A method for monitoring an environment using a plurality of carriers and associated devices.

Abstract

Method for monitoring an environment using a plurality of carriers and associated devices. The present invention relates to a method for monitoring an environment using a plurality of carriers, each equipped with a sensor (14) capable of pointing at the environment in a respective pointing direction to acquire information on a part of the environment. The method comprises the steps of: - dividing the environment into several elementary zones, - calculating the geographical position relative to each sensor (14), - evaluating the contribution in terms of the level of information about the environment for each pointing direction of the sensors (14) of each carrier (12), the gain in the level of information taking into account the calculated geographical positions, - determining the best pointing direction of each sensor (14) as a function of the evaluated contributions in terms of the level of information.and - control of each sensor (14) so ​​that each sensor (14) points in the best determined direction. Figure for the abbreviation: figure 2,

Description

Title of the invention: Method for monitoring an environment using a plurality of carriers and associated devices

[0001] The present invention relates to a method of monitoring an environment by a plurality of carriers. It also relates to a monitoring device and an assembly.

[0002] Surveillance is a rapidly growing field, whether in the air, land or sea domain.

[0003] Examples include meteorological monitoring or seabed exploration.

[0004] For such monitoring, it is possible to use a single rotating sensor and perform repeated scans from one end to the other of the range accessible to the sensor. A typical example is that of an aircraft equipped with a mechanically scanning radar.

[0005] However, for some applications, such a scan does not allow the area to be monitored to be covered quickly enough.

[0006] Also, to remedy such a drawback, a plurality of sensors can be used which must cooperate to cover the area to be monitored.

[0007] However, the coordination of these different sensors is complex and often results in monitoring an environment with poorly monitored areas.

[0008] There is therefore a need for a method of monitoring an environment by a plurality of carriers which is more efficient.

[0009] To this end, the description describes a method for monitoring an environment by a plurality of carriers, each carrier being equipped with at least one sensor capable of pointing at the environment in a respective pointing direction to acquire information on a part of the environment, the method being implemented by a monitoring device and comprising the steps of:

[0010] - division of the environment into several elementary zones,

[0011] - for each elementary zone, calculation of the geographical position relative to each sensor, to obtain calculated geographic positions,

[0012] - evaluation of the contribution in terms of level of information on the environment for each pointing direction of the sensors on each carrier,

[0013] The level of information on the environment is the sum of the information levels on each elementary zone, the information level of an elementary zone being between a zero value if no information is known about the elementary zone and a maximum value when the elementary zone is pointed at by a sensor,

[0014] the information level gain being obtained by calculating the gain in information level on each elementary zone reduced by the energy cost related to the use of the sensor, the gain in information level taking into account the calculated geographical positions,

[0015] - determination of the best pointing direction of each sensor as a function assessed information levels, and

[0016] - control of each sensor so that each sensor points in the best determined direction.

[0017] According to particular embodiments, the monitoring method has one or more of the following characteristics, taken individually or in all technically possible combinations:

[0018] - the environment is a three-dimensional space and the elementary zones are spheres.

[0019] - the spheres are distributed according to a compact hexagonal arrangement.

[0020] - the determination step comprises several iterations of a set of operations, each iteration comprising:

[0021] - a pointing direction selection operation for which the input in The information level is highest, the selected pointing direction being the best pointing direction determined for the corresponding sensor, and

[0022] - an operation to modify the information level input obtained for each pointing direction of the remaining sensors with each sensor placed in the best pointing direction determined previously.

[0023] - the iterations are implemented until an information level criterion or verified, the remaining sensors retaining their pointing direction.

[0024] - during the obtaining step, the calculation of the gain takes into account the probabilities of detection of each elementary zone when the sensor is positioned in the considered pointing direction.

[0025] - during the obtaining step, the calculation of the gain takes into account a decrease in information over time, notably in the form of a decreasing exponential.

[0026] - the energy cost takes into account the occupancy rate of the sensor considered on a time interval.

[0027] - the domain accessible to each sensor is discretized into a finite number of di possible reactions.

[0028] The description also relates to a device for monitoring an environment by a plurality of carriers, each carrier being equipped with at least one sensor capable of pointing at the environment in a respective pointing direction to acquire information on a part of the environment, the monitoring device being capable of:

[0029] - divide the environment into several elementary zones,

[0030] - for each elementary zone, calculate the geographical position relative to each sensor, to obtain calculated geographic positions,

[0031] - evaluate the level of information provided about the environment for each direction of sensor readings for each wearer

[0032] The level of information on the environment is the sum of the information levels on each elementary zone, the information level of an elementary zone being between a zero value if no information is known about the elementary zone and a maximum value when the elementary zone is pointed at by a sensor,

[0033] the information level gain being obtained by calculating the gain in information level on each elementary zone reduced by the energy cost related to the use of the sensor, the gain in information level taking into account the calculated geographical positions,

[0034] - determine the best pointing direction of each sensor according to the assessed information levels and contributions

[0035] - control each sensor so that each sensor points in the best determined direction.

[0036] The description also describes an assembly comprising carriers equipped with at least one sensor capable of pointing the environment in a respective pointing direction and a monitoring device as previously described.

[0037] In this description, the expression "specific to" means interchangeably "suitable for", "adapted to" or "configured for".

[0038] Some features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, in which:

[0039] - [Fig. 1] [Fig. 1] is a schematic representation of an assembly comprising carriers equipped with a sensor and a monitoring device,

[0040] - [Fig.2] [Fig.2] is a flowchart of an example of the implementation of a monitoring method, and

[0041] - [Fig.3][Fig.4][Fig.5] Figures 3 to 5 are schematic representations example of how to divide a space.

[0042] A set 10 is shown in [Fig.1].

[0043] The assembly 10 comprises carriers 12 and a monitoring device 20.

[0044] The assembly 10 is intended to observe an environment.

[0045] Each carrier 12 is equipped with at least one sensor 14.

[0046] A carrier 12 is, for example, an aircraft.

[0047] In this respect, the carrier 12 can be mobile.

[0048] Each sensor 14 is designed to point at the environment in a respective pointing direction to acquire information on a part of the environment.

[0049] The sensors 14 are of the same nature, such as several radars or several optronic devices, in order to carry out and maintain surveillance of an area of ​​interest.

[0050] More precisely, the sensors are homogeneous in the sense that they are capable of observing their environment in the same domain, whether it be sound, radio frequency, infrared or visible.

[0051] In particular, the assembly 10 may be an assembly of aircraft each equipped with one or more radar antennas having an aerial surveillance mission or an assembly of several ships or submarines equipped with a sonar having an underwater surveillance mission.

[0052] The monitoring device 20 is suitable for implementing an environmental monitoring method.

[0053] According to the example described, the monitoring device 20 includes a computer 30 interacting with a computer program product 50 to enable the implementation of steps of the monitoring process, some of which are implemented by computer.

[0054] Calculator 30 is here a desktop computer. Alternatively, calculator 30 is a rack-mounted computer, a laptop, a tablet, a personal digital assistant (PDA) or a smartphone.

[0055] In specific embodiments, the computer is adapted to operate in real time and / or is in an embedded system, in particular in a vehicle such as an airplane or a car.

[0056] In the case of [Fig.1], the calculator 30 comprises a calculation unit 52, a user interface 54 and a communication device 56.

[0057] The calculation unit 52 is an electronic circuit designed to manipulate and / or transform data represented by electronic or physical quantities in registers of the calculator 30 and / or memories into other similar data corresponding to physical data in register memories or other types of display devices, transmission devices or storage devices.

[0058] By way of specific examples, the computing unit 52 includes a single-core or multi-core processor (such as a central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, and a digital signal processor (DSP)), a programmable logic circuit (such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device (PLD), and programmable logic arrays (PLAs)), a state machine, a logic gate and discrete hardware components.

[0059] The computing unit 52 includes a data processing unit 58 adapted for processing data, in particular by performing calculations, memories 60 adapted for storing data and a reader 62 adapted for reading a computer-readable medium.

[0060] The user interface 54 includes an input device 64 and an output device 66.

[0061] The input device 64 is a device enabling the user to enter information or commands on the computer 30.

[0062] In [Fig. 1], the input device 64 is a keyboard. Alternatively, the input device 64 is a pointing device (such as a mouse, a touchpad and a graphics tablet), a speech recognition device, an eye tracker or a haptic (motion analysis) device.

[0063] The output device 66 is a graphical user interface, that is to say a display unit designed to provide information to the user of the computer 30.

[0064] In [Fig. 1], the output device 66 is a display screen enabling a visual presentation of the output. In other embodiments, the output device 66 is a printer, an augmented and / or virtual display unit, a loudspeaker or other sound-generating device for presenting the output in audible form, a unit producing vibrations and / or odors, or a unit adapted to produce an electrical signal.

[0065] In a specific embodiment, the input device 64 and the output device 66 are the same component forming human-machine interfaces, such as an interactive screen.

[0066] The communication device 56 enables unidirectional or bidirectional communication between the components of the computer 30. For example, the communication device 56 is a bus communication system or an input / output interface.

[0067] The presence of the communication device 56 allows that, in certain embodiments, the components of the computer 30 are distant from each other.

[0068] The computer program product 50 includes a computer-readable medium 68.

[0069] The computer-readable medium 68 is a tangible device readable by the reader 62 of the computing unit 52.

[0070] In particular, the computer-readable medium 68 is not a transient signal in itself, such as radio waves or other freely propagating electromagnetic waves, such as light pulses or electronic signals.

[0071] Such a computer-readable storage medium 68 is, for example, an electronic storage device, a magnetic storage device, a storage device optical, electromagnetic storage device, semiconductor storage device or any combination thereof.

[0072] As a non-exhaustive list of more specific examples, computer-readable storage medium 68 is a mechanically coded device, such as punched cards or embossed structures in a groove, a floppy disk, a hard disk, a read-only memory (ROM), a random-accessible memory (RAM), a read-only programmable erasable memory (EROM), an electrically erasable and readable memory (EEPROM), a magneto-optical disk, a static random-accessible memory (SRAM), a compact disc (CD-ROM), a digital multipurpose disc (DVD), a USB key, a floppy disk, a flash memory, a solid-state drive (SSD), or a PC card such as a PCMCIA memory card.

[0073] A computer program is stored on the computer-readable storage medium 68. The computer program comprises one or more sequences of stored program instructions.

[0074] Such program instructions, when executed by the data processing unit 52, cause the execution of steps in the process.

[0075] For example, the form of the program instructions is a form of source code, a computer-executable form, or any intermediate form between source code and a computer-executable form, such as the form resulting from the conversion of the source code via an interpreter, assembler, compiler, linker, or locator. Alternatively, the program instructions are microcode, firmware instructions, state definition data, integrated circuit configuration data (e.g., VHDL), or object code.

[0076] Program instructions are written in any combination of one or more languages, for example an object-oriented programming language (FORTRAN, C++, JAVA, HTML), a procedural programming language (C language for example).

[0077] Alternatively, the program instructions are downloaded from an external source via a network, as is particularly the case for applications. In this case, the computer program product includes a computer-readable data carrier on which the program instructions are stored or a data carrier signal on which the program instructions are encoded.

[0078] In each case, the computer program product 50 comprises instructions that can be loaded into the data processing unit 52 and adapted to cause the process to be executed when executed by the data processing unit 52. Depending on the embodiment, the execution is carried out wholly or partially either on the computer 30, i.e., a single computer, or in a distributed system among several computers (in particular via the use of cloud computing).

[0079] The monitoring method aims to obtain the best possible configuration of the sensors 14 of the carriers 12 at a later time.

[0080] This later instant is called the horizon value A? and is predetermined.

[0081] To choose this value of the horizon A?, it is bounded by the information of which we has access to the trajectories of the 12 different carriers who collaborate.

[0082] Furthermore, depending on the need for responsiveness and precision in choosing the points, a high value of Ar implies point management with better anticipation at the expense of responsiveness. Conversely, a low value of A? implies better responsiveness to potential trajectory deviations, but there will be little anticipation, leading to less collaborative point management.

[0083] The value of the horizon Af may be modified during the implementation of the monitoring process to adapt to possible changes in the collaboration of the carriers 12 or unforeseen events in their trajectory, for example by decreasing its value.

[0084] In the following, we assume that the value of the horizon Af is fixed to simplify the exposition that will follow.

[0085] This value of the horizon Ar corresponds to the implementation time of the monitoring process, that is to say that the process is able to perform the necessary actions between the present time t0 and t0 + Af.

[0086] In this case, the monitoring process includes a cutting step, a calculation step, an evaluation step, a determination step and a control step.

[0087] It is further assumed that the monitoring device 10 has access to the navigation data (position, speed, orientation) of all the carriers 12 at the present moment as well as some moments of trajectory anticipation.

[0088] During the segmentation step, the monitoring device 20 segments the environment into several elementary zones.

[0089] The elementary zones are identical and correspond to cells intended to occupy the entire environment.

[0090] The monitoring device 20 therefore discretizes the environment to be monitored.

[0091] In the example described, the environment is considered to be three-dimensional.

[0092] In this case, the elementary zones are spheres. There is then a strong analogy with atoms. Therefore, in the rest of the description, the elementary zones will be called by this name for ease of reading.

[0093] An example of a honeycomb atom distribution on a layer is shown in [Fig.3].

[0094] Moreover, in the example described, the spheres are distributed according to stacked layers staggered.

[0095] As can be seen in [Fig.4], by superimposing layers of atoms with a lateral offset between each layer, it is possible to define A-type and B-type layers. These layers are staggered so that an alternation of AB AB layers is created.

[0096] Continuing the previous analogy, such an arrangement corresponds to atoms organized according to a so-called "hexagonal compact" mesh.

[0097] Such an arrangement is thus the most compact possible mesh, the compactness c being such that c = ■

[0098] Furthermore, an advantage of the hexagonal close-packed structure is that the distance from any point in space to the nearest atom is smaller than in any other arrangement. This has the effect of reducing aliasing effects when attempting to count the number of atoms seen by an observer within a cone of vision.

[0099] Furthermore, the smaller the space between atoms, the more precise the monitoring the process can provide, but at the cost of significant computing power. This trade-off is controlled by the distance between two identical unit cells, which is also called the lattice parameter. This lattice parameter is denoted by 'a' in the following description.

[0100] In the example described, the mesh parameter a is equal to twice the radius of the atoms.

[0101] To explain the link between the computational load, it is necessary to show that the lattice parameter a allows us to obtain the number of atoms natomes in the environment.

[0102] Indeed, the volume occupied by the atoms satisfies the following mathematical relationship:

[0103] y ■ atoms “atoms 3 \ 2 /

[0104] Taking into account the side effects, it follows that: T01051 V — -2- *V >■ afOmes vr environment r environment

[0106] where Venvironment designates the volume of the environment to be monitored.

[0107] This then leads to the following relationship:

[0108] ^4 / t / a V ~ “-atoms 3 \ 2 / 3^ ' environment

[0109] And so:

[0110] n / 0' f'-atoms= y —

[0111] The preceding relationship shows that the lattice parameter a is related to the number of atoms nmome. However, the number of operations to be performed depends strongly on the number of atoms, so that the lattice parameter allows the charge to be adjusted via the decrease in the number of atoms (natoms).

[0112] As an alternative to what has been presented so far, it is also possible to use three layers A, B and C of atoms as seen in [Fig.5].

[0113] The three layers A, B and C are stacked one on top of the other, B on A and C on B. Each layer is offset from the next by the same amount.

[0114] Compactness is maintained.

[0115] To further mitigate the effects of aliasing, a layer stacking arrangement comprising A, B, or C layers may be used, provided that the stacking does not contain two adjacent layers of the same type. For example, ABACABCACA would be a stacking arrangement not containing two adjacent layers of the same type, unlike ABACABCACA. The more irregular the layer sequence, the more the aliasing effect is reduced.

[0116] The types of layers used in a stacking can be chosen randomly.

[0117] Finally, if the environment is considered as two-dimensional, the elementary areas are disks and the stacking remains a honeycomb mesh.

[0118] The atoms remain fixed over time.

[0119] This means that each atom is characterized by an absolute position (position in a fixed frame of reference) and an identifier that is specific to it.

[0120] However, the environment seen by the carriers 12 varies over time if they move.

[0121] To take this variation into account, it is sufficient to modify the partitioning over time by adding or removing atoms. The addition is done while respecting the continuity of the shells.

[0122] At the end of the cutting step, a set of 10 elementary zones is thus obtained, allowing the environment to be discretized to be monitored.

[0123] During the calculation step, the monitoring device 20 calculates for each elementary zone its geographical position relative to each sensor 14.

[0124] The geographical position is obtained simply here by considering that the geometry of the situation changes only slightly throughout the value of the horizon Af.

[0125] Also, it is assumed in this example that the geographical position is evaluated at the evaluation time t — t a- — -* m — * 2

[0126] The monitoring device 20 here calculates the distance, site and bearing under which each atom is “seen” from each carrier 12.

[0127] Other parameters can be taken into account as long as they allow the relative position of the atom with respect to the carrier 12 to be obtained.

[0128] It can also be pointed out that the number of calculations to be carried out at this stage is given by 3 x natomes x nporteurs where 3 is here the number of parameters characterizing the geographical position.

[0129] The monitoring device 20 thus obtains the calculated geographical positions for each atom and each carrier 12.

[0130] During the evaluation step, the monitoring device 20 evaluates the level of information provided about the environment for each pointing direction of the sensors 14 of each carrier 12.

[0131] This means that, for each sensor 14 of each carrier 12, the monitoring device 20 obtains an information level input value for each pointing direction.

[0132] As a very simple example, if the sensor 14 has three pointing directions, the monitoring device 20 calculates 3 values ​​of information level input.

[0133] By definition, the information level contribution here is the gain in information level on each atom minus the energy cost related to the use of the sensor 14.

[0134] In the evaluation step, the monitoring device 20 thus evaluates the gain in information level on each atom and the energy cost.

[0135] Before explaining an example of calculating the gain in information level, it is necessary to define what an information level is.

[0136] The level of information accounts for the fact that if an atom is seen by the pointing of a sensor 14, the content of that atom is better known, whereas in the absence of pointing, knowledge about the content of the atom goes back to the last pointing made on the atom.

[0137] It is thus possible to define the information level of an atom as a value between a zero value if no information is known about the content of the atom and a maximum value when the atom is pointed by a sensor 14.

[0138] By way of example, a maximum value of 1 may be chosen.

[0139] From the information level of each atom, a level can be defined information about the environment as the sum of the levels of information on each elementary zone.

[0140] The gain therefore seeks to determine which atoms will be seen by the sensor 14 of the carrier 12 at the time of evaluation and to calculate the increase in the resulting information level while taking into account the fact that in parallel the non-pointed atoms will lose information.

[0141] To account for the loss of information, a probabilistic approach can be used by taking into account the detection probabilities of each atom when the sensor 14 is positioned in the considered pointing direction.

[0142] In fact, for any detection probability p G [0; 1], if the information on the atom in question is initially zero and nP points are made, if an object is present in the atom, the probability p^1 that the object is detected is then:

[0144] Thus, if we have information 4^ at a time t before pointing, then a pointing with a local detection probability Pj modifies the information to give post-pointing information equal to:

[0145] 4^=1-(1-^^(1-^)

[0146] The probability of detection depends on the positioning between the atom and the sensor 14 in the pointing direction considered.

[0147] Since this positioning is known thanks to the previous step in the context of this process, it is possible to know the probability of detection of each elementary zone when the sensor 14 is positioned in the pointing direction which is the subject of the calculation.

[0148] Moreover, in the absence of pointing between two instants ti and t2, the information level on an atom decreases until it tends towards zero.

[0149] The calculation of the gain thus takes into account a decrease in information with the

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] time. According to the particular example described, it is assumed that the decrease takes place in the form of a decreasing exponential. The expression used in the example described is: PA, fT t, Where T confidence is a parameter whose value is fixed to quantify the loss of information over time. In a situation resembling an aerial combat engagement, for example, a small value for 'confidence' will be used. Conversely, if the situation is quasi-static, aiming for a single exploration (nautical or even underwater objects, for example), a larger value may be used. Thus, to obtain the gain in information level from pointing at an atom, as we move the entire horizon closer to the median time < + , this gain is here :

[0156]

[0157]

[0158] aj = pd x (1 - It x ^2^“ j

[0159] To obtain the total gain, it is necessary to accumulate the gain over all the atoms seen by the sensor 14 by a simple addition of the gains in information level of a pointing on an atom.

[0160] According to one variant, the total gain uses a multiplicative factor in front of the cumulative gain.

[0161] By way of a specific example, if the multiplicative factor is the inverse of the number of atoms or the inverse of the number of atoms accessible at the time of evaluation — this is a normalization of the accumulation.

[0162] The monitoring device 20 thus obtains the information level gain value for each pointing direction of each sensor 14.

[0163] The monitoring device 20 also evaluates, during the evaluation step, the energy cost associated with the use of the sensor 14.

[0164] This cost will be deducted from the calculated gain in information level.

[0165] The cost chosen in the example described is such that the maximum value of the cost is equal to the maximum value of the gain in information level.

[0166] For this, the cost is normalized, so that the highest cost is 1.

[0167] More generally, a relative weight between the cost and the gain in level of information depending on whether it is desired to prioritize a certain distribution of scores or the level of information obtained.

[0168] Weight is, for example, a multiplicative factor of the normalized cost.

[0169] The energy cost is defined here as a non-linear function. This effectively means that a one-off use corresponds to a low penalty, while repeated use corresponds to a high penalty.

[0170] For this, according to the example described, the cost is the integral of a function whose tangent is horizontal for a totally free sensor and whose tangent is vertical for a saturated sensor.

[0171] For example, the energy cost here corresponds to a function K written as:

[0172]

[0173] Since we want the cost to reach the value 1 in the case of saturated use, we must normalize this cost, that is to say, we must have:

[0174]

[0175] We can then deduce:

[0176] B i-4

[0177] And:

[0178]

[0179]

[0180]

[0181]

[0182]

[0183]

[0184] 1-4 Using this expression, the energy cost Cm of using a sensor 14 of index m whose planned occupancy rate over the planning horizon (over the interval [ / (); / () + A / ] ) was initially dnjnit is written: c m =. t -p-dx Where represents the additional occupancy rate due to a new use of sensor 14 with index m. For example, in the case of a sensor 14, which is an electronically scanned radar, the value of A^ is constant. Indeed, the time it takes to switch from one pointing direction to another is constant and is approximately the inverse of the pointing time. This would not be true for a mechanically scanned radar. According to a more elaborate variant, it is also possible to penalize the use of certain 14s sensors rather than others. To achieve this, each sensor 14 can be assigned a respective weight wm and a cumulative energy cost defined as follows:

[0185] EY~« r mJJiit nd'mCm ~ — dx 4

[0186] where the weights wm are such that wm = 1-

[0187] In such a case, it is the cumulative energy cost that will be taken to reduce the gain in information level and thus obtain the contribution in information level.

[0188] At the end of the evaluation stage, the monitoring device 20 has the input in level of information for each pointing direction of each sensor 14.

[0189] During the determination step, the monitoring device 20 determines the best pointing direction of each sensor 14 according to the evaluated information level inputs.

[0190] By way of example, the determination step is implemented iteratively, that is to say that the determination step includes several iterations of a set of operations.

[0191] During a first operation, called the selection operation, the monitoring device 20 selects the pointing direction for which the information level input is the highest.

[0192] The monitoring device 20 then associates the selected pointing direction as the best pointing direction determined for the corresponding sensor 14.

[0193] The corresponding sensor 14 is then set aside since a pointing direction has has been awarded.

[0194] During a second operation, called the modification operation, the monitoring device 20 modifies the information level input obtained for each pointing direction of the remaining sensors 14 with each sensor 14 placed in the best pointing direction determined previously.

[0195] According to a particular example, this modification operation is limited to sensors 14 having access to the same atoms as the sensor 14 discarded during the first operation.

[0196] The operations are iterated until an information level criterion is met.

[0197] This level of information can be achieved even though some sensors 14 did not have an associated pointing direction.

[0198] In such a case, these remaining 14 sensors retain their pointing direction.

[0199] This conservation can be understood in a broad sense, that is to say that if the sensor 14 was inactive, this sensor 14 remains inactive.

[0200] During the control step, the monitoring device 20 commands each sensor 14 so that each sensor 14 points in the best determined direction.

[0201] The process just described makes it possible to monitor an environment by a plurality of carriers 12 in a more efficient manner.

[0202] In particular, the determination and use of an energy cost makes it possible to use the sensors 14 sparingly, resulting in a good level of information implying reduced energy consumption.

[0203] This benefit is obtained for any application involving surveillance, whether for military or civilian purposes.

[0204] Thus, the present method makes it possible to manage monitoring in the presence of several sensors 14 moving along arbitrary trajectories, and the monitoring mission is not limited to a single pass but requires regular updating. Indeed, depending on the positions and angular ranges accessible to the different sensors 14, the distribution of pointings among the sensors 14 to best monitor a space can prove complex. The method makes it possible to dynamically assign the pointing directions of the different sensors 12 over time, provided that the future trajectories of the sensors 14 are known in advance (typically a few seconds ahead), which is generally the case in the context of collaborative monitoring.

Claims

Claims

1. Method for monitoring an environment by a plurality of carriers (12), each carrier (12) being provided with at least one sensor (14) capable of pointing the environment in a respective pointing direction to acquire information on a part of the environment, the method being implemented by a monitoring device (20) and comprising the steps of: - dividing the environment into several elementary zones, - for each elementary zone, calculating the geographical position relative to each sensor (14), to obtain calculated geographical positions, - evaluating the contribution in terms of level of information on the environment for each pointing direction of the sensors (14) of each carrier (12), the level of information on the environment is the sum of the levels of information on each elementary zone,the information level of an elementary zone being between a zero value if no information is known on the elementary zone and a maximum value when the elementary zone is pointed by a sensor (14), the information level contribution being obtained by calculating the gain in information level on each elementary zone reduced by the energy cost linked to the use of the sensor (14), the information level gain taking into account the calculated geographical positions, - determination of the best pointing direction of each sensor (14) according to the information level contributions evaluated, and - control of each sensor (14) so ​​that each sensor (14) points in the best determined direction.,

2. A monitoring method according to claim 1, wherein the environment is a three-dimensional space and the elementary zones are spheres.

3. A monitoring method according to claim 2, wherein the spheres are distributed in a close-packed hexagonal arrangement.

4. Monitoring method according to any one of claims 1 to 3, in which the determining step comprises several iterations of a set of operations, each iteration comprising: - an operation of selecting the pointing direction for which the information level contribution is the highest, the pointing direction selected being the best pointing direction determined for the corresponding sensor (14), and - an operation of modifying the information level input obtained for each pointing direction of the remaining sensors (14) with each sensor (14) placed in the best pointing direction determined previously.

5. Monitoring method according to claim 4, in which the iterations are implemented until an information level criterion is verified, the sensors (14) remaining maintaining their pointing direction.

6. Monitoring method according to any one of claims 1 to 5, in which, during the obtaining step, the calculation of the gain takes into account the probabilities of detection of each elementary zone when the sensor (14) is positioned in the pointing direction considered.

7. Monitoring method according to any one of claims 1 to 6, in which, during the obtaining step, the calculation of the gain takes into account a decrease in the information over time, in particular in the form of a decreasing exponential.

8. Monitoring method according to any one of claims 1 to 7, in which the energy cost takes into account the occupancy rate of the sensor (14) considered over a time interval.

9. Monitoring method according to any one of claims 1 to 8, in which the domain accessible to each sensor is discretized into a finite number of possible directions.

10. Device (20) for monitoring an environment by a plurality of carriers (12), each carrier (12) being provided with at least one sensor (14) capable of pointing the environment in a respective pointing direction to acquire information on a part of the environment, the monitoring device (20) being capable of: - dividing the environment into several elementary zones, - for each elementary zone, calculating the geographical position relative to each sensor (14), to obtain calculated geographical positions, - evaluating the contribution in terms of level of information on the environment for each pointing direction of the sensors (14) of each carrier (12), the level of information on the environment is the sum of the levels of information on each elementary zone, the level of information of an elementary zone being between a zero value if no information is known on the elementary zone and a maximum value when the elementary zone is pointed by a sensor (14), the contribution in information level being obtained by calculating the gain in information level on each elementary zone reduced by the energy cost linked to the use of the sensor (14), the gain in information level taking into account the calculated geographical positions, - determine the best pointing direction of each sensor (14) according to the contributions in information level evaluated, and - control each sensor (14) so ​​that each sensor (14) points in the best determined direction.

11. Assembly (10) comprising carriers (12) provided with at least one sensor (14) capable of pointing the environment in a respective pointing direction and a monitoring device (20) according to claim 10.

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