EP0908854A2 - Method and device for detecting persons and objects in a given area - Google Patents

Abstract

The detection system uses a laser beam to optically scan the controlled space. The beam is emitted at regular intervals from a source (2) above the persons (3) or objects (4) in the controlled space. The light beam is directed downward, approximately perpendicular to the surface (R) supporting the person or object. The reflected light is detected, and the time shift between light reflected from the person or object and light reflected from the support surface is detected.

Description

The present invention relates to a method and device for detecting people and objects in a given space, for the purpose of localization and / or counting people and objects, whether they are fixed or mobile, as well as, in particular in the case of people, in order to define characteristics of their movements, such as direction, direction, speed and trajectory.

We already know various techniques for the detection of people and objects, in particular with a view to their counting. In particular, a classic technique consists of interception, by people or objects to detect, from one or more fixed light rays, by general infrared rays, emitted horizontally. This technique lacks precision as soon as "targets" (objects or people to be detected) intercept simultaneously the light rays. In addition, it becomes totally inoperative in the case of people or objects fixed or in very slight movement.

Another known technique consists in analyzing the brightness levels detected by video cameras or other photosensitive devices oriented towards people or objects to be detected. This process is only effective only for constant or varying levels of illumination weakly. It is unsuitable, in particular, for outdoor detections as well as in spaces partially or fully enclosed, naturally lit.

The use of devices based on transmission / reception of electromagnetic waves (radars) constitutes another type of solutions, for which the detection ranges, the powers used and costs are hardly compatible with practical needs proximity detection in public spaces or private, which is particularly interested in present invention.

• la détection de présence de personnes et d'objets dans un plan de référence,
• la détection des déplacements de personnes et d'objets mobiles de part et d'autre d'une ligne de référence,
• la détection de présence de personnes et d'objets dans un volume de référence,
• la localisation et le comptage de personnes et d'objets immobiles dans un volume de référence,
• la détection des directions, sens, vitesses et trajectoires des déplacements de personnes et d'objets mobiles dans un volume de référence.

The present invention aims to remedy the drawbacks or inadequacies of the existing techniques mentioned above, by providing a method and a device for detecting people and objects in a given space, allowing precise detection of objects or people who are mobile or in low movement or fixed, aligned or randomly distributed in the space considered, without disturbance by ambient lighting, the solution proposed by the invention adapting to many more or less complex applications and aiming, in particular:

• detecting the presence of people and objects in a reference plane,
• detecting the movement of people and moving objects on either side of a reference line,
• detecting the presence of people and objects in a reference volume,
• the location and counting of people and immobile objects in a reference volume,
• the detection of directions, directions, speeds and trajectories of the movements of people and mobile objects in a reference volume.

To this end, the method according to the invention for the detection of people and objects in a given space basically consists in performing an optical scan resulting from laser-type optical rays emitted at regular intervals from a source above of people or objects to be detected, emissions of successive rays being produced in a so-called plane measurement plane, which extends inside the space considered by forming a zero or relatively small angle with respect to a direction perpendicular to a plane of reference in which are located and / or move the people or objects to be detected, detection being performed by determination and comparison, for each emission, time shifts observed between the emission of optical rays by the source and the reception of the optical rays reflected by the plane of reference or by people or objects located in the space considered.

In the most generally encountered case, the people or objects to be detected are located and / or are move in a horizontal reference plane or substantially horizontal; optical scanning is performed then in a vertical measurement plane, or forming an angle relatively low (in practice less than 45 °) by compared to the vertical.

The method according to the invention is based on the relative positions and movements of the measurement plane and of people or objects to be detected, which leads to two main modes of implementation of this process.

According to a first mode of implementation, the optical scanning is carried out in a fixed measurement plane, substantially perpendicular to the reference plane in which are located and / or move people or objects to be detected. This simple implementation allows in particular, by comparison of the results (shifts between emission and reception of optical rays) observed in the same measurement plane at successive times, from detect and / or count people or objects movable, moving in a predetermined direction and invariable, substantially perpendicular to the plane of measure, for example: people moving in a corridor, road vehicles moving on a lane, objects transported on a conveyor.

According to a second mode of implementation of the method of the invention, optical scanning is performed in a variable measurement plane, occupying positions successive angulars different from each other by relation to the reference plane in which are located and / or move the people or objects to be detected, the emission of optical rays being repeated in each position of the measurement plane. This other mode of setting work, more complex since it comprises in a way a succession of scans, is suitable for detecting people or fixed or slow moving objects in a certain reference space. The combination and comparison shifts between the emission and the reception of the rays optics in successively scanned measurement planes, allows here to locate people perfectly or even immobile objects in a reference volume, and determine the characteristics (direction, direction, speed, trajectories) possible movements of these people or objects. In practice, this mode of implementation of the process makes it possible to detect and analyze the appearance and the evolution of groups of people, for example forming a queue, in a given space, as well as the types of objects or people identified by their size and their shape. It is thus possible to distinguish the adults children, the presence of special objects (luggage or carts) linked to people, or the circulation of vehicles in motion according to various directions in a delimited space such as square or crossroads.

As for the device intended for the implementation of the previously defined detection method, this one mainly includes a ray emitting source laser-type optics, performing optical scanning in the measurement plane, the source being placed above the reference plane in which are located and / or is move the people or objects to be detected, and being associated with means for receiving optical rays reflected by the reference plane or by people or objects, means of determining and comparing time lags observed between transmission and reception of optical rays, and means of analysis and of treatment, able to characterize and locate people or objects located in the space considered. Analysis and processing, by these latter means, are performed simultaneously with scanning.

According to one embodiment of the device detection object of the invention, the source emitting laser-type optical rays is pivotally mounted so as to vary the angular position of the plane of measurement in a reference space, the means of analysis and processing being provided to compare or combine the results, namely the shifts between transmission and reception of optical rays, in the measurement planes distinct successively swept. This embodiment applies to the location of people or objects fixed or in slight movement in a reference volume.

Figure 1 est schéma illustrant le principe du balayage optique selon l'invention et son résultat, dans un plan de mesure ;

Figure 2 est une vue en perspective montrant très schématiquement un dispositif de détection et de comptage d'objets selon l'invention, travaillant dans un plan de mesure fixe ;

Figure 3 est un diagramme expliquant le mode de détection et de comptage utilisé par le dispositif de la figure 2 ;

Figure 4 est une autre vue en perspective, montrant un dispositif selon l'invention pour la détection de personnes à l'intérieur d'un volume donné, permettant la détermination des caractéristiques de leurs déplacements ;

Figure 5 illustre une visualisation des localisations, vitesses, directions et trajectoires de plusieurs personnes, telle qu'elle peut être obtenue au moyen de dispositif de la figure 4.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing illustrating various modes of implementation of this method for the detection of people or objects, and representing the device for the implementation of this process, in relation to various types of applications:

Figure 1 is a diagram illustrating the principle of optical scanning according to the invention and its result, in a measurement plane;

Figure 2 is a perspective view very schematically showing a device for detecting and counting objects according to the invention, working in a fixed measurement plane;

Figure 3 is a diagram explaining the detection and counting mode used by the device of Figure 2;

Figure 4 is another perspective view showing a device according to the invention for detecting people inside a given volume, allowing the determination of the characteristics of their movements;

5 illustrates a visualization of the locations, speeds, directions and trajectories of several people, as it can be obtained by means of the device of FIG. 4.

In Figure 1, there is shown very schematically in 2 a beam transceiver laser type optics, arranged above a plane of reference R, here a horizontal plane, on which lie and / or move people 3 and / or objects 4 to detect. Transceiver 2 performs a scan optic in a measurement plane P, which coincides with the plan of Figure 1, emitting optical rays 5 in direction of the reference plane R. The rays 5 are reflected, as the case may be, by the reference plane R or by 3 people or 4 objects to detect, and the rays reflected by the transceiver 2. The latter is associated with means 6 for determining and comparison of the time lags observed between the emission of rays 5 and the reception of rays corresponding reflections, and to means 7 of analysis and treatment. Here we mean by time difference the observed time difference between receiving a beam reflected by the reference plane R, or any other fixed obstacle inside the reference volume, and the reception of the same ray reflected by the "target" (person 3 or object 4) concerned by the detection to be carried out.

The measurement of this time difference makes it possible to determine, in the measurement plane P considered, a "profile "8 characterizing people 3 and 4 objects detected, in particular by a certain height h or H measured, allowing then to perform a discrimination, by eliminating non-significant objects in relation to the objectives of the detection (for example isolated objects in the case of detection of persons) and especially when comparing with types predetermined.

Referring to Figure 2, we consider more particularly a fixed 2 transceiver, transmitting its optical rays 5 in a measurement plane P also fixed, here a vertical plane perpendicular to the direction general movement F of objects 4 to be detected and count, which here are moving moving objects along a predetermined direction in the plane of reference R.

• A l'instant initial t1, trois objets A, B et C sont simultanément détectés.
• A l'instant suivant t2, seul l'un de ces objets B reste détecté, ce qui signifie que les deux autres objets A et C n'intersectent plus le plan de mesure P et l'ont par conséquent entièrement franchi ; les deux objets A et C sont ainsi comptés entre les instants t1 et t2.
• A l'instant suivant t3, l'objet B lui aussi n'est plus détecté, mais deux nouveaux objets D et E sont détectés. L'objet B est ainsi compté.
• Au dernier instant t4 ici considéré, le "profil d'émission" 8 est entièrement plat, ce qui signifie que plus aucun objet n'intersecte le plan de mesure P. Les objets D et E sont alors comptés eux aussi.

The "emission profile", as defined above, is here determined at successive instants, in the same measurement plane P. FIG. 3 illustrates more precisely the detection and counting mode implemented here, showing the "emission profiles" recorded in the plane P at successive times t1, t2, t3 and t4, in the context of a particular example:

• At the initial time t1, three objects A, B and C are simultaneously detected.
• At the time following t2, only one of these objects B remains detected, which means that the other two objects A and C no longer intersect the measurement plane P and consequently have completely crossed it; the two objects A and C are thus counted between times t1 and t2.
• At the next instant t3, the object B too is no longer detected, but two new objects D and E are detected. Object B is thus counted.
• At the last instant t4 considered here, the "emission profile" 8 is entirely flat, which means that no more objects intersect the measurement plane P. The objects D and E are then counted too.

Figures 4 and 5 illustrate another application, in which the device is used for detection of 3 people inside a volume V given, such as a waiting room whose floor constitutes here the reference plane R, people 3 can be stationary or moving in directions any horizontal.

The transceiver 2 is installed here by example on the ceiling of the room considered, and it went up oscillating around a horizontal axis 9, in such a way that the measurement plane P is no longer fixed but occupies variable angular positions, not moving too far strongly from the vertical. This variable measurement plan P thus "scans" the reference volume V.

The device here again determines at times successive "emission profiles" (according to the principle illustrated in Figure 1), but it does so in plans separate from each other such as P1, P2, P3, the oblique planes P1 and P3 forming angles α and β with respect to the plane P2 which occupies an average position vertical.

The comparison in 6 of the results, namely the shifts in the emission and reception of optical rays 5, between successive positions such as P1, P2 and P3 of the measurement plan P, makes it possible to locate the people 3 as well as any objects that are located and / or are move into the reference volume V.

• les directions, sens et vitesses des déplacements de ces personnes 3, pouvant être caractérisés par des vecteurs tels que V1 et V2,
• les trajectoires des mêmes personnes, définies comme une succession de points reliés par une ligne brisée L.

The scanning of the whole of this volume V, and the appropriate processing of the results carried out in 7, make it possible not only to detect, locate and count the people 3, but also to determine:

• the directions, directions and speeds of movement of these people 3, which can be characterized by vectors such as V1 and V2,
• the trajectories of the same people, defined as a succession of points connected by a broken line L.

The visualization of these characteristics, such that it can be displayed on a screen 10, is illustrated by figure 5.

In the two examples of implementation of the device, outlined above, the comparison and combination of offset measurements between transmission and reception of optical rays, carried out at instants successive and sufficiently close together either in a plane of fixed measurement P, i.e. in separate measurement plans P1, P2, P3, can detect 3 people or objects 4, the processing carried out then making it possible to determine other features.

This device is adapted, in particular, to the detection and forecasting of movements, passages and queues of people in places public or private, as well as detection and analysis movement of road vehicles and objects transported by continuous fixed devices or discontinuous, like transport systems. However the invention as defined in the claims remains applicable regardless of the nature of the objects detected, and whatever the peculiarities of the information processing carried out from the detection of people or objects.

Claims (9)

Method for detecting people and of objects in a given space, characterized in that it basically consists in performing an optical scan resulting from optical rays (5) of laser type emitted at regular intervals from a source (2) located above people (3) or objects (4) to be detected, successive spoke emissions being carried out in a plane called measurement plane (P), which extends inside the space considered by forming a zero or relatively angle weak compared to a direction perpendicular to a reference plane (R) in which are located and / or is move the people (3) or objects (4) to be detected, the detection being performed by determination and comparison, for each program, of the time differences observed between the emission of optical rays (5) by the source (2) and reception of reflected optical rays by the reference plane (R) or by the people (3) or objects (4) located in the space considered. Method according to claim 1, for the detection of people (3) or objects (4) located and / or moving in a reference plane (R) horizontal or substantially horizontal, characterized in that the optical scanning takes place in a measurement plane (P) vertical, or forming a relatively small angle (α, β) with respect to the vertical. Method according to claim 1 or 2, characterized in that the optical scanning is carried out in a fixed measurement plane (P), substantially perpendicular to the reference plane (R) in which is locate and / or move people (3) or objects (4) to be detected, the detection being carried out by comparison results, i.e. shifts between transmission and reception of optical rays, observed in the same plane of measurement (P) at successive instants. Method according to claim 3 characterized in that it is intended to detect and / or count moving people (3) or objects (4), moving according to a predetermined and invariable direction (F), substantially perpendicular to the measurement plane (P). Method according to claim 1 or 2, characterized in that the optical scanning is carried out in a variable measurement plane (P1, P2, P3), occupying successive angular positions different from each other others with respect to the reference plane (R) in which locate and / or move people (3) or objects (4) to be detected, the emission of the optical rays (5) being repeated in each position of the measurement plane (P), and the location of people (3) or objects (4) being performed by combining and comparing offsets between transmission and reception of optical rays (5) in the measurement planes (P1, P2, P3) successively scanned. Method according to claim 5, characterized in that it is intended for the detection of persons (3) or objects (4) fixed or moving slowly in a space of reference (V), and in particular for the determination characteristics, such as direction, direction, speed and trajectories, possible displacements of these people or objects. Method according to any one of claims 1 to 6, characterized in that determines, by comparing the offsets between emission and receiving the optical rays (5), in the or each measurement plan (P; P1, P2, P3), an "emission profile" (8) characterizing the persons (3) or objects (4) detected, and in that we then discriminate by evaluating the forms detected by comparison with predetermined types. Device for detecting people and objects in a given space, for the implementation of the process according to any one of claims 1 to 7, characterized in that it mainly comprises a source emitter (2) of laser type optical rays, performing an optical scan in the measurement plane (P), the source being placed above the reference plane (R) in which are located and / or move people (3) or objects (4) to be detected, and being associated with means of reception (2) of the optical rays reflected by the plane of reference (R) or by people (3) or objects (4), means (6) for determining and comparing time lags observed between transmission and reception of optical rays, and means (7) of analysis and processing, able to characterize and locate people or objects located in the space considered. Device according to claim 8, characterized in that the emitting source (2) of rays laser type optics (5) is pivotally mounted to vary the angular position of the measurement plane (P) in a reference space (V), the means (7) of analysis and processing being provided to compare and combine the results, namely the shifts between transmission and reception of optical rays, in the measurement planes (P1, P2, P3) successively scanned.

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