FR2727523A1 - DEVICE FOR THE RECOGNITION OF MOVING OBJECTS - Google Patents

Abstract

The invention relates to a device for the recognition of moving objects using an active optical rangefinder (12) and at least one vertical series of several reception channels (4a, 4b ... 4f ) arranged in radiation and whose signals are exploited in time and space by an evaluation circuit (18) in order to differentiate between determined objects and parasitic objects.

Description

Device for recognizing moving objects.

  The present invention relates to a device for recognizing moving objects by using an active optical rangefinder scanning the object in the form of a network.

  We know from the German patent 29 49 453 a process allowing

  both to increase the number of hits on flying objects, on active portions of flying objects and on projectiles by

  automatic target tracking and target scanning with realiza-

  tion of an image of the target, which is compared via

  diary of a correlation circuit with an image of the target m mori-

  pulsed, the image of the target thus scanned being

  further compared to another image of the target to be shot down before-

  memorized which image presents areas of center of gravity of vulnerability, the information thus obtained being the subject, in a unit, of correlation and of exploitation in

  view of firing point setting.

  Also known from German patent application 30 43 238

  a search head for flying bodies for research and pros-

  sequence of terrestrial targets by means of a laser range finder and a laser beam deflection device thanks to which it is possible to cover the area of the target in the manner of a network, and in which a discontinuity detector distance is associated with the receiver of the scattered light in return, this detector being able

  be managed by an evaluation unit.

  Such devices are, on the one hand relatively complex as regards the circuits used and the processing of the signals and on the other hand do not allow any information to be obtained as regards

  concerns distance and speed or no possibility of difference

  tiation depending on the size and speed of the object observed.

  The subject of the invention is the production of a device for

  recognition of moving objects moving in direction

  tangentially relative to the active direction of the device, the device being able to discriminate between the objects sought

  according to their size, their direction of movement, their distance and -

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  their azimuthal speed relative to parasitic objects and being in

  at the same time simple and safe construction.

  This object is fulfilled according to the invention by the fact that the provision

  sitive presents at least a vertical series of each time several optical receivers arranged substantially parallel whose reception signals are the subject of a correlation both in time and in space in an evaluation circuit, the information obtained from the reception signals and concerning the vertical or horizontal spatial extent, the direction of movement and the speed of the moving object being exploited and an output signal being emitted as soon as the surface center of gravity of the object

  in motion is determined from the operating reception signals

  or the spatial extent of the moving object exceeds one

predetermined threshold.

  The evaluation circuit preferably includes a microprocessor

  sor equipped with appropriate peripherals which performs the operation according to a program determined according to variable parameters. The optical receivers are preferably connected to the microprocessor via a multiplexer and an analog / digital converter. The microprocessor is connected to memories with invariable or modifiable contents and to selection switches as well

  than a controller for other devices.

  According to an advantageous embodiment of the invention, the focal distance of the optical receiving system and / or the scanning frequency of the optical rangefinder and other parameters of the operating procedure (for example: evaluation of the vertical extent of the object only in the case of a determined range of distance and / or speed) can be modified according to the result of

  the use of reception signals.

  The device can also include several vertical series

  wedges of optical receivers separated horizontally from each other

  others by optically unreached sectors.

  The device can also be simplified by not providing

  only one optical receiver in each vertical series.

  In addition, the device takes into account, when processing the signal, the forward viewing angle so that the arrangement

  geometrical field of view of the optical receiver can be symmetrical

  than or only unilateral with respect to the direction of sight towards the front. An exemplary embodiment of the invention is shown in the

  drawings and is the subject of a detailed description below. On the

  drawings: FIG. 1 shows in elevation an example of application of a device for the recognition of moving objects; Figure 2 is a section along line A-A of Figure 1; Figure 3 is a top view of Figure 1; FIG. 4 is a functional diagram of the processing of the signals of a device for recognizing moving objects; and

  FIG. 5 is a block diagram of a device for recognizing

birth of moving objects.

  Figure 1 shows an example of application for the recon-

  birth of moving objects in accordance with the present invention.

  This is an optical detector operating on the relief principle, mounted for example on a directional mine with horizontal direction of action. This directional mine must, after its installation, prevent the crossing of the vertical plane defined by

  the axis of action, by objects of a predetermined geometric extent

  born in a predetermined range of speeds, for example by blocking the passage of large vehicles to a desired location in a throttle of a valley. A detector having a fixed geometrical alignment of its sensitivity characteristic with respect to the mine's axis of action causes the mine to be triggered at an appropriate time when passing a corresponding target without reacting to other objects in movement in the field of observation such as animals, plants, pedestrians etc. For this purpose, the device according to the present invention comprises, as shown in FIGS. 1, 2 and 3, a laser rangefinder with an arrangement of several optical receivers 4a, 4b, ... 4f arranged in a radiant formation and in two vertical series 2, 3 as well as an evaluation circuit 10 represented in FIG. 5 which exploits the reception signals 5a, 5b, ... 5f supplied by the receivers 4a, 4b, ... 4f . The main optical axis 8 of the receiver is offset with respect to the direction of action 9 of the mine from the forward viewing angle Y. The individual receivers

  4a, 4b, ... 4f present in the horizontal and vertical directions

  holds an opening angle CY and are spatially separated from each other. For simple uses just provide a

  single vertical series 2 of receivers.

  10. The use of reception signals 5a, 5b, ... 5f of

  receivers 4a, 4b, ... 4f is advantageously done in a microprocessor

  sister. The parameters necessary for the processing of the signals can partly be introduced by means of selector switches or similar devices or even be included as constants in

  the program can then be called as needed.

  Various parameters can be influenced during the calculation, depending on the results of the reception signal processing, such as the focal length of the reception optics, the scanning frequency and the choice of process.

  operating. The purpose of signal processing is to determine

  identify the optical center of gravity of the observed object and / or its spatial extent within given limits and deduce the

  calculation of the appropriate triggering moment as a function of the distance

  speed, and dimensions of the object.

  The following information can be obtained using the operating circuit from the distance information which periodically reaches each reception channel: 1) No receiver detects a significant change in the value of the distance determined at the start of the measurement process: the detector simply observes the environment, no object

  in motion not in the field of vision.

  2) First significant change in the distance value -

  in a reception channel: the receiver in question is controlled at

  from this moment as "active" insofar as the value corresponds

  remoteness distance is within the range of predeter distance-

undermined the system.

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  3) The number of activated receptors located one at a time

  above others in a vertical series 2, 3 provides a measure of the height of the object 6 in relation to the corresponding values

  distance (or their average, minimum or maximum).

  4) In the case of several receivers activated in the two vertical series, the time elapsed from the activation of a receiver to the activation of the neighboring horizontal receiver provides, in relation to the corresponding values of distance, a

object speed measurement 6.

  5) Since the distance values measured in each activated reception channel generally decrease first and then increase, it is possible to determine the optical center of gravity of the object during its movement, for example by subtraction of successive measured values for each receiver and simultaneous calculation of the average for all activated receivers. This is also possible even with a single vertical series 2 of

receivers 4a, 4b ... 4f.

  The device of the invention can be arranged for different

  uses by the appropriate combination of evaluation possibilities

  mentioned above as well as by the choice of focal distance, detection range and number of receivers (available

vertical and horizontal).

  The operation of the device will be explained from the functional diagram of Figure 4 to which it is made here.

  expressly referred to as an integral part of the

  cription. The following variables are used for operation: - the speed of the projectile and the aiming angle towards the front of the ammunition; the geometric arrangement of the receivers (here two slots of each 6 channels), the scanning frequency and the measurement field of the sensors; - the speed range, the minimum length Iin and the height

minimum hmin of the object.

rain

  In this case, only one of the directors will be taken into account.

  possible tangential displacement of the object; for both

  directions it is necessary to use a second device available

  s symmetrically to the aiming direction towards

  the front and with the same signal processing.

  The reception signal processing program proceeds as follows:

  First (START) all channels 4a, 4b ... 4f are deactivated

  and the corresponding memory elements as well as the parameter-

  OBJ object, and the length and forward aiming time counters are set to "Zero". As a result, the information concerning the observed area can be memorized without the presence of an object in

  background embossed movement in the background matrix.

  Then there is a repetitive scan interrogation

  cyclically controlled (CYCLE) reception channels without

  quence on the progress of the program until one of the reception channels is activated by the penetration of a moving object 6 in its reception area which results in setting to "A" the corresponding element of the memory array. If a slot 2 receiver

  directed towards the forward line of sight 9, is active, this means

  either the object was too fast or it came from the wrong direction. In this case, the program will start again. In the case, however, where a receiver of the slot i is active, a selection procedure begins with regard to the size and the speed of the object discovered. For this it is first necessary to operate

  a classification of the moving object using the OBJ parameter.

  This parameter has the following meanings: OBJ = 0: the two slots 2, 3 are empty; OBJ = 1: slot 3 is activated, slot 2 is empty; OBJ = 2: slots 2 and 3 are activated; OBJ = 3: the minimum length is detected, the slot 3 is (again)

  activated, the minimum height is not (yet) reached.

  The speed of the moving object 6 is determined by means of the time counter ZZ which is placed at ZZ = l and operates

  then down counting. An interruption and a restart of the program-

  occur when the moving object is too slow (ZZ too large), too fast (ZZ too small), too small (slot 3 is no longer activated) or too low (the channel height threshold is

  one above the other is not reached).

  The length counter ZL makes it possible to determine to what extent the moving object 6 is within a predetermined length range. At the same time the state of the counter provides a starting threshold for the forward aiming counter ZH, this threshold being able to be determined by calculating the optical center of gravity of the target in

movement.

  We deduce from the distance from the DM object, from the state of the comp-

  ZZ and ZL, the state of the forward sight counter ZH which represents

  feels the triggering moment for the greatest probability of hitting the target taking into account the given values of the aiming angle

  forward and the speed of the projectile.

  FIG. 5 illustrates in a simplified manner an example of cons-

  overall construction of a device for recognizing moving objects. The pulse transmitter 12, controlled by the control unit 11 under the control of the time base of the microprocessor 18, emits light by radiation through the optics 13, this

  light being reflected by the environment or on an observable target

  vee. The reflected light is directed by another optic 14 on

  one or more series 2, 3 of optical receivers 4a, 4b ... 4f.

  The output signals 16 (distance values as a function of the duration of the path of the light) from the receivers 15 are supplied to the buffer memory 17 from which they are called in the microprocessor 18 and operated according to the procedure illustrated in the figure. 4. If a moving object is recognized, a signal is provided on output 19 at

optimal time.

  The particular advantages of the device according to the present invention for the recognition of moving objects reside in the fact that an apparatus is easy to build and compact which allows an exact detection of the moving object with elimination of parasitic objects and this without the addition of others

  detectors that previously had to be placed around the device.

  In addition, it is also possible with such a device to observe a larger area by automatic change of direction by means of other information sensors. This results in a large number of possibilities for implementation other than those which have been described here by way of examples.

Claims (7)

  1. Device for recognizing moving objects using an active optical rangefinder scanning the object in the form of a network, characterized in that the device (1) has at least one vertical series (2, 3) of each several optical receivers (4a, 4b ... 4f) arranged substantially parallel, of which   reception signals (5a, 5b ... 5f) are correlated   tion in time and space in an evaluation circuit, the   information obtained from the reception signals (5a, 5b ...   5f). concerning the vertical or horizontal spatial extent, the direction   displacement and the speed of the moving object (6) being exploited and an output signal (7) emitted as soon as the surface center of gravity of the moving object (6) is determined from the reception operated (5a, 5b ... 5f) or that the extent   of the moving object (6) exceeds a predetermined threshold.   2. Device for recognizing moving objects according to   claim 1, characterized in that the optical receivers   that (4a, 4b ... 4f) are connected to a microprocessor by means of   diary of a multiplexer and an analog / digital converter, the microprocessor being connected to memories with invariable or modifiable contents and to selector switches as well as to a   control device for other devices.   3. Device for recognizing moving objects according to   claims 1 or 2, characterized in that the distance   focal length of the reception optics and / or the scanning frequency of the optical rangefinder can be modified according to the result of the processing of the reception signals from the optical receivers (4a, 4b ... 4f).   4. Device for recognizing moving objects according to   any one of claims 1 to 3, characterized in that   that certain parameters of the operating procedure (for example: evaluation of the vertical extent of the object only in the case of a determined range of distance and / or speed) can be modified according to the result of the signal processing   reception of optical receivers (4a, 4b ... 4f).   5. Device for recognizing moving objects according to   any one of claims 1 to 4, characterized in that   that the device (1) comprises several vertical series (2, 3) of optical receivers (4a, 4b ... 4f) which are spaced from one another in horizontal direction so as to create between the fields of   vision of optical receivers in optically unaffected areas.   6. Device for recognizing moving objects according to   any one of claims 1 to 5, characterized in that   only one optical receiver is mounted in each vertical series (2, 3).   7. Device for recognizing moving objects according to   any one of claims 1 to 6, characterized in that   that it includes another identical device arranged horizontally symmetrically with respect to the axis of action offset by the angle of   aiming forward Y relative to the main axis (8).