Collision prevention system for a mobile device

Abstract

The invention relates to a collision prevention system (1) for an autonomous mobile device (D) configured to move in three dimensions. The system comprises an onboard memory (10) configured to store an optimal trajectory (Topt) for reaching a target 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) surrounding the mobile device (D), and a control system (30) configured to impose, on the mobile device (D), a modified trajectory (T') enabling it to reach the target position. The modified trajectory is dependent on the optimal trajectory and on the position of each intruding mobile device at each instant t during movement.

Description

[0001] "Anti-collision system for mobile devices"

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] 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.

[0004] STATE OF THE ART

[0005] 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.

[0006] The number of mobile devices moving through the air and oceans is thus growing every year. However, the increase in traffic of autonomous mobile devices is accompanied by a greater risk of accidents due to collisions, particularly collisions between mobile devices.

[0007] While airplanes are constantly monitored from control towers, which can instruct pilots to alter their flight plans to avoid collisions 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.

[0008] The state of the art in collision avoidance systems for aircraft is well-established. However, for numerous reasons, these systems cannot be adapted for autonomous mobile devices. First, these collision avoidance systems 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 change in trajectory and / or speed are completely different: while, for a short time, the trajectory and speed of an aircraft can only be modified by small amounts, those of a drone can be modulated over a large range. Therefore, collision avoidance programs designed for aircraft are entirely unsuitable for drones.Furthermore, given the extremely low probability of more than two aircraft being close together in the air, aircraft collision avoidance systems are primarily designed to handle situations in which only two aircraft are likely to collide. However, in the case of autonomous mobile systems, numerous devices can be in close proximity to one another without this necessarily indicating a danger.

[0009] One objective of the present invention is therefore to propose an anti-collision system adapted to the problems surrounding autonomous mobile devices.

[0010] SUMMARY OF THE INVENTION

[0011] To achieve this objective, according to one embodiment, a system is provided for an autonomous mobile device configured to move in three dimensions, the anti-collision system being embedded in the mobile device and comprising:

[0012] - an onboard memory configured to save an optimal trajectory to reach a destination position,

[0013] - a detection system configured to, at at least one time t, detect the presence of intrusive mobile devices within a detection zone around the mobile device and to determine the position of each intrusive mobile device present in the detection zone,

[0014] - 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.

[0015] 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.

[0016] 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 destination position from the deflected position of the mobile device. However, this approach would have required significant computational processing 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 and currents. These calculations are therefore very complex, consume a great deal of energy, and require large and powerful computing systems. Furthermore, these calculations require a considerable amount of processing time relative to the time required for a single deflection.This solution would therefore have been difficult to implement on small mobile devices and would have resulted in periods of instability during which the trajectory would have been recalculated. Such a solution, while feasible, would therefore not have been optimal.

[0017] By using a recorded optimal trajectory as a parameter for the modified trajectory, the calculations required at the mobile device level are significantly 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. This allows for a smaller onboard computing system, making the device lighter and enabling faster movement.

[0018] Furthermore, by ensuring that the mobile device is constantly brought back towards its optimal trajectory, we ensure that it does not drift far from its arrival position due to deviations induced by the presence of intrusive mobile devices.

[0019] The present invention therefore proposes a particularly effective system for reducing the probability of collision while optimizing the trajectory of the mobile device.

[0020] Preferably, the system also includes a calculation system configured to perform calculations following at least one detection of intruding mobile devices by the detection system during the movement of the mobile device:

[0021] - a repulsive force that depends on the position of the intruding mobile devices present in the detection zone,

[0022] - an attractive force that is a function of the optimal trajectory,

[0023] 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.

[0024] Preferably, the magnitude of the attractive force is proportional to the square of a distance, called the deviation distance, between the moving device and an optimal position of the moving device on the optimal trajectory.

[0025] The optimal position is typically distinct from the arrival position for most of the journey. The optimal position may be identical to the arrival position when the mobile device is deviated from the optimal trajectory in an area close to the arrival position. In other words, typically, the optimal position is distinct from the arrival position except possibly at the end of the journey where the optimal position and the final destination may coincide.

[0026] Preferably, the attractive force applied to the moving device is directed towards the optimal position. In other words, the direction vector of the attractive force is oriented along a straight line connecting the moving device and the optimal position, and is directed in the direction of the attractive force.

[0027] These characteristics limit deviations in the mobile device's trajectory and optimize trajectory parameters (travel time, energy consumption, and travel conditions, in particular). Indeed, if, once the mobile device is diverted from its optimal trajectory due to the presence of an intruding device, the gravitational force were to pull the mobile device directly toward its final destination, the mobile device would follow a path almost entirely, or even entirely, outside the optimal trajectory. Since the optimal trajectory is calculated based on external conditions, such a path outside the optimal trajectory is, by definition, accompanied by a greater risk that the mobile device will encounter obstacles (urban terrain, underwater topography), intruding mobile devices, or environmental conditions less conducive to flight.However, each time the mobile device encounters external elements in its path, it is deflected by the control system. Thus, through a cascading effect, the mobile device moves further and further from its optimal trajectory. These successive deflections force the mobile device into an erratic movement, consequently lengthening the distance traveled. As a result, the travel time of the mobile device is also increased.

[0028] Conversely, in the method according to the invention, after the mobile device deviates from its optimal trajectory, the control system returns the mobile device to an optimal position located on the optimal trajectory. This limits the time the mobile device spends outside the optimal trajectory. This therefore limits the number of encounters with external objects to be avoided and thus reduces the risk of the mobile device drifting. Furthermore, it increases the time spent on the optimal trajectory, which, by definition, corresponds to the desired compromise in terms of time and safety. Consequently, the travel time of the mobile device to reach its final destination is shortened. Remaining on the optimal trajectory for as long as possible also ensures that, under the prevailing weather conditions (wind, turbulence, etc.), the device remains stable.), energy consumption will be minimal (compared to the wind) and flight conditions optimal (exclusion of turbulent areas in particular).

[0029] Thus, the fact that the magnitude of the attractive force is proportional to the square of a distance, called the deviation distance, between the moving device and an optimal position of the moving device on the optimal trajectory, makes the system particularly effective at optimizing the trajectory of the moving device and reducing the probability of collision.

[0030] A second aspect of the invention relates to a mobile device comprising the system according to the first aspect of the invention.

[0031] A third aspect of the invention relates to a fleet comprising a plurality of mobile devices according to the second aspect of the invention.

[0032] A third aspect of the invention relates to a method for managing the movement of a mobile device comprising the following steps:

[0033] - Recording, in the mobile device's onboard memory, of an optimal trajectory for achieving the movement,

[0034] - 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,

[0035] - 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.

[0036] 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.

[0037] BRIEF DESCRIPTION OF THE FIGURES

[0038] 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:

[0039] Figure 1 represents a mobile device incorporating a system according to the invention.

[0040] Figure 2 represents a moving device on its optimal trajectory.

[0041] Figures 3, 4 and 5 represent a mobile device and one or more intruder mobile devices located in its detection zone.

[0042] Figure 6 illustrates the deviation of the mobile device from its optimal trajectory when an intruder mobile device is in its detection zone.

[0043] Figure 7 illustrates the force of attraction applied to the moving device towards its optimal trajectory when it has been deflected from it.

[0044] Figures 8A to 8E illustrate simulations of the integration of the present invention with mobile devices. Figures 8A to 8C are simulations for two mobile devices moving at the same altitude.

[0045] Figures 8D to 8F are simulations in the case of two mobile devices moving at distinct altitudes.

[0046] Figure 8G is a simulation in the case of three mobile devices.

[0047] Figure 8H is a simulation in the case of eight mobile devices.

[0048] Figure 9 is a diagram of the different steps of an embodiment of the process according to the invention.

[0049] The drawings are provided as examples and are not intended to limit the scope of the invention. They are schematic representations of the 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.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0052] 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 within the detection zone, with the magnitude of each repulsion component being inversely proportional to the square of the distance between the mobile device and a separate intruding mobile device. Thus, the closer the mobile device(s) are, the greater the repulsion force. In other words, the greater the danger, the more significant 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 with good responsiveness.

[0053] According to a preferred example, the magnitude of the attractive force is proportional to the square of the distance, called the deviation distance, between the moving device and its optimal position on the optimal trajectory. Thus, the more the moving device has been deviated from its optimal trajectory, the greater the attractive force, which pulls it back towards its optimal path. This prevents the moving device from spending long periods away from the optimal trajectory, thereby reducing the travel time to reach the destination position.

[0054] In 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 achievable 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.

[0055] According to a preferred example, the repulsion force is further a function of a repulsion coefficient which itself is 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.

[0056] According to a preferred example, the force of attraction is further a function of an attraction coefficient which itself is a function of at least one of the following parameters: a safety coefficient, a quantity of fuel available, an acquisition accuracy of the detection system, an acquisition frequency of the detection system.

[0057] According to a preferred example, the control system is configured to modulate the speed of the mobile device based on the position of intruding mobile devices at time t and the optimal trajectory.

[0058] In a preferred example, the speed modulation 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.

[0059] 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.

[0060] According to a preferred example, the mobile device and intruding mobile devices are aerial or underwater drones. According to a preferred example, the detection zone is a sphere centered on the mobile device, said sphere having a radius of between 3 and 10 meters, preferably between 4 and 6 meters.

[0061] 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 for the mobile device, of:

[0062] - a repulsive force that is a function of the position of the intruding mobile devices present in the detection zone at time t,

[0063] - an attractive force that is a function of the optimal trajectory,

[0064] Furthermore, in this embodiment of the process, the modification of the trajectory of the mobile device by the control system is a function of said repulsive force and said attractive force.

[0065] 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 could include, in particular, an aerial drone or an underwater drone.

[0066] System 1 according to the present invention will now be described with reference to Figures 1 to 7.

[0067] System 1 is intended to be mounted on a mobile device D, as illustrated in Figure 1. The mobile device D on which system 1 is mounted is configured to move in three dimensions.

[0068] The mobile device D can take several forms. It can, in particular, be an aerial drone or an underwater drone. The mobile device D is typically autonomous, meaning it is not remotely controlled, or at least not continuously. In the case of an underwater device, it is typically an autonomous underwater vehicle, commonly referred to as an AUV (Autonomous Underwater Vehicle).

[0069] An example of a mobile device D will now be described. System 1 may first include an onboard memory 0. This memory 10 is capable of storing data. This data may include, in particular, an optimal trajectory T. opt to reach a destination position. An optimal speed can also be stored in the onboard memory 10. This optimal speed may depend on time and / or the position of the mobile device D on the optimal trajectory T opt(for example, the optimal speed may decrease when approaching the arrival position or depending on the environment: wind, ...).

[0070] The optimal trajectory T opt can be defined in various ways and according to various objectives to reach a finish position.

[0071] The optimal trajectory T opt is defined without taking into account potential intrusive mobile devices whose trajectory could approach, or even intersect, that of mobile device D.

[0072] According to a non-limiting example, the optimal trajectory T optis typically obtained by optimizing a consumption function that represents the cost function. In other words, it is calculated so that, among all possible trajectories (i.e., all possible trajectories taking into account no-fly zones) and all possible speeds along these trajectories, the optimal trajectory minimizes the total cost C. The total cost C is the integral over the trajectory of the instantaneous cost C(P,V,t) where P is the position, V the speed, and t the time. The consumption (cost) function depends, in particular, on the drag as a function of the speed of the moving device D relative to the wind, as well as on the acceleration. This cost function can depend on parameters such as the fuel consumption required for the movement, the duration of the journey, the flight stability, and the proximity of the movement to no-fly zones or inhabited areas. The optimal trajectory T opt is determined from this function, for example, by reinforcement learning techniques or by applying the so-called Euler-Lagrange equations. opt can notably be obtained through a learning method involving, for example, a neural network.

[0073] 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).

[0074] Alternatively or in combination, the optimal trajectory T opt can be achieved differently, for example by primarily or solely optimizing travel time and / or fuel consumption.

[0075] The optimal trajectory T opt 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 many parameters such as urban or underwater terrain, can be carried out at the remote base B, while less resource-intensive calculations are performed at a computing system 40 of system 1, as described above.

[0076] The optimal trajectory T optcan thus be recorded in the on-board memory 10 before the mobile device D begins moving towards the arrival position.

[0077] System 1 also includes 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 system 1 is mounted (Figure 2). The intruder bodies are typically mobile intruder devices D'i, D'2, ... D'j, ... D'N. These mobile intruder devices may include 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.

[0078] The detection system 20 is also configured to determine a position of each of the intruder mobile devices present within the detection zone 100.

[0079] The position of intruder devices is not necessarily understood as an absolute position in a geostatic coordinate system. It is typically a relative position with respect to the moving device D. Obtaining a relative position using an onboard radar is perfectly well known to those skilled in the art.

[0080] The position of any mobile device D'j can be described using a unit vector denoted UD^Di in the figures and the distance do separating the mobile device D from the intruder mobile device considered D'j (i=1, 2... N). This unit vector and this distance are therefore known to system 1 thanks to the detection device 20.

[0081] The detection zone 100 is typically a sphere whose center is located at the level of the moving device D. The radius R o of this sphere can notably be defined as a function of at least one of the following parameters:

[0082] - constraints related to the intended application,

[0083] - security constraints,

[0084] - a maximum speed that can be reached by the mobile device D,

[0085] The detection range of the detection system 20 can extend beyond the detection zone 100. However, the control system 30 described earlier will only modify the trajectory of the device D if intruder mobile devices D'i, D'2, ... D'j, ... D'N are detected within the detection zone 100. The detection system 20 is configured to probe the detection zone 100 at different times t during its 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.

[0086] 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.

[0087] 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.

[0088] The control system 30 modifies the trajectory of the mobile device D when at least one intruder mobile device D'j 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 device D is the optimal trajectory T optstored in the on-board memory 10 (see the case illustrated in Figure 2). If intruder mobile devices D'i, D'2, ... D'j, ... D'N are detected in the detection zone 100 during 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 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'i, D'2, ... D'j, ... D'N during the movement, i.e., at different detection times.

[0089] Advantageously, 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 intruder mobile devices D'i, D'2, ... D'j, ... D'N, a repulsion force F r e P ,D and a force of attraction Fatt.o-

[0090] The repulsive force F r e P ,D 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.

[0091] The repulsive force F r e P D is typically a function of the position of the intruder mobile devices D'i, D'2, ... D'j, ... D'N present in the detection zone 100 at the time of detection leading to this calculation. When N intruder mobile devices are detected simultaneously by the detection system 20, the repulsion force F r e P,D can for example follow the following equation: with d DD / the distance separating the mobile device D from the intruder mobile device considered D'j, u D ^ D the unit vector between the mobile device D and the intruder mobile device considered D'j (u D / ^ D = -u D ^ D >) and has a repulsion coefficient.

[0092] Thus, the repulsive force comprises as many components (F D?D than the number of intruding mobile devices present within detection zone 20. This ensures the integrity of mobile device D with respect to each of the intruding mobile devices simultaneously. Instead of successively addressing the danger posed by each intruding mobile device, a repulsive force is applied to mobile device D, preventing any collision. This approach is more efficient and safer than a sequential approach.

[0093] We note that the magnitude of each component is inversely proportional to the square of the distance separating the mobile device D from the intruder mobile device D'j considered: thus, the closer the intruder mobile device D'j is (the greater the danger), the stronger the repulsion.

[0094] 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'j, ... D'N within the detection zone 100.

[0095] The repulsion coefficient may depend on various parameters, including:

[0096] - a safety coefficient: this safety coefficient is typically dependent on the legislation in force in the territory where system 1 is deployed.

[0097] - 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.

[0098] - 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.

[0099] These different parameters can be recorded in the on-board memory 10. Their values ​​can be constant during the movement or modulated, for example by recording updated values ​​sent by the remote base B.

[0100] The attractive force Fatt.o is the force applied to the mobile device D via the control device 30 in such a way as to limit the deviation of the mobile device D from the optimal trajectory T optIt is thus a function of the optimal trajectory T. opt stored in onboard memory 10.

[0101] The attractive force Fatt.o is configured to return the mobile device D to an optimal position P opt located on the optimal trajectory T opt This optimal position P opt This could be the position at which the moving device D would have been located at the instant Fatti is calculated if it had not been deflected from the optimal trajectory T opt due to the presence of intrusive mobile devices. The optimal position P opt can also correspond to a position that the mobile device D would have been located at the instant after Fatt.o is calculated. This latter case can allow the mobile device D to be brought back to its optimal trajectory along a less abrupt path and potentially reduce the travel time. The optimal position P optis typically distinct from the arrival position, at least for part of the course, typically for a majority of the course. The optimal position P opt may possibly coincide with the arrival position, for example at the end of the journey, when the device is outside the optimal trajectory and in an area close to the arrival position.

[0102] The distance between the position of the mobile device D and the optimal position P opt is called the deviation distance ddev. The unit vector directed from the moving device D to the optimal position P opt is denoted U ev.

[0103] Thus, the force of attraction F a tt,D can for example follow the following equation: att,DP^-dev ^-dev

[0104] With p being a coefficient of attraction. The coefficient of attraction p determines the intensity with which the trajectory of the moving device D is brought back towards its optimal trajectory T o P t.

[0105] The attraction coefficient p can be a function of various parameters, including:

[0106] - a safety coefficient: this safety coefficient is typically dependent on the legislation in force in the territory where system 1 is deployed.

[0107] - 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 p.

[0108] - 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 p.

[0109] - 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 attraction coefficient p.

[0110] 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.

[0111] We observe that the magnitude of the attractive force Fatt.o is proportional to the square of the deviation distance ddev: thus, the more the moving device D has been deviated from its optimal trajectory, the stronger the attraction. This allows, on the one hand, for the moving device D to allocate more resources to making up for lost time due to deviations when these have been significant. It also prevents the moving device D from being increasingly deviated from its optimal trajectory and encountering other intruding moving devices, which would take it further and further away from its optimal trajectory T. opt .

[0112] The control system 30 is therefore preferably configured to apply the repulsive force F to the mobile device D r e P ,D and the attractive force Fatt.o- In concrete terms, the calculation system 40 is configured for, once F r e P D and F aGiven the calculated values ​​of tt and D, calculate the modified velocity and associated modified trajectory by solving, through integration, the fundamental equation of dynamics incorporating F. P ,D and F att.D- The calculation system 40 can thus communicate the modified speed and the modified trajectory to the control system 30 which then imposes on the device 1 this modified speed and this modified trajectory, typically by acting on the motor 70.

[0113] Advantageously, the repulsive force F is predicted to r e P The gravitational force D and the gravitational force Fatt.o are dampened 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 computational system 40.

[0114] 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, and even transmit signals to the remote base B. For example, it is conceivable that the remote base B could send 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 allows for the offloading of complex computing systems requiring space and processor power to the remote base B. The complex calculation of an updated optimal trajectory, which requires taking into account numerous parameters such as urban or underwater topography, can be performed at the remote base B, while the calculations of the repulsive forces F r e P,D and attractive forces F a Successive, less energy-intensive calculations 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.

[0115] The updated optimal trajectory and the updated optimal speed can notably take into account surrounding conditions such as wind, the intensity and direction of which can vary during the journey.

[0116] The communication system 50 can also be used for recording the optimal trajectory T opt and the initial optimum speed, typically before the start of the movement.

[0117] The operation of system 1 described above thus allows an excellent compromise between safety and optimization of movement in terms of time and cost.

[0118] 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.

[0119] Figures 8A, 8B, and 8C illustrate the trajectories followed by two moving devices D initially traveling 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 90° crossing angle between the two moving devices. In each case, we observe that the two moving 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.

[0120] 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, although the difference is not sufficient to avoid a collision. It is noted that here again, the mobile devices D deviate from their respective optimal trajectories. However, the deviation is less significant than when the devices were moving at the same altitude. This demonstrates 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 navigational circumstances.

[0121] If the altitude difference between the mobile devices D were sufficient to avoid a collision, then the mobile devices would not deviate from their optimal trajectories. Figures 8G and 8H are the results of simulations including three and eight mobile devices respectively, 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.

[0122] 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 Figure 1.

[0123] 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 entire 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, the mobile device D is repelled by the repulsive force F D / D caused by the presence of the mobile device D'i in its detection zone, and the mobile device D'i is repelled by the repulsive force F DD> caused by the presence of the 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 figure 3).

[0124] A fourth aspect of the invention relates to a method for managing the movement of the mobile device D. This movement has as its destination the arrival position mentioned previously.

[0125] The main steps in this process are as follows (see figure 9):

[0126] - Recording in onboard memory 10 of the optimal trajectory T opt to perform the movement (step 1001),

[0127] - Detection, at at least one instant t during the movement, by the detection system 20 of the position of intruder mobile devices D'i, D'2, ... , D'i, ... D'N (step 1002),

[0128] - 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'i, D'2, ... , D'i, ... D'N at time t during the displacement and the optimal trajectory T opt (step 1004).

[0129] Advantageously, and as described above with reference to system 1, the process includes a calculation step 1003 of the repulsive force F r e P ,o and the attractive force Fatt.o between the detection step 1002 of the intruder mobile devices D'i, D'2, ... , D'i, ... D'N and the trajectory modification step 1004. This step is carried out at the level of the computing system 40 of the mobile device D.

[0130] As illustrated in Figure 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.

[0131] The mobile device D thus typically undergoes several successive redirections during different iterations of the trajectory modification step 1004.

[0132] Finally, the mobile device D arrives at its destination position (step 1005). 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 T op t recorded at step 1001.

[0133] 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 an 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 (T op t) 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'j, ... , D'N) present within a detection zone (100) around the mobile device (D) and to determine a position of each intruder mobile device (D'j) 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 destination position, the modified trajectory (T) being a function of the optimal trajectory (T opt) and the position of each intruder mobile device (D'i, D'2, ... D'N) at each instant t during the displacement, iv. a calculation system (40) configured to calculate, following at least one detection of intruder mobile devices (D'i, D'2, ... D'j, ... D'N) by the detection system (20) during the displacement of the mobile device (D): i. a repulsion force (Frép.o) as a function of the position of the intruder mobile devices (D'i, D'2, ... D'j, ... , D'N) present in the detection zone, ii. an attraction force (Fatt.o) as a function of the optimal trajectory (Topt), the magnitude of the attraction force (Fatt.o) being proportional to the square of a distance, called the deviation distance (ddev), between the mobile device (D) and an optimal position (P opt ) of the mobile device (D) on the optimal trajectory (T opt ), the modified trajectory (T') being a function of the repulsive forces (Frép.o) and the attractive forces (Fatt.o) calculated during the displacement.

2. System (1) according to the preceding claim in which the repulsion force (Frép.o) is a linear combination of as many repulsion components as there are intruding mobile devices (D'i, D'2, ... D'j, ... , 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 (doD'i, doD'2, ... doo'N) between the mobile device (D) and a distinct intruder mobile device (D'i, D'2, ... D'j, ... , D'N).

3. 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'j, ... , D'N) within the detection zone (100), with N>2.

4. System (1) according to any one of the preceding claims wherein the repulsion force (Frép.o) 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).

5. System (1) according to any one of the preceding claims wherein the attraction force (Fatt.o) is further a function of an attraction coefficient 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 (20), an acquisition frequency of the detection system (20).

6. 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) as a function of the position of the intruder mobile devices (D'i, D'2, ..., D'j, ..., D'N) at time t and the optimal trajectory (T opt ).

7. 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).

8. 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.

9. 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'j, ... , D'N) are aerial or underwater drones.

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

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

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

13. Method for 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 (T opt) to perform the displacement, ii. Detection at at least one instant t during the displacement, by a detection system (20) of the mobile device (D), of the position of intruder mobile devices (D'i, D'2, ..., D'j, ..., 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 instant t and of the optimal trajectory (To Pt), the method 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 (Frép.o) as a function of the position of the intruding mobile devices (D'i, D'2, ... D'j, ... , D'N) present in the detection zone (100) at time t, ii. an attraction force (Fatt.o) as a function of the optimal trajectory (T opt ), the magnitude of the attractive force (F^.D) being proportional to the square of a distance, called the deflection distance (ddev), between the moving device (D) and an optimal position (P opt ) of the mobile device (D) on the optimal trajectory (T op (t), the modification of the trajectory of the mobile device (D) by the control system (30) being a function of said repulsive force (F r e P ,o) and of said force of attraction (F^.D).

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