Master-slave drones connected via cable

Abstract

Drone system consisting of at least 2 drones, characterized in that one drone (slave drone) is suspended below the other drone (master drone) by means of a signal-carrying cable.

Description

[0001] The invention relates to a pair of two drones or FPV drones, master and slave, e.g. for military use, where the master drone could also be referred to as the mother ship. The slave drone is suspended below the master drone by means of a connecting cable (e.g. fiber optic), hanging 100 or 200 m lower, and is only lowered in the target area. The suspended slave drone can operate virtually silently. Control elements such as propellers or rotating masses of the slave drone only have to make minimal position and / or orientation corrections. The slave drone does not have to generate any vertical forces and therefore does not require fast-spinning, noisy propellers. As a result, it is difficult to locate acoustically and, due to the cable connection, is difficult to jam with jammers. The master drone can operate far above, out of line of sight, even in cloud cover and / or out of range of jammers.The slave drone can be designed as a disposable drone, which is particularly cost-effective.

[0002] In military conflicts, small drones or FPV drones have established themselves both for visual reconnaissance and for direct combat use. For combat missions, there are drones that drop the detonating ordnance (e.g., grenades with impact fuses), self-firing drones, and kamikaze drones, which are destroyed upon attack. Parallel to the development of ever-increasing drone technologies, a wide variety of defense solutions are also being developed, such as nets, breeding birds of prey, and attack drones. A primary defense method is so-called jammers, which interrupt the wireless data transmission from the transmitter to the drone, thus causing the drone to crash.

[0003] To circumvent jammer defenses, there are wired solutions in which a drone carries a fiber optic cable with a retractable mechanism. Cables of up to 10 km are possible. However, these cables significantly limit maneuverability. The cable can only be used once, and these drones are often designed for a single outbound flight. The cable only solves the problem of signal transmission and interference, but not the problem of loud propeller noise.

[0004] The goal of the invention is a drone that can fly freely, is difficult to disrupt by jamming, and can fly silently to its target. Ideally, the goal is a reusable drone. Furthermore, unlike kamikaze drones, the drone can visually document its success, even several seconds after detonation.

[0005] A use of the silent approach to a target is also conceivable in non-military areas. One example is the observation of shy animals or animals living high in trees.

[0006] The invention makes use of the master-slave principle. The main drone is the so-called master drone or mother ship, which flies very high above the target area and is also responsible for longer horizontal distances to the target area. An example of deployment at the target location would be altitudes of 100 to 200 m, for example. This makes the master drone difficult to detect from the ground, both visually and acoustically. While there are jammers with ranges well beyond 200 m, the following applies to the use of jammers: 1. There are far more drones than jammers, 2. The greater the range, the larger the jammers, and thus the more location-specific. 3. Many jammers are only activated after someone has heard the drone. The master drone can even fly in or above cloud cover. It does not need visibility to the ground.

[0007] The slave drone is connected to the master drone via a cable (e.g., fiber optic), thus suspended below the master drone. The cable has a winch on the master drone, allowing the slave drone to be lowered and raised again during flight. Instead of a winch, a one-time cable release function is also possible, making the cable one-way, or the master drone must return to the takeoff point with the cable fully extended, which also has disadvantages. For fast cross-country flights to the destination, the slave drone is secured in a docking position beneath the master drone. It is then lowered into the target area. With the slave drone lowered, only minimal movement is usually advisable, but a quick "escape" is also possible with the slave drone lowered. All signals to and from the slave drone (e.g. control, alignment, image transmission) are wired, so that the slave drone can neither be located nor disturbed by wireless signal transmission.

[0008] Compared to normal drones, the slave drone has the following possible features, which are divided into 6 areas. 1. Power supply: Much less power is required than conventional drones because no propellers are used to counteract the vertical gravity forces. Recharging in flight while docked to the master drone is also possible. Power transmission via cable is also conceivable. 2. Alignment: While the camera's alignment works similarly to the gimbal principle of a normal drone, the slave drone's alignment can be achieved using both rotating counterweights and slow-running propellers. Ideally, rotations around the vertical axis are achieved using counter-rotating internal masses. Silent tilt adjustment around a lateral axis can ideally be achieved by shifting the cable's attachment point on the slave drone longitudinally. If munitions are used that are independent of gravity (e.g., pistol shots or mini-rockets), this pivoting around the lateral axis can also serve as an aiming device. Alignment (rotation around the vertical axis) is independent for the master and slave.For easier operation, it can be advantageous if the operator focuses on controlling the slave drone when the slave drone is lowered and the master drone automatically follows suit. 3. Position. Simply hanging the slave drone on a long cable below the master drone in a pendulum motion leads to positioning difficulties, prolonged pendulum motion, and is very susceptible to wind. Therefore, it is recommended that the slave drone have its own propellers. These are, for example, two pairs of propellers with horizontally running propeller axes, two in different directions, e.g., two lengthways and two crossways. These only need to run very slowly and quietly, and they can be switched off immediately in an emergency. One possible strategy is to "level off" and position the drone at a height of approximately 50 meters, and from there, a purely vertical descent without any propellers. 4. Payload. The payload is primarily intended for reconnaissance and combat assets. A variety of options are possible: gravity-drop grenades, self-propelled rockets, pistols, and projectiles, such as those that can drop a grenade a few meters horizontally under cover. Delivering materials such as bandages or ammunition refills is also conceivable. Furthermore, it is also conceivable that payloads of up to 150 kg could be used to rescue wounded personnel. 5. Cameras. While it is clear that the slave drone itself needs a camera, with or without a gimbal, another camera is also considered, for example, 15 meters above the cable. With each combat mission, validation of the results is desirable, ideally without the need for another observer drone. In cases of heavy fireball, smoke, or dust, it may be necessary to delay validation until 5 to 15 seconds after the impact. Since the slave drone may be destroyed during the impact, another camera above the cable can still provide a good overview. 6. Cutting device. It is recommended that both the slave and master drones have a cutting device for the cable. This allows the slave drone to be cut off if it is destroyed, but ideally the camera positioned above it still functions. If the cable becomes trapped, for example, in a tree or power line, or for a quick escape, the cable can also be cut on the master drone.

[0009] Various alternative variants are conceivable for the master drone: 1. 1 master drone with a slave drone and a cable winch 2. 1 master drone with one slave drone and a cable release function for one-time lowering of the slave drone. 3. 1 master drone with 2 or more slave drones each with its own cable 4. 1 master drone with a cable winch on which several slave drones hang, for example, at a distance of 25 meters, so that if the first drone is lost, another one is simply lowered 5. 1 master drone with a cable winch, which can be automatically hooked into several available slave drones one after the other (automatic plug connection)

[0010] For example, for a camera 15 m above the slave drone in the cable, various solutions are conceivable. Shown here is a solution where both the master and slave drones have a cable winch, so that the master drone can roll up the upper 200 m (approximately) and the slave drone the lower 15 m. This solution is also based on the option that quickly reacting height adjustment of the slave drone is best achieved using a cable winch in the slave drone. This is then used not only for minimal height corrections, but also to roll up the lower 15 meters (approximately) of cable. If the camera at a height of 15 m does not need to be so small that it has to be rolled up onto the cable drum, it can be larger and contain more electronic components and even a cutting device.This is particularly interesting if you want to ensure that the camera above a slave drone is destroyed and can still document the results of a mission. Furthermore, a consistently functioning image transmission is important for future developments in drone technology.

[0011] Application WO 2022 / 244934A1 shows a transport drone with a cable winch that can lower a payload to the ground while the drone itself remains in hover for delivery. However, the load is not another drone with additional active capabilities.

[0012] The invention is described in more detail below. Fig. 1 shows the entire system without further detailed designations. Fig. Figure 2 explains the main components. The master drone flying above has six arms (1) each with a motor (2) and a propeller (3). The number of propellers is not important for the invention. The upper cable (4) (e.g. fiber optic, up to 200 m long) extends downwards below the center of gravity of the master drone. It is not important for the purposes of the invention whether the cable is a pure fiber optic cable, a copper cable, or a combined cable made of several materials to perform both the task of signal transmission and the absorption of vertical weight forces. The cable is led upwards approximately in the middle of the master drone to a pulley (5) and from there to a cable winch (6). For the sake of simplicity, a winch from fishing supplies was chosen as the cable winch because it is inexpensive and mass-produced and because the cable drum itself does not rotate, so that the cable does not have to be permanently connected to the drone.Instead of a hand crank, the winch is driven by a motor (7). For the purposes of the invention, this is referred to as a cable release device, since the one-time release of a disposable cable including a cutting device is also conceivable.

[0013] The drone has four outriggers (8) as landing gear. The 200 m of upper cable (4) is shown in a shortened form (9). At the lower end of the upper cable is the camera element (10). This is used to observe the space below and its special shape also serves as a docking aid. The lower cable (11) extends from this camera element and is 15 m long, for example, and is also shown in a shortened form (12). At the lower end of the lower cable hangs the slave drone (13). Attached to this are four horizontally aligned propellers (14) with a propeller protection ring (15), and the drone has a payload, here a grenade (16) as an example.

[0014] Fig. Figure 3 shows the master drone (17) and the attached upper cable (18), which is shown longer here, but still shorter (19) than in reality (up to approximately 200 m). Below this is the camera element (20), then the lower cable (21), which is approximately 15 meters long and is also shown shortened here (22). The slave drone (23) is shown here in wind (24), which can be either a ground wind or the airstream during horizontal movement of the master drone.

[0015] This wind, or rather the inertia of the system due to the long cable, causes a horizontal oscillation (25) of the cable, which in turn causes a slight change in altitude (26) of the slave drone. This change in altitude (26), if it becomes disruptive, can be corrected either by the propellers of the master drone or by the winch (6) in the master drone, or by another winch in the slave drone. The solution with a winch in the slave drone enables the fastest reaction time for altitude corrections. This winch in the slave drone, as well as a cable cutting device in the slave drone, are not shown here. It is also conceivable that the lower winch and / or the cable cutting device are located in the camera element (10, 20).

[0016] Fig. Figure 4 shows the master drone viewed from below in docked mode. The slave drone is located between the landing gear feet (28) during takeoff and on the flight path to the operation site, and is pulled from below to the base plate (27) of the master drone by means of the camera element (not visible here) as a connection adapter.

[0017] Fig. 5 and partly also Fig. Figure 6 is an exploded view of some of the components showing the slave drone. This is suspended from the lower cable (29) below the camera element (20). The cable extends through the oval-shaped opening (30) in the housing cover plate (31). The main housing and propeller holder function is achieved by four identical side plates (32). The motors (33) are located on these, and the propellers (34) are located on the motors. The propeller axes are aligned horizontally. Rings (35) are also formed from the side plates to protect the propellers and to protect hands or objects from coming into contact with the propeller. The side plates (32) can be punched out of inexpensive sheet material, for example, but they can also be made of injection-molded plastic or 3D-printed material.

[0018] The side panels have several additional details. The joining tabs (35) are inserted into the slots (36) for assembly, forming a positive connection. A cable tie (37) extends through the slots (38), thus holding the construction consisting of four side panels together.

[0019] The square housing cover plate (31) securely holds the four side plates (32) at a 90-degree angle to each other. The housing cover flap has a tab (39) on all four sides, which fits into the slots (40) and thus firmly connects the cover plate to the side plates, all held together by a cable tie (37).

[0020] The side plates (32) have a recess (41) at the bottom which enables a positive connection with a payload.

[0021] Furthermore, the side walls (32) have a rectangular recess (42) for the mass discs (43) and on the upper edge there are tabs (44) for the form-fitting docking to the base plate (27) of the master drone. (see also Fig. 8).

[0022] To control the slave drone within a limited area while suspended below the master drone, the four propellers are aligned approximately horizontally. The number of propellers required for movement does not necessarily have to be four, as is the case with the invention. Sufficient movements can also be achieved with two or three propellers. The relatively large propellers shown only need to generate minimal horizontal forces or movements. Their size was chosen so that they can rotate relatively slowly and thus operate quietly.

[0023] The slave drone contains two rotating mass discs (43), each rotating in reverse around a vertical axis, and each independently driven. Due to the conservation of angular momentum of the rotating masses, the slave drone's orientation is stabilized. The individually controllable rotation speeds of the individual mass discs also allow the drone's orientation around the vertical axis to be controlled. This means that once the slave drone is in position, it can be aligned using the mass discs without any fan noise. This serves both for camera alignment and for potential target firing.

[0024] Fig. Figure 7 shows the camera element located in the cable, between the lower cable (45) toward the slave drone and the upper cable (46) toward the master drone. The camera element consists of a housing in the shape of a flattened sphere (47) (elliptical cross-section). This shape allows the object pulled into an elliptical hole with a cable winch to rotate around the vertical axis. The ring (48) at half height serves as an end stop. The upper half of the camera element allows alignment with the master drone, the lower half with the slave drone.

[0025] In the lower half of the camera element there are two recesses with cameras, arranged in such a way that one camera (49) with a viewing angle (50) and a second camera (51) with a viewing angle (52) together enable a viewing angle of at least approximately 180 degrees downwards to at least all the way around up to the horizon.

[0026] The camera position was deliberately chosen approximately 15 meters above the slave drone so that the mission can be visually documented and supports continuous improvement of drone technology. This documentation is still possible even if there has been an explosion below, visibility is restricted by smoke or fire, for example, or even if the slave drone has been destroyed. This eliminates the need for an additional drone for documentation purposes.

[0027] It is quite conceivable that the cable winch for the lower cable and / or a cable cutting device for the lower cable could be integrated into the camera element.

[0028] Fig. Figure 8 shows the master drone from an angled bottom view, with the slave drone hanging from the cable at a minimal distance below. The camera element (53) is located approximately halfway along the cable. This view represents, for example, the initial moment of lowering the slave drone or its retrieval shortly before docking. The base plate of the master drone features an elliptical recess (54) into which the camera element with its elliptical cross-section is pulled in, secured against rotation. The four tabs (44) of the slave drone can additionally form a positive connection by engaging with the oval openings (55) in the base plate (27).

[0029] The elliptical cross-section shown here for joining and aligning the docking components does not have to be elliptical within the meaning of the invention. Other shapes and target functions are also conceivable.

[0030] Fig. 9 and Fig.Figure 10 shows two possible payload variants, e.g., a pistol (56) or a grenade (57). The possibilities for military and civilian use are diverse. Possible applications include rockets, flamethrowers, horizontal launchers, load handling for delivering or retrieving objects, medical support, wildlife observation, and crime prevention.

[0031] Based on the invention shown here, various variants are possible, e.g.: 1. Master drone flying 200 m high, 150 meters below on the cable an intermediate drone with quiet propeller noise, but with more horizontal movement options and can also be used in windy conditions, and the drone hanging at the very bottom has no propeller at all. 2. A slave drone, which is reduced to a camera and a grenade. 3. A slave drone, which is reduced to a camera and a magnet or adhesive object that can be attached to a target. A grenade then falls down along the cable (guided by the cable). 4. A master drone, with several slave drones lined up next to it, each approximately 25 meters apart. When the lowest drone is deployed, the one above it takes over the documentation. If the lowest drone is lost, the next one above it takes over the active role. 5. A master drone which, instead of a cable winch, only has a cable outlet device with which the one-way cable is continuously released using a brake if necessary and is cut off after use. 6. A master drone with a payload of 150 kg, for example, where the slave drone can silently rescue a wounded person, e.g. equipped with a carabiner or chest strap. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2022 / 244934A1

[0011]

Claims

[1] Drone system consisting of at least 2 drones, characterized by that one drone (slave drone) is suspended below the other drone (master drone) by means of a signal-carrying cable. [2] Drone system according to claim 1, characterized by that the counteraction to the vertical weight forces of the slave drone is achieved primarily by the tensile forces of the cable. [3] Drone system according to claim 1 and 2, characterized by that the cable on the master drone has an outlet device that allows the slave drone to be lowered from the master drone. [4] Drone system according to claims 1, 2 and 3, characterized by that the signals necessary for control and video transmission of the slave drone can be transmitted via the cable. [5] Drone system according to claims 1 and 2, characterized bythat the slave drone includes a cable winch for at least part of the cable length, which allows fine adjustment of the altitude position of the slave drone. [6] Drone system according to claims 1, 2 and 3, characterized by that the slave drone has at least one mass element which controls the orientation of the drone through electric motor-driven self-rotation. [7] Drone system according to claims 1, 2 and 3, characterized by that the slave drone has several differently arranged propellers, which can at least control the horizontal position of the drone. [8] Drone system according to claims 1, 2 and 3, characterized by that there is an additional camera in the cable a few meters above the slave drone. [9] Drone system according to claims 1, 2 and 3, characterized bythat the slave drone has a device for receiving a payload, whereby the payload can be connected to the slave drone both permanently and detachably.

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