Method for laser guiding of rail bearing plate insertion device for forming railway track, involves calculating position of arm from known position of arm relative to portion and position of portion relative to measurement station

Method and laser guidance system for inserting elements into the ground

The invention relates to a method of guiding a device intended to insert elements into the ground for the realization of a work and in particular to a method of guiding a device for inserting saddles for the realization of a railway track, of the type described in patent application EP 1 578 153, making it possible to obtain the insertion of saddles in concrete, at a given position with an accuracy less than a millimeter.

The invention also relates to a system for inserting elements into the ground implementing such a guiding method.

In document EP 1 578 153, the insertion system comprises a motorized frame and a saddle insertion arm which is mounted to move relative to the frame under the action of actuators controlled by a computer. Three optical reflectors are arranged at the rear of the vehicle on the insertion arm at ground level. A final reflector is placed at the top of the device on the frame.

These optical reflectors make it possible, by means of a laser-type measuring method using a measuring station placed on the ground at the rear of the vehicle, to measure with precision the position of the insertion arm, which is otherwise mobile with respect to the vehicle chassis. For this purpose, the distance between the measuring station and each reflector of the arm as well as the angular position of each reflector with respect to the measuring station are determined and processed.

However, the measurements carried out using these reflectors, because of the relief and the curves of the track layout or else of various site obstacles masking the laser beam, require frequent movement of the measuring station in order to preserve the optical line of sight of the laser beam.

The aim of the present invention is therefore to remedy this drawback by proposing a guiding method allowing the precise and rapid positioning of a device for inserting elements into the ground.

To this end, the invention relates to a method for guiding an insertion device intended to insert elements into the ground for the realization of a work, the insertion device comprising a vehicle frame mounted on wheels and an insertion arm movable relative to the frame operable by an automatic pilot unit, comprising the steps of:

- set up a measuring station near the structure and determine the position of the measuring station in a topographic reference mark,

- using the measuring station to measure information characteristic of a relative position between a part of the insertion device and the measuring station,

- determine the relative position of the part of the insertion device in the topographic reference mark using the characteristic information measured, and the determined position of the measuring station,

- calculate the position of the arm in the topographic coordinate system from the determined position of the part of the insertion device in the topographic coordinate system,

- move the insertion device so that an element is facing, and in the insertion axis of a given position at which it is desired to insert an element into the ground, characterized in that the part of the insertion device is the vehicle frame, and the calculation of the position of the insertion arm is made from the known position of the arm relative to the frame and the determined relative position of the frame relative to the station of measurement.

According to particular embodiments, the guiding method according to the invention can comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:

- The characteristic information measured from a relative position between the chassis of the vehicle and the measuring station comprises a distance and an angle separating the chassis from the measuring station;

- The measurement of information characteristic of a relative position between the frame and the measuring station comprises an optical measurement method cooperating with at least two reflectors carried by the vehicle frame;

- the reflectors are located on the top of a body of the chassis;

- the measurement of the distance and the angle separating the frame from the measuring station comprises an optical measurement method cooperating with two reflectors carried by the vehicle frame and a method for measuring two angles of inclination and of cant at the 'using two inclinometers placed on the frame;

- the installation of the measuring station near the structure is carried out at any azimuthal angle with respect to the frame;

- the installation of the measuring station near the structure is carried out at a height of at least two meters from the ground level where the frame is located;

the insertion system comprises at least two insertion arms and the calculation of the position of each arm is carried out using the determined relative position of the frame with respect to the measuring station;

- The arm is motorized in translation and in rotation along three axes orthogonal to each other, the movement of the arm being controlled by the control unit so as to bring the elements precisely opposite and in the axis of insertion of the given positions; and

- the structure is a railway track and the elements are saddles intended to support a railway rail, the saddles being inserted into a concrete slab not yet hardened.

The invention also relates to a system for inserting at least one element in the ground comprising an insertion device having a vehicle frame mounted on wheels and an insertion arm movable relative to the frame and operable by a unit. automatic piloting, and a station for measuring information characteristic of a relative position between a part of the insertion device and the position measuring station, characterized in that it comprises at least two reflectors intended to reflect an emission sent by the measuring station, arranged on the frame, in that the part of the insertion device is the frame of the vehicle, and in that the The automatic piloting unit is able to calculate the position of the insertion arm as a function of the known position of the arm with respect to the frame and of the determined relative position of the frame with respect to the measuring station.

According to particular embodiments, the system for inserting elements into the ground according to the invention can comprise one or more of the following characteristics, taken in isolation or according to all the technically possible combinations:

- the arm is free of reflectors;

- the reflectors are located at least two meters from the ground where the wheels rest;

- the control unit is able to receive information from the measurement station, to calculate the position of the frame from information from the measurement station, to calculate the position of the arm from the position of the frame and from the known relative position of the arm with respect to the chassis, to send movement control signals to the vehicle and to the arm in order to ensure the insertion of the elements in the ground at predetermined locations;

- The arm is motorized in translation and in rotation along three axes orthogonal to each other;

the device comprises at least two arms each actuated by the automatic pilot unit as a function of the same relative position of the frame determined using the at least two reflectors; and

- Said elements are saddles intended to support a railway rail, the saddles being inserted into a concrete slab not yet hardened.

The invention will be better understood on reading the description of an embodiment which will follow, given solely by way of example and made with reference to the appended drawings in which:

- Figure 1 is a perspective view of a saddle insertion device using a guiding method according to a particular embodiment of the invention, in a curve;

- Figure 2 is a schematic view of the control means of the insertion device of Figure 1;

- Figure 3 is a detail view of the articulated arm of the saddle insertion device of Figure 1;

- Figure 4 is a schematic top view of the saddle insertion device of Figures 1 and 2; and

- Figure 5 is a flowchart of the guidance method according to the embodiment of Figure 1.

According to FIG. 1, the saddle insertion device 10 consists of a vehicle 12 mounted on four wheels 14, two of which are steered and the other two are driven.

The vehicle 12 comprises a frame 16 carried by the wheels 14. The frame 16 is formed by the body of the vehicle and incorporates the upper body of the vehicle. The frame 16 carries at least one traction motor 18 as well as jacks 20 for the orientation of the steered wheels illustrated in FIG. 2. An automatic control unit 22 is provided to control the or each motor 18 and the jacks 20 allowing to 'ensure autonomous movement of the vehicle in a given direction.

The frame 16 is equipped with two inclinometers 24A, 24B, making it possible to provide an angular positioning of the frame 16 in an absolute topographic reference linked to the ground denoted Xa, Ya, Za. In particular, the two inclinometers 24A, 24B are suitable for providing the angles of inclination and of cant of the frame 16.

The vehicle 12 comprises along its rear face a motorized arm 26 movable in translation and in rotation with respect to the following frame 16 and around three orthogonal axes X, Y, Z of a reference frame on the frame 16.

The motorized arm 26, linked to a reference of axes x, y, z and center P, comprises a set of stepping motors 26A (to be confirmed) allowing very high precision movements of the arm 26 with respect to the frame 16 according to the six degrees of freedom of movement defined with respect to the reference mark X, Y, Z of frame 16.

The set 26A of motors is connected to the automatic pilot unit 22 so as to receive control signals.

The arm 26 illustrated in FIG. 3 has a structure 27 in general H shape and supports on its lower part two jacks 28 at the end of which are fixed two saddles 30 intended to be inserted into a freshly poured concrete slab, both saddles 30 being held by the arm 26, at a distance from each other corresponding to the template of the track to be installed.

The arm 26 is equipped with three inclinometers 32A, 32B, 32C permanently measuring the orientation of the arm 26 with respect to the X, Y and Z axes of the chassis 16 of the vehicle and with a displacement sensor 32D of the arm 26 by relative to the chassis 16 suitable for determining the displacement in the three directions.

According to Figure 1, the vehicle body which is rigidly linked to the frame 16 comprises on its upper part two reflectors 34A, 34B intended to cooperate with a measuring station 36 installed in the vicinity of the railway track to be installed.

The measuring station 36 arranged in the vicinity of the track is installed on a tripod positionable in the absolute topographic reference frame linked to the ground Xa, Ya, Za using a satellite positioning system of the GPS type.

The measuring station 36 comprises an optical device 38 laser for measuring distance equipped with an emitting optic and a receiving optic making it possible to know with very high precision the distance and the angle separating the measuring station 36 from the two reflectors. 34A, 34B carried by the body of the vehicle. The laser measuring device 38 used is for example a device marketed under the reference TC / 2003 by the company LEIKA.

The measuring station 36 also includes a radio transmitter 40 sending the results of the measurements carried out at each instant by the laser measuring device 38 towards a receiver 42 carried by the vehicle. The receiver 42 of the vehicle is connected to the automatic piloting unit 22 on board the vehicle.

The automatic piloting unit 22 comprises a memory and a computer allowing it to calculate the exact position of the arm 26 in space, in particular in the absolute topographic reference frame linked to the ground Xa, Ya, Za from the information sent by the monitoring station. measurement 36, of the known position of the measuring station 36, of the angles of inclination and of cant provided using the two inclinometers 24A, 24B arranged on the frame 16, orientation angles of the arm 26 with respect to the frame 16 supplied by the three inclinometers 32A, 32B, 32C and the translational movement of the arm 26 with respect to the frame 16 supplied by the translational movement sensor 32D.

The automatic piloting unit 22 associated with a PLC is able to control the movement of the arm 26 via the assembly 26A of associated motors, jacks 20 as well as the motors 18 making it possible to orient and move the vehicle 12.

The automatic piloting unit 22 associated with a PLC is also able to control the movement of the insertion jacks 28 of the saddles 30.

The method of guiding the saddle insertion device will now be described according to Figures 4 and 5.

According to FIG. 4, on the day of the insertion of the saddles, the insertion vehicle 12 is brought over a portion of the track where a concrete slab which has just been freshly poured and is not yet hardened. From this starting position of the vehicle 12 and from an arrival position, the measuring station 36 is placed at a carefully chosen location taking into account the relief and the layout of the track to be built and at a height such that 'a direct sight on the set of the two reflectors 34A, 34B fixed on the body of the vehicle is possible permanently whatever the position of the vehicle on the layout of the track to be built between the starting point and the ending point .

According to FIG. 5, the positioning of the measuring station 36 at this chosen location is carried out very precisely in a first step 52 by using a geolocation system of satellite type, for example of GPS type. In an alternative embodiment of the method according to the invention, the coordinates of the measuring station 36 can be determined by a triangulation method from topographic markers whose positions are known with precision.

In a step 54, the exact coordinates in the absolute topographic reference frame linked to the ground Xa, Ya, Za of the points at which the saddles must be inserted are stored in the memory of the control unit 22.

The position of the measuring station 36 being known, while the vehicle is stationary, in a step 56 the laser measuring device 38 is oriented successively in the direction of the two reflectors 34A, 34B located on the body of the vehicle so that it measures the distance and the angle separating each of the reflectors 34A, 34B from the measuring station 36.

In a step 58, the result is sent immediately by radio wave from the transmitter 40 to the automatic piloting unit 22 placed on board the vehicle. Unit 22 then calculates the exact current position of the vehicle, that is to say of its associated reference point X, Y, Z centered in Q in the absolute topographic reference point linked to the ground Xa, Ya, Za, from the data sent by the measuring station 36, of the known position of the measuring station 36 and of the inclination and tilt angles provided by the two inclinometers 24A, 24B arranged on board the chassis 16 of the vehicle.

The automatic piloting unit 22 then calculates in a step 60, from the coordinates of the points at which the saddles are to be inserted 2941973 rees and from the exact current position of the vehicle calculated by the unit 22 in step 58, 'gap separating the arm 26, then in a rest position, from the position at which the next saddles are to be inserted.

From the difference calculated in step 60, the automatic control unit 22 sends in a step 62 signals to the automaton which controls the driving and steered wheels 14 so as to move the vehicle along the axis of the track until bringing the articulated arm 26, immobile in the rest position, substantially at the height of the theoretical points of insertion of the saddles. Of course, taking into account the existing clearances in the transmission of the vehicle, the positioning of the vehicle on the track is then not very precise, the positioning inaccuracy being of the order of centimeters.

Once the vehicle has stopped in this intermediate position, in a step 64, new angle and distance measurements are made using reflectors 34A, 34B and are sent immediately by radio wave from the transmitter 40 to the autopilot unit 22.

The automatic piloting unit 22 then determines in a step 66 the position of the arm 26 in the reference frame Xa, Ya, Za from the new data transmitted by the measuring station 36, from the angles of inclination and of updated cant. provided using the two inclinometers 24A, 24B arranged on the frame 16, orientation angles of the arm 26 relative to the frame 16 provided by the three inclinometers 32A, 32B, 32C which correspond to the rest position of the arm.

The automatic pilot unit 22 then determines in the same step 66 the difference between the position of the arm 26 and that sought in which the saddles 30 carried by the arm 26 are opposite the theoretical points of insertion of the saddles according to the planned insertion axis.

The automatic piloting unit 22 then sends, in a step 68, signals to the automaton to control the motors of the assembly 26A for the movement of the articulated arm 26 according to the six degrees of freedom so as to compensate for the deviation determined at step 66 and to bring with very great precision the saddles 30 carried by the arms 26 opposite the theoretical points of insertion of the saddles. The jacks 28 are then actuated in a step 70 to insert the saddles into the concrete not yet hardened according to a process described in patent application EP 0 803 609.

Once the two saddles have been inserted, the arm 26 is returned to the rest position in a step 72 and the computer searches for the coordinates of the following points at which new saddles 30 must be inserted by returning to step 54.

Such a guidance method has the advantage of being quickly operational and inexpensive to implement and requiring the installation of the measuring station 36 only once on the day of the saddle insertion operation.

In addition, such a guidance method has the advantage of not being disturbed by untimely masking caused by the movement of personnel on the site, or by the path of the track, the laser sighting becoming impossible due to the masking. by the size of the vehicle.

Advantageously, this makes it possible to be able to use the insertion vehicle in both directions of travel along the track.

As a variant, at least three laser sighting reflectors are arranged on the body of the vehicle 12, which makes it possible to determine the position of the chassis 16 in the absolute topographic reference frame linked to the ground Xa, Ya, Za without the need for two inclinometers 24A, 24B.

Preferably, the measuring station 36 is placed in the vicinity of the structure at a height of at least two meters from the level of the ground where the frame is located. This eliminates any ordinary masking problem resulting from the movements of personnel on the site.

Preferably, the measuring station 36 is arranged at any azimuthal angle with respect to the frame 16, which allows the reflectors to be aimed freely regardless of the position of the vehicle.

As a variant, the insertion device 10 comprises at least two arms identical to the arm 26 actuated by the automatic pilot unit. The position of each arm 26 is calculated using the same relative position of the frame 16 determined using at least two reflectors.

Thus, several arms mounted in series according to the direction of movement of the vehicle can be controlled in parallel, their respective position in the topographic reference being calculated from the exact position of the chassis without requiring optical visibility from outside the vehicle. Simultaneous or sequential guidance in a rapid manner of the insertion arms is thus achieved, making it possible to increase the saddle-laying rates by placing the insertion tasks associated respectively with each of the arms in parallel.