NL2036436B1

NL2036436B1 - Method for determining a position range of a third-party drone or a transmitter of a control device of the third-party drone

Info

Publication number: NL2036436B1
Application number: NL2036436A
Authority: NL
Inventors: Niesen Klaus; Bratz Kurt; Brinkmeyer Joerg
Original assignee: Bosch Gmbh Robert
Priority date: 2022-12-07
Filing date: 2023-12-06
Publication date: 2025-07-15
Also published as: DE102022132548A1; NL2036436A

Abstract

The invention relates to a method and system for determining a position range (30, 32) of a third-party drone (20) or of a transmitter (44) of a control device of the third-party drone, wherein a transmission signal of the third- party drone or of the transmitter is detected with a ﬁrst radio frequency, RF, sensor which is attached to a sensor drone (10), wherein a ﬁrst solid angle range (24, 26) starting from a first detection position located on a ﬂight path of the sensor drone (10) is determined based on the detected transmission signal, and wherein the position range (30, 32) is narrowed down (120) to the first solid angle range or is determined as the ﬁrst solid angle range or as a subrange of the ﬁrst solid angle range, and/or wherein the position range is determined as a function of the detected transmission signal. (Figure 1D)

Description

P136309NL00

Title: Method for determining a position range of a third-party drone or a transmitter of a control device of the third-party drone

The present invention relates to a method for determining a position range of a third-party drone or a transmitter of a control device of the third-party drone and a system for carrying it out.

Background of the invention

Drones, especially in the form of so-called multicopters, are becoming increasingly widespread. These drones pose a potential security risk for sensitive areas or objects, such as airports or aircraft, buildings, crowds of people, production facilities, military installations, nuclear power plants and the like. For example, a collision (whether intentional or unintentional) with an aircraft can cause considerable damage to the aircraft.

Commercially available drones can weigh between approx. 100 g and approx. 25 kg or more and reach speeds of up to 50 km/h to 100 km/h, depending on the type. At the same time, the maximum flight altitude can be one kilometre or more. The maximum payload of such drones can be around 1 kg to 5 kg or around a quarter of their own weight. Typical ranges can be several kilometres.

US 10 866 597 B1 relates to systems and methods for detecting and intercepting drones in order to counter dangers posed by drones.

Disclosure of the invention

According to the invention, a method for determining or narrowing down a position range of a third-party drone or a transmitter of a control device of the third-party drone and a system with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

The invention utilises the measure of using a sensor drone with an RF sensor (RF: radio frequency; approximately 3 kHz to 300 GHz) at a detection position on a flight path of the sensor drone to determine a solid angle range emanating from the sensor drone or the RF sensor, in which the third-party drone is located, and to constrict or narrow down a position range of the third-party drone or a transmitter of a control device of the third-party drone to the specific solid angle range. This procedure is expedient because the detection position or the flight path can be freely selected and, in particular, can also be changed, e.g. can be selected at a height at which interference of RF signals by topography and vegetation does not occur, and thus the narrowing of the position range can be improved compared to an estimation of the position of the third-party drone by a fixed drone detection system.

The sensor drone is set up to detect at least one RF signal by means of the

RF sensor, which 1s attached to the sensor drone, and to determine a solid angle range in which a transmitter of the RF signal is located as seen from the sensor drone or from the RF sensor. In particular, the RF sensor is tuned to frequency ranges or bands in which RF control signals are typically transmitted by control devices for drones or in which drones transmit data to the control devices, for example in the GHz range, such as 2.4 GHz or 5.8

GHz.

RF sensors are sensors that are set up to determine the direction or a corresponding solid angle range (e.g. by using antennas with directional characteristics) of RF signals. Typically, the power density or energy flow of the RF signal is determined for this purpose. In particular, the term RF sensor does not refer to RF receivers used on drones to receive RF control signals. However, it is possible for an RF sensor to also act as an RF receiver,

By providing an input signal with an exact position (e.g. GNSS) and an exact time stamp (e.g. DCF 77), the position of the transmitter can be determined from three of these transit time values using a triangulation method, i.e. here the position of the third-party drone, if it 1s transmitting communication signals, and the remote control system (control device) of the third-party drone on the ground. At least three HF sensors should be used for triangulation, for example. More HF sensors lead to a higher accuracy of the position.

Further advantages and embodiments of the invention are shown in the description and the accompanying drawing.

The invention is illustrated schematically in the drawing by means of embodiment examples and is described below with reference to the drawing.

Brief description of the drawings

Figures 1A to 1F show an example of the procedure for narrowing down a position range of a third-party drone or a transmitter of a control device of the third-party drone.

Figure 2 shows a situation in which the sensor drone is in the immediate vicinity of the transmitter and the operator 46 of the control device of the third-party drone.

Figures 3A and 3B illustrate the use of two sensor drones.

Figure 4 shows a flow chart of the method for determining a position range of a third-party drone or a transmitter of a control device of the third-party drone.

Embodiment(s) of the invention

Figures 1A-1F show an example of the procedure for narrowing a position range of a third-party drone and/or a transmitter of a control device of the third-party drone.

Figures 1A-1F each show a sensitive air zone 2, i.e. a defined air zone in which unknown drones or third-party drones are not desired. The air zone 2 can be defined in a suitable manner, e.g. so that it surrounds an object 4 to be protected, such as an airport. In particular, the air zone 2 can be an air zone into which unauthorised entry by drones or other aircraft is not permitted due to legal standards. The figures show, for example, a third- party drone 20, which is located outside the defined air zone 2 in Figure 1A.

The system shown comprises a drone detection system 12, at least one sensor drone 10, in Figure 1A for example in a parking position, and preferably a guidance system 14. The guidance system 14 is in particular set up to evaluate and/or summarise data from the drone detection system and/or the sensor drone and/or to transmit data and/or control commands to the sensor drone.

The drone detection system 12 is fixedly positioned relative to the sensitive (defined) air zone 2, e.g. standing on the ground inside or outside the air zone or attached to or on a building, and is set up to detect drones, in particular multicopters, within the sensitive air zone 2. In general, of 5 course, drones outside the air zone and/or other objects are also detected, 1.e. the detection range of the drone detection system 12 generally extends beyond the sensitive air zone 2.

The drone detection system 12 is formed here, for example, by two fixed (i.e. with a fixed position) RF sensors 18 (radio frequency sensor). In general, any number of fixed RF sensors can be provided, e.g. also more than two fixed RF sensors or no fixed RF sensor if other sensors are used. RF sensors can be used to detect drones and/or drone control devices, as both drones and drone control devices typically have an RF transmitter.

In general, the drone detection system 12 comprises one or more sensors that detect drones and generally other objects in the air zone 2, in particular at least one radar sensor and/or at least one lidar sensor (light detection and ranging, also known as light imaging, detection and ranging) and/or at least one RF sensor (radio frequency sensor) and/or at least one camera (optical and/or infrared) and/or at least one microphone. Preferably, the drone detection system is set up in such a way that it is possible to distinguish drones from other objects (e.g. birds). For this purpose, the so-called “micro-

Doppler effect" can be used with radar sensors or lidar sensors. This utilises the fact that vibrating and/or rotating elements on the detected object (in particular the propeller of a multicopter) lead to a modulation, i.e. frequency modulation due to the Doppler effect, of the radar signal or lidar signal, which is imposed on the radar signal in addition to the frequency shift due to the speed of the detected object. Such a modulation can be recognised by evaluating the radar signal or lidar signal and thus a drone can be distinguished from a bird, for example. It is also possible to recognise drones on the basis of the noise caused by their propellers. Camera images can also be used to distinguish drones from other objects. For example, an image recognition system could be used, such as a neural network (or an algorithm based on machine learning), which has been trained accordingly using existing camera images of drones and other objects.

The drone detection system 12 is set up to determine position data of detected objects, in particular of detected drones. In general, sensors of the drone detection system 12 cannot determine the exact position of drones.

For example, RF sensors can only determine a direction or a solid angle range within which an RF transmitter is located, while the distance cannot be determined precisely. Figure 1B, for example, shows a situation in which the third-party drone 20 is detected by the fixed RF sensors 18 as it enters the defined air zone 2, whereby a solid angle range 22 is shown for each of the two RF sensors, within which the third-party drone 20 is located based on the RF signals detected by the respective RF sensor. These solid angle ranges 22 indicate the probable location of the third-party drone, as there is only a certain degree of measurement accuracy and/or interference, such as signal reflections from buildings, can occur. The solid angle ranges 22 can be used to narrow down or constrict the position of the third-party drone 20 to the location range 31, namely the intersection of the solid angle ranges.

As soon as the location range 31 of the third-party drone 20 determined by the RF sensors 18 (or other sensors of the drone detection system) is at least partially in the defined air zone 2, it is assumed that the third-party drone 20 has entered the air zone 2. In this case, the sensor drone 10 can be started, as shown in Figure 1B. In general, the sensor drone 10 may already be flying in the air, i.e. it may have been launched at an earlier point in time.

Target data or trajectory data, which indicate the direction or trajectory 1n which the sensor drone should fly, can be determined, for example, based on the already known position within the location range 31 where the third- party drone is located and can be transmitted to a control unit or drone control unit of the sensor drone 10 and/or the guidance system 14. Based on the target data or trajectory data, a corresponding flight path of the sensor drone can be determined by controlling the sensor drone. The drone control unit can be or include an automatic control unit, i.e. the sensor drone is at least partially controlled automatically, and/or be or include a remote control unit for a (human) user, i.e. the sensor drone is remotely controlled by the user, who makes control inputs by means of operating elements of the remote control unit (in particular possible via radio as well as via mobile radio networks or direct link). For example, a corresponding computer program for the remote control unit can be executed in a computer in the guidance system. The remote control unit can, for example, be provided in the guidance system 14 and/or be a portable remote control unit. The automatic control unit can, for example, be implemented in a computer unit in the sensor drone itself and/or in a computer unit in the guidance system (by means of corresponding computer programs).

In Figure 1C, the sensor drone 10 is located at a position referred to as the detection position, which is located on the flight path of the sensor drone, i.e. on the flight path of the sensor drone resulting from the target data or trajectory data. The detection position can be at a predetermined height, for example. This height can be determined in such a way that it can be assumed that RF signals from the third-party drone to the sensor drone are not disturbed by buildings, trees or the like. An RF sensor is attached to the sensor drone 10, which 1s also used to detect the third-party drone 20 or its

RF transmitter. A solid angle range 24 is therefore determined, within which the third-party drone 20 is (probably) located as seen from the sensor drone 10. The position of the third-party drone 20 can therefore be narrowed down or constricted to the solid angle range 24. In addition, the solid angle ranges 22 within which the third-party drone 10 is located as seen from the fixed RF sensors can be taken into account, so that overall the position of the third-party drone 20 can be narrowed down to the position range 30 shown as a dashed line. Due to the free and, in particular, less interference- prone positioning of the sensor drone 10, a considerable improvement in the position determination of the third-party drone 20 can be achieved, i.e. a reduction in the specific position range 30 within which the third-party drone 20 is probably located (based on the detection by RF sensors) can be achieved.

Figure 1D shows a situation corresponding to Figure 1C, 1.e. the third-party drone 20 is detected by the sensor drone 10 or its RF sensor from a first detection position (which may be the same as the detection position in

Figure 1C or may be a different detection position) located on the flight path of the sensor drone 10, so that the position of the third-party drone 20 can be narrowed down to a (first) solid angle range 24. For the sake of clarity, in

Figure 1D, as in Figures 1E and 1F, not all reference signs from Figure 1C have been repeated.

In addition or as an alternative to Figure 1C, in Figure 1D the transmitter 44 of a control device of the third-party drone 20, which is held for example by an operator 46 of the third-party drone, is detected by the sensor drone 10 or its RF sensor, respectively. Accordingly, a position of the transmitter 44 of the control device can be narrowed down to a (first) solid angle range 26 in which the transmitter 44 of the control device is located as seen from the sensor drone 10. More precisely, from the point of view of the sensor drone 10, it is initially a transmitter of a potential control device of the third-party drone 20, since the sensor drone generally cannot decide whether it is the transmitter 44 of the control device of the third-party drone 20 or any other RF transmitter. In particular, an assignment of the detected RF signals is possible if they contain identification information, e.g. a MAC address and/or a remote identification described below. Other (physical) properties (e.g. frequency) of the RF signals can also be analysed to enable assignment. If, as described below, for example, several solid angle ranges are determined, those that were determined based on associated RF signals are taken into account.

The position range of the third-party drone or its control device can also (additionally or alternatively) be determined as a function of the detected transmission signal (RF signal), for example by analysing a remote identification or remote ID transmitted with it or in it, which can also be regarded as identification information. For example, information is transmitted that includes the identification of an unmanned aerial vehicle (UAV) (in this case a drone or third-party drone). Remote identification can include one or more of the following data: unmanned aircraft system (UAS) operator number, serial number, position data, current flight altitude, flight direction, flight speed, starting point of the drone. Direct remote identification means a system that ensures the local transmission of information about an unmanned aircraft in operation and also includes the identification of the unmanned aircraft so that this information can be retrieved without physical access to the unmanned aircraft.

Furthermore, trees 50 and a lake 52, which are located in an exemplary environment of the air zone 2, are shown. The topology of the environment can be taken into account so that, assuming that the transmitter 44 is located approximately at ground level, the dashed position range 32 for the transmitter 44 can be determined (for example as the intersection of the first solid angle range 26 and a height range above the ground, e.g. a height range with a height of 5 m or 10 m).

The situation depicted in Figure 1E essentially corresponds to that depicted in Figure 1D, with the difference that the sensor drone 10 is at a new (second) detection position. The second detection position can, for example, be determined based on the first solid angle range 26, i.e. the target data or trajectory data is adjusted accordingly so that a desired second detection position is on the flight path of the sensor drone. For example, the solid angle range can be followed so that the second detection position is within the first solid angle range 26 in order to reduce the distance to the transmitter. Alternatively, the second detection position could be outside the first solid angle range 26 to allow triangulation of the transmitter (which is assumed not to change its position at all or only slowly).

Based on the second detection position, a second solid angle range 28 in which the transmitter 44 is (probably) located can be determined by the sensor drone 10 or its RF sensor, respectively. If, as shown, the second detection position is located in the first solid angle range, the position range 32m which the transmitter 44 is (probably) located can be reduced compared to that in Figure 1C, for example by taking topological information into account. If, as not shown, the second detection position is located outside the first solid angle range, the intersection of the first and second solid angle ranges can be formed, for example, so that triangulation is possible in principle Gf the second detection position is suitably selected).

The RF sensor of the sensor drone can detect RF signals continuously, for example, so that solid angle ranges in which a transmitter (of the third- party drone and/or the control device of the third-party drone) is located as seen from the respective position of the sensor drone are determined continuously (continuously or at certain time intervals, which are determined, for example, by the computing unit used to analyse the RF signals) on the flight path of the sensor drone. In general, therefore, a large number of detection positions and associated solid angle ranges can be determined. When determining the position range in which the transmitter is located, all or part of this plurality of detection positions and associated solid angle ranges can be taken into account, i.e. the position range can be formed as an intersection of all or part of this plurality of solid angle ranges (as seen from the respective detection positions) or, insofar as other information, e.g. of the fixed RF sensors, is used, can be narrowed down to this intersection. How many and which of this plurality are taken into account can be determined, for example, depending on the distance between the detection positions and/or on the available computing power and/or on whether it is assumed that the transmitter is moving. The first and second detection positions shown in Figures 1D and 1E represent examples of this generally plurality of detection positions. The RF sensor of the sensor drone may, but need not, continuously detect RF signals, wherein if RF signals are not continuously detected, RF signals are at least detected when the sensor drone 1s at the detection positions.

The situation shown in Figure 1F essentially corresponds to that shown in

Figure 1E, with the difference that the fixed RF sensors 18 additionally determine respective (third) solid angle ranges 23 within which the transmitter 44 of the control device of the third-party drone 20 is located.

The position range 32, in which the transmitter 44 is (probably) located, can then be narrowed down to the intersection of the three solid angle ranges (second solid angle range 28, solid angle ranges 23 of the two fixed RF sensors 18).

Figure 2 shows a situation in which the sensor drone 10 is located in the immediate vicinity of the transmitter 44 and the operator 46 of the control device of the third-party drone, e.g. at a third detection position on the flight path of the sensor drone, for example as a result of a determination of the position range of the transmitter 44 of the control device of the third-party drone 20. The sensor drone 10 or its RF sensor, respectively, can also be used to determine solid angle ranges (e.g. the solid angle range 29 shown) within which the third-party drone 20 or the transmitter 44 are located. The third-party drone 20 is, for example, approaching a landing site 66.

A camera 62 can be attached to the sensor drone 10, with which images of the third-party drone 10 and/or the control device or the operator 46 can be taken, in particular in order to determine their position in relation to the surroundings and thus further narrow down the corresponding position ranges. A loudspeaker 64 can also be attached to the sensor drone 10, with which an announcement can be made, for example to inform the operator 46 of the unauthorised entry into the defined air zone 2.

The sensor drone 10 may remain at this location, for example, until members of a competent authority, such as the police, who have been informed via the guidance system 14, for example, can reach this location via a nearby road 68 using a motor vehicle 70.

Figures 3A and 3B illustrate the use of two sensor drones 10 flying on different trajectories. In Figure 3A, which essentially corresponds to the situation in Figures 1D and 1E, the two sensor drones 10 are at different detection positions, so that two solid angle ranges 29 can be determined by the data from the sensor drones 10 or their RF sensors, respectively, and the position of the transmitter 44 of the control device of the third-party drone 20 can be narrowed down to the intersection of these two solid angle ranges 29 (position range 32).

In the situation illustrated in Figure 3B, two third-party drones 20a, 20b, which are controlled by two control devices with transmitters 44a, 44b by operators at different locations, have also entered the defined air zone 2. A sensor drone 10 can determine a solid angle range 24a, in which a first of the third-party drones 20a is located, a solid angle range 29a, in which the transmitter 44a of the control device of the first third-party drone 20a is located, and a solid angle range 29b, in which the transmitter 44b of the control device of the other, second third-party drone 20b is located.

Furthermore, the sensor drone 10 can determine a solid angle range in which a second of the third-party drones 20b is located (not shown for the sake of clarity). The other sensor drone 10 can determine a solid angle range 24b in which the second third-party drone 20b is located, a solid angle range 29b in which the transmitter 44b of the control device of the second third- party drone 20b is located, and a solid angle range 29a in which the transmitter 44a of the control device of the first third-party drone 20a is located. Furthermore, the other sensor drone 10 can determine a solid angle range in which a first of the third-party drones 20a is located (not shown for the sake of clarity). The positions of the third-party drones 204, 20b or the transmitters 44a, 44b can be narrowed down accordingly by the respective solid angle ranges.

In optional step 100, the intrusion of a third-party drone into a defined air zone 1s detected, for example by a drone detection system, and a sensor drone with an RF sensor attached to it is launched (see Figure 1B).

In step 110, the sensor drone is controlled to determine, at a first detection position on a flight path of the sensor drone (on which the sensor drone is approximately controlled to fly), a first solid angle range in which the third- party drone or a transmitter of a control device of the third-party drone is located as seen from the first detection position by detecting and evaluating

RF signals (transmission signal).

In step 120, the position of the third-party drone or of the transmitter of the control device is narrowed down or constricted to a position range corresponding to the first solid angle range or narrowed down to the first solid angle range. In particular, the position range may be determined to be equal to the solid angle range, for example if no further information about the location of the third-party drone or the transmitter of the control device is available, or, if such further information is available, the position range may be determined as an intersection of the solid angle range and a location range derived from this information, i.e. as a subrange of the solid angle range. In general, the position range is therefore determined as being equal to the solid angle range or as a subrange of the solid angle range. The position range can be determined as a function of the RF signal that transmits a remote identification or remote ID, for example.

In the optional step 130, the sensor drone is controlled to determine a second solid angle range, in which the third-party drone or the transmitter of the control device of the third-party drone is located, at a second detection position on the flight path of the sensor drone by detecting and analysing

RF signals (transmission signal). The flight path and/or the second detection position can be determined, for example, based on the first solid angle range and/or other information.

In the optional step 140, the position of the third-party drone or of the transmitter of the control device is narrowed down to the position range corresponding to or to the second solid angle range. In particular, the position range can be determined as the intersection of the first solid angle range with the second solid angle range and possibly further information. In order to be able to better allocate solid angle ranges to one another (i.e. allocate solid angle ranges belonging to the same transmitter to one another), identification information contained in the transmission signal and/or a remote identification can be taken into account. The procedure of steps 110 and 120 or 130 and 140 can be repeated as often as desired or continuously. The position range determined during a previous repetition can be taken into account, e.g. as further information (of steps 120 or 140).

In the optional step 150, the sensor drone is controlled (automatically or manually) to fly to a third detection position and, during the flight and/or after reaching the third detection position, to take images of the specific position range using a camera attached to the sensor drone. Such images can be used to narrow down the position range in relation to the surroundings or objects located in the surroundings, such as houses or trees or similar.

Claims

Conclusions

1. Method for determining a position range (30, 32) of a foreign drone (20) or of a transmitter (44) of a control device of the foreign drone, wherein a transmission signal of the foreign drone or of the transmitter is determined with a first high-frequency, HF, sensor, which is mounted on a sensor drone (10), wherein a first solid angle range (24, 26) starting from a first registration position, which is located on a flight path of the sensor drone (10), is determined based on the determined transmission signal, and wherein the position range (30, 32) to which the first solid angle range is limited (120) is determined as the first solid angle range or as a sub-range of the first solid angle range, respectively, and/or the position range is determined as a function of the determined transmission signal.

Method according to claim 1, wherein at least a second solid angle range (24, 28) is determined based on the transmission signal determined with the first RF sensor, starting from at least a second registration position located on the flight path of the sensor drone (10), and wherein the position range (30, 32) is further limited (140) to the at least one second solid angle range.

Method according to claim 2, wherein the flight path of the sensor drone after the first registration position and/or the at least one second registration position is/are determined based on the first solid angle range (26) and/or based on the position range (32) in accordance with the limitation applicable up to now.

Method according to any one of the preceding claims, wherein the transmit signal is determined with at least a second RF sensor (18) located at at least one fixed position, wherein at least a third solid angle range (23) is determined starting from the at least one first position based on the transmit signal determined with the second RF sensor, and wherein the position range (32) is further limited to the at least one third solid angle range.

Method according to any one of the preceding claims, wherein identification information and/or properties of the transmit signal present in the transmit signal are evaluated and taken into account when determining or limiting the position range, in particular for the allocation of one or more of the determined solid angle ranges.

Method according to any one of the preceding claims, wherein the sensor drone (10) is controlled to fly (150) to at least one third registration position in the position range (32) in accordance with the restriction applicable up to now, wherein during the flight to at least one third registration position and/or after reaching the at least one third registration position one or more camera recordings are recorded (160) with a camera (62) mounted on the sensor drone.

Method according to any one of the preceding claims, wherein, in particular for determining the first solid angle range (24, 26), a drone registration system (12) recognizes that the foreign drone (20) has entered a defined air area (2), wherein a presence range (31) of the foreign drone and/or of the transmitter of the control device of the foreign drone is determined by the drone registration system, wherein the flight path of the sensor drone and/or the first registration position is determined based on the presence range of the foreign drone and/or of the transmitter of the control device of the foreign drone.

Method according to claim 7, wherein the sensor drone (10) is started in response to detecting that the foreign drone has entered the defined air range 1s.

Method according to any one of the preceding claims, wherein a further sensor drone (10), to which a third RF sensor is arranged, is controlled to fly to a fourth registration position, wherein a transmission signal from the foreign drone or from the transmitter with the third RF sensor is determined, wherein a fourth solid angle range (29) starting from the fourth registration position is determined based on the determined transmission signal, and wherein the position range (32) is limited to the fourth solid angle range.

10. Sensor drone (10), to which an RF sensor is mounted, the sensor drone being designed to register an RF signal by means of the RF sensor and to determine a solid angle range (24, 26, 28, 29) in which a transmitter of the RF signal is located as seen from the RF sensor, and/or being designed to evaluate identification information and/or properties of the RF signal present in the RF signal and optionally take this into account when determining the solid angle range, and/or being designed to determine a position range of the RF signal in dependence on the RF signal detected by the RF sensor.

A system comprising a sensor drone (10) according to claim 10 and a drone control unit for the sensor drone, the system being adapted to carry out the method according to any one of claims 1 to 9.

12. A system as claimed in claim 11, wherein the drone control unit comprises an automatic control unit and/or a remote control unit for manual flight.

A system according to claim 11 or 12, further comprising a drone registration system (12) adapted to register a foreign drone, determine a presence range of the foreign drone (20), and recognize the intrusion of the foreign drone into a defined air range (2).