Anti-collision system for mobile devices

Abstract

Title: Anti-collision system for a mobile device. The invention relates to an anti-collision system (1) for an autonomous mobile device (D) configured to move in three dimensions. The system comprises an onboard memory (10) configured to save an optimal trajectory (Topt) to reach a destination position, a detection system (20) configured to detect the presence and position of intruding mobile devices (D'1, D'2, … D'i, …, D'N) within a detection zone (100) around the mobile device (D), and a control system (30) configured to impose a modified trajectory (T') on the mobile device (D) to reach the destination position. The modified trajectory is a function of the optimal trajectory and the position of each intruding mobile device at each time t during the movement. Figure for the abstract: Fig. 7

Description

Title of the invention: Anti-collision system for mobile device technical field

[0001] The present invention relates to the field of autonomous mobile devices and associated methods. It finds a particularly advantageous application in the field of aerial and underwater drones. STATE OF THE ART

[0002] Autonomous mobile devices are used in a wide variety of fields. Aerial drones, for example, are used in land-use planning for cadastral surveys, in the audiovisual industry for capturing aerial videos and photographs, in agriculture for detecting crop diseases, and in logistics for delivering packages to individuals or businesses, emergency supplies, or medicines in war zones. Underwater drones, on the other hand, are used in fields as diverse as geophysical prospecting, monitoring marine protected areas, mapping or monitoring Exclusive Economic Zones (EEZs), locating objects at sea, such as shipwrecks or black boxes, assessing the environmental impact of offshore wind farm projects, and preserving archaeological heritage.

[0003] The number of mobile devices moving in the air and oceans thus increases every year. However, the increase in traffic of autonomous mobile devices is accompanied by an increased risk of accidents due to collisions, particularly collisions between mobile devices.

[0004] While airplanes are constantly monitored from control towers, which can instruct pilots to modify their flight plan to avoid a collision if necessary, autonomous devices are not subject to such comprehensive monitoring. For this reason, managing the movements of autonomous mobile devices is very complex, and accidents between drones could occur and increase with the growing number of drones.

[0005] The prior art of anti-collision devices for use on aircraft is known. However, for many reasons, these devices cannot be transposed to autonomous mobile devices. First, these anti-collision devices are very heavy and bulky and cannot reasonably be integrated into small devices such as drones. Furthermore, the response of an aircraft and that of a drone to a command to change trajectory and / or speed are completely different: whereas, for a short time, the trajectory and speed of an While aircraft can only be modified to a small extent, drones can be modulated over a much larger range. Therefore, anti-collision systems designed for airplanes are completely unsuitable for drones. Furthermore, given the extremely low probability of more than two aircraft being close together in the air, anti-collision systems for airplanes are primarily designed to handle situations where only two aircraft are likely to collide. However, in the case of autonomous mobile devices, numerous devices can be in close proximity to one another without this necessarily indicating a danger.

[0006] One objective of the present invention is therefore to propose an anti-collision system adapted to the problems surrounding autonomous mobile devices. SUMMARY

[0007] To achieve this objective, according to one embodiment, a system for an autonomous mobile device configured to move in three dimensions is provided, the anti-collision system being embedded in the mobile device and comprising: a. an onboard memory configured to save an optimal trajectory to reach a destination position, b. a detection system configured to, at at least one time t, detect the presence of intruding mobile devices within a detection zone around the mobile device and to determine the position of each intruding mobile device present in the detection zone, c. a control system configured to impose a modified trajectory on the mobile device to reach the arrival position, the modified trajectory being a function of the optimal trajectory and the position of each intruder mobile device at each instant t during the movement.

[0008] The system according to the invention thus makes it possible, based on data on the position of intruding mobile devices, to reduce the risk of collision or even eliminate it completely, while maintaining a trajectory that deviates as little as possible from the optimal trajectory.

[0009] A more obvious approach would have been to design a system in which the control system deflects the mobile device from its trajectory to avoid a collision, and then a computing system recalculates a trajectory to reach the arrival position from the deflected position of the mobile device. However, this approach would have required significant computation at the mobile device level. Complete trajectory calculations take into account numerous parameters such as the urban or underwater landscape, as well as data relating to wind or currents. These calculations are therefore very complex, consume a great deal of energy, and require large and complex computing systems. Furthermore, these calculations require a The computation time required was significant, especially considering the time required for a deviation. This solution would therefore have been difficult to implement on small mobile devices and would have resulted in periods of inactivity during which the trajectory would have been recalculated. Such a solution, while feasible, would thus not have been optimal.

[0010] By taking a recorded optimal trajectory as a parameter of the modified trajectory, the calculations required at the mobile device are considerably reduced. The optimal trajectory can be calculated at a remote base station and then stored in the mobile device's onboard memory before it begins moving. The onboard computing system can therefore be smaller, thus reducing the device's weight and enabling faster movement.

[0011] Furthermore, by ensuring that the mobile device is constantly brought back towards its optimal trajectory, we ensure that it does not drift very far from its arrival position due to deviations induced by the presence of intrusive mobile devices.

[0012] The present invention therefore proposes a particularly effective system for reducing the probability of collision while optimizing the trajectory of the mobile device.

[0013] A second aspect of the invention relates to a mobile device comprising the system according to the first aspect of the invention.

[0014] A third aspect of the invention relates to a fleet comprising a plurality of mobile devices according to the second aspect of the invention.

[0015] A third aspect of the invention relates to a method for managing the movement of a mobile device comprising the following steps: a. Recording, in an onboard memory of the mobile device, of an optimal trajectory for achieving the movement, b. Detection at at least one instant t during the movement, by a detection system of the mobile device, of the position of intruding mobile devices within a detection zone around the mobile device, c. Modification, by a mobile device control system, of the trajectory of the mobile device as a function of the position of the intruding mobile devices at time t and the optimal trajectory.

[0016] The advantages provided by the system according to the first aspect of the invention apply mutatis mutandis to the device, the fleet of devices and the method according to the invention. BRIEF DESCRIPTION OF THE FIGURES

[0017] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0018] [Fig.1] Fig.1 represents a mobile device incorporating a system according to the invention.

[0019] [Fig.2] Fig.2 represents a mobile device on its optimal trajectory.

[0020] [Fig.3] Figures 3, 4 and 5 represent a mobile device and one or more intruder mobile devices located in its detection zone.

[0021] [Fig.4]

[0022] [Fig.5]

[0023] [Fig.6] Fig.6 illustrates the deviation of the mobile device from its optimal trajectory when an intruder mobile device is in its detection zone.

[0024] [Fig.7] Fig.7 illustrates the force of attraction applied to the moving device towards its optimal trajectory when it has been deflected from it.

[0025] [Fig. 8A] Figures 8A to 8E illustrate simulations of the integration of the present invention with mobile devices. Figures 8A to 8C are simulations in the case of two mobile devices moving at the same altitude.

[0026] [Fig.8B]

[0027] [Fig.8C]

[0028] [Fig.8D] Figures 8D to 8F are simulations in the case of two mobile devices moving at distinct altitudes.

[0029] [Fig.8E]

[0030] [Fig.8F]

[0031] [Fig.8G] The [Fig.8G] is a simulation in the case of three mobile devices.

[0032] [Fig.8H] The [Fig.8H] is a simulation in the case of eight mobile devices.

[0033] [Fig.9] Fig.9 is a diagram of the different stages of an embodiment of the method according to the invention.

[0034] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the dimensions are not representative of reality. DETAILED DESCRIPTION

[0035] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0036] According to a preferred embodiment, the system further comprises a calculation system configured to calculate following at least one detection of intruding mobile devices by the detection system during the movement of the mobile device: a. a repulsive force depending on the position of the intruding mobile devices present in the detection zone, b. an attractive force that is a function of the optimal trajectory,

[0037] Furthermore, in this embodiment, the modified trajectory is a function of the repulsive and attractive forces calculated during the movement. The repulsive force prevents the mobile device from colliding with one or more intruding mobile devices, while the attractive force brings it back to its optimal trajectory.

[0038] According to a preferred example, the repulsion force is a linear combination of as many repulsion components as there are intruding mobile devices detected at time t in the detection zone, the magnitude of each repulsion component being inversely proportional to the square of the distance between the mobile device and a distinct intruding mobile device. Thus, the closer the mobile device(s) are, the greater the repulsion force. In other words, the greater the danger, the greater the means deployed to move away from the intruding devices. This is made possible in particular by the low weight of autonomous mobile devices, which can change trajectory and speed with relatively low inertia and therefore good responsiveness.

[0039] According to a preferred example, the attractive force is a linear combination of as many attractive components as there are intruding mobile devices detected at time t in the detection zone, the magnitude of each attractive component being proportional to the square of the distance, called the deviation distance, between the mobile device and an optimal position of the mobile device on the optimal trajectory. Thus, the more the mobile device has been deviated from its optimal trajectory, the greater the attractive force, which brings it back to its optimal trajectory. This prevents the mobile device from spending long periods away from the optimal trajectory. The travel time to reach the arrival position is thus reduced.

[0040] According to a preferred example, the detection system is configured to be able, at time t, to detect and determine the position of N intruding mobile devices within the detection zone, with N>2. This is perfectly feasible with a conventional detection system such as radar. This makes it possible to cope with the increasing traffic of mobile devices in the air or in the oceans.

[0041] According to a preferred example, the repulsion force is further a function of a repulsion coefficient itself a function of at least one of the following parameters: a safety coefficient, an acquisition accuracy of the detection system, an acquisition frequency of the detection system.

[0042] According to a preferred example, the attractive force is further a function of an attraction coefficient which is itself a function of at least one of the following parameters: a safety factor, a quantity of fuel available, an acquisition accuracy of the detection system, an acquisition frequency of the detection system.

[0043] According to a preferred example, the control system is configured to modulate the speed of the mobile device according to the position of the intruding mobile devices at time t and the optimal trajectory.

[0044] According to a preferred example, the modulation of the speed of the moving device is a function of a viscous term proportional to the speed of the moving device. This makes it possible to limit large oscillations in the speed of the moving device.

[0045] According to a preferred example, the system further includes a communication system configured to receive, during the movement of the mobile device, an updated optimal trajectory.

[0046] According to a preferred example, the mobile device and the intruding mobile devices are aerial or underwater drones.

[0047] According to a preferred example, the detection zone is a sphere having the mobile device as its center, said sphere having a radius between 3 and 10 meters, preferably between 4 and 6 meters.

[0048] According to an advantageous embodiment of the method according to the invention, it further comprises, following the detection of intruding mobile devices by the detection system, a calculation step by a calculation system of the mobile device, of: a. a repulsive force that is a function of the position of the intruding mobile devices present in the detection zone at time t, b. an attractive force that is a function of the optimal trajectory,

[0049] Furthermore, in this embodiment of the method, the modification of the trajectory of the mobile device by the control system is a function of said repulsion force and said attraction force.

[0050] The term autonomous mobile device is used in this application to refer to any device capable of moving autonomously in three dimensions, that is, without continuous pilot control. This may include, in particular, an aerial drone or an underwater drone.

[0051] System 1 according to the present invention will now be described with reference to Figures 1 to 7.

[0052] System 1 is intended to be mounted on a mobile device D, as illustrated in [Fig. 1]. The mobile device D on which system 1 is mounted is configured to move in three dimensions.

[0053] The mobile device D can take several forms. In particular, it can be an aerial drone or an underwater drone. The mobile device D is typically autonomous, that is to say, it is not remotely controlled, or at least not by permanence. In the case of an underwater device, this is typically a robot or autonomous underwater vehicle, commonly referred to as AUV, from the English Autonomous Underwater Vehicle.

[0054] An example of a mobile device D will now be described. The system 1 may first of all include an on-board memory 10. This memory 10 is capable of storing data. This data may include, in particular, an optimal trajectory Topt to reach a destination position. An optimal speed may also be stored in the on-board memory 10. This optimal speed may depend on time and / or the position of the mobile device D on the optimal trajectory Topt (for example, the optimal speed may decrease when approaching the destination position or depending on the environment: wind, etc.).

[0055] The optimal trajectory Topt can be defined in various ways and according to various objectives to reach a finish position.

[0056] The optimal trajectory Topt is defined without taking into account potential intruding mobile devices whose trajectory could approach, or even cross, that of the mobile device D.

[0057] By way of non-limiting example, the optimal trajectory Topt is typically obtained by optimizing a consumption function that represents the cost function. The consumption (cost) function depends, in particular, on the drag as a function of the speed of the mobile device D relative to the wind, as well as on the acceleration. This cost function depends on the fuel consumption required for the movement, the duration of the journey, the flight stability, and the proximity of the movement to excluded flight regions or inhabited areas. The optimal trajectory Topt is determined from this function, for example, by reinforcement learning techniques or by applying the so-called Euler-Lagrange equations. Topt can notably be obtained by a learning method involving, for example, a neural network.

[0058] An example of a method for calculating the optimal trajectory, a non-limiting example, is described in European patent application EP23306769.3. Other examples are described in the following publications: Optimal velocity planning based on the solution of the Euler-Lagrange equations with a neural network based velocity regression, Chady Ghnatios, Daniele di Lorenzo, Victor Champaney, Elias Cueto, and Francisco Chinesta (April 2023), and Optimal trajectory planning combining model-based and data-driven hybrid approaches, Chady Ghnatios, Daniele Di Lorenzo, Victor Champaney, Amine Ammar, Elias Cueto, Francisco Chinesta (April 2024).

[0059] Alternatively or in combination, the optimal trajectory Topt can be obtained differently, for example by mainly or solely optimizing travel time and / or fuel consumption.

[0060] The optimal trajectory Topt is typically calculated at a remote base B. This allows heavy computing systems requiring space and processor consumption to be moved to the remote base B. The calculation of an optimal trajectory, requiring consideration of numerous parameters such as urban or underwater topography, can be carried out at the remote base B, while the less resource-intensive calculations are performed at a computing system 40 of system 1, as described above.

[0061] The optimal trajectory Topt can thus be recorded in the on-board memory 10 before the mobile device D begins moving towards the arrival position.

[0062] The system 1 further comprises a detection system 20. This detection system 20 is typically a radar. The detection system 20 is configured to detect intruder bodies within a detection zone 100 around the device D in which the system 1 is mounted ([Fig. 2]). The intruder bodies are typically mobile intruder devices D'b D'2, ... D';, ... D'N. These mobile intruder devices may, in particular, be aerial or underwater drones. However, it is conceivable that the intruder bodies could be of other types, such as birds or, very exceptionally, urban structures appearing in the detection zone 100 after the device D deviates from its trajectory. For the sake of simplicity, the description below refers to mobile devices, but it is understood that all the features of the invention can be applied to intruder bodies of other types.

[0063] The detection system 20 is also configured to determine a position of each of the intruder mobile devices present within the detection zone 100.

[0064] The position of the intruder devices is not necessarily understood as an absolute position in a geostatic reference frame. It is typically a relative position with respect to the mobile device D. Obtaining a relative position using an onboard radar is perfectly known to those skilled in the art.

[0065] The position of any mobile device D' can be described using a unit vector denoted uD D4 in the figures and the distance dDD- separating the mobile device D from the intruder mobile device considered D' (i=l, 2.. .N). This unit vector and this distance are therefore known to the system 1 thanks to the detection device 20.

[0066] The detection zone 100 is typically a sphere whose center is located at the level of the moving device D. The radius Rk» of this sphere can in particular be defined as a function of at least one of the following parameters: a. constraints related to the intended application, b. security constraints, c. a maximum speed that can be achieved by the mobile device D,

[0067] The detection range of the detection system 20 can extend beyond the detection zone 100. However, the control system 30 described above will only modify the trajectory of the device D if intruder mobile devices D'b D'2, ... D';, ... D'N are detected in the detection zone 100.

[0068] The detection system 20 is configured to probe the detection zone 100 at different times t during movement. The detection system 20 typically probes the detection zone 100 at a frequency called the acquisition frequency. This acquisition frequency can be greater than 1 kHz. It is preferably greater than 1 GHz, or even greater than 3 GHz, and preferably greater than 5 GHz.

[0069] The system 1 further includes a control system 30 configured to optionally modify the trajectory of the mobile device D. The control system 30 is also preferably configured to modify the speed and / or trajectory of the mobile device D.

[0070] The control system 30 can in particular be configured to control a motor 70 of the mobile device D and a control system for this motor 70.

[0071] The control system 30 modifies the trajectory of the mobile device D when at least one intruder mobile device D' is detected in the detection zone 100 by the detection system 20. If no intruder mobile device is detected during the movement of the mobile device D, then the effective trajectory of the device D is the optimal trajectory Topt stored in the on-board memory 10 (see the case illustrated in [Fig. 2]). If intruder mobile devices D'b D'2, ... D', ... D'N are detected in the detection zone 100 during the movement towards the arrival position, then the control system 30 modifies the trajectory of the mobile device D to a modified trajectory T'. The trajectory that is actually followed by the mobile device D to reach the arrival position takes into account the trajectory modifications imposed on the mobile device D by the control system 30 following the detection of intruder mobile devices D'b D'2, ...D';, ... D'N during the movement, that is to say at different detection times. .

[0072] Advantageously, the system 1 includes a calculation system 40. This calculation system 40 can, in particular, be configured to calculate, when the detection system 20 detects the presence of intruding mobile devices D' b D'2, ... D', ... D'N, a repulsive force FréP>Det and an attractive force Fann-

[0073] The repulsive force Frép Dest is the force applied to the mobile device D via the control device 30 in order to move it away from intruding mobile devices and thus avoid any collision.

[0074] The repulsion force FréP>Dest is typically a function of the position of the intruding mobile devices D'b D'2, ... D';, ... D'N present in the detection zone 100 during the detection leading to this calculation. When N intruder mobile devices are detected simultaneously by the detection system 20, the repulsion force Frép>D can, for example, follow the following equation:

[0075] P p . ^repl) ~ ^i=ldD^ UD^D ~

[0076] with dDD the distance separating the mobile device D from the intruder mobile device considered D';, MD^D the unit vector between the mobile device D and the intruder mobile device considered D'i ~ ~ud-*d'^ and a a repulsion coefficient.

[0077] Thus, the repulsive force comprises as many components as there are Mobile devices are detected within detection zone 20. This ensures the integrity of mobile device D with respect to each of the intruding mobile devices simultaneously. Instead of addressing the danger posed by each intruding mobile device sequentially, a repulsive force is applied to mobile device D, preventing any collision. This approach is more efficient and safer than a sequential approach.

[0078] It is noted that the norm of each component is inversely proportional to the square of the distance separating the mobile device D from the intruder mobile device D'i considered: thus, the closer the intruder mobile device D'; is (the greater the danger), the stronger the repulsion.

[0079] The repulsion coefficient a determines the intensity with which the trajectory of the mobile device D is modified by the presence of the intruder mobile devices D'i, D'2, ... D'i, ... D'N within the detection zone 100.

[0080] The repulsion coefficient may depend on various parameters, including: a. a safety coefficient: this safety coefficient is typically dependent on the legislation in force in the territory where system 1 is deployed. b. an acquisition accuracy of the detection system 20: the less precise the acquisition, the more we will want to impose safety margins, i.e. a high repulsion coefficient a. c. an acquisition frequency of the detection system 20: the lower the acquisition frequency, the more safety margins one wishes to impose, i.e. a high repulsion coefficient a.

[0081] These different parameters can be stored in the on-board memory 10. Their values ​​can be constant during the movement or can be modulated, for example by storing updated values ​​sent by the remote base B.

[0082] The attractive force FattD is the force applied to the mobile device D via the control device 30 in order to limit the distance of the mobile device D from the optimal trajectory Topt. It is thus a function of the optimal trajectory Topt stored in the on-board memory 10.

[0083] The attractive force FattjD is configured to return the mobile device D to an optimal position Popt located on the optimal trajectory Topt. This optimal position Popt can be the position that the mobile device D would have been in at the time Fatt>Dest is calculated if it had not been deflected from the optimal trajectory Topt due to the presence of intruding mobile devices. The optimal position Popt can also correspond to a position that the mobile device D would have been in at a time after FattjDest is calculated. This latter case can allow the mobile device D to be returned to its optimal trajectory along a less abrupt path and potentially reduce the travel time.

[0084] The distance between the position of the mobile device D and the optimal position Popt is called the deviation distance ddev. The unit vector directed from the mobile device D to the optimal position Popt is denoted udev.

[0085] Thus, the attractive force Fatt>D can, for example, follow the following equation:

[0086] =

[0087] With [3] a coefficient of attraction. The coefficient of attraction [3] determines the intensity with which the trajectory of the mobile device D is brought back to its optimal trajectory Topt.

[0088] The coefficient of attraction [3] can be a function of various parameters, including: a. a safety coefficient: this safety coefficient is typically dependent on the legislation in force in the territory where system 1 is deployed. b. an acquisition accuracy of the detection system 20: the less precise the acquisition, the more we will want to impose safety margins, i.e. a high attraction coefficient [3. c. an acquisition frequency of the detection system 20: the lower the acquisition frequency, the more safety margins one wishes to impose, i.e. a low attraction coefficient [3. d. A quantity of fuel available to the mobile device D: the higher the fuel level, the more acceptable it is to consume this fuel to optimize travel time, and therefore the higher the coefficient of attraction [3].

[0089] These different parameters can be recorded in the on-board memory 10. Their value can be constant during the journey or can be modulated, for example as fuel is consumed with regard to the quantity of fuel.

[0090] It is noted that the magnitude of the attractive force FattD is proportional to the square of the deviation distance ddev: thus, the more the mobile device D has been deviated from its optimal trajectory, the stronger the attraction. This allows, on the one hand, for the mobile device D to allocate more resources to making up for lost time due to deviations when these have been significant. It also prevents the mobile device D from being increasingly deviated from its optimal trajectory and encountering other intruding mobile devices, thus taking it further and further away from its optimal trajectory Topt.

[0091] The control system 30 is thus preferably configured to apply to the mobile device D the repulsive force FrépjD and the attractive force Fanp. Specifically, the calculation system 40 is configured to, once Frép>D and Fatt>D have been calculated, calculate the modified velocity and the associated modified trajectory by solving, through integration, the fundamental equation of dynamics incorporating Frép>D and Fattn. The calculation system 40 can thus communicate the modified velocity and the modified trajectory to the control system 30, which then imposes this modified velocity and this modified trajectory on the device 1, typically by acting on the motor 70.

[0092] Advantageously, the repulsive force Frép>D and the attractive force Fattn are expected to be attenuated by a viscous term. This limits excessively large oscillations in the velocity of the moving device D. The viscous term is typically proportional to the velocity of the moving device D. It is also integrated into the fundamental equation of dynamics solved by the computing system 40.

[0093] The mobile device D also advantageously includes a communication system 50 configured to receive and optionally send data. The mobile device D can thus receive signals from a remote base B, or even transmit signals to the remote base B. For example, it is conceivable that the remote base B could send to system 1, via its communication system 50, an updated optimal trajectory and / or an updated optimal speed during the movement of the mobile device D. This makes it possible to offload resource-intensive computing systems requiring space and processor power to the remote base B.The heavy calculation of an optimal updated trajectory, requiring consideration of numerous parameters such as urban or underwater topography, can be carried out at the level of the distant base B, while the calculations of the successive repulsive forces FréP>D and attractive forces Fattn, less. consumer, are carried out at the level of the calculation system 40 of system 1. The same applies to the calculation of an optimal updated speed.

[0094] The updated optimal trajectory and the updated optimal speed may in particular take into account surrounding conditions such as wind, the intensity and direction of which may vary during the movement.

[0095] The communication system 50 can also be used for recording the optimal trajectory Topt and the initial optimal speed, typically before the start of the movement.

[0096] The operation of system 1 described above thus allows an excellent compromise between safety and optimization of movement in terms of time and cost.

[0097] Figures 8A to 8E are numerical simulations illustrating the usefulness of the system according to the invention. These simulations show the effect of the system according to the invention on the trajectory of mobile devices equipped with this system 1.

[0098] Figures 8A, 8B, and 8C illustrate the trajectories followed by two mobile devices D initially moving at the same altitude and coming close to each other during their respective movements. Figure 8A simulates a case where these two devices move in the same direction but in opposite directions (crossing angle of 180°). Figure 8B is the result of a simulation in which the crossing angle between the devices is arbitrary. Finally, Figure 8C deals with the case of a crossing angle of 90° between the two mobile devices. In each case, it is observed that the two mobile devices D deviate from their initial trajectories, thus avoiding a collision, and then return to their respective optimal trajectories. The collision is therefore successfully avoided, and the travel time is only slightly increased.

[0099] Figures 8D, 8E, and 8F also illustrate the trajectories followed by two mobile devices D whose crossing angles are respectively 180°, arbitrary, and 90°. However, this time the two mobile devices D are moving at different altitudes, the difference of which is not sufficient to avoid a collision. It is noted that here again, the mobile devices D deviate from their respective optimal trajectories. However, it is observed that the deviation is less significant than in the case where the devices were moving at the same altitude. This shows that, while ensuring an excellent level of safety, the system according to the invention imposes on the mobile device D a modified trajectory that is as optimized as possible given the navigation circumstances.

[0100] If the difference in altitude between the mobile devices D was sufficient to avoid a collision, then the mobile devices would not deviate from their optimal trajectories.

[0101] Figures 8G and 8H are the results of simulations including, respectively, three and eight mobile devices equipped with systems 1 according to the invention. It is noted again that the system according to the invention makes it possible to avoid any collision while allowing each mobile device to maintain a trajectory with minimal deviation and therefore the most optimized possible.

[0102] A second aspect of the invention relates to a mobile device D incorporating a system 1 as described above. This device D is illustrated in [Fig. 1].

[0103] A third aspect of the invention relates to a fleet of mobile devices D according to the second aspect of the invention, that is, a set of several mobile devices D. Each of the mobile devices D in the fleet incorporates a system 1 according to the invention. This allows the set of mobile devices D to move while avoiding both collisions between devices D in the fleet and collisions with intruding mobile devices. As illustrated in Figure 3, each mobile device is repelled by a repulsive force induced by the other mobile device. Thus, in Figure 3, mobile device D is repelled by the repulsive force FDD caused by the presence of mobile device D in its detection zone, and mobile device D'i is repelled by the repulsive force FDD' caused by the presence of mobile device D in its detection zone.If the repulsion coefficient a is the same for both devices, then these repulsive forces are equal in magnitude and opposite in direction (see the representation of the forces by arrows in [Fig.3]).

[0104] A fourth aspect of the invention relates to a method for managing a movement of the mobile device D. This movement has as its destination the arrival position mentioned above.

[0105] The main steps of this process are as follows (see [Fig.9]): a. Recording in onboard memory 10 of the optimal trajectory Topt to perform the movement (step 1001), b. Detection, at at least one instant t during the movement, by the detection system 20 of the position of intruder mobile devices D' b D'2, ..., D';, ... D'N(step 1002), c. Modification by the control system 30 of the trajectory of the mobile device D as a function of the position of the intruder mobile devices D'b D'2, ..., D'i, ... D'n at time t during the movement and the optimal trajectory Topt(step 1004).

[0106] Advantageously, and as described above with reference to system 1, the method includes a calculation step 1003 of the repulsion force Frép>Det of the attraction force FattD between the detection step 1002 of the intruder mobile devices D'b D'2, D'i, ... D'n and the trajectory modification step 1004. This step is carried out at the level of the calculation system 40 of the mobile device D.

[0107] As illustrated in [Fig.9], steps 1002, 1003 and 1004 are typically repeated several times during the movement of the mobile device D. The number of times these steps are repeated depends on the time spent by the intruder mobile devices within the detection zone 100. It also depends on the acquisition frequency of the detection system 20.

[0108] The mobile device D thus typically undergoes several successive redirections during different iterations of the trajectory modification step 1004.

[0109] Finally, the mobile device D arrives at its arrival position (step 1005).

[0110] It is understood that if no intruding mobile device is detected during the movement, step 1005 directly follows step 1001: the trajectory actually followed by the mobile device D will be the optimal trajectory Topt recorded in step 1001.

[0111] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

Demands

1. Anti-collision system (1) for autonomous mobile device (D) configured to move in three dimensions, the anti-collision system (1) being embedded in the mobile device (D) and comprising: i. an embedded memory (10) configured to save an optimal trajectory (Topt) to reach a destination position, ii. a detection system (20) configured to, at at least one time t, detect the presence of intruder mobile devices (D'i, D'2, ... D'i, ...,D'n) present within a detection zone (100) around the mobile device (D) and to determine a position of each intruder mobile device (D'i) present in the detection zone, iii. a control system (30) configured to impose on the mobile device (D) a modified trajectory (T') to reach the arrival position, the modified trajectory (T') being a function of the optimal trajectory (Topt) and the position of each intruder mobile device (D'i, D'2, ...D'N) at each instant t during the displacement.

2. System (1) according to the preceding claim further comprising a calculation system (40) configured to calculate following at least one detection of intruder mobile devices (D'i, D'2, ... D';, ... D'n) by the detection system (20) during the movement of the mobile device (D): i. a repulsion force (FréPjD) as a function of the position of the intruder mobile devices (D'i, D'2, ... D';, ..., D'N) present in the detection zone, ii. an attraction force (Fatt>D) as a function of the optimal trajectory (Topt), and wherein the modified trajectory (T') is a function of the repulsion forces (Frép>D) and the attraction forces (Fatt>D) calculated during the movement.

3. System (1) according to the preceding claim in which the repulsive force (FréP>D) is a linear combination of as many repulsion components than of intruder mobile devices (D'b D'2, ... D'i, ..., D'n) detected at time t in the detection zone (100), the magnitude of each repulsion component being inversely proportional to the square of the distance (dDD i, dDD- 2, ... dDD- N) between the mobile device (D) and a distinct intruder mobile device (D'i, D'2, ... D'i, ..., D'n).

4. System (1) according to any one of the two preceding claims wherein the attraction force (Fatt>D) is a linear combination of as many attraction components as there are intruder mobile devices (D'i, D'2, ... D'i, ..., D'N) detected at time t in the detection zone (100), the magnitude of each attraction component being proportional to the square of the distance called deviation distance (ddev) between the mobile device (D) and an optimal position (Popt) of the mobile device (D) on the optimal trajectory (Topt).

5. System (1) according to any one of the preceding claims wherein the detection system (20) is configured to be able, at time t, to detect and determine the position of N intruder mobile devices (D'i, D'2, ... D';, ..., D'N) within the detection zone (100), with N>2.

6. System (1) according to any one of claims 2 to 5 wherein the repulsion force (FréPjD) is further a function of a repulsion coefficient itself a function of at least one of the following parameters: a safety factor, an acquisition accuracy of the detection system (20), an acquisition frequency of the detection system (20).

7. System (1) according to any one of claims 2 to 6 wherein the attraction force (Fatt>D) is further a function of an attraction coefficient itself a function of at least one of the following parameters: a safety coefficient, an available quantity of fuel, an acquisition accuracy of the detection system (20), an acquisition frequency of the detection system (20).

8. System (1) according to any one of the preceding claims, wherein the control system (30) is configured to modulate the speed of the mobile device (D) according to the position of the intruding mobile devices (D'i, D'2, ... D';, ..., D'N) at time t and the optimal trajectory (Topt).

9. System (1) according to the preceding claim in which the modulation of the speed of the moving device (D) is a function of a viscous term proportional to the speed of the moving device (D).

10. System (1) according to any one of the preceding claims further comprising a communication system (50) configured to receive, during the movement of the mobile device (D), an updated optimal trajectory.

11. System (1) according to any one of the preceding claims wherein the mobile device (D) and the intruder mobile devices (D'i, D'2, ... D'i, ..., D'n) are aerial or underwater drones.

12. System (1) according to any one of the preceding claims wherein the detection zone (100) is a sphere having the mobile device (D) as its centre, said sphere having a radius between 3 and 10 meters, preferably between 4 and 6 meters.

13. Mobile device (D) comprising the system (1) according to any one of the preceding claims.

14. Fleet comprising a plurality of mobile devices (D) according to the preceding claim.

15. Method of managing the movement of a mobile device (D) comprising the following steps: i. Recording, in an on-board memory (10) of the mobile device (D), an optimal trajectory (Topt) to carry out the movement, ii. Detection at at least one time t during the movement, by a detection system (20) of the mobile device (D), of the position of intruder mobile devices (D'i, D'2, ..., D'i , ... D'n) within a detection zone (100) around the mobile device (D), iii. Modification, by a control system (30) of the mobile device (D), of the trajectory of the mobile device (D) as a function of the position of the intruder mobile devices (D'i, D'2, ..., D'i, ... D'N) at time t and of the optimal trajectory (Topt).

16. A method according to the preceding claim further comprising, following the detection of intruding mobile devices (D'i, D'2, ... D'N) by the detection system (20) a calculation step by a calculation system (40) of the mobile device, of: i. a repulsion force (FréPjD) as a function of the position of the intruding mobile devices (D'b D'2, ... D';, ..., D'N) present in the detection zone (100) at time t, ii. an attractive force (Fatt>D) as a function of the optimal trajectory (Topt), and in which the modification of the trajectory of the mobile device (D) by the control system (30) is a function of said repulsive force (Frép>D) and said attractive force (Fatt>D).

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