1/de active
  • 2007-12-10 CA CA2708580A patent/CA2708580A1/en not_active Abandoned
  • 2007-12-10 KR KR1020107015357A patent/KR101157756B1/ko not_active IP Right Cessation
  • 2007-12-10 WO PCT/FR2007/002031 patent/WO2009074725A1/fr active Application Filing
  • 2007-12-10 PL PL07871826T patent/PL2219931T3/pl unknown
• 2008
  • 2008-12-09 TW TW097147746A patent/TW200931308A/zh unknown

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