Unmanned aerial vehicle self-guided by dual-purpose optoelectronic distance measuring device

Abstract

The invention relates to an aerial drone (1). The aerial drone (1) comprises a fixed structure (2), a motor assembly (3) for propelling and orienting the drone, an optoelectronic distance measuring device (6) and an electronic guidance unit (5) connected to the motor assembly (3) and the optoelectronic distance measuring device (6) so as to control the motor assembly (3) according to signals emitted by the optoelectronic distance measuring device (6). The device (6) comprises an optical system (6.1) and a photosensor (6.2), the optical system (6.1) and the photosensor (6.2) being fixed in orientation relative to the fixed structure (2). The electronic guidance unit (5) is arranged to control the motor assembly (3) in order to move the drone over an exploration area, to scan the exploration area by the photoelectric sensor (6.2) until electromagnetic radiation emitted by a target is detected, and then to guide the drone by distance measurement to the target.

Description

[0001] This invention relates to the field of aerial unmanned aerial vehicles (UAVs), particularly transport and delivery UAVs, and more specifically to any unmanned vehicle capable of autonomously traveling from one point to another. Background Technology

[0002] When remote-controlled drones are unavailable, for example because radio communication with the drone is impossible, the known practice is to resort to self-guided drones.

[0003] This type of drone typically includes a self-guiding device that controls the drone's steering mechanism to guide it from a pre-programmed starting point to a pre-programmed destination. The self-guiding device most often includes a receiver for receiving satellite positioning signals (or GNSS) from satellites in a constellation (GPS, Galileo, GLONASS, BeiDou, etc.) orbiting the Earth, and an electronic navigation unit connected to the satellite receiver to calculate satellite navigation. Satellite navigation is highly accurate over long periods, but satellite signal reception is not always possible, for example, due to terrain or the presence of jamming devices that interfere with satellite signals.

[0004] Some drones also incorporate an inertial unit (IMU) connected to an electronic navigation unit (ENA), which is then designed to compute hybrid satellite / inertial navigation. This hybrid navigation offers the advantage of providing reliable navigation and is more resistant to satellite signal unavailability. On the other hand, when satellite signals are unavailable for a relatively long period, the hybrid navigation drifts and becomes unusable unless a more accurate IMU is used, but the cost, size, weight, and energy consumption of IMUs are generally incompatible with their use on drones.

[0005] There are also drones equipped with mobile platforms that carry photoelectric sensors sensitive in the visible and / or infrared range. Imagery of the drone's environment can then be used to enable it to locate itself and establish navigation; however, image-based navigation requires significant computing resources. The environment also needs to include previously known and identifiable landmarks.

[0006] Furthermore, it is known to guide a missile toward a spot of light projected onto an object by a laser. The missile is equipped with a seeker system having an optoelectronic deviation measurement device, which includes an optical system with an optical axis on which a photoelectric sensor is positioned. The photoelectric sensor includes four photodiodes that provide a signal proportional to the received light energy, and the four photodiodes have a field of view that is combined to form the sensor's field of view. A distinction should be made between the sensor's total field of view and its linear field of view. The total field of view is the optical field of view where at least one photodiode can detect the spot, while the linear field of view is the portion of the total field of view where multiple photodiodes observe the spot, thus enabling deviation measurement. To facilitate spot detection and deviation measurement, it is known to design the optical system to defocus the spot on the sensor.

[0007] The device is associated with a computing circuit designed to perform deviation measurement, i.e., determining the position of the light spot within the sensor's linear field of view by calculating the centroid of the light spot based on the energy detected by the photodiode. More specifically: When the light spot is located at the center of the sensor's field of view, all four photodiodes measure the same light energy, and therefore they transmit signals with the same value (within the measurement noise). Thus, the calculated centroid is also located at the center of the linear field of view. - If the light spot is offset toward one of the photodiodes, that photodiode will transmit a larger signal than the other photodiodes, and the centroid calculated for the detected light spot will be offset toward the photodiode.

[0008] After the light spot is defocused on the sensor, the flux distribution in the image spot represents the distribution of the incident flux in the entrance pupil of the optical channel. However, the sensor's total field of view is relatively narrow, and it is necessary to point the missile sensor in the direction of the target object so that it can lock onto the target indicated by the laser beam.

[0009] It's possible to use a deviation measurement device to guide the drone, but it would be necessary to mount the sensor on a directional platform, similar to the image sensor described above, to compensate for the sensor's limited total field of view. However, this would increase the drone's weight and size, thus limiting its payload and stealth capabilities in applications requiring caution.

[0010] Purpose of the invention

[0011] One particular objective of this invention is to enable guidance in environments where the use of satellite positioning receivers or radio communications is prohibited. Summary of the Invention

[0012] Therefore, the present invention relates to an aerial unmanned aerial vehicle (UAV) having a fixed structure, a motor assembly for propulsion and orientation of the UAV, an optoelectronic deviation measurement device, and an electronic guidance unit connected to the motor assembly and the optoelectronic deviation measurement device to control the motor assembly based on signals emitted by the optoelectronic deviation measurement device. The optoelectronic deviation measurement device includes an optical system and a photoelectric sensor, the optical system and the photoelectric sensor being oriented fixed relative to the fixed structure. The electronic guidance unit is designed to control the motor assembly to move the UAV above an exploration area, scan the exploration area using the photoelectric sensor until electromagnetic radiation emitted by a target is detected, and then guide the UAV to the target via deviation measurement.

[0013] Fixed structure refers to all fixed components of the drone, such as the fuselage, fixed wings, and fixed panels of the tail assembly. Therefore, in this invention, the scanning motion of the drone is used to compensate for poor field of view and the lack of a directional platform, thereby enabling the use of an optoelectronic deviation measurement device to detect electromagnetic radiation.

[0014] Based on the optional features that can be used individually, in whole or in part: -The electronic guidance unit commands a circular scan of the exploration area; - The electronic guidance unit commands a lateral scan relative to the UAV's substantially linear direction of movement above the exploration area; - The drone includes a self-destruct component connected to the electronic guidance unit, the electronic guidance unit being designed to activate the self-destruct component upon detection of at least one predetermined event, the predetermined event advantageously corresponding to a predetermined time exceeding the time required to detect the target or corresponding to a predetermined characteristic of electromagnetic radiation emitted by the target; - The drone includes an inertial unit connected to the electronic guidance unit; the electronic guidance unit is designed to guide the drone to the exploration area based on signals from the inertial unit; - The electromagnetic radiation is emitted around an axis that is substantially locally perpendicular to the ground at a semi-apex angle between + / -85° and + / -45°; - The electromagnetic radiation is emitted by a laser emitter associated with a diverging optical system; The electromagnetic radiation is obtained by reflection of a laser beam from a laser pointer associated with a diverging optical system on a surface that is at least partially reflective; - The target is a beacon having a laser emitter that emits the electromagnetic radiation.

[0015] Other features and advantages of the invention will become apparent upon reading the following description of specific and non-limiting embodiments of the invention.

[0016] Brief description of the attached figures

[0017] The accompanying drawings will be referenced, in which: [ Figure 1 ] Figure 1 This is a schematic perspective view of the UAV according to the present invention; [ Figure 2 ] Figure 2 This is a schematic bottom view of the UAV according to the present invention; [ Figure 3 ] Figure 3 This is a schematic perspective view illustrating the UAV of the present invention searching for a target according to a first embodiment; [ Figure 4 ] Figure 4 It is a schematic top-down view of the area being explored according to the first exploration mode; [ Figure 5 ] Figure 5 It is a schematic top-down view of the area being explored according to the second exploration mode; [ Figure 6 ] Figure 6 This is a schematic perspective view illustrating the formation of a guide target according to a second embodiment; [ Figure 7 ] Figure 7 This is a flowchart illustrating the drone guidance method.

[0018] Detailed Description of the Invention

[0019] refer to Figure 1 and Figure 2This document describes the application of the invention to an aerial unmanned aerial vehicle (UAV), generally indicated by reference numeral 1, which in this case is a quadcopter type, having a structure 2 and a motorized propeller 3 forming an electric motor assembly for propulsion and orientation of the UAV. In this example, the motorization of the motorized propeller 3 is powered by an electric mechanism powered by a battery (not shown) mounted in structure 2. Structure 2 includes a body 2.1, arms 2.2 extending from the body 2.1, and each motorized propeller 3 is mounted at the free end of one arm 2.2. The body 2.1 includes a cabin 4, which in this example is open at the top of the body 1. The body 2.1 also forms a sealed housing that houses an electronic guidance unit, generally indicated by reference numeral 5, which is battery powered and connected to the motorized propeller 3 for orientation and maneuvering of the UAV 1. The electronic guidance unit 5 includes, for example, at least one processor and a memory containing a computer program executable by the processor. The construction and operation of these elements are known in themselves and will not be described further here.

[0020] The electronic guidance unit 5 is also connected to a photoelectric deviation measuring device, generally indicated by reference numeral 6, which includes: - The optical system, generally indicated by reference numeral 6.1 in the attached figure, has an optical axis. - The photoelectric sensor 6.2 is positioned on the optical axis behind the optical system 6.1, and - Electronic weighting circuit 6.3 connected to photoelectric sensor 6.2.

[0021] Optical system 6.1 includes one or more lenses for shaping the luminous electromagnetic radiation (in the form of an incident beam) entering the photoelectric angle error measuring device 6 to form an image spot on the sensitive surface of photoelectric sensor 6.2. Photoelectric sensor 6.2 includes a detector having four adjacent photodiodes arranged in a four-quadrant configuration, each photodiode associated with an optical group whose field of view is combined with the fields of view of the other photodiodes' optical groups to define the field of view of the detector, and thus the field of view of photoelectric sensor 6.2. In this example, the photodiodes are single photodiodes, collectively defining the sensitive surface of photoelectric sensor 6.2. In this example, as an example, the combination of photoelectric sensor 6.2 and optical system 6.1 forms the photoelectric component of photoelectric deviation measuring device 6, which has a field of view (FoV) between + / -5° and + / -40° and a pupil with a diameter between 5 mm and 40 mm.

[0022] The electronic weighting circuit 6.3 includes an electronic card that, in a manner known per se, includes a processor and a memory containing operating programs for the photoelectric device 6. Four photodiodes provide signals to the electronic weighting circuit 6.3, the signals being proportional to the light energy of an incident beam having at least one wavelength of interest sensitive to the photodiodes (for simplicity; this is actually a preferably narrow wavelength range), forming an image spot on the photoelectric sensor 6.2. The electronic weighting circuit 6.3 is designed to perform a deviation measurement, known per se, based on the signals from the photoelectric sensor 6.2, and to send a signal to the electronic guidance unit 5 representing the deviation between the spot and the center of the photoelectric sensor 6.2, the deviation representing the deviation between the direction of the incident beam and the direction pointed to by the deviation measuring device 6. In this case, the deviation measuring device 6 is mounted on the lower part of the body 2.1. More precisely, the optical system 6.1 and the sensor 6.2 are rigidly fixed to the body 2.1, i.e., it is impossible to make the latter motorized orientation relative to the body 2.1 (so-called strapdown mounting) and open to the lower surface of the body 2.1 of the UAV 1.

[0023] The electronic guidance unit 5 is also connected to the inertial unit 7 and the communication component 8.

[0024] The inertial unit 7 includes, in a manner known per se, a linear inertial sensor, such as an accelerometer, arranged along the axis of the measurement reference frame to measure the components of the specific force vector, and an angular inertial sensor, such as a gyroscope, designed to measure the orientation of the measurement reference frame relative to the inertial reference frame. The inertial unit 7 provides the electronic guidance unit 5 with signals representing the motion of the UAV 1.

[0025] The communication component 8 can be wired or wireless (e.g., short-range radio type such as NFC system) and allows an operator with a suitable computer terminal (computer, smartphone or dedicated terminal) or suitable interface device (keyboard associated with screen) to exchange data with the electronic guidance unit 5 and / or modify parameters used to control the operation of the UAV 1.

[0026] The electronic guidance unit 5 is designed in a manner known per se to control the rotation of the motorized propulsion propeller 3 in order to orient the UAV 1 in the roll, pitch and yaw directions, and to move the UAV 1 along a trajectory while controlling the attitude of the UAV 1.

[0027] The electronic guidance unit 5 is more specifically designed to implement three guidance modes in the guidance method preferably implemented by the present invention.

[0028] According to the first guidance mode, or approach guidance, the electronic guidance unit 5 is designed to guide the UAV 1 from the starting position to an intermediate position. The first guidance mode is used here to guide the UAV 1 to the area to be explored using signals provided by the inertial unit 7. The intermediate position is located at the center of the area to be explored and / or at the boundary of the area to be explored. The intermediate position and the boundary of the area to be explored are programmed into the electronic guidance unit 5 via the communication component 8.

[0029] according to Figures 3 to 5 More specifically shown is the second guidance mode, or exploration guidance, in which the electronic guidance unit 5 is designed to scan the exploration area ZE through the field of view of the optoelectronic assembly formed by the combination of the optoelectronic sensor 6.2 and the optical system 6.1 until predetermined electromagnetic radiation is detected. The electronic guidance unit 5 steers the UAV 1 solely based on signals from the inertial unit 7, influencing the roll, pitch, and yaw of the UAV 1 so that the optical axis of the optoelectronic assembly formed by the combination of the optoelectronic sensor 6.2 and the optical system 6.1 moves along the scanning trajectory TB within the exploration area ZE. Figure 4 In this process, the electronic guidance unit 5 commands a lateral scan relative to the UAV 1's substantially linear direction of movement above the exploration area ZE. The scan width and length are stored in the electronic guidance unit 5. Figure 5 In this example, the electronic guidance unit 5 commands a concentric scan of the exploration area ZE, which is a circular scan in this case. It should be understood that in the latter case, the starting position of the intermediate scan can be at the boundary of the exploration area ZE (scanning from the periphery to the center) or at the center of the exploration area ZE (scanning from the center to the periphery). The scan radius is stored in the electronic guidance unit 5.

[0030] The electronic guidance unit 5 is designed to interrupt exploration guidance once the photoelectric sensor 6.2 of the photoelectric deviation measurement device 6 detects predetermined electromagnetic radiation. The predetermined electromagnetic radiation originates from the target and, in this case, takes the form of a series of laser beam pulses. The wavelength of the laser beams, the frequency of the pulses, and the duration are predetermined and have been input into the memory of the electronic guidance unit 5.

[0031] According to the third guidance mode, or terminal guidance, which immediately follows exploration guidance, the electronic guidance unit 5 controls the UAV 1 based on the deviation measurement signal transmitted by the photoelectric deviation measurement device 6 to ensure that the deviation between the light spot and the center of the photoelectric sensor 6.2 is reduced. The memory of the electronic guidance unit 5 contains a table that correlates the light spot size with the approach speed, so that the piloting UAV 1 decelerates as the distance between UAV 1 and the target decreases (the light spot size increases when UAV 1 approaches the target).

[0032] As mentioned above, the intended electromagnetic radiation originates from the target. There are several ways to create a target.

[0033] exist Figure 3 In the first embodiment shown, the target is represented by a beacon 10, which includes a laser emitter designed to emit a laser beam in a direction substantially locally perpendicular to the ground (vertical in this case), corresponding to the emission axis AE of the beam. The laser emitter is associated with a diverging optical system such that electromagnetic radiation is emitted within a cone at a half-apex angle α about the axis AE, between + / -85° and + / -45°.

[0034] exist Figure 6 In the second embodiment shown, the target is revealed by a reflective fabric 11 (e.g., a simple white or metallized fabric) laid on the ground S. A laser emitter 12 (e.g., a tripod-mounted laser pointer) associated with a diverging optical system 13 projects a laser beam onto the reflective fabric 11, such that the beam is reflected substantially vertically by the fabric, forming electromagnetic radiation with a half-apex angle α between + / -85° and + / -45° about the principal reflection direction. In variations, the reflective fabric 11 can be replaced by any reflective screen (rigid or non-rigid, rough or smooth), or even omitted if the ground (or surrounding elements, such as rocks, buildings, or others) is sufficiently reflective. Preferably, the spot formed by the beam on the fabric will have a radius of approximately 1 meter, and the reflective fabric will have substantially the same size. Also preferably, the diverging optical system 13 will filter the laser beam to avoid speckle or flicker effects.

[0035] In both embodiments, the electromagnetic radiation emitted by the target has predetermined characteristics. More specifically, if the electromagnetic radiation detected by the photoelectric sensor 6.2 does not have these characteristics, it is ignored. Therefore, the laser emitter is designed to generate a pulse sequence of laser beams, in this case with wavelengths between 700 nm and 1650 nm. The pulses have a predetermined frequency and duration (here between 10 ns and 10 ms, preferably between 10 ns and 100 ns). It can also be specified that a given sequence includes pulses of different durations.

[0036] In a preferred embodiment of the invention, the drone 1 includes a self-destruct component 9 (here, a pyrotechnic charge) connected to the electronic guidance unit 5, and laser pulses are emitted as needed at at least two useful frequencies, Fut1 and Fut2. Each frequency, Fut1 and Fut2, is associated with an action to be performed by the drone 1, in which case: -Fut1 corresponds to the nominal landing, and -Fut2 corresponds to self-destruction.

[0037] An operational example for completing a task will now be described in detail, which involves a first operator transmitting an electronic data carrier to a second operator located in territory where neither radio communication nor satellite positioning signals are possible. The delivery must take place at a time previously agreed upon by the two operators and at the destination location of UAV 1, and it should be understood that the second operator may be within a radius of several hundred meters of the agreed destination location.

[0038] During the initial steps, at the starting position, the first operator places the electronic data medium in the cabin 4 and uses a computer terminal connected to the communication component 8 to store the starting position and destination position of the UAV 1, previously agreed with the second operator, in the electronic control unit 5.

[0039] Meanwhile, at the destination location (or nearby), the second operator activates the laser emitter to emit electromagnetic radiation with a useful frequency Fut1 to achieve terminal guidance of the UAV 1.

[0040] The electronic guidance unit 5 commands the UAV 1 to proceed to the destination location via approach guidance and calculates the intermediate position at a predetermined distance from the destination location (here, 2 kilometers). As long as the electronic guidance unit 5 has not reached the intermediate position (check 102), the electronic guidance unit 5 continuously calculates the distance between itself and the intermediate position using the signal provided by the inertial unit 7 (step 101).

[0041] Once the intermediate position is reached, the electronic guidance unit 5 initiates exploration guidance (step 103) without detecting the predetermined electromagnetic radiation (check 104).

[0042] Once the predetermined electromagnetic radiation is detected, the electronic guidance unit 5 initiates terminal guidance (step 105), while continuously monitoring the frequency of the pulse to confirm that it is indeed frequency Fut1 (step 106).

[0043] If the frequency of the pulse remains equal to frequency Fut1 (check 107), the electronic guidance unit 5 lands in nominal mode (step 108), enabling the second operator to retrieve the electronic data medium. The second operator can then command the electronic guidance unit 5 to return the UAV 1 to its starting position (empty or with the electronic data medium in the cabin) or retain the UAV 1 for future reuse.

[0044] If the frequency of the pulse becomes equal to frequency Fut2 (check 107), the electronic guidance unit 5 interrupts final guidance and activates the self-destruct component 9 (step 109), which destroys the drone 1. It is possible that the electronic guidance unit 5 commands the drone 1 to perform a move away before activating the self-destruct component 9 to limit the risk of the drone 1 exploding near the second operator.

[0045] Simultaneously, when the electronic guidance unit 5 initiates exploration guidance (step 103), it also initiates a backup process by counting the exploration time (step 110) and verifying that the exploration time is less than a predetermined maximum threshold (verification 111). If the predetermined maximum threshold is reached, the electronic guidance unit 5 activates the self-destruct component 9 (step 109), and the self-destruct component 9 destroys the drone 1.

[0046] Alternatively, if UAV 1 needs to return to its starting position in all cases, the maximum exploration time threshold can be determined in real time by electronic guidance unit 5 based on the remaining endurance of UAV 1 and the distance between UAV 1's current position and its starting position, ensuring that UAV 1 has sufficient endurance to return to its starting position when the exploration time equals the maximum threshold. At this point, electronic guidance unit 5 interrupts exploration guidance to return to its starting position using approach guidance.

[0047] It should be understood that exploration guidance can also overcome the problem of insufficient accuracy of inertial units; the lower the accuracy of the inertial unit, the wider the exploration area must be.

[0048] Of course, the present invention is not limited to the described embodiments, but includes any variations that fall within the scope of the invention as defined by the claims.

[0049] In particular, drones may have structures different from those described, and may include, for example, fixed wings, different numbers of propellers, tail assemblies, control surfaces and / or different modes of motorization, such as internal combustion engines; and / or no self-destruct components, etc.

[0050] Other guidance modes are possible. For example, the intermediate position could be the destination position. Once the UAV 1 reaches the destination position, the electronic guidance unit 5 begins exploration and guidance, drawing concentric circles around the destination position and expanding these circles as needed: 1. No predetermined electromagnetic radiation was detected; or 2. If the maximum exploration time threshold is not reached, the system will either self-destruct or return to the starting position once the maximum threshold is reached.

[0051] The number of useful frequencies can be less than or more than two. Therefore, it can have: - Command the useful frequency of nominal landings, and optionally... - The useful frequency of commanding emergency landings and / or - The useful frequency of commands interrupting the initial task and returning to the starting position, and / or - Useful frequencies for commanding rerouting to another destination location, and / or - The useful frequency of command self-destruction, etc.

[0052] The predetermined event used to trigger self-destruction may correspond to a predetermined time for detecting the target and / or one or more predetermined characteristics of the electromagnetic radiation emitted by the target (the frequency of the laser beam, and / or the duration of the pulses, and / or the interval between pulses, and / or the pulse sequence organized according to Morse code, etc.).

[0053] Drones can carry satellite positioning signal receivers to allow them to get as close as possible to the area to be explored when satellite positioning signals are available along part of their path.

[0054] Drones can carry radio signal receivers to provide radio wave guidance for the drone when radio waves are available and interference-free along a portion of its path, so that the drone can get as close as possible to the area being explored.

[0055] Regardless of the shape of the exploration area, the exploration guide can scan the exploration area from one end to the other, from the center to the periphery, or vice versa.

Claims

1. An aerial unmanned aerial vehicle (1), the aerial unmanned aerial vehicle (1) having a fixed structure (2), a motor assembly (3) for propulsion and orientation of the unmanned aerial vehicle, an optoelectronic deviation measuring device (6), and an electronic guidance unit (5) connected to the motor assembly (3) and the optoelectronic deviation measuring device (6) for controlling the motor assembly (3) according to a signal emitted by the optoelectronic deviation measuring device (6), characterized in that, The photoelectric deviation measurement device (6) includes an optical system (6.1) and a photoelectric sensor (6.2), the optical system (6.1) and the photoelectric sensor (6.2) being fixed in orientation relative to the fixed structure (2), and the electronic guidance unit (5) is designed to control the motor assembly (3) so that when the UAV moves over the exploration area, it scans the exploration area using the photoelectric sensor (6.2) until it detects electromagnetic radiation emitted by the target and then guides the UAV to the target by deviation measurement.

2. The UAV (1) as described in claim 1, characterized in that, The electronic guidance unit (5) commands the exploration area to be scanned in a circular pattern.

3. The UAV (1) as described in claim 1 or claim 2, characterized in that, The electronic guidance unit (5) commands a lateral scan relative to the UAV’s substantially linear movement direction above the exploration area.

4. The drone (1) as claimed in any of the preceding claims, characterized in that, Includes a self-destruct component (9) connected to the electronic guidance unit (5), the electronic guidance unit (5) being designed to activate the self-destruct component (9) upon detection of at least one predetermined event.

5. The UAV (1) as described in claim 4, characterized in that, The predetermined event corresponds to a time exceeding the predetermined time for detecting the target.

6. The drone (1) as claimed in any of the preceding claims, characterized in that, Includes an inertial unit (7) connected to the electronic guidance unit (5), the electronic guidance unit (5) being designed to guide the drone (1) to the exploration area based on signals from the inertial unit (7).

7. The drone as claimed in any of the preceding claims, characterized in that, The electromagnetic radiation is emitted around an axis that is substantially locally perpendicular to the ground at a semi-apex angle between + / -85° and + / -45°.

8. The drone as described in claim 7, characterized in that, The electromagnetic radiation is emitted by a laser emitter (12) associated with the diverging optical system (13).

9. The UAV as described in claim 7 or claim 8, characterized in that, The electromagnetic radiation is obtained by reflection of a laser beam from a laser pointer (12) associated with a diverging optical system (13) on a surface that is at least partially reflective.

10. The drone as described in claim 7, characterized in that, The target is a beacon (10) having a laser emitter that emits the electromagnetic radiation.

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