FR2702856A1 - Image-assisted position tracking method and device for carrying out said method. - Google Patents

Abstract

The invention relates to a method of locating the orientation with respect to a fixed coordinate system of a non-fixed coordinate system of an object (VM) controlled to correct the direction of advance. The piloted object, (VM) is rigidly linked to a three-dimensional body (ONK) provided with optical elements forming optical reference points (LQ1 - LQ5). By means of a camera unit (BAE) arranged at a defined distance from the object, with a visual connection, the optical elements (ONK) are identified with high precision. In an associated image processing unit (BV), the orientation of the axes of the coordinate system of the controlled object (KO NK) is determined relative to the fixed coordinate system of the shooting unit ( KB AE) and the values are transmitted to a control unit (SE) to control the movements of the object (VM).

Description

I Image-assisted position finding method and device for

  implementation of said method The invention relates to a method which makes it possible to identify with respect to a fixed coordinate system the orientation of a

  coordinates specific to an object whose movement it is to order

  and use it to correct the aiming direction (direction

tion in advance).

  In the state of the art, it is known to determine the po-

  sition of a coordinate system not fixed in space, specific to an object, compared to a fixed coordinate system Let us quote as example the piloting of the advance during the digging of tunnels In this case, for a planned linear advance , the desired direction of advance is defined by means of a precisely oriented laser beam In this

  so-called radius-controlled method, the difference in reference points is measured

  applied to the rear of the digging machine with respect to

  the theoretical direction indicated by the laser beam, the reference points

  most often consisting of optical receivers associated

  However, this method does not

  not allow direct measurement of roll, tan-

  pledge and yawning but, because of the resulting trajectory, only their indirect measurement, with moreover a certain delay This translates

  by the fact that the digging machine does not work in a straight line

  te, as desired In fact, its displacement varies in the three di-

  mensions around the directing laser beam.

  Another disadvantage of this method is that it requires a

  "visual connection" between the laser and the optical sensors placed at the rear

  If the digging machine is no longer provided by

  following a curvature of the trajectory, the laser must be moved, operating

  tion which requires long measurement and adjustment of the radius.

  Added to this is the fact that the use of laser devices is subject to strict regulations for "sight protection" reasons and it is common that such devices cannot be used for this reason The use of three-axis gyros would avoid the drawbacks mentioned. It is however not possible in most practical applications because of the harsh conditions of use, the need to periodically perform a

  control of the coordinates and also for reasons of cost.

  The object of the present invention is to provide a method and a device for the implementation thereof which makes it possible to identify continuously, practically without complication and without additional expense but with high precision, the orientation of the axes of a maneuverable object, for example of a machine for digging

  tunnels relative to the observer's fixed coordinate system.

  The problem is solved by the fact that the unit to be piloted is rigidly connected (for example the tunneling machine) to

  a three-dimensional reference body provided with optical elements

  in front of optical reference points, that by means of a shooting unit arranged at a defined distance with a visual connection, the optical elements are identified with high precision and that, in an associated image processing unit , we determine the orientation

  axes of the unit coordinate system to be controlled by

  port to the coordinate system of the camera unit and we trans-

  puts the values to a control unit to control the moves

ment.

  In accordance with an improvement of the invention, the elements

  optical elements are arranged on the three-dimensional body so as to

  guarantee a clear identification of its axes.

  According to another improvement of the invention, the position of the optical reference body is precisely measured by

  relation to the unit to be controlled and the position of the reference points

  as compared to each other and we store the values in the met

memory of a system computer.

  In accordance with another improvement of the invention, it is

  adjusts the detection axis manually or automatically

tion of the shooting unit.

  By means of a sighting program integrated into the computer of the system, an optimal adjustment of the shooting unit is carried out continuously according to the correlation method or the method

intensities.

  The device for implementing the method according to the invention

  tion includes a three dimensional optical reference body which is

  rigidly fixed to the rear of the digging machine and whose an-

  They are provided with light sources, the emission of which is arranged so as to allow individual spectral identification and

  unequivocal time camera as well as a camera unit

  variable focal length which is associated with the reference body and is

  arranged at a determined distance from the digging machine.

  According to an advantageous embodiment of the device

  according to the invention, the reference body has the shape of a pyramid

  of the angles of which the light sources are arranged.

  According to a variant of the device according to the invention,

  the varial focal unit is mounted on the back of the camera

  digging china with a defined orientation of its axes and

  light sources serving as reference points occupy a posi-

fixed in space.

  In accordance with an improvement of the invention, the transmitter

  the different light sources are selectively activated

ve by the control unit.

  In accordance with another improvement of the device se-

  lon invention, a detection element reads the magnification factor

  of the optics and transmits it to the computer.

  In accordance with another improvement of the device se-

  lon the invention, for the purpose of ensuring the location of the digging machine-

  even when the visual connection between the camera unit and

  the reference body is interrupted, we measure during the pro-

  the reciprocal position of pre-

  smells in the vicinity of the machine or artificially created

  depending on the speed of progression and the trajectory and before-

  clearly defined by the camera unit with respect to the camera body

  ference. The invention is described below in detail in detail.

  referring to exemplary embodiments represented on the drawings.

  shown: Figure 1, a block diagram showing the principle of a digging machine and a camera unit with the corresponding links and coordinate systems, Figure 2, three examples (2 a 2 c) d body orientation

  reference placed at the rear of the digging machine.

  The basic idea on which the invention is based consists of

  rer a three-dimensional body of shape adapted to the unit or the support which carries it, in this case a machine for digging VM tunnels, and provided with optically identifiable elements such as light-emitting diodes, etc and to thus create a so-called ONK optical reference body This optical reference body is continuously observed during the advance of the machine by means of a BAE camera unit, from which information is continuously obtained on the orientation of each of the axes of said body (coordinate system

  KNK) relative to the observer's coordinate system (system-

  me of KBAE coordinates), which information is transmitted to

  an SE control unit for the purpose of correcting the aim.

  The orientation of the coordinate system of the VM unit including

  this is to control the movement and which is equipped with the reference body

  rence ONK mentioned above is determined in a simple way

  and with great precision by optically locating said body with the aid of

  from the BAE camera unit and using the data using

  of the associated BV image processing unit.

  The characteristics of the BAE camera unit and the form

  me geometric of the ONK reference body being known, we calculate

  from the image data, in addition to the orientation of the axes, direct-

  the distance between the object and the camera unit.

  their thus obtained are advantageously used for the very precise control of displacements The process described above can be

  used and implemented in many situations.

  An exemplary embodiment of the invention is presented below

  from the example of a tunneling machine.

  Figure 1 shows schematically this embodiment The ONK optical reference body described above is rigidly fixed to the rear of the VM Ce digging machine

  ONK reference body is arranged to allow identification

  unequivocal fication of its axes A body of spherical shape for example-

  ple would be totally unsuitable due to its high degree of symmetry

  vé; as shown in Figures 2 a to 2 c, the body appears under the

  form of a pyramid in this case.

  The position of the reference body ONK is precisely measured relative to the digging machine VM as well as the position of the optical reference points LQ 1 to LQ 5 relative to each other and they are stored in the operating system d image

  level of the angles which, simultaneously, constitute the reference points

  References mentioned for the measurement process are arranged with the sources

  light LQ 1 to LQ 5 with defined emission characteristics

  spectrum and over time to allow identifi-

  unequivocal individual cation The emission of each light source

  is controlled in a targeted manner by the control unit.

  At a distance of for example 50 m, which is determined by the application, there is the BAE camera unit provided with a variable focal length lens. A sensor reads the factor of

  magnification (distance or approximation) of the optics and the

  puts to the computer of the system The position and the direction of observation

  the BAE camera unit are precisely determined

  by the KBM coordinate system As a rule, the representation

  ONK reference body occupies the entire image format

  ge; this is the reason for the variable focus optics of the lens unit.

BAE views.

  When the direction of observation is perpendicular to the base of the reference body ONK, which in this case has the shape of a pyramid (see Figure 2 a), the reference point LQ 5 appears in the center of the image as as shown in FIG. 2 b Any deviation in position or direction of the reference body ONK and, consequently, of the digging machine VM relative to the camera unit BAE causes

  a modification of the position of the images of all the reference points

  rence LQ 1 to LQ 5 with respect to the BAE camera unit If for example the longitudinal axis of the VM digging machine has pivoted

  down with respect to the direction of observation, we obtain the posi-

  tion of the reference points shown in Figure 2 c This is

  calculated using known algorithms and the SR calculator determined

  do from the data obtained the current distance and orientation

  axis of the ONK reference body with respect to the coordinate system

  BAE camera reference numbers.

  When study data concerning the evolution of the

  these are stored in a system memory, these can be compared with the actual data and correction signals can be sent to the control unit of the digging machine in

  case of deviation We thus have an automatic advance with an op-

  timal to plan data.

  It is provided in a second embodiment to fix

  BAE camera unit with a rigidly defined axial orientation

  dement on the object which moves in the present case on the digging machine VM and to give to the reference points LQ 1 to LQ 5 to measure a fixed position in space The method of measurement, etc

  is similar to that described above.

  In a particular embodiment, when the pro-

  gression takes place in a curve, with a visual connection, however,

  manual or automatic adjustment of the position of the axis of the BAE camera unit In all cases, variations in the direction of observation are precisely measured and

  they are transmitted as updated data to the computer of the system.

  teme for the exploitation of the new set of points If it is necessary to follow fast displacements, a program of follow-up of target (aiming) which works either according to the correlation method or according to the method of intensities ensures a reliable follow-up (adjustment) optimized, from the BAE camera unit The algorithms used for this make

part of the state of the art.

  These measurements result in the representation of the body

  ONK reference file fills the entire image format Thus the resolution

  lution, given for example by the number of pixels of the charge transfer element (CCD), is it used to obtain an accuracy

maximum measurement.

  There are many possibilities of arrangement of the

  So it can be used to identify the position of the reference body

  rence ONK the projection on the image plane of the BAE camera of the reference surfaces defined by the reference points

  LQ 1 LQ 5; these reference surfaces can be arranged individually

  dual, for example color or emission behavior,

  to allow identification on the basis of these characteristics

  fast and undoubtedly possible by the image processing unit.

  By adapting the optical representation of the ONK optical reference body on the detector of the camera unit, for example a CCD element, maximum measurement accuracy is obtained with regard to the orientation of the axis and the distance Reading and holding

  account of the image parameters of the BAR camera unit on

  ends the distance between the optical reference body ONK and the camera unit BAE, which is adjusted manually or automatically so that an optimal image of the reference body is obtained, so that the angular deviations are determined with precision and that these data as indicated above are taken into account for the control of the advance of the object (digging machine).

  When the camera unit is mounted on the moving object

  the, another alternative embodiment of the invention consists after having

  defines the position of the reference body, to measure the position in relation

  port to the reference body of existing natural reference points-

  or artificially created reference points during pro-

  gression of the VM digging machine We thus obtain a first

  set of reference optical points When continuing to move

  additional sets of reference points are identified and their position relative to the position coordinates of the preceding points is measured. This method makes it possible to obtain, for image-assisted detection of the position, a series of reference points in the from which we can control the digging machine even in cases where the visual connection that originally existed between

  the BAE camera unit and the reference body is interrupted.

Claims (8)

  1 Method for locating the orientation with respect to a fixed coordinate system of a coordinate system specific to an object whose movement is to be controlled and to use this to correct the sighting direction (direction in advance), characterized in that the unit to be piloted (VM) (for example a tunneling machine) is rigidly linked to a three-dimensional body provided with optical elements (ONK) forming reference points optical   (LQ 1 LQ 5), that by means of a camera unit (BAE) available   At a defined distance with a visual link, the optical elements (ONK) are identified with high precision and, in an associated image processing unit (BV), the orientation of the axes of the coordinate system is determined. the unit to be controlled (KONK) relative to the coordinate system of the camera unit (KBAE)   and the values are transmitted to a control unit (SE) to com- order trips.   2 Method according to claim 1, characterized in that   the three-dimensional body carrying the optical elements (ONK) is arranged   created in such a way as to guarantee a clear identification of its axes.   3 Method according to claim 1 or 2, characterized in that the position of the optical reference body (ONK) with respect to the piloted unit (VM) and the position of the   optical reference points (LQ 1 LQ 5) relative to each other   very and the values are stored in the memory of a computer of the system (SR).   4 Method according to any one of claims 1 to 3,   characterized in that the detection axis of the camera unit   (BAE) can be adjusted manually or automatically.   Process according to any one of Claims 1 to 4,   characterized in that by means of a target tracking program   included in the system calculator (SR), a continuous   optimized setting of the shooting unit (BAE) according to the   correlation or according to the intensity method.   6 Device for implementing the method according to the resale   dication 1, characterized in that an optical reference body (ONK)   three-dimensional is rigidly attached to the back of the digging machine-   ment (VM), which reference body carries at its angles light sources (LQ 1 LQ 5) whose emission behavior is arranged in terms of the spectrum and over time so as to allow unambiguous individual identification and that a camera unit   (BAE) equipped with a variable focal length lens placed at a defined distance   of the digging machine (VM) is associated with the reference body.   7 Device according to claim 6, characterized in that the geometric shape of the optical reference body (ONK) is that of a pyramid at the angles of which are arranged the light sources (LQ 1 LQ 5).   8 Device for implementing the method according to the claim   cation 1, characterized in that the camera unit (BAE) for-   view of a variable focal length lens is mounted with an axial orientation defined at the rear of the digging machine (VM) and that the sources   (LQI LQ 5) to be measured occupy as reference points   ment a fixed position in space.   9 Device according to any one of claims 6 to 8,   characterized in that the emission behavior of the various light sources (LQ 1 LQ 5) is activated in a targeted manner by the unit (SE).   Device according to any one of Claims 6 to 9,   characterized by the fact that the magnification factor of the optics (object   tif with variable focal length) is read by a sensor and transmitted to the computer of the system. 11 Device according to claim 8, characterized in that, at the fms to ensure the location of the digging machine even in cases where the visual connection between the shooting unit (BAE) and the   reference body (ONK) is interrupted, it is measured during the pro-   gression the reciprocal position of optical reference points present   in the vicinity of the machine or artificially created in function   progression speed and trajectory and previously defined   defined by the camera unit with respect to the reference body.