• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The drone comprises M antennas, including two remote antennas (30) located symmetrically at the ends of two arms (22) for connection to the propulsion units (24), and a ventral antenna (32) under the drone body (20). The radio transmission is operated simultaneously on N similar RF channels, with 2 ≤ N <M. An antenna switching circuit selectively couples each of the N RF channels to N antennas among the M antennas according to a plurality of different coupling schemes, dynamically via a control logic that selects one of the coupling schemes. The selection is made according to a signal delivered by the onboard microprocessor of the drone, depending on the flight conditions and signal transmission, determined at a given time.
    公开号:FR3061028A1
    申请号:FR1670789
    申请日:2016-12-27
    公开日:2018-06-29
    发明作者:Eric Gasnier；Raphael Prod'homme
    申请人:Parrot Drones SAS；
    IPC主号:
    专利说明:

    Holder (s):
    PARROT DRONES.
    O Extension request (s):
    ® Agent (s): DUPUIS-LATOUR DOMINIQUE.
    FR 3 061 028 - A1 ® DRONE WITH DYNAMIC DIVERSITY OF ANTENNAS.
    (57) The drone comprises M antennas, with in particular two offset antennas (30) located symmetrically at the ends of two arms (22) connecting to the propulsion units (24), and a ventral antenna (32) under the drone body (20 ). The radio transmission is operated simultaneously on N similar RF channels, with 2 N <M. An antenna switching circuit selectively couples each of the N RF channels with N antennas among the M antennas according to a plurality of different coupling schemes, so dynamic through a control logic selecting one of the coupling schemes. The selection is made as a function of a signal delivered by the on-board microprocessor of the drone, as a function of the flight conditions and signal transmission, determined at a given instant.

    The invention relates to the remote control of motorized devices, hereinafter generally designated under the name of drones, and more precisely the radiocommunication antennas used by these devices for their remote control.
    These may especially be flying drones, rotary wing or fixed wing. The invention is however not limited to piloting and exchanging data with flying devices, and it can be applied to rolling devices operating on the ground under the control of a remote operator, the term drone to be heard in its most general sense.
    A typical example of a consumer flying drone is Parrot's Bebop Drone (Paris, France), which is a rotary-wing drone of the quadricopter type, or the Disco, also from Parrot, which is a fixed-wing drone of flying wing type. Another type of drone to which the invention can be applied is the Jumping Sumo remote control jumping toy, also from Parrot (all the trade names cited in this description are registered trademarks).
    WO 2010/061099 A2, EP 2 364 757 A1, and EP 2 613 213 A1 (Parrot) describe the principle of piloting a drone by means of a multimedia telephone or tablet with a touch screen and integrated accelerometers, executing specific remote control application software such as the Parrot FreeFlight mobile application.
    The phone or tablet can possibly be relayed by specific equipment such as the Parrot Skycontroller, which is a console interfaced with the phone or tablet, in the form of a box provided with two handles with broom handles and various buttons intended to allow an ergonomic piloting by the user in the manner of a dedicated console.
    The user can also use immersion pilot glasses, called FPV glasses (First Person View).
    The remote control is provided with radio link means with the drone, for example of the local WiFi network type (IEEE 802.11), for the bidirectional exchange of data: i) from the drone to the remote control for the transmission of the video image captured by the camera and flight parameters of the drone, and ii) the remote control to the drone for sending the latter flight instructions.
    Various aspects of radio communication between remote control and drone are described in particular by EP 2,450,862 A1 and EP 3,020,460 A1 (Parrot).
    It will be understood that the quality of the radio link between the remote control and the drone is an essential parameter, in particular to ensure a satisfactory range. In addition, the data volumes transmitted are significant, in particular due to the very high need for video bit rate of the downlink. In fact, any deterioration in the quality of the radio link will have an impact on the quality of the transmission and on the radio range, with a risk of sporadic loss affecting the data and commands exchanged.
    At the level of the drone, the radio link uses one or more antennas incorporated in the drone which, on reception, receive the signals of the uplink transmitted by the remote control equipment and, in transmission, radiate the power of the HF transmitter circuit supporting the link downlink, in particular for the remote control transmission of the video stream and flight data.
    The invention relates precisely to these antennas and to the radio frequency (RF) transmission and reception chain associated with them.
    An important limitation is the regulatory constraints applicable to RF communication systems such as WiFi communication systems used by drones (or any other RF power transmitter system).
    For example, the regulations currently applicable in the United States in the 2.4 GHz ISM band provide: 1) a limit of 30 dBm (1 mW) of total power at the transmitter outlet, and 2) a limit of 36 dBm (4 mW) EIPR (Equivalent Isotropically Radiated Power, or PIRE) of power radiated by the antenna, this second limit corresponding to the natural power of the transmitter increased by the gain of the antenna in the direction of its main lobe d 'program.
    The WiFi specifications advantageously provide for the possibility of using simultaneously - in different bands or in the same band - several transmitters and several antennas in accordance with the technique known as Multiple (Multiple Input Multiple Output), a multiplexing technique allowing Longer-range data transfers with higher data rates than SISO (Single Input Single Output) techniques.
    The difficulty comes from the fact that, in this case where several transmitters simultaneously deliver an RF signal, compliance with the regulatory radiated power threshold requires lowering the inherent RF power of each active transmitter so that the total RF power overall radiated remains below set threshold (36 dBm in the example above).
    Thus, for two antennas radiating simultaneously, it will be necessary to reduce by half (- 3 dB) the natural power of each transmitter, which should not deliver as output more than 27 dBm (0.5 mW).
    Similarly, for three antennas radiating simultaneously, it will be necessary to divide by three (- 4.7 dB) the natural power of each transmitter, which should not output more than 25.3 dBm (0.35 mW).
    Likewise, for four antennas radiating simultaneously, it will be necessary to divide by four (- 6 dB) the natural power of each transmitter, which should not deliver as output more than 24 dBm (0.25 mW).
    The basic idea of the invention consists, in order to improve the quality of radio transmission between the drone and the remote control, therefore with the user, to embark a number of antennas (M antennas) greater than the number of transmitters simultaneously active (N transmitters, at least two in number), and to select by appropriate switching only N antennas on the M antennas equipping the drone.
    It is for example possible to provide M> 3 antennas, typically M = 3 or 4 antennas, for N = 2 transmitters, and therefore select only two antennas among three, or two antennas among four.
    This switching is effected dynamically, for example at regular time intervals, so as to modify if necessary the specific switching scheme of the N transmitters to the M antennas so that the configuration of the antennas actually switched remains optimal.
    In the example given above, by selecting only two antennas among three (or four) one can obtain by antenna a radiated power higher than that of a conventional system with three (or four) an-35 tennes operating simultaneously in ΜΙΜΟ.
    Still in this example, in a conventional ΜΙΜΟ system with four antennas it would be necessary to reduce the natural power of each transmitter by 6 dB to comply with the regulations, while with the solution according to the invention, still with four antennas, the reduction necessary will only be 3 dB because only two of the four antennas will be active.
    This dynamic reconfiguration of the configuration path thus makes it possible to create a dynamic diversity of the antenna array taking into account the movements of the drone relative to the remote control, even though these movements produce permanent modifications of the orientation of the drone (and therefore of its antennas), environmental conditions, remoteness, etc., which permanently disrupt the radio link. The dynamic reconfiguration of the antenna network then makes it possible to always keep the best RF transmission condition which maximizes the data rate and minimizes the signal / noise ratio, especially when the drone antennas do not have isotropic radiation.
    More specifically, the invention proposes for this purpose a drone comprising, in a manner known per se, a drone body, a digital controller circuit, an RF transmitter stage comprising a baseband processor circuit capable of delivering an RF signal to be emitted, and M fixed antennas secured to the drone body.
    Characteristically of the invention, the RF transmitter stage further comprises: an RF distributor stage receiving as input the RF signal to be transmitted and delivering as output N similar RF power supply signals, with 2 <N <M; an antenna switching circuit, capable of selectively coupling each of the N RF power signals with N antennas among the M antennas according to a plurality of different coupling schemes; and a logic for controlling the antenna switching circuit, capable of dynamically determining one of said coupling diagrams as a function of a selection signal delivered by the controller circuit.
    According to various advantageous subsidiary characteristics:
    the logic for controlling the antenna switching circuit is capable of dynamically determining one of said coupling schemes also as a function of a synchronization signal delivered by the cooked baseband processor cir3061028, so as to inhibiting the application of the selection signal to the antenna switching circuit at least during the transmission time of an RF signal frame to be transmitted;
    - when N = 2 and M = 3, the antenna switching circuit is able to selectively couple: a first RF power signal to one or the other from a first antenna and a third antenna, and a second RF power signal to either one of a second antenna and the third antenna;
    - In this same case, the first antenna and the second antenna are advantageously lateral antennas positioned symmetrically on either side of the drone body, and the third antenna is a ventral antenna positioned under the drone body;
    when N = 2 and M = 4, the antenna switching circuit is able to selectively couple: a first RF power signal to one or the other from among a first antenna and a third antenna, and a second RF power signal to either one of a second antenna, the third antenna and a fourth antenna;
    - The RF distributor stage comprises N similar RF front modules, each receiving the RF signal to be transmitted at the input and outputting one of the N similar RF power signals;
    at least one of the N RF power supply signals comprises a first signal component in the 2.4 GHz band duplexed with a second signal component in the 5 GHz band.
    We will now describe an example of implementation of the present invention, with reference to the accompanying drawings where the same references designate from one figure to another identical or functionally similar elements.
    Figure 1 is a general view showing a drone controlled by a remote control device.
    Figure 2 is a perspective view from below of the drone in flight, showing in particular the geometry of the antenna array used for the implementation of the invention, in this example a network with three antennas.
    Figures 3a, 3b and 3c are radiation diagrams of the aerials of the drone illustrated in Figure 2, respectively for the right antenna, the ventral antenna and the left antenna.
    Figure 4 is a block diagram of the drone's RF chain implementing the teachings of the invention, in a configuration with two radio channels and three antennas.
    Figure 5 is a block diagram of the drone's RF chain implementing the teachings of the invention, in a configuration with two radio channels and four antennas.
    Figure 6 is a diagram illustrating a drone in flight, with various changes of position corresponding to the trajectory of this drone relative to a static user on the ground.
    Figures 7a and 7b illustrate the variations in the signal level received by the user when the drone evolves in the manner illustrated in Figure 4, respectively with and without implementing the teachings of the invention.
    We will now describe an embodiment of the device of the invention.
    In Figure 1, the reference 10 generally designates a drone, for example a quadricopter such as the Bebop model from Parrot. This drone has four coplanar rotors 12, the motors of which are independently controlled by an integrated navigation and attitude control system. It is provided with a front view camera 14 making it possible to obtain an image of the scene towards which the drone is heading.
    The drone 10 is controlled by a user by means of a remote control device 16, hereinafter remote control, provided with a screen 18 configured to display the image captured by the camera 14 of the drone. The remote control 16 is for example the Skycontroller model from Parrot, on which has been mounted a smartphone (handheld mobile terminal) or a digital multimedia tablet with standard type touch screen, not modified except for the loading of software. specific application (such as the AR Free Flight mobile application from Parrot) to control the piloting of the drone 10 and the viewing of the images taken by the camera 14. The screen 18 displays, superimposed on the image captured by the camera 14, a certain number of flight parameters as well as symbols allowing the activation of piloting commands (ascent / descent, etc.) by simple contact of a finger of the user on these symbols, and / or by printing at the remote control of the inclinations along roll and pitch axes to move the drone forward or backward. User actions are interpreted by specific application software, which transforms them into control signals for the drone.
    The remote control 16 is also provided with radio link means with the drone, for example of the local WiFi network type, very advantageously a link of the standard WiFi type (IEEE 802.11η) of the 2.4 GHz and 5 GHz dual band type (more precisely 2 , 40 GHz-2.4835 GHz and 5.15 GHz-5.85 GHz) and ΜΙΜΟ, directly established with the drone.
    More precisely, this wireless radio link is bidirectional and includes an uplink (from the remote control to the drone) and a downlink (from the drone to the remote control) for transmitting data frames containing:
    - (from the remote control to the drone) piloting and control instructions, sent at regular intervals and systematically, as well as various information or parameters intended for the drone;
    - (from the drone to the remote control) the video stream from the camera; and
    - (from the drone to the remote control) as necessary, flight data established by the drone or status indicators such as: battery level, flight phase (takeoff, automatic stabilization, landed, etc.) ), altitude, fault detected, etc.
    The WiFi network implemented is advantageously an unmodified standard network, which makes it possible to benefit from the multiple functionalities of the WiFi specification: protection against collisions, encapsulation of data, management of network access, encryption and authentication, management of the frequencies, etc.
    Note however that the use of a standard WiFi is in no way limitative of the invention, and that the latter applies equally well to any proprietary RF transmission system produced according to non-standard specifications, specific to a manufacturer. .
    Figure 2 illustrates the drone 10 in flight. This drone comprises, in the illustrated example of a quadricopter, a drone body 20 from which extend four arms 22, with two front arms and two rear arms. Each arm 22 carries at its distal end a motor unit 24 driving in rotation a respective propeller. The engine block 24 is extended downwards by an extension forming a foot 26 which supports the drone when it is placed on the ground.
    The drone comprises, in a manner known per se for example on the aforementioned Bebop model from Parrot, two remote antennas 30 arranged in the front legs. Each of these antennas is for example produced in printed form on a circuit board inserted in a homologous housing provided in the foot 26, with an appropriate connection making it possible to connect the antenna to the RF circuits located in the drone body 20. This configuration remote antennas allows in particular to move the antennas away from the metal masses contained in the drone body 20. The antennas 30 each have a substantially homogeneous sectored radiation pattern with large aperture included in a hemispherical half-space, ensuring good coverage lateral on either side of the drone taking into account the symmetrical arrangement of the two antennas 30.
    In other configurations, in particular better suited to drones of the flying wing type where there is no arm extending from a drone body, the two antennas can be arranged symmetrically in the fuselage of the drone, with however the disadvantage that these antennas are more sensitive to nearby metallic elements located in the fuselage, which can lead to a less homogeneous radiation pattern due to these disturbing elements.
    In all cases, the two antennas of the drone are coupled to respective RF inputs / outputs of the WiFi RF chip, the chips generally used being provided with two identical RF inputs / outputs.
    Conventionally, the WiFi antennas used are dual-band antennas, capable of radiating in two different bands such as the two 2.4 GHz and 5 GHz WiFi bands, in particular to allow operation in ΜΙΜΟ where these two bands are used concurrently.
    To allow these simultaneous space transmissions (and, similarly, simultaneous receptions), each input / output of the RF chip then has four terminals, namely two transmission terminals (TX 2.4 and TX 5) and two terminals. reception (RX 2.4 and RX 5).
    However, the known configuration described above with two transmitters and two antennas is not always optimal.
    Indeed, when the drone is vertically close to the user or close to this vertical (therefore approximately in a cone whose top would be located where the user is located), the combined radiation pattern of the two antennas presents strong gain irregularities, because this direction corresponds to the two edge regions of the diagrams of each of the antennas. This results in erratic weakening of the radiated power (or of the received signal), which can occasionally lead to very noisy communications and to a weakening of the data transmission rate between the drone and the remote control.
    With a rotary-wing drone, this drawback can arise even when the drone is far enough from the user: in fact, the rapid changes in horizontal speed of the drone are obtained by nose-up, tilting, etc. movements. drone relative to the vertical, which suddenly change the orientation of the antenna array, and therefore of the radiation pattern, relative to the direction of the user. In this way, in certain flight configurations, the user may be in a particular direction of the radiation diagram having a trough or large irregularities.
    To overcome these drawbacks, the starting point of the invention lies in the addition of one (or more) additional antenna (s), in particular having a radiation diagram with a main lobe oriented in the direction of the hollow. gain or gain irregularities of the first two antennas. In this way it is possible to compensate for these dips or irregularities and, overall, to establish a substantially isotropic radiation pattern.
    In the example illustrated in Figure 2, the drone was provided with a third antenna 32 arranged in a ventral region in the center of the drone body
    20. The main axis of radiation of this ventral antenna 32 is oriented vertically and turned downwards.
    This configuration with three (or more) antennas ensures satisfactory communication between the drone and the remote control in all configurations of the drone, with homogeneous radio performance in all circumstances.
    Reference is made in this regard to FIGS. 3a, 3b and 3c, which are radiation diagrams of the antennas of the drone illustrated in FIG. 2, respectively for the right antenna 30, the ventral antenna 32 and the left antenna 30. These diagrams give, for each antenna, in contour lines, the gain in the different directions of space defined by the site angle θ and the azimuth angle φ. As can be seen, the ventral antenna 32 provides a significant gain in the direction of the ground (FIG. 3b, towards the direction θ = 0), while the lateral antennas 30 (FIGS. 3a and 3c) on the other hand have a small gain in that direction. Conversely, for directions close to the horizon (Θ = 90 °), the side antennas 30 provide better performance than the ventral antenna 32 in terms of gain.
    However, if the number of antennas is increased and each antenna is coupled to a respective transmitter / receiver, in order to comply with the regulatory constraints of maximum total radiated power, it is necessary to proportionally reduce the natural power of each transmitter. Thus, for example with a typical antenna gain of 6 dBi, if two transmitters are used, the unit power must be reduced by - 3 dB, with three transmitters, by - 4.7 dB and with four transmitters, by - 6 dB.
    The basic idea of the invention consists, instead of simultaneously using as many transmitters as antennas, to select only a reduced number of antennas, for example two antennas among three, or two antennas among four , and to feed only the selected antennas (therefore to use only two transmitters simultaneously active in this example).
    Thus, in the example cited above, by using only two transmitters simultaneously active it will only be necessary to reduce the unit power by - 3 dB in all circumstances because only two antennas among three or four will be active at a given time , thus with a unitary radiated power per antenna greater than that of a system using three or four antennas operating simultaneously, in ΜΙΜΟ.
    The antennas are switched dynamically, in real time, according to a selection signal delivered by the microprocessor of the drone which executes an appropriate algorithm determining which antennas must be selected at a given time.
    Figure 4 is a block diagram of the drone's RF chain implementing the teachings of the invention, in a configuration with two radio channels and three antennas.
    All of the circuits are controlled by a digital controller circuit 100, constituted by the on-board microcontroller of the drone piloting in particular the various flight control and communication functions with the remote control.
    This digital controller circuit 100 exchanges information with a baseband processor circuit 110, which is a circuit in itself known (for example a Qualcomm QCA6174 chipset) and which will not be described in detail.
    The baseband processor manages all radio control functions such as signal modulation, coding / decoding, frequency transposition, etc. li is on the one hand interfaced to the digital controller circuit 100 which drives it, and iî is on the other hand provided with a certain number of terminals for its interfacing with the RF transmission / reception circuit proper. In the particular case of a dual-band WiFi transmission, the baseband processor circuit includes output (transmission) terminals TX 2.4 and TX 5 corresponding to each of the two respective WiFi bands 2.4 and 5 GHz, and RX 2.4 and RX 5 input (reception) terminals corresponding to these same two bands. In addition, these four input / output terminals are split, so that they can be coupled to two identical RF circuits, in particular to be able to ensure simultaneous transmission on two RF channels coupled to two respective antennas.
    The baseband processor circuit 110 is coupled to an RF distributor stage made up of two identical front modules 120 by the TX / RX input / output terminals that have just been described.
    The front modules 120 comprise front-end type chips making it possible to process analog signals at high RF frequency, from the base band signals delivered or received by the base band processor circuit 110. They essentially comprise, in transmission , a power amplifier (PA) and, on reception, a low noise amplifier (LNA). These front modules 120 are conventional type circuits, unmodified, comprising for example chips from the Skyworks 85723 family, and they will not be described in detail.
    Each of the front modules 120 transmits (or receives) a respective radio frequency signal RF1, RF2. Each of the signals RF1 or RF2 transmitted or received by a front module 120 comprises a first signal component in the 2.4 GHz band, duplexed with a second signal component in the 5 GHz band.
    In a conventional configuration, each of the front modules would be directly coupled to a respective transmit / receive antenna for WiFi transmission, according to a static, invariable configuration.
    In the present invention, the coupling between the front modules 120 and the antennas is effected by means of a specific antenna switching circuit 130 ensuring the interfacing between, on the one hand, the two radiofrequency signals RF1, RF2 and, on the other hand, three antennas A1, A2, A3 (in the embodiment illustrated in Figure 4). The antennas A1 and A2 may in particular be the remote antennas 30 situated at the end of the arms connecting to the propulsion unit of the drone, the antenna A3 being the ventral antenna 32 situated under the drone body, in the central position.
    In the illustrated embodiment, the antenna switching circuit 130 comprises a first switch 132 receiving the signal RF1 as an input and directing it either to the antenna A1 or to a first pole of a second switch 134. A third switch 136 receives the signal RF2 as an input and directs it either to the antenna A3 or to a second pole of the second switch 134. The second switch
    134 selects one or other of its poles to couple it to the antenna A2.
    The RF switches used by the circuit 130 are switches of the type known per se (for example chips from the Sky-35 works 13350/13320 family) and will not be described in more detail.
    The states of the three switches 132, 134 and 136 are controlled by respective switching signals SW1, SW2, SW3 delivered by a control logic 140 controlled by the digital controller circuit 100.
    The control logic 140 comprises a circuit 142 receiving as input switching signals Cmd1 and Cmd2 delivered by the digital controller circuit 100 as a function of a certain number of parameters produced by an algorithm which determines which antennas must be selected. For this selection, the algorithm can notably take into account:
    - the position of the drone and the orientation of the drone (more or less steep inclination taking into account in particular the horizontal speed changes) relative to the user in an absolute reference linked to the ground: the algorithm then determines the antennas of the drone whose the radiation diagram presents the best orientation with respect to the user;
    - the measurement of the received signal level (RSSI) by each of the antennas receiving the signals coming from the remote control: the measured RSSI indeed gives information on the quality of the radio link between drone and remote control;
    an automatic selection of the antennas according to a sequence which can be random and regular, so as to measure the RSSI on each of the antennas (this selection taking into account that, due to the presence of the switching circuit 130, the antennas are not never all simultaneously coupled to the receiver stages of the RF chain).
    Furthermore, since the digital controller circuit 100 is not synchronized with the baseband processor circuit 110 and the front modules 120, it is necessary to synchronize the switching of the antennas on the frames transmitted or received so as not to risk cutting these frames. during transmission.
    To do this, the control logic 140 is coupled to the baseband processor circuit 110 by a link 148 ensuring synchronization between the signals sent by the digital controller circuit 100 and the frames processed in transmission / reception by the tape processor circuit. basic 110.
    In the embodiment illustrated in FIG. 4, the control logic 140 comprises an inverter 144 receiving the signal Cmd2 as an input, and an AND gate 146 receiving on one of its inputs the signal Cmd1 and on the other input the signal Cmd2 after inversion. The selection signal SW1 of the switch 132 corresponds to the signal Cmd1, the switching signal SW3 of the switch 136 corresponds to the inverted signal Cmd2, and the control signal SW2 of the switch 134 corresponds to the output of the gate 146.
    The corresponding truth table is as follows:
    Truth table for 3 antennas / 2 transmitters
    Cmd1 Cmd2 SW1 SW2 SW3 RF1 RF2 1 1 1 0 0 ANT 1 ANT 3 0 1 0 0 0 ANT2 ANT 3 1 0 1 1 1 ANT 1 ANT 2 0 0 0 0 1 ANT 2 -
    Of course, the different possible coupling schemes between, on the one hand, the two channels RF1 and RF2 and, on the other hand, the three antennas A1, A2 and A3 corresponding to this truth table are not limiting; other coupling configurations can also be envisaged, in particular taking into account the particular geometry of the various antennas of the drone, their location thereon and their own radiation pattern.
    Figure 5 is a block diagram illustrating a variant in which the drone no longer has three, but four different antennas A1, A2, A3, A4 selectively switchable to allow their coupling to the two transmission / reception channels of signals RF1 and RF2. The elements bearing the same reference numbers as in Figure 4 provide identical functions, and will not be described in more detail.
    In the case of FIG. 4, the antenna switching circuit 130 only comprises two switches 132 and 136. The switch 132 receives the signal RF1 as an input and couples it either to a first antenna A1 or to a second antenna A2, while the switch 136 couples the signal RF2 either to a third antenna A3 or to a fourth antenna A4. The switches 132 and 136 are controlled by the selection signals SW1 and SW3 delivered by the control logic 144 in the same manner as that which has been described in connection with FIG. 4.
    The truth table is as follows:
    Truth table for 4 antennas / 2 transmitters
    Cmd1 Cmd2 SW1 SW3 RF1 RF2 1 1 1 0 ANT 1 ANT 3 0 1 0 0 ANT2 ANT 3 1 0 1 1 ANT 1 ANT 4 0 0 0 1 ANT 2 ANT 4
    Of course, this configuration of coupling diagrams is not limiting, and other configurations with two RF channels and four antennas can also be envisaged while remaining within the scope of the invention.
    Similarly, the invention is not limited to coupling N = 2 RF channels (signals RF1 and RF2 in the examples described) to M = 3 or 4 antennas (antennas A1-A3 or A1-A4 in the examples described), but can be generalized to the coupling of N RF channels to M antennas, with 2 <N <M, this coupling being a dynamic coupling which can be modified in real time. The coupling is modified as a function of selection signals delivered by a control logic controlled by the digital controller circuit of the drone on the basis of an algorithm for searching and selecting the optimal scheme for coupling the RF channels to the antennas.
    Figures 6, 7a and 7b illustrate an example of implementation of the embodiment of the invention shown in Figure 4 and described above.
    Figure 6 is a diagram illustrating a drone in motion, with various changes of position corresponding to the trajectory of this drone relative to a static user on the ground. Figures 7a and 7b illustrate the variations in the level of signa! received by the user when the drone evolves as illustrated in Figure 6, respectively with and without implementing the teachings of the invention.
    Figure 6 illustrates the example of a drone flying at an altitude of about 50 m above a user U equipped with a remote control for piloting the drone. At an instant t = 0 the drone is vertical to the user, then it moves in horizontal flight, at constant altitude, to the right, thereby moving away from the user. This trajectory continues over a distance of approximately 400 m, up to t = t3, where the drone stops and rotates on itself until a time t = t4.
    Figure 7a illustrates the level of the signal received by the drone (RSSI indicator) of the emissions produced by the user's remote control on the two channels RF1 and RF2, in a conventional configuration where the two antennas A1 and A2 (for example the antennas 30 in the representation of FIG. 2) are directly coupled to the respective RF channels RF1 and RF2.
    In this static configuration of the antennas (the channel RF1 is always coupled to the antenna A1 and the channel RF2 is always coupled to the antenna A2), there is a rapid decrease in the level of signal received between times t1 and t2 when the drone, although relatively close in distance from the user, moves away from the latter laterally relative to the vertical.
    Figure 7b illustrates the level (RSSI) of the signal received by the drone in the same flight phase, but with the implementation of the dynamic selection of three antennas, according to the invention.
    The timing diagrams added at the bottom of Figure 7b indicate the values of the control signals Cmd1 and Cmd2 produced by the control logic 140 to dynamically select a coupling scheme of the three antennas to the two RF channels, according to instructions developed by the circuit digital controller 100 and transmitted to the antenna switching circuit 140.
    At time t = 0, the drone uses the antenna A1 on the channel RF1 and the antenna A2 on the channel RF2 (initial configuration by default). At t = t1, the digital controller circuit decides to use the antenna A3 (corresponding to the ventral antenna 32) for the RF2 channel, instead of the antenna A2, because this configuration provides better transmission. This configuration is maintained until time t = t2. For the RF1 channel, between t1 and t2 this channel is coupled either to the antenna A1 or to the antenna A2 (which is no longer used for the channel RF2), depending on the circumstances and the levels of the signals received.
    From t = t2, the digital controller circuit decides to use the antenna A1, which is again coupled to the channel RF1, the antenna A2 then being coupled to the channel RF2. Concretely, this change in configuration corresponds roughly to a distance of the drone of approximately 94 m from the vertical of the user.
    If we compare the respective RSSI signal levels in FIGS. 7a (state of the art) and 7b (invention), it can be seen that the level of the signal received is notably increased in the period between t1 and t2, which corresponds overall at a flight phase where the drone is located relative to the user in a cone of about 94/50 with a half angle at the top.
    权利要求:
    Claims (9)
    [1" id="c-fr-0001]
    1. A drone (10), comprising:
    - a drone body (20);
    - a digital controller circuit (100);
    - an RF transmitter stage comprising a band processor circuit of
    5 base (110) capable of delivering an RF signal to be transmitted; and
    - M fixed antennas (A1, A
    [2" id="c-fr-0002]
    2, A3) integral with the drone body, characterized in that the RF transmitter stage further comprises:
    - an RF distributor stage (120), receiving at input the RF signal to be transmitted and delivering at output N similar RF power supply signals
    10 (RF1, RF2), with 2 <N <M;
    - an antenna switching circuit (130), capable of selectively coupling each of the N RF power signals (RF1, RF2) to N antennas among the M antennas (A1, A2, A3) according to a plurality of cutting patterns different ; and
    15 - logic (140) for controlling the antenna switching circuit, capable of dynamically determining one of said coupling diagrams as a function of a selection signal delivered by the controller circuit.
    2. The drone of claim 1, in! the logic (140) for controlling the antenna switching circuit is able to dynamically determine one of said coupling schemes also as a function of a synchronization signal (148) delivered by the baseband processor circuit (110), so as to inhibit the application of the selection signal to the
    25 antenna switching circuit at least for the duration of transmission of an RF signal frame to be transmitted.
    [3" id="c-fr-0003]
    3. The drone of claim 1, wherein N = 2 RF power signals and M = 3 antennas.
    [4" id="c-fr-0004]
    4. The drone of claim 3, in which the antenna switching circuit (130) is capable of selectively coupling:
    • a first RF power signal to either one or the other from a first antenna and a third antenna, and • a second RF power signal to either one or the other from a second antenna and the third antenna.
    [5" id="c-fr-0005]
    5. The drone of claim 3, in which the first antenna and the second antenna are lateral antennas (30) positioned symmetrically on either side of the drone body (20), and the third antenna is a ventral antenna ( 32) positioned under the drone body (20).
    [6" id="c-fr-0006]
    6. The drone of claim 1, in which N = 2 RF power signals and M = 4 antennas.
    [7" id="c-fr-0007]
    7. The drone of claim 6, in which the antenna switching circuit (130) is capable of selectively coupling:
    a first RF power signal to one or both of a first antenna and a third antenna, and a second RF power signal to one or the other of a second antenna, the third antenna and a fourth antenna.
    [8" id="c-fr-0008]
    8. The drone of claim 1, in which the RF distributor stage comprises N similar RF front modules (120), each receiving the RF signal to be transmitted as an input (TX 2.4, TX 5) and outputting one of the N similar RF power signals (RF1, RF2).
    [9" id="c-fr-0009]
    9. The drone of claim 1, in which at least one of the N RF power signals comprises a first signal component in the 2.4 GHz band duplexed with a second signal component in the 5 GHz band.
    f7c, Sa- c «
    3/4
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    法律状态:
    2017-12-06| PLFP| Fee payment|Year of fee payment: 2 |
    2018-06-29| PLSC| Search report ready|Effective date: 20180629 |
    2018-12-12| PLFP| Fee payment|Year of fee payment: 3 |
    2020-10-16| ST| Notification of lapse|Effective date: 20200906 |
    优先权:
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    FR1670789|2016-12-27|
    FR1670789A|FR3061028B1|2016-12-27|2016-12-27|DRONE A DYNAMIC DIVERSITY OF ANTENNAS|FR1670789A| FR3061028B1|2016-12-27|2016-12-27|DRONE A DYNAMIC DIVERSITY OF ANTENNAS|
    EP17208351.1A| EP3343529B1|2016-12-27|2017-12-19|Drone with dynamic antenna diversity|
    US15/856,014| US10491272B2|2016-12-27|2017-12-27|Drone with dynamic antenna diversity|
    CN201711446574.1A| CN108242945A|2016-12-27|2017-12-27|Unmanned plane with dynamic antenna diversity|
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