CH716639A2 - Research drone and associated research method. - Google Patents

Abstract

The invention relates to a research drone (1), comprising: a frame with at least one motor (3) installed on said frame (2), said motor being configured to allow at least one take-off and/or landing and/or movement in forward flight of said search drone (1), a data processing unit housed at or within the frame, said data processing unit being configured at least to process a microphone signal; at least one microphone (5) arranged on said frame, operatively connected to the data processing unit, said microphone being configured to receive an audio signal from a predetermined spatial position with respect to said search drone (1), said search drone (1) being characterized in that it comprises a system configured to locate at least one source of said audio signal and to electronically process a microphone signal comprising at least part of the audio signal received by said at least one microphone (5) in order to perform said localization . Furthermore, the invention also relates to a search method for an audio signal source.

Description

Description

TECHNICAL FIELD

[0001] The present invention pertains to the field of drones, i.e. unmanned aircraft. In detail, this disclosure concerns a research drone. This disclosure also concerns a drone search method.

BACKGROUND

[0002] Drones are unmanned aircraft capable of being used for a large variety of applications.

[0003] Currently drones are known which are used for surveillance and research applications, both of animals and of people. Such drones are typically equipped with a camera and take pictures or videos of a predefined area below.

[0004] It is currently known that the search for animals and people, or more generally for objects, can be carried out using infrared or thermal cameras, the latter being capable of distinguishing heat sources from the surrounding environment. The use of the thermal camera makes it possible to see subjects even in the dark, provided that there is a temperature difference between these subjects and the surrounding environment that can be detected by the camera sensor.

[0005] Infrared and thermal cameras are characterized by the disadvantage of not being able to see subjects or objects covered by trees, foliage or clothing such as to prevent the transmission of radiation useful for detection. The same drawback is - similarly - also present for visible radiation television cameras, since they cannot see subjects or objects with respect to which trees, foliage or other objects are interposed.

[0006] Even if the aforesaid cameras are used with an installation on a drone, the limitations mentioned above remain.

[0007] The purpose of the present disclosure is to describe a research drone and a research method which, by exploiting a particular technology which will be described hereinafter, are capable of overcoming the drawbacks described above.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is therefore that of substantially solving the problems highlighted by the prior art, by means of a drone and a research method which exploit the use of audio signals.

[0009] According to a first aspect of the present disclosure, a research drone (1) is described, comprising:

- a frame (2),

- at least one motor (3) installed on said frame (2), said motor being configured to allow at least one take-off and/or landing and/or movement in forward flight of said search drone (1),

- a data processing unit (4) housed at the frame (2) or within the frame (2), said data processing unit being configured at least to process a microphone signal;

- at least one microphone (5) arranged on said frame (2), operatively connected to the data processing unit (4), said microphone being configured to receive an audio signal from a predetermined spatial position with respect to said search drone (1 ),

said search drone (1) being characterized in that it comprises a system configured to locate at least one source (200, 300) of an audio signal and to electronically process a microphone signal comprising at least part of the audio signal received by said at least one microphone (5) in order to perform said localization.

[0010] According to a further non-limiting aspect, the search drone (1) comprises at least a first microphone (5), a second microphone (5) and a third microphone (5) each arranged on said frame (2), in particular on a respective portion of said frame (2), and operatively connected to the data processing unit (4), each of said first, second and third microphones being configured to receive an audio signal from a predetermined position with respect to said drone for research (1).

[0011] According to a further non-limiting aspect, the system is configured to perform an electronic comparison between a previously stored sample audio signal and at least part of said microphone signal, and to identify a source (200, 300) of said audio signal as a source emitting an audio signal compatible with and/or similar to said sample audio signal.

[0012] According to a further non-limiting aspect, the motor (3) is installed in correspondence with an arm (2b) of the frame (2).

[0013] According to a further non-limiting aspect, the research drone (1) is a wireless drone and/or is a drone without ground connections of the wired type.

[0014] According to a further non-limiting aspect, the search drone (1) is a drone without external cables and/or it is a drone with IP65 or higher protection.

[0015] According to a further non-limiting aspect, the said at least one first microphone (5) is a directional microphone.

[0016] According to a further non-limiting aspect, the said at least one first microphone (5) is an omnidirectional microphone.

[0017] According to a further non-limiting aspect, said system comprises a data processing unit (4) installed on board the drone.

[0018] According to a further non-limiting aspect, the at least one microphone (5), optionally the at least one first, second and third microphone (5), and/are configured to transmit their own respective microphone signal towards the data processing unit (4).

[0019] According to a further non-limiting aspect, the research drone (1) is a quadricopter.

[0020] According to a further non-limiting aspect, the microphone signal is an electric signal.

[0021] According to a further non-limiting aspect, the at least one microphone (5) is positioned in a peripheral position

of the research drone (1); optionally, the first, second and third microphones (5) are each positioned in one

respective and distinct peripheral position of the search drone (1).

[0022] According to a further non-limiting aspect, the frame (2) comprises a plurality of arms (2b) and a central body (2c) from which said arms (2b) depart.

[0023] According to a further non-limiting aspect, the at least one microphone (5) is positioned in a peripheral and/or end position of said arm (2b), optionally at an opposite end of said arm (2b) with respect to the joint end with the central body (2c) of the frame (2).

[0024] According to a further non-limiting aspect, the at least one microphone (5) is directed substantially downwards, and/or is configured to receive an audio signal coming from a source which, when the search drone (1) is in flight, is at a lower altitude than the altitude at which the search drone itself is.

[0025] According to a further non-limiting aspect, the at least one omnidirectional microphone (5) is configured to receive an audio signal coming from sources located at lower, equal or higher altitudes than the altitude at which the search drone is located same.

[0026] According to a further non-limiting aspect, the at least one motor (3) is positioned in correspondence with said at least one arm (2b), optionally in correspondence with an intermediate position of said at least one arm (2b).

[0027] According to a further non-limiting aspect, the at least one arm (2b) comprises a support tip (6) configured to support at least part of the search drone (1) when on the ground, and configured, in use, to enter in contact with the ground, optionally at least at one end position thereof.

[0028] According to a further non-limiting aspect, the support rod (6) is positioned substantially in correspondence with said at least one motor (3), and/or is positioned substantially below said motor (3), and is configured for at least partially supporting its weight through a support substantially axially aligned with said motor (3).

[0029] According to a further non-limiting aspect, the frame (2) comprises a stiffening beam (6k) comprising a first substantially end portion fixed to a portion of said arm (2b) near said microphone (5) and/ or fixed to a portion of said arm (2b) radially more external than the portion of said arm (2b) at which said at least one motor (3) is fixed, and a second substantially end portion, opposite to the first portion of substantial end, fixed to a portion of said support tip (6).

[0030] According to a further non-limiting aspect, the at least one motor (3) is an electric motor and the research drone (1) comprises at least one battery configured to supply power to the at least one motor (3).

[0031] According to a further non-limiting aspect, the at least one battery is positioned within said central body (2c).

[0032] According to a further non-limiting aspect, said central body (2c) comprises a passive cooling system (11v) configured to allow ventilation of at least part of the central body (2c) and/or to allow cooling of at least a battery.

[0033] According to a further non-limiting aspect, the number of engines (3) of said search drone (1) is at least equal to the number of arms (2b) of said frame (2).

[0034] According to a further non-limiting aspect, the frame (2) comprises four arms (2b) and a central body (2c) from which said arms (2b) depart.

[0035] According to a further non-limiting aspect, the search drone (1) comprises four motors (3) each positioned in correspondence with a respective arm (2b), optionally in correspondence with an intermediate position of said at least one arm (2b) .

[0036] According to a further non-limiting aspect, the research drone (1) comprises at least one ESC (Electronic Speed Controller) flight stabilization module, installed in correspondence with the central body (2c), and configured to manage the operation of the 'at least one engine (3), optionally of the first engine (3), of the second engine (3), of the third engine (3) and of the fourth engine (3) simultaneously, in order to ensure flight stability.

[0037] According to a further non-limiting aspect, said at least one motor (3), optionally said four motors (3), are positioned in such a configuration as to have portions rotating along an axis substantially perpendicular locally to the direction of development of the arm ( 2b) and/or substantially perpendicular to the direction of translation of the drone and/or rotating on a substantially horizontal plane when the search drone (1) is positioned on the ground.

[0038] According to a further non-limiting aspect, the search drone (1) comprises at least one motor support (3a) substantially installed in correspondence with the at least one motor (3); the motor support (3a) is fixed in a predetermined position on said arm (2b); the motor mount (3a) accommodates the motor and, or acts as a damper, optionally passive, configured to reduce and/or dampen the vibrations induced by the at least one motor (3) on the frame of the research drone (1).

[0039] According to a further non-limiting aspect, the engine support (3a) comprises at least one, preferably a plurality of passive dampers (3d) each provided with a screw (3v) able to fix elastically part of the engine support (3a) to the said arm (2b).

[0040] According to a further non-limiting aspect, the ESC flight stabilization module is positioned near the at least one battery, and is optionally configured to allow at least partial heating thereof.

[0041] According to a further non-limiting aspect, the search drone (1) comprises a detection electronic module (20) installed at the central body (2c) and substantially fixed thereto; the said detection electronic module being optionally positioned at a higher level than the height of the central body (2c).

[0042] According to a further non-limiting aspect, the central body (2c) comprises a first main internal cavity (11a) and a second secondary internal cavity (11k), positioned under the main internal cavity (11a).

[0043] According to a further non-limiting aspect, the search drone (1) comprises a recorder for microphone signals, optionally a hardware recorder for microphone signals, optionally operatively connected to the at least one microphone (5).

[0044] According to a further non-limiting aspect, the hardware recorder for microphone signals is integrated in the data processing unit (4), and/or is positioned within the secondary internal cavity (11k).

[0045] According to a further non-limiting aspect, the central body (2c) comprises at least one, optionally a plurality of antenna supports (8), said at least one antenna support (8) extending from a lower portion of the central body ( 2c).

[0046] According to a further non-limiting aspect, said antenna support (8) comprises at least one antenna, of the directional or omnidirectional type, configured in use to receive a signal from a remote control (100) for controlling the search drone ( 1), said antenna being optionally operatively connected to the data processing unit (4).

[0047] According to a further non-limiting aspect, the search drone (1) comprises at least one, preferably a plurality of passive damping elements (11d) configured to absorb vibrations induced and/or transmitted by the central body (2c) towards the module sensing electronics (20); optionally the search drone (1) comprising four passive dampers (11d) positioned in substantial corner positions of the electronic detection module (20).

[0048] According to a further non-limiting aspect, the research drone (1) comprises a global satellite positioning module, in particular a GPS and/or Galileo and/or Glonass and/or Beidou module, and comprises a first antenna (7 ), optionally a helical type antenna and/or an antenna protruding out of the detection electronic module (20).

[0049] According to a further non-limiting aspect, the search drone (1) is configured to optionally execute, at least in flight, an RTK (Real Time Kinematic) algorithm for improving the positioning accuracy of the search drone (1) at following reception of said global satellite positioning signal, optionally wherein said RTK algorithm is configured to obtain an improvement in the positioning accuracy of said search drone (1) with precision at the centimeter level.

[0050] According to a further non-limiting aspect, the search drone (1) comprises a system for improving the global satellite positioning signal, said improvement system being configured to obtain an increase in the positioning accuracy of the search drone (1) , said global satellite positioning signal enhancement system optionally comprising at least one of the systems of the following list: WAAS, EGNOS, GAGAN, MSAS.

[0051] According to a further non-limiting aspect, the search drone (1) comprises a telemetry module (9t) equipped with a second antenna (9) suitable for transmitting and/or receiving telemetry data respectively from and/or towards a remote electronic device.

[0052] According to a further non-limiting aspect, the detection electronic module (20) is an actively cooled module, and comprises at least one fan (50) configured to forcibly expel at least part of the air contained and/or introduced into the electronic module detection (20).

[0053] According to a further non-limiting aspect, the detection electronic module (20) comprises at least one, preferably a plurality of, inlets (20i) configured to allow an air inlet or flow within the detection electronic module (20) same.

[0054] According to a further non-limiting aspect, the search drone (1) comprises a video camera (40), optionally installed on the electronic detection module (20).

[0055] According to a further non-limiting aspect, the fan (50) is configured to cool at least one transmitter module, operatively associated with the video camera, and configured to cool at least part of the electronics contained within the search drone (1), in particular at least part of the electronics contained in the detection electronic module (20).

[0056] According to a further non-limiting aspect, said search drone (1), in particular the system configured to locate the at least one source (200, 300) of said audio signal, comprises an active noise reduction system, configured to reduce and/or eliminate from said microphonic signal produced by the at least one microphone (5) an unwanted signal component due to the noise produced by the at least one motor (3) and/or by the rotor (12).

[0057] According to a further non-limiting aspect, said active noise reduction system comprises at least one reference sensor (30), optionally a plurality of reference sensors (30) equal to the number of arms (2b) of the frame (2 ); said reference sensor being configured to detect the noise produced by said at least one motor (3), optionally by a respective motor (3), and also being configured to produce in output a reference signal transmitted towards said data processing unit ( 4).

[0058] According to a further non-limiting aspect, said reference sensor is an infrared sensor, or a microphone sensor, or an accelerometer sensor, or an ESC (Electronic Speed Controller) sensor.

[0059] According to a further non-limiting aspect, said infrared sensor is installed in such a way as to point the rotor (12) and/or to receive a radiation or a variation of infrared radiation from a direction coming from the rotor (12) and /o to reduce the influence of the infrared radiation coming from the sun with respect to the useful infrared signal component received by the rotor (12).

[0060] According to a further non-limiting aspect, the data processing unit (4) comprises a first input, Hardware or Software, for the microphone signal coming from said at least one microphone (5) and a second input, Hardware or Software, for the reference signal coming from said reference sensor (30).

[0061] According to a further non-limiting aspect, the data processing unit (4) is configured to subtract said reference signal from the microphone signal, optionally to subtract, for each arm (2b), the reference signal of the reference installed on said specific arm (2b) by the microphone signal of the microphone (5) positioned on said specific arm (2b).

[0062] According to a further non-limiting aspect, the data processing unit (4) is configured to subtract the reference signal from the microphone signal in real time.

[0063] According to a further non-limiting aspect, the search drone (1) comprises a transmitter module configured to transmit at least part of the microphone signal of said at least one microphone (5), in particular of the plurality of microphones (5) towards a predetermined recipient electronic device.

[0064] According to a further non-limiting aspect, the frame (2) of the research drone (1) is made at least partially, preferably entirely, of plastic material and/or is made of material comprising polyamide, in particular polyamide loaded with glass and/or or with aluminum and/or with carbon.

[0065] According to a further non-limiting aspect, the frame (2) is a 3D printed frame, and/or at least part of said frame (2) is 3D printed.

[0066] According to a further non-limiting aspect, the search drone (1) comprises at least one filter, configured to allow the electronic filtering of at least one microphone signal produced by the at least one microphone (5) in correspondence with a predefined band.

[0067] According to a further non-limiting aspect, the search drone (1) comprises at least one filter for each of said first, second, third and, optionally fourth, microphones (5); each filter being configured to allow the electronic filtering of the microphone signal produced by the respective first, second, third and, optionally, fourth microphone (5) in correspondence with a predefined band.

[0068] According to a further non-limiting aspect, the predefined band is between 600Hz and 1800 Hz, preferably between 800 Hz and 1600 Hz, more preferably between 1000 Hz and 1400 Hz, more preferably substantially between 1200 Hz.

[0069] According to a further non-limiting aspect, said filter is a band-pass filter, and/or is a software filter, and/or is a hardware filter.

[0070] According to a further non-limiting aspect, said search drone (1) is configured to perform said filtering before transmitting the microphone signal to said active noise reduction system.

[0071] According to a further non-limiting aspect, the search drone (1) comprises at least one beacon for emitting a predefined audio signal, said beacon being configured to transmit said audio signal towards a predetermined direction, optionally towards the ground, in such a way that at least part of the transmitted audio signal can be reflected by an object on the ground, acting as a source of audio signal (300) by reflection, and can be received by said at least one microphone (5).

[0072] According to a further non-limiting aspect, the search drone (1) comprises a plurality of beacons according to the previous aspect; said plurality of beacons being optionally installed in such a way that a beacon is present for each arm (2b) of the frame (2).

[0073] According to a further non-limiting aspect, the plurality of beacons comprises independently controllable and/or selectively activated beacons.

[0074] According to a further non-limiting aspect, the research drone (1) is a disassembled drone, and the frame can be at least partially disassembled into several distinct portions.

[0075] According to a further non-limiting aspect, the central body (2c) can be disassembled from the at least one arm (2b) and/or at least part of said at least one arm (2b) can be disassembled with respect to a portion of said arm (2b ) immovably fixed to the central body (2c).

[0076] According to a further non-limiting aspect, a portion of the arm (2b) radially external with respect to the engine (3) and/or the engine support (3a), the stiffening beam (6k) and the support push rod (6) they create an assembly of elements that cannot be disassembled operationally.

[0077] According to a further non-limiting aspect, a portion of the arm (2b) radially external with respect to the engine (3) and/or the engine support (3a), the stiffening beam (6k) and the support rod (6) they form an assembly of elements which can in turn be disassembled operatively.

[0078] According to a further non-limiting aspect, the search drone (1) comprises at least one vibrometer, configured to detect a vibration or reverberation of at least a predetermined area of land, said vibration or reverberation resulting from a transmission of an audio signal towards the said predetermined area of land.

[0079] According to a further non-limiting aspect, the predetermined area of land is an area under the search drone (1) itself.

[0080] According to a further aspect, a search method for an audio signal source (200, 300) is described, said method comprising:

- an overflight phase of a predefined area of territory by means of a search drone (1), said overflight phase being performed at least by activating at least one engine (3) of the search drone (1);

- an activation of at least a first microphone (5) of said search drone (1) during at least the overflight phase, following which the microphone (5) transmits a microphone signal towards a data processing unit (4) positioned at search drone board (1),

- electronic signal processing, performed to locate the position of at least one audio signal source (200, 300), said electronic signal processing comprising at least one data processing step performed on the microphone signal produced at the output from the first microphone (5) , said data processing step determining a position of the source (200, 300) of audio signals in relation to the position assumed by the drone for search (1).

[0081] According to a further non-limiting aspect, the microphone signal comprises at least part of the audio signal produced and/or reflected by the source (200, 300).

[0082] According to a further non-limiting aspect, the method comprises the reception of an audio signal through said at least one microphone (5) and comprises a subsequent generation of said microphone signal comprising said audio signal and/or in which the microphone signal replicates at least part of said audio signal.

[0083] According to a further non-limiting aspect, the method comprises the activation of at least three microphones (5) of said search drone (1), in particular a second and a third microphone in addition to said first microphone (5), optionally positioned in mutually distinct positions on said search drone (1), and the step of locating the position of the at least one source (200, 300) of audio signals comprises at least one data processing step performed on the microphone signal produced at the output from each of said three microphones (5).

[0084] In particular, according to a further non-limiting aspect, the method comprises an electronic signal processing step performed on a first microphone signal produced at the output of a first microphone (5), on a second microphone signal produced at the output of a second microphone (5) and on a third microphone signal produced in output from a third microphone (5).

[0085] According to a further non-limiting aspect, the method comprises a data processing step performed on a first, second, third, fourth microphone signal produced at the output from a first, second, third and fourth microphone (5) each positioned on a respective arm (2b) of a research drone (1).

[0086] According to a further non-limiting aspect, the data processing step performed on said first, second, third, fourth microphone signal is performed on contemporary portions of said first, second, third, fourth microphone signal.

[0087] According to a further non-limiting aspect, the search drone (1) is configured to perform electronic noise cancellation from said microphone signal (5).

[0088] According to a further non-limiting aspect, the data processing step comprises an active reduction of a noise picked up by said microphone (5), said active electronic reduction comprising the reception of a reference signal from a reference sensor (30) installed on the research drone (1) and configured to detect the noise produced by at least one engine (3) of the said research drone (1) and producing at the output a microphone signal electronically cleaned at least partially of the noise by means of the said reference signal .

[0089] According to a further non-limiting aspect, the electronic signal processing step comprises the calculation of an arrival time (TOA) and power (SS,) of the microphone signal of each of said at least one first, second and third microphone ( 5) to obtain a first, second, third arrival time (TOA1, TOA2, TOA3) and a first, second, third power of the microphone signal (SS1, SS2, SS3); the electronic signal processing step comprising a comparison between said first, second and third arrival times (TOA1, TOA2, TOA3) and between said first, second and third power of the microphone signal (SS1, SS2, SS3) to electronically determine the position of said audio source with respect to the position assumed by said search drone (1).

[0090] According to a further non-limiting aspect, the power of the microphone signal (SSi) is directly correlated to the power of the audio signal received from the source (200, 300).

[0091] According to a further non-limiting aspect, the microphone (5) is a fixed gain microphone.

[0092] According to a further non-limiting aspect, the electronic signal processing step comprises the calculation of an arrival time (TOAi) and power (SSi) of the audio signal transmitted from the audio signal source (200, 300) towards each of the said at least a first, second and third microphone (5) to obtain a first, second, third arrival time (TOA^ TOA2, TOA3) and a first, second, third power of the audio signal (SS^ SS2, SS3); the electronic signal processing step comprising a comparison between said first, second and third arrival times (TOAi, TOA2, TOA3) and between said first, second and third power of the audio signal (SS1, SS2, SS3) for electronically determining the position of said audio source with respect to the position assumed by said search drone (1).

[0093] According to a further non-limiting aspect, the calculation of the arrival time (TOA) and of the power (SS,) of the microphone signal comprises the analysis of a predetermined portion of said microphone signal and comprises the search for peaks and/or peaks in the waveform in the time domain of said microphone signal.

[0094] According to a further non-limiting aspect, following the electronic determination of the position assumed by the audio source with respect to the position assumed by the search drone (1), the method comprises a transmission of a position signal towards a user interface device (100 ) logically connected to said research drone (1) on a predetermined data communication channel.

[0095] According to a further non-limiting aspect, the method comprises a guide step of the search drone (1), in particular an automatic guide step, comprising carrying out a plurality of calculations of the at least first, second, third arrival time (TOA,, TOA2, TOA3) and/or comparisons of at least one first, second, third arrival time (TOA,, TOA2, TOA3), said driving step being aimed at bringing the drone for research ( 1) in correspondence, optionally in substantial vertical alignment, with the source (200, 300) of the audio signal.

[0096] According to a further non-limiting aspect, the method comprises a guide step of the research drone (1), in particular an automatic guide step, comprising carrying out a plurality of calculations of the at least first, second, third power level (SS1, SS2, SS3) and/or comparisons of at least one first, second, third power level (SS1, SS2, SS3) of microphone signal, said guide step being aimed at bringing the drone for search (1) in correspondence, optionally in substantial vertical alignment, with the source (200, 300) of the audio signal.

[0097] According to a further non-limiting aspect, the phase of active reduction of the noise picked up by said at least one microphone (5) takes place before the phase of calculating the arrival time (TOA,) and the power (SS,) of the microphone signal .

[0098] According to a further non-limiting aspect, the active noise reduction phase is performed by a data processing unit (4) installed on the research drone (1).

[0099] Alternatively, according to a further non-limiting aspect, the active noise reduction phase is performed by a data processing unit (4) and follows a transmission of at least part of the microphone signal from said search drone (1) towards the said data processing unit (4).

[0100] According to a further non-limiting aspect, the calculation of the arrival time (TOA,), respectively of the power (SSi), of the microphone signal of each of said at least one first, second and third microphone (5) and an electronic calculation performed by a data processing unit (4) installed on board the research drone (1).

[0101] According to a further non-limiting aspect, the calculation of the arrival time (TOA,), respectively of the power (SS,), of the microphone signal of each of said at least one first, second and third microphone (5) and a calculation electronic

performed by a data processing unit installed in a remote position with respect to the research drone (1), and follows a transmission of at least part of the microphone signal from said research drone (1) towards the remote data processing unit.

[0102] According to a further non-limiting aspect, the method comprises a memorization step of at least part of the microphone signal inside a recorder positioned on board the search drone (1), and the transmission step of at least part of the signal microphone from the research drone (1) to the data processing unit follows said storage.

[0103] According to a further non-limiting aspect, the method comprises a step of receiving a global satellite positioning signal on the search drone (1), following which a geographical position of the search drone (1) is electronically determined.

[0104] According to a further non-limiting aspect, said global satellite positioning signal is a signal of the GPS and/or Glonass and/or Beidou, and/or Galileo type.

[0105] According to a further non-limiting aspect, the method comprises the execution of an RTK (Real Time Kinematic) algorithm for improving the positioning accuracy of the search drone (1) following reception of said global satellite positioning signal , optionally wherein said RTK algorithm is configured to obtain an improvement in the positioning accuracy of said search drone (1) with precision at the centimeter level.

[0106] According to a further non-limiting aspect, the method comprises exploiting a global satellite positioning signal improvement system, said improvement system being configured to obtain an increase in the positioning accuracy of the search drone (1), said improvement of the global satellite positioning signal optionally including at least one of the systems in the following list: WAAS, EGNOS, GAGAN, MSAS.

[0107] According to a further non-limiting aspect, the position of said source of audio signals is localised, and/or a geographical position thereof is determined, following the reception of the satellite positioning signal and by means of the calculation of the arrival time (TOA,) and Tone Strength (SSI).

[0108] According to a further non-limiting aspect, the method comprises an electronic association step between an identifier of an audio signal source (200, 300) and the geographic position of the audio signal source (200, 300) itself.

[0109] According to a further non-limiting aspect, the method comprises the activation of a beacon device (200) for searching for subjects, worn or in any case transported by a user, in which, following said activation, an audio emitter (201) of said beacon device (200) emits an audio signal at at least one predetermined frequency or range of frequencies so that this audio signal can be received by at least one microphone (5) of the search drone (1).

[0110] According to a further non-limiting aspect, the method comprises the emission, by the audio emitter (201), of an audio signal at a frequency between 600Hz and 1800Hz, preferably between 800Hz and 1600Hz, more preferably between between 1000 Hz and 1400 Hz, more preferably substantially comprised in the neighborhood of 1200 Hz.

[0111] According to a further non-limiting aspect, the method comprises the emission, by the audio emitter (201), of an audio signal with a power of at least equal to 80dB, more preferably at least equal to 90 dB, more preferably at least equal to 100dB, more preferably at least equal to 110dB.

[0112] According to a further non-limiting aspect, the drone is configured to move automatically towards the audio source (200, 300), in order to assume a geographical position substantially coinciding, in particular at least on the horizontal plane, with the geographical position assumed by the audio source itself.

[0113] According to a further non-limiting aspect, the method comprises an electronic filtering of at least one microphone signal produced by the at least one microphone (5) in correspondence with a predefined band, said electronic filtering being configured to subtract noise components from the microphone signal and/or audio signals of no interest.

[0114] According to a further non-limiting aspect, the electronic filtering takes place by means of at least one filter for each of said first, second, third and, optionally fourth, microphone (5); each filter being configured to allow the electronic filtering of the microphone signal produced by the respective first, second, third and, optionally, fourth microphone (5) in correspondence with a predefined band.

[0115] According to a further non-limiting aspect, the predefined band is between 600Hz and 1800 Hz, preferably between 800 Hz and 1600 Hz, more preferably between 1000 Hz and 1400 Hz, more preferably substantially between 1200 Hz.

[0116] According to a further non-limiting aspect, the filtering is hardware filtering and/or software filtering, of the band-pass type.

[0117] According to a further non-limiting aspect, the band-pass type filtering phase is performed on board the drone.

[0118] According to a further non-limiting aspect, the band-pass filtering step is performed before the active noise reduction step and/or before the step of calculating said arrival time (TOA,) and said signal power ( SS,).

[0119] According to a further non-limiting aspect, the source of audio signals (200, 300) comprises a beacon device (200) configured to emit audio signals, in particular of a predefined type.

[0120] According to a further non-limiting aspect, the source of audio signals (200, 300) is a source wearable and/or transportable by the user.

[0121] According to a further non-limiting aspect, the method comprises a mapping step, in particular electronic mapping, of a plurality of audio signal sources (200, 300), said mapping step comprising the localization of a plurality of audio signal sources audio signal (200, 300) according to one or more of the foregoing aspects.

[0122] According to a further non-limiting aspect, the method comprises an emission step of an audio signal, optionally an ultrasound signal and/or an infrasound signal, by at least one audio beacon installed on board the search drone ( 1), so that the emitted signal said beacon can be reflected by a source (300) acting as a passive source and/or by reflection.

[0123] According to a further non-limiting aspect, the method comprises an at least partial reflection of part of the audio signal transmitted by the beacon installed on board the search drone (1), said at least partial reflection being performed by the source (300) and causing a retransmission of said at least part of the audio signal towards the at least one microphone (5) of the search drone (1).

[0124] According to a further non-limiting aspect, the method comprises the installation and/or use of at least one vibrometer installed on board the research drone (1) to electronically determine a differentiation between a vibration and/or reverberation of the ground in a first configuration and ground vibration and/or reverberation in a second configuration; said ground vibration and/or reverberation resulting from a transmission of an audio signal, optionally an ultrasound signal and/or an infrasound signal, performed by an emitter device, optionally by the beacon installed on board the search drone (1).

[0125] According to a further non-limiting aspect, the first configuration is a configuration in which a mine buried in the ground is present; the second configuration is a configuration in which the said lead is absent.

[0126] According to a further aspect, a beacon device (200) for searching for subjects is described, said beacon device comprising a body, an audio emitter (201) configured to emit an audio signal at at least a predetermined frequency or range of frequencies , said device being configured to be carried and/or worn by a user and to direct an audio signal towards a search drone (1) according to one more of the present aspects, so as to allow said search drone (1) to locate the subject via said audio signal.

[0127] According to a further non-limiting aspect, the beacon device is configured to emit, via the audio emitter (201), an audio signal at a frequency between 600Hz and 1800Hz, preferably between 800Hz and 1600Hz, more preferably between 1000 Hz and 1400 Hz, more preferably substantially comprised in the neighborhood of 1200 Hz.

[0128] According to a further non-limiting aspect, the beacon device is configured to emit, through the audio emitter (201), an audio signal with a power of at least equal to 80dB, more preferably at least equal to 90 dB, more preferably at least equal to 10OdB , more preferably at least equal to 110 dB.

[0129] According to a further non-limiting aspect, said beacon transmits said audio signal in the form of a burst and/or in discontinuous mode, optionally by spacing time intervals in which an audio signal is emitted by the audio emitter (201) at intervals of time in which the audio emitter (201) does not emit any audio signal.

[0130] According to a further aspect, a kit is described comprising a search drone (1) according to one or more of the present aspects, and a beacon device according to one or more of the previous aspects.

[0131] According to a further aspect, the use of the search drone (1) is described in accordance with one or more of the previous aspects, for the search and/or rescue and/or tracking of subjects, in particular of people or animals, and/or for the search and/or tracking of objects.

[0132] According to a further aspect, the use of the search drone (1) is described in accordance with one or more of the previous aspects, for the localization and/or electronic mapping of at least one, preferably a plurality, of sources (200 , 300) of audio signals.

[0133] According to a further non-limiting aspect, the source (200, 300) of audio signals is an active source.

[0134] According to a further non-limiting aspect, the audio signal source (300) is a passive source, in particular configured to reflect at least a part of an audio signal transmitted towards it by an emitter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0135] The description of the present invention will be made in relation to some possible embodiments of a search drone:

- figure 1 illustrates a first perspective view of a research drone object of the present disclosure;

- figure 2 shows a side view of the search drone object of the present disclosure;

- figure 3 shows a plan view of the research drone object of the present disclosure;

- figure 4 and figure 5 illustrate the respective partial perspective sections of part of the research drone object of the present disclosure;

- figure 6 illustrates a detail of part of an arm of the research drone subject of the present disclosure;

- figure 7 illustrates a section of an engine unit of the research drone object of the present disclosure

- figure 8 illustrates a front perspective view of the research drone object of the present disclosure; And

- figure 9 illustrates a rear perspective view of the research drone object of the present disclosure.

[0136] The invention is not limited to the embodiments illustrated in the accompanying figures. Therefore, it is to be understood that where features or parts of the subject matter of the present disclosure are identified by signs, particularly numerals, of reference, such signs are included solely for the purpose of enhancing the intelligibility of the description and the claims, and are not intended in any way as limiting.

DETAILED DESCRIPTION

[0137] With reference to the annexed figures, and in particular to figure 1, a drone for searching for audio sources is described. The drone object of the present disclosure exploits at least one microphone to allow the source of an audio signal to be located.

[0138] The drone in the form shown in the annexed figures is a quadcopter drone, without connections to the ground and equipped with a frame 2 which includes a central body 2c from which four arms identified by the reference number 2b depart. The absence of connections to the ground allows the drone great operational flexibility, and allows it to reach even remote places with the limitation mainly due to the autonomy in flight given by the batteries. In a non-limiting embodiment, which is the one illustrated in the accompanying figures, each of the four arms 2b has a section identifying a curved profile without angular points, and preferably this profile is circular. Thanks to this aspect, the arms take on an optimal shape from an aerodynamic point of view.

[0139] The drone object of the present disclosure is substantially devoid of external cables, above all cables protruding and returning from the central body 2c and/or from the detection module 20, with the possible exception of the microphone cables and/or the reference sensors which will be described in detail below. The absence of "flying", or in any case free cables, in addition to giving the drone a "clean" appearance also from an aesthetic point of view, helps to increase the level of robustness of the drone with respect to hostile environments, characterized by dust or other agents atmospheric. The non-limiting embodiment illustrated in the figures of the present disclosure is characterized by a protection level of IP 65, or higher. Thanks to this aspect, the drone object of the present disclosure can for example be used for applications, for example in a tropical environment and/or in a polar environment.

[0140] Although in the annexed figures and in the subsequent description reference is made to a drone of the quadricopter type, this configuration must not be understood in a limiting way, since the number of rotors, and therefore of arms 2b which depart from the central body 2c could vary accordingly.

[0141] The arms 2b of the drone object of the present disclosure are identical, therefore the structure of only one arm 2b is described hereinafter.

[0142] Each arm 2b departs radially from the central body 2c along a substantially horizontal direction. A first end portion of the arm 2b is fixed to the central body 2c and the second end portion of the arm 2b, opposite to the previous one, is free and constitutes the radially outermost portion of the drone 1.

[0143] At an intermediate portion, the arm 2b has a support tip 6 configured to support at least part of the search drone 1 when on the ground, and configured, in use, to make contact with the ground at a its end portion. The support tip 6 has a first end fixed at the arm 2b and a second end opposite to the previous one, which is the one in use and intended to rest on the ground.

[0144] Each arm 2b also comprises a stiffening beam 6k which is fixed to the support ferrule 6 at a first end and is fixed to a portion of the arm 2b, at a second end thereof opposite to the first. The first and second ends are respectively fixed to the support tip 6 and to the arm 2b by means of respective joints 2g. The purpose of the stiffening beam 6k is to allow strengthening of the arm 2b at least in a plane parallel to the vertical direction; the use of the stiffening beam 6k must not be understood in a limiting or necessary way, but is particularly convenient when the radial extension of the arm 2b, ie its length, is significant.

[0145] At an intermediate portion of the arm 2b there is a motor indicated with the reference number 3. This motor, which is an electric motor, powers a rotor 12 which in the accompanying figures and - without limitation - a rotor 12 in rotation with two opposing blades. The axis of rotation of the blades is parallel to the vertical axis. In the embodiment illustrated in the annexed figures, the motor 3 is installed substantially in correspondence with the portion of the support rod 6 joined to the arm 2b, and therefore and substantially overlying the first end of the support rod 6 itself, therefore in an intermediate position and preferably at substantially half the length of the arm. The joints 2g are installed in the middle of the semi-portion of the arm 2b which connects the motor 3 with the radially outermost part of the arm itself.

[0146] Preferably, but not limitedly, the motor 3 is installed on a motor support 3a, which is fixed in a predefined position on the arm 2b in such a way as to surround at least part of it. The engine mount 3a lies in a lower position than the engine 3. In addition to supporting the engine 3, the purpose of the engine mount 3a is to reduce and/or break down the vibrations induced by the engine 3 and transmitted on the arm 2b up to the microphone 5 and /or to the central body 2c, which could compromise the quality of the flight and detection of the audio source.

[0147] The engine mount 3a and/or comprises a damper of the passive type, ie acting with an elastic action to reduce vibrations which is not compensated by active means such as motors or actuators. The engine support 3a, which in the annexed figures has a substantially square shape, comprises four elastic buffers at its corners, each provided with a sealing screw 3v. Each elastic pad is divided into three subsections, of which a first and a first subsection placed at a first and greater level, a second and a second subsection placed at a second and intermediate level and a third and a third subsection placed at a third level lower than the first and second. Each subsection is elastic, and subsections can have distinct degrees of elasticity. [0148] The engine support 3a is fixed to the arm 2b of the frame 2 partly by means of a keying and in general with a fastening without screws or other control elements, and partly by means of two screws suitable for preventing rotation of the engine support 3a around the axis along which the arm 2b extends substantially and/or mainly (the axis substantially lying in the horizontal plane). Thanks to this aspect, the weight of the drone is further contained.

[0149] The central body 2c is a body with a substantially square section, installed in a central position of the drone 1 and without an engine. The purpose of the central body 2c is to contain the power sources and the ESC flight stabilization modules as well as to support the detection electronic module 20 containing all the circuits of the drone object of the present disclosure, which will be better described in the following portion of description.

[0150] As can be seen in the annexed figures, the central body 2c has a main cavity 11a and a secondary cavity 11k positioned under the main cavity and of a more modest size. The main cavity contains batteries (not shown in the figure) which serve at least to supply electrical power to the motors of the drone 1, and optionally also power the electronics of the drone itself. In a preferred and non-limiting embodiment, the above batteries are lithium batteries. On the lower portion of the central body 2c, openings and/or contacts are present which allow the batteries of the drone to be recharged, in particular on a dedicated landing station, and in turn equipped with counter-contacts configured to couple to said contacts at the moment of landing of the drone.

[0151] The main cavity 11a and/or the secondary cavity 11k of the central body 2c are cavities ventilated, preferably passively, through openings 11v positioned perimetrically on the lateral surface of the central body 2c. The openings 11v are configured to allow aeration of the main cavity 11a and/or of the secondary cavity 11k, avoiding the unwanted entry of rain or other atmospheric agents. These openings allow the inflow and outflow of fresh air into and out of the aforementioned cavities. In particular, these 11v openings make it possible to expel hot air generated by the overheating of the batteries in the hot months, reducing the risk of overheating above a safe temperature, thus guaranteeing optimal discharge of the batteries, increasing their life.

[0152] Laterally, the central body 2c comprises a compartment 11z, preferably a plurality of compartments 11z, for ESC flight stabilization modules (not shown in the figures), which comprise electronic circuits configured and/or programmed at least to allow to manage the stabilization and movement of the drone in flight, in particular by coordinating the electric power to be supplied to the motors 3 in a controlled manner. The 11z bays can also accommodate electronic modules for drone telemetry management, and/or can accommodate electronic modules for active noise reduction. Preferably, as illustrated in the accompanying figures, the flight stabilization modules are positioned close to the drone batteries. Thanks to this aspect, part of the heat generated in use by the aforementioned modules can be directed towards the batteries of the drone, heating them. This heating is useful for preventing the batteries from freezing if the drone object of this disclosure is used in the winter months or in any case in particularly cold conditions.

[0153] At the lower perimeter, the central body 2c has at least one, optionally a plurality of antenna supports 8, which are configured to accommodate one or more antennas dedicated to receiving radio commands from the user interface device 100, ehe and for example and not limited to a remote control. Such stands can be positioned so that one antenna is perpendicular to the other to optimize reception. Alternatively, or in combination, the drone described here has a tracking device which is configured to move the aforementioned directional antenna based on the position of the drone and the position assumed by the remote control identified by the reference 100. The antennas supported by the antenna supports 8 can be directive or omnidirectional. The antenna supported by the antenna mounts 8 is preferably operationally connected with the data processing unit 4 and is configured to receive and/or transmit radio signals from and/or to a radio controller 100 for the search drone 1.

[0154] Each of the arms 2b of the drone is introduced and fixed to the central body 2c without the aid of screws: thanks to this aspect, the sturdiness and at the same time the lightness of the drone object of the present disclosure are increased.

[0155] The central body 2c has a flat surface at the top where, in correspondence with predetermined holes, there are passive damping elements 11d, which are configured to absorb vibrations which would otherwise be transmitted to an electronic detection module 20.

[0156] In fact, the drone 1 object of the present disclosure comprises a detection electronic module 20 which houses the data acquisition and data transceiver control electronics from and to the drone 1. The passive damping elements 11d can for example be rubber buffers positioned substantially along the perimeter between the electronic detection module 20 and the central body 2c. In the annexed figures, the number of such passive dampers is equal to four units. Thanks to this aspect, any vibrations which may occur during flight and spread towards the central body 2c are effectively damped. In this way also the images and videos captured by the video camera 40 are more stable, and less affected by micro-vibrations. The electronics contained in the electronic sensing module 20, being less affected by vibrations, and less affected by the risk of breakage or damage.

[0157] The electronic detection module 20 comprises a global satellite positioning module (not shown in the figures), in particular a GPS and/or Glonass and/or Beidou and/or Galileo module, provided with its own first antenna, and configured to receive global satellite positioning signals in order to determine a geographical position of the drone 1.

[0158] The survey electronic module 20, or in any case the drone 1 in its more generic configuration, can optionally comprise a module (possibly replaced by the data processing unit 4) for executing an RTK (Real Time Kinematic) algorithm for improving the positioning accuracy of the search drone following receipt of said global satellite positioning signal; said RTK algorithm is configured to obtain an improvement in the positioning accuracy of said drone for centimeter-level precision research.

[0159] Also optionally, the drone object of the present disclosure can comprise a receiver for a system for improving the global satellite positioning signal, to obtain an increase in the positioning accuracy of the drone for research itself. For example, the global satellite positioning signal enhancement system optionally including at least one of the systems in the following list: WAAS, EGNOS, GAGAN, MSAS.

[0160] The electronic detection module 20 also comprises a telemetry module 9t, preferably equipped with at least its own second antenna 9, capable of transmitting and receiving telemetry data respectively from and/or towards the drone starting from and/or towards a remote electronic device such as, for example and not limited to, a personal computer or equivalent device.

[0161] The electronic detection module 20 also comprises a video camera or video camera 40, configured to film an area surrounding the drone 1 in a direction substantially including the horizontal plane of the drone itself. In detail, this video camera is positioned in a fixed manner on the electronic detection module 20 and is operatively connected to a dedicated video data transmission module provided with its own first antenna 7 in order to allow the remote transmission of images and/or videos towards a remote device on a wireless channel. The antenna 7 is preferably but not limited to a helical type antenna and extends out of the body of the electronic detection module 20.

[0162] The detection electronic module 20 is a module whose electronic components can heat up considerably. In order to reduce the risk of overheating beyond a predetermined safety temperature, this electronic detection module 20 has been equipped with a fan 50 configured to cause active ventilation of the inside of the electronic detection module itself and therefore of the electronic components housed therein ; in a non-limiting embodiment, this fan 50 is a suction type fan, ie configured to suck the air from inside the electronic detection module 20 and push it towards the outside of the module itself. In particular, the air is sucked in through openings 20i positioned in correspondence with the electronic detection module 20.

[0163] In a non-limiting embodiment, this fan 50 is configured to actively cool the video camera 40 and/or a dedicated video data transmission module.

[0164] Although the position of the openings 20i of the electronic detection module 20 should not be understood as limiting, these openings are preferably positioned in correspondence with a lower portion of the electronic detection module itself, in particular in a position substantially corresponding to the junction with the central body 2c of the frame 2. Thanks to this aspect, these openings are sheltered from the rain, and the risk that part of the latter may enter even significantly within the module described here is reduced, with consequent protection of the electronics present there. Always preferably, these openings are positioned in a frontal position of the drone, and this frontal position substantially coincides with the predefined direction of advance of the drone, in turn determined by the axis of the video camera 40. In fact, the dimensions and application of the drone described here are such that this can be made to fly even very remotely with respect to a remote control, so that it can also be lost from sight by the pilot. In this case, through the telemetry module 9t and the antenna 7, in addition to the control signals of the motors 3 and the stability of the drone, electronic data are also transmitted - from the drone to the remote control, and in real time - containing images taken by the video camera 40. For the purposes of this disclosure, therefore, "forward" direction is understood as the direction towards objects pointed by the axis of the video camera, as "backward" direction is understood as the opposite direction, i.e. moving away from objects pointed by the camera axis. Left and right directions will be defined with respect to the camera axis.

[0165] In one embodiment, such a video camera 40 is a video camera which captures images only in the visible spectrum. In an alternative embodiment such a video camera is designed to allow infrared reception, so

to be able to allow the control of the drone even in a dark environment, especially the net; this video camera can also be - also in combination with what has been described - a video camera of the thermal type. Optionally, this video camera can be associated with and/or include a rangefinder.

[0166] The frame 2 of the research drone 1 object of the present disclosure is preferably made of plastic material. Thanks to this aspect, the weight of the drone 1 is contained, and with the same battery capacity and consumption of the motors 3, it can accommodate a higher payload or, equivalently, have a greater flight range. In a particular embodiment of the drone 1 object of the present disclosure, the frame 2 of the drone is 3D printed, and this allows a considerable saving in production costs. The aforementioned plastic material is a plastic material of the polyamide-based type or in any case a thermoplastic material. Preferably, if polyamide, this polyamide is glass filled (e.g. PA 3200GF) and/or is aluminum filled polyamide (Alumide) and/or carbon filled polyamide (e.g. PA 3200CF). Thanks to this aspect it is possible to maintain a higher strength and at the same time a lightness substantially equal to that found by using an unfilled thermoplastic material.

[0167] A particular, but non-limiting, embodiment of the research drone 1 object of the present disclosure, comprises a body 2c, and/or the electronic detection module 20, and/or the motor supports 3a, made of plastic material substantially transparent or light colored, preferably but not limited to white. Thanks to this aspect, during use in the warmer months, the heating of the drone and its internal electronic components due to the influence of the sun's rays is decreased, and it is therefore possible to avoid using active cooling elements, where possible.

[0168] As previously mentioned, the drone is equipped with at least one microphone 5 configured to allow detecting an audio signal source. In general, this drone integrates a system, comprising a data processing unit 4, configured to identify the position of said source of audio signals with respect to the position assumed by the drone itself, searching for its direction and/or distance from the drone.

[0169] In principle, the aforementioned system can be configured to search for any type of audio signal, and therefore be programmable to search for a specific type of audio signal; in a preferred, albeit non-limiting, embodiment, the data processing unit 4 installed on board the research drone and configured to identify or in any case search within the microphone signal for a signal, in particular a waveform, compatible with that of a sample signal variably selected by a user. Alternatively, the data processing unit 4 is configured to identify or in any case search within the microphone signal for a signal, in particular a waveform, compatible with that of a sample signal stored in the data processing unit itself or in a memory made operationally accessible by the data processing unit itself.

[0170] This source is represented in figure 1 with the reference 300 or with a beacon 200 for the emission of audio signals which will be better described in the following description portion.

[0171] In a preferred and non-limiting embodiment, the drone object of the present disclosure comprises a microphone 5 installed at the radially outer end of the arm 2b; in a first non-limiting configuration, the microphone is a directional microphone and is designed to allow the reception of audio signals only starting from a predetermined direction. The distance which exists between each microphone 5 and the respective motor 3 (respectively installed in the radially outermost end and substantially corresponding to the median portion of the arm 2b) helps to reduce the amount of noise which the microphone 5 receives from the motor 3 during use. It should be noted that this noise comprises both an aerodynamic noise produced by the rotors 12 of the engine and a noise proper to the engine 3 itself.

[0172] Preferably this microphone 5 is designed to allow the reception of audio signals coming from a lower altitude than the altitude at which the drone 1 is located. The microphone 5 installed on the research drone 1 object of the present disclosure, and in particular a directive type microphone. This microphone 5 is therefore configured to receive an audio signal from a given direction or within a given angle (identified in figure 1 with the reference "A") audio signals which come from different directions and/or angles with respect to the predetermined ones. Thanks to In this aspect, the quality and accuracy of detection of the noise source are optimized.In fact, although the drone 1 in use produces noise through its motors 3, such noise is automatically filtered due to the directivity of the microphone 5. Compared to the use of a directional microphone, however possible, the influence of the noise of the motors 3 on the quality and accuracy of detection of the audio source is reduced.

[0173] The directivity of the microphone 5 must not be understood in a limiting way, since the microphone 5 can be an omnidirectional type microphone and thanks to this aspect it can be able to receive audio signals coming from sources located at a lower altitude, or equal to, or higher than the altitude at which the drone itself is located.

[0174] It has already been said that at least one microphone 5 is necessary. Cleverly, though not limitedly, the number of microphones 5 installed on board the search drone 1 is at least equal to 3 units. This allows triangulation of the audio source. However, the specific embodiment of the research drone 1 described here is equipped with four arms 2b: for this reason, the specific embodiment of the drone object of the present disclosure has four microphones 5, each installed on its own arm 2b. In particular, as can be seen from the annexed figures, on each arm 2b the microphone 5 is installed at the radially outermost end of the arm

same. Moreover, this, in addition to allowing the microphone to be moved away as far as possible from noise sources installed on board the drone itself, helps to reduce the precision dilution error which occurs in reading the arrival times of the audio signal from the source 200 , 300 compared to what would occur when an installation of the microphones finds a configuration such that they are all concentrated in a central position of the drone itself. The use of four microphones 5 advantageously allows to have an optimized triangulation of the audio source with respect to that which could be obtained using only three microphones. Moreover, since the membrane of the microphones is very sensitive, there could be the risk of it being damaged. In the case of three microphones this could be of considerable detriment for carrying out the search method described here and based on arrival times and power of the audio signal. Consequently, by using four microphones, even if one fails, the impact of this failure on the efficiency of the functionality of the search drone is progressively reduced. Obviously, this impact could be proportionally reduced by further increasing the number of arms and/or microphones.

[0175] The microphone 5 is operatively connected to the electronic detection module 20, and in particular to an on-board data processing unit by means of an electric cable and is configured to transform the audio signal into an electric microphone signal. The microphone signal need not be exclusively electric, because the electric cable could be replaced, for example, by an optical fiber; in this case the microphone signal would be an optical signal.

[0176] The microphone signal received by the microphone 5, optionally by the plurality of microphones 5 installed on board the drone 1, is memorized in a recorder, which, but not limited to, is of the hardware type and is installed in correspondence with the secondary internal cavity 11k of the body central 2c. In a particular non-limiting embodiment, the hardware recorder is integrated within the data processing unit 4.

[0177] The embodiment of the drone object of the present disclosure is advantageously equipped with a noise compensation system introduced by the motors 3 on the audio signal picked up by the microphones 5. In this way the quality of the audio signal which can be received is increased, and therefore sources of audio signals 300, 200 even of low power or very far from the drone can be effectively individualized and located.

[0178] To this end, at least one reference sensor 30 has been provided, configured to detect the noise of the engine 3 and to send a reference signal towards the aforementioned data processing unit 4 so that this data processing unit can subtract from the signal microphone the reference signal. In the embodiment illustrated in the annexed figures, the number of reference sensors is equal to the number of arms 2b; therefore, for each arm 2b there is a reference sensor 30, preferably positioned in a position radially more internal than the position assumed by the motor 3 on the arm 2b. This reference sensor 30 can be an infrared sensor (preferred), or equivalently be a microphone or accelerometric sensor, or an ESC (Electronic Speed Controller). The reference sensor 30 can be operationally, in particular electrically, connected to the telemetry module 9t in order to transmit towards the data processing unit 4, or towards a data processing unit external to the drone, data relating to at least the revolutions of the respective engine 3.

[0179] The particular embodiment conceived by the applicant has an infrared sensor mounted in such a way as to point the rotor 12 or, equivalently, receive infrared signals from a direction substantially and/or mainly coming from the rotor 12. This particular configuration allows to reduce the influence of the infrared radiation coming from the sun with respect to the useful infrared signal component received by the rotor 12. There may be elongated support elements (not shown in the annexed figures) which have a first end rigidly connected to the central body 2c ( or to the sensing module 20) and a second end at which the reference sensor 30 is fixed. In this way the positioning of the reference sensor can be released from the relative arm 2b.

[0180] Therefore, in the embodiment represented in the attached figures, for each arm 2b there are: a microphone 5 and a reference sensor 30. For each arm, the data processing unit 4 is configured to subtract from the microphone signal installed on a particular arm 2b, the reference signal of the same arm 2b. In this way it is possible to carry out an ad hoc noise compensation for each motor. Preferably but not limitedly, the compensation performed by the data processing unit 4 is performed in real time and is performed by a data processing unit located on board the drone. It should be noted that the active compensation of the noise produced by the motors 3 comes out together and in synergy with the directivity of the microphones 5: the combined use of an active compensation of the noise with the directivity of the microphones oriented in a different direction than that from the which noises from the engines 3 could reach, further optimizes the localization quality of the audio source.

[0181] A particular embodiment of the drone object of the present disclosure is characterized in that it can be disassembled. In particular, each of the arms 2b can be disassembled from the assembly formed by the central body 2c and the sensing module 20. More precisely, the assembly formed by the arm 2b - in its radially outermost portion of the motor assembly made by the motor 3 and by the support 3a - from the stiffening beam 6k and from the support ferrule 6 and, in a first alternative, a single assembly which cannot be disassembled operationally and can be disassembled from the arm portion 2b which is radially more internal than the previously mentioned motor group. In a further alternative, this assembly can instead be disassembled. This latter portion constitutes a second arm portion 2b distinct from the radially outer first portion, and the second portion is therefore immovably fixed to the central body 2c.

[0182] It should be noted that the term "irremovably fixed" must not be understood in absolute semantics, as inseparably and solidly produced with the central body in a single piece. This term means that in traditional operational use, the first portion of arm 2b radially more internal is not disassembled from the central body 2c. This disassembly, although possible, can be carried out in the event of overhaul or control or maintenance or replacement outside the traditional operational context. The same can be said for the term "operationally not disassembled" previously mentioned.

[0183] Thanks to this aspect, it is possible to store the drone in smaller spaces: in fact, each of the assemblies formed by the arm 2b - in its radially outermost portion of the motor unit made by the motor 3 and by the support 3a - by the stiffening beam 6k and from the support tip 6 and almost developing on two dimensions of main development. Therefore, the four assemblies can be superimposed, and for example and not limited to, placed in a container next to, above or below the drone, containing the overall volume occupied with respect to that otherwise necessary to house the entire drone. As can be seen from the annexed figures, the radial bulk of the four arms is significant with respect to the bulk possessed by the central body 2c with the detection module 20, and for this reason the dismantling of the arms 2b, more precisely of part of the arms 2b, leads to a significant advantage in terms of size reduction. This advantage is particularly felt by observing the real dimensions of the drone, which can even exceed the meter in diameter as a whole circumscribed by the union of the microphones 5.

[0184] The drone object of the present disclosure is configured to allow detection of the audio source by measuring a time of flight, or time of arrival (TOA,) and the power (SS,) of the audio signal.

[0185] In the particular embodiment of operation conceived by the inventors, it is calculated:

- a first arrival time (TOAt) of the audio signal coming from the audio source, by the first microphone 5,

- a second arrival time (TOA2) of the audio signal coming from the audio source, by the second microphone5,

- a third arrival time (TOA3) of the audio signal coming from the audio source, by the third microphone 5.

[0186] When the microphones 5 are equal in number to four units, as in the case of the attached figures, a fourth arrival time (TOA4) of the audio signal coming from the audio source, by the fourth microphone 5, is also calculated.

[0187] It is also calculated:

- a first power (SSt) of the microphone signal on the first microphone 5;

- a second power (SS2) of the microphone signal on the second microphone 5;

- a third power (SS3) of the microphone signal on the third microphone 5;

- (optionally) a fourth power (SS4) of the microphone signal on the fourth microphone 5.

[0188] The powers described here depend on the power of the audio signal. In particular, since the microphones 5 are preferably fixed gain microphones, the powers indicated above are equivalent to a first, second, third and optionally fourth power of the audio signal received on the first, second, third and fourth microphone respectively.

[0189] The electronic processing of the times of arrival (TOA,, TOA2, TOA3; optionally TOA4) and power of the signals (SS^ SS2, SS3; optionally SS4) coming from the various microphones, and such that from their electronic comparison , it is possible to determine the direction of origin and the distance of the audio signal transmitted from the audio source with respect to the direction of the drone. In particular, a given direction of advance of the drone is defined, which preferably though not limitedly can be the direction in which the video camera installed on board the drone 1 is oriented; on the basis of the arrival times and of the power of the audio signal on the various microphones 5, in particular on the basis of their difference, the direction with respect to said predetermined direction of advancement is established.

[0190] In a preferred but non-limiting embodiment, the first of the arrival times (TOA) of the audio signal on a specific microphone 5 is established as zero time, and the comparison of the remaining arrival times is carried out with respect to this first arrival time defined as time zero. The data processing unit 4 which performs the comparison of the times of arrival (TOA) and the power of acoustic signals (SSi) knows the position of each of the arms of the frame of the drone 1 and/or is able to establish a positional relationship of each of the arms 2b with respect to the forward or forward direction of the drone itself. This advantageously makes it possible to establish an angle of the microphone 5 with respect to the direction of origin of the audio signal, relative to the direction of advance of the drone on the basis of knowledge of the microphone 5 from which the audio signal itself came.

[0191] The data processing unit 4 which performs the comparison of the arrival times and the power of the acoustic signals, analyzes at least a predetermined portion of the microphone signal. This predetermined portion can be the entire microphone signal of each of the microphones 5 or a specific portion of the microphone signal, of shorter time length than, for example , what is recorded.

[0192] The data processing unit 4 executes an algorithm whereby, for each microphone signal received through each microphone 5, a search for peaks or maxima within the signal itself is performed in the time domain. The time corresponding to the reception of at least one peak or maximum on the microphone signal is electronically established as an arrival time. The height, or rather the width of the peak (optionally peak-to-peak), or the area under the peak

of the microphone signal is electronically established as power (SSJ) of the acoustic signal arriving at the respective microphone 5. The area under the peak can be equivalently replaced with a calculation of an RMS value.

[0193] The Applicant has devised two different embodiments, in which in a first the data processing unit 4 which performs the electronic calculation of the times of arrival and of the power of the audio signals towards the microphones 5, is installed on board the research drone 1. In an alternative embodiment, the data processing unit which performs the electronic calculation on the arrival times and power of the audio signals towards the microphone signals 5, and a remote data processing unit with respect to the assumed position from the research drone 1. In the latter case, at least part of the microphone signals picked up by the microphones 5 is transmitted towards the data processing unit positioned remotely with respect to the drone and, preferably, this transmission takes place by means of the antenna of the research module 9t telemetry. However, in order to offer data processing in sufficient time in relation to the amount of data to be transmitted, in this embodiment it may be convenient to carry out this transmission over a wireless optical channel and/or using a radio channel with 5G technology ; if a wireless optical channel is used, the drone object of the present disclosure will be equipped with a suitable optical modulator which includes at least one optical radiation emitting diode, operating in one or more of the ranges of the following list: visible, infrared (near and/or or far), ultraviolet (near and/or far).

[0194] Between the drone and an electronic device which includes the aforesaid data processing unit, a logical channel is created, preferably even though not limitedly secure and/or encrypted, and part of the microphone signals necessary for calculating the aforesaid are transmitted over the logical channel comparison of times of arrival (TOAi) and power of acoustic signals (SSi). Preferably, because without limitation the processing of the arrival times and the power of the audio signals, regardless of the embodiment in which the data processing unit is or is not installed on board the drone 1, takes place substantially in real time or in any case in the minimum possible interval with respect to the actual arrival time of the audio signal itself on the microphone. This allows you to optimize and speed up the audio source search phase.

[0195] Where the data processing unit is also positioned outside the body of the drone 1, when at least part of the processing of the microphone signal electronically performed through a data processing unit is performed in a remote position with respect to the assumed position from the drone, effectively a distributed computing environment. This distributed computing environment performs part of the operations of electronic processing of the microphone signal on board the research drone 1, and part of the operations of electronic processing of the microphone signal is performed in a remote position with respect to the drone itself. In particular, in this distributed computing environment, in accordance with what has been previously described, at least one active reduction of the noise of the microphone signal by means of the electronic subtraction of the reference signal from the microphone signal itself and performed on board the drone for research.

[0196] The applicant points out that the processing for the active cancellation of the noise produced by the motors 3 with respect to the microphone signal picked up by the microphones 5, makes it possible to reduce the size of the audio files stored on the recorder. When part of this microphone signal has to be transmitted to the data processing unit positioned remotely with respect to the drone 1, the active cancellation of the noise produced by the motors 3 makes it possible to take less time to transmit the aforementioned microphone signal or, equivalently, at the same time , requires less bandwidth on said logical channel. Conveniently, where active type noise cancellation is performed, such noise cancellation is always performed before performing the calculation on the arrival times and on the power of the audio signal.

[0197] Since the search drone 1 object of the present disclosure also comprises a receiver of global satellite positioning signals, it is possible to attribute a precise geographical position to the audio source.

[0198] In a first phase, the drone receives a signal from the satellite through which it is possible to calculate the position assumed by the drone itself. Subsequently, on the basis of the arrival time (TOAi) and the power of the audio signal (SS,) it is possible to estimate:

- a direction of origin of the audio signal with respect to the position determined by the progress of the drone

- the distance of the audio source from the drone itself.

[0199] In this way it is also possible to electronically calculate the geographical position assumed by the audio source.

[0200] A software program can therefore be described, which comprises portions of code which, when executed by the data processing unit, cause the execution of:

- a phase for calculating the times of flight or arrival (TOAi) and power (SS,) of an audio signal to one or more microphones 5 as previously described,

- a step for calculating a geographical position assumed by the drone 1 upon receiving a global satellite positioning signal (in particular by means of the at least temporary activation of the global satellite positioning signal receiver module), and

- a subsequent electronic processing step such that it is possible to attribute to the audio source which has broadcast an audio signal towards the plurality of microphones 5 an estimated geographical position on the basis of said time of flight or arrival (TOAi) and power of the audio signal (SS, ), and is the position assumed by the drone 1 object of the present disclosure, and by the electronically calculated direction from which the audio signal emitted by the audio source arrives with respect to a given direction of advance of the drone 1.

[0201] In a preferred and non-limiting embodiment, through the previously described Software program, the drone can be configured to move automatically towards the aforementioned audio source, in order to assume a geographical position substantially coinciding at least on the horizontal plane with the position geographical assumed by the audio source itself.

[0202] In other words, on the basis of at least the difference in arrival times (TOAj), and in particular also on the basis of the differences in the power of the audio signal (SSj) which reach each of the microphones 5, a direction from make the search drone 1 described here follow, so that the drone can be moved towards the position in which the audio signal source is present, and in particular the drone can be made to reach the vertical line of the audio signal source. For the purposes of this disclosure, it should be noted here that it is not necessary for the drone to approach the source itself vertically, and therefore it is not necessary for the drone to also complete a substantial landing or approach phase to the audio source such that, upon arrival on the vertical of the audio signal source, there is also a reduction in substantially vertical height.

[0203] In this position, the arrival times (TOA|) of the audio signal towards each of the microphones 5 positioned on each of the arms 2b of the frame 2, is identical and/or there is no difference between the aforementioned arrival times (TOAi ). It should be noted that this configuration also allows tracking a moving audio source 200: it is in fact sufficient to cyclically execute some subroutines of the previously described Software program to check whether there is a change in the reception of the arrival times of the audio signal transmitted by the source, and in the affirmative, proceed with the new movement of the search drone 1 so as to once again obtain the cancellation of the differences in arrival times (TOA) on the microphones 5 and the equalization of the powers received on each of the microphones 5.

[0204] In particular, the aforementioned tracking is performed by means of an automatic guidance step of the search drone 1 subject of the present disclosure, aimed at bringing the drone itself substantially close to the audio signal source 200, 300; preferably this substantial proximity is such that the drone, at the end of the driving procedure, is positioned substantially in alignment with the vertical of the audio signal source 200, 300.

[0205] The automatic guidance of the drone can be activated by a command imposed by the operator through the remote control of the drone itself. In this case, when this command is received through the telemetry module 9t, the data processing unit 4 present on board the drone itself configures itself in such a way as to move the drone by means of a selective activation of the motors 3, or their regulation independent of power or rotation speed, so that from the comparison of the arrival times of the audio signal on the microphones 5 present on each of the arms 2b there is an ever greater reduction of the temporal differences of the arrival times on the various microphones (5).

[0206] The applicant has also designed a beacon 200, which is configured and specifically designed to cooperate with the search drone 1 object of the present disclosure. The beacon 200 is in particular an audio source which emits an audio signal at a determined frequency or in a predetermined range of frequencies, specifically studied in order to be receivable as far away and as best as possible from the microphones 5 of which the drone subject of this disclosure and gifted. The beacon 200 described here, and in particular designed to be worn or in any case carried by a user. The beacon 200 comprises a body, and an audio emitter adapted to emit an audio signal receivable by the drone. This audio emitter 201 can be for example, and not limited to, a loudspeaker for example of the magnetodynamic type, or be or in any case include a loudspeaker of the piezoelectric type.

[0207] The range of frequencies emitted by the audio emitter 201 of the beacon 200, in order to obtain the aforementioned purposes, is preferably between 600 Hertz and 1800 Hertz, even more preferably between 800 Hertz and 1600 Hertz, and is still more preferably between 1000 Hertz and 1400 Hertz. The Applicant has in particular observed that an object of the present disclosure, in order to be received as far away as possible from the drone, is equal to 1200 Hertz. The audio signal emitted by the beacon 200 is preferably of the sinusoidal type. In any case, this specific waveform must not be understood as limiting since other waveforms, for example square or triangular wave, can be used to cause the audio emitter 201 to emit an appropriate audio signal.

[0208] The audio emitter 201 is in particular designed to produce a sound with a power of at least 80 decibels, preferably at least 90 decibels, more preferably at least 100 decibels, more preferably at least 110 decibels. This allows you to receive the audio signal at a sufficient distance and compatible with flying a drone over a certain area.

[0209] In a non-limiting embodiment, the audio emitter 201 is powered by a battery contained in the body of the beacon 200. In use, the user first wears the beacon 200 and then activates it when needed, for example and not limited to pressing an emergency button. At this point, the drone can be flown as previously described. When the drone 1 reaches an area close to that of the beacon 200 such that the audio signal emitted by it can be received by the microphones 5 with sufficient power to be distinguished from the background noise, the drone 1 searches for the geographical position of the beacon 200 as previously described.

[0210] When the search drone 1 described here is used to search for an audio signal coming from a beacon 200 actively emitting a frequency of known type, at least part of the electronic processing of the signal

performed by the data processing unit on board the drone 1, and/or in a device installed in a remote position with respect to that assumed by the drone itself, comprises a filtering step of the microphone signal. This filtering step is advantageously performed on each microphone signal of each of the microphones 5 installed at each arm 2b. This filtering step in particular comprises a band pass type filtering in which the pass band of said filtering corresponds to the signal bands previously described, it includes the central frequency of 1200 Hertz.

[0211] The filtering phase can be performed by a software filter, and therefore properly performed through a data processing unit, or it can be a filtering phase of the hardware type. In this case, the search drone 1 described here comprises, preferably for each microphone 5, a hardware filter of the band pass type which can be selectively activated in order to allow said filtering. The selective activation of the aforesaid filter can be advantageously performed through a command sent through the telemetry module 9t to the data processing unit installed on board the drone 1. The filtering phase is performed, in logical order, before the calculation phase and/or comparison of arrival times (TOAi) and, preferably, before subtracting the noise of the engines 3 by subtracting the reference signal.

[0212] Preferably, in order to optimize the ability of the beacon 200 to distinguish from other audio sources, especially continuous ones, a particular embodiment of the beacon 200 can be configured to transmit signals discontinuously, or "bürst" by alternating time periods, preferably of predetermined length, during which an audio signal is emitted with other time periods, equally of predefined length also different from the previously mentioned predefined length, during which the audio emitter 201 does not transmit any audio signal.

[0213] A first use for the beacon 200 described herein is to allow the search of human or animal subjects and in particular, in the case of human subjects, the search for search and rescue applications, for example for medical rescue applications. A further use for the beacon 200 is that of identifying objects, for example and not limited to bombs or mines. In this case, an expert operator who can be for example a bomb squad, when he finds a bomb or mine can associate it by depositing it in the vicinity of a beacon 200. In this case, the overflight by the drone 1 described here of an area where present one or more bombs allows to determine the position assumed by the same, so that it is possible to trace a geographical mapping of the position of several objects (in the specific case described here, mines or bombs) in the area of interest. The same concept of use for geographic mapping can be carried out for the position of several subjects, for example human beings, who wear the aforementioned beacon 200. Conveniently, where it is necessary to map several objects or subjects in a given area, have the audio emitter 201 of each beacon 200 an audio signal different from the one emitted by the other beacons 200 can help to carry out a rapid and precise determination of the position of each beacon 200. In a particular and non-limiting configuration, this mapping can be facilitated by having a each audio emitter 201 of each beacon 200 an audio signal at a different frequency from that emitted by the other beacons 200. Further applications of the research drone 1 object of the present disclosure can be mine clearance through the use of beacons installed on board the research drone same. These beacons can be of the ultrasonic type (frequencies above the audible spectrum) or infrasonic (frequencies below the audible spectrum). In this case the microphones receive the echo (ultrasonic and/or infrasonic) transmitted by the beacons and reflected by the possible presence of mines. The mine, in this case, behaves as a source, but it is not an audio signal source with active emission, but an audio signal source by reflection. In this case, preferably the number of beacons can be equal to the number of microphones and/or arms 2b present! on the drone. These beacons can be selectively activated independently of each other. The control of their selective activation can be carried out through the data processing unit 4. However, a configuration is also envisaged in which at least one beacon is installed on board the search drone 1 at the central body 2c. The beacons installed on board the search drone 1 may have the characteristics of the previously described beacons 200, or further or different characteristics.

[0214] Such beacons can preferably be of the directional type, and directed towards a predetermined downward radiation direction. It will be convenient to carry out a low altitude flight to obtain an optimal geographical positioning precision of the mines, in order to allow their electronic mapping. The mapping can be carried out both for metal mines and for mines with bodies substantially made of composite or plastic material. Thanks to this aspect it is therefore possible to carry out in a substantially automatic way an electronic mapping for mines which otherwise would not be possible to search through a metal detector. The reverberation of the ground in correspondence with a portion of land where mines are present, is different from the reverberation of the ground in portions where there are no mines.

[0215] In a particular embodiment, in order to obtain the aforesaid mapping, the research drone 1 object of the present disclosure has a vibrometer, able to receive an echo of ground vibration induced by the beacons described above. The aforementioned vibrometer can in particular be able to produce a map of vibration values per square unit of space, such that the buried mine can be distinguished from the remaining surrounding areas.

[0216] The data processing unit, or control unit, which has been described in the course of the previous part of the description may be a general purpose processor specifically configured to execute one or more parts of the process identified in the present disclosure through the Software or firmware program, or be an ASIC or dedicated processor or FPGA, specifically programmed to perform at least part of the operations of the process described herein.

Claims (10)

[0217] The memory medium can be non-transitory and can be internal or external to the processor, or control unit, or data processing unit, and can - specifically - be a memory geographically located remotely from the electronic processor. The memory medium can also be physically divided into several portions, or in the form of a "cloud", and the software or firmware program can physically include portions stored on memory portions geographically divided from each other. [0218] Finally, it is clear that parts of the object and process described herein may be subject to additions, modifications or variations, obvious to a person skilled in the art, without thereby departing from the scope of protection provided by the appended claims. Claims 1. Research drone (1), comprising: - a frame (2), - at least one motor (3) installed on said frame (2), said motor being configured to allow at least one take-off and/or landing and/or movement in forward flight of said search drone (1), - a data processing unit (4) housed at the frame (2) or within the frame (2), said data processing unit being configured at least to process a microphone signal; - at least one microphone (5) arranged on said frame (2), operatively connected to the data processing unit (4), said microphone being configured to receive an audio signal from a predetermined spatial position with respect to said search drone (1 ), said search drone (1) being characterized in that it comprises a system configured to locate at least one source (200, 300) of an audio signal and to electronically process a microphone signal comprising at least part of the audio signal received by said at least one microphone (5) in order to perform said localization. 2. Research drone (1) according to claim 1, comprising at least a first microphone (5), a second microphone (5) and a third microphone (5) each arranged on said frame (2), in particular on a respective portion of said frame (2), and operatively connected to the data processing unit, each of said first, second and third microphones being configured to receive an audio signal from a predetermined position with respect to said search drone (1). 3. Research drone according to claim 1 or claim 2, wherein said at least one first microphone (5) and a directional microphone, said system comprises a data processing unit installed on board the research drone (1) and the at least one microphone (5), optionally the at least a first, second and third microphone (5), and/are configured to transmit its own respective microphone signal towards the data processing unit (4). 4. Search drone according to one or more of the preceding claims, wherein: - the at least one microphone (5) is positioned in a peripheral position of the drone for research (1); optionally, the first, second and third microphones (5) are each positioned in a respective and distinct peripheral position of the search drone (1), - the frame (2) comprises a plurality of arms (2b) and a central body (2c) from which said arms (2b) depart; - the at least one microphone (5) is positioned in a peripheral and/or end position of said arm (2b), optionally at an end of said arm (2b) opposite to the end joint with the central body (2c) of the frame (2); and in which the at least one microphone (5) is directed substantially downwards, and/or is configured to receive an audio signal coming from a source which, when the search drone (1) is in flight, is at an altitude lower, optionally equal to and/or higher than the altitude at which the search drone is located. The search drone according to claim 4, wherein the at least one arm (2b) comprises a support tip (6) configured to support at least part of the search drone (1) when on the ground, and configured, in use, to contact the ground at an end position; the support tip (6) being positioned substantially in correspondence with said at least one motor (3), and/or being positioned substantially below said motor (3), and being configured to at least partially support its weight through a support substantially axially aligned with said motor (3). Research drone according to one or more of the preceding claims when dependent on claim 4, comprising at least one motor mount (3a) substantially installed at the at least one motor (3); the motor support (3a) is fixed in a predetermined position on said arm (2b); the engine mount (3a) being configured to accommodate the engine 3 and/or being a damper, optionally passive, configured to reduce and/or break down the vibrations induced by the at least one engine (3) and/or by the at least one rotor ( 12) on the frame of the research drone (1). The drone according to one or more of the preceding claims when dependent on claim 3, wherein said search drone (1), in particular the system configured to locate the at least one source (200, 300) of said audio signal, comprises a active noise reduction system, configured to reduce and/or eliminate from said microphone signal produced by the at least one microphone (5); an unwanted signal component due to the noise produced by the at least one motor (3) and/or by the rotor (12); Said active noise reduction system comprises at least one reference sensor (30), optionally a plurality of reference sensors (30) equal to the number of arms (2b) of the frame (2); said reference sensor being configured to detect the noise produced by said at least one motor (3), optionally by a respective motor (3), and also being configured to produce at the output a reference signal transmitted towards said data processing unit; said reference sensor is an infrared sensor, or a microphone sensor, or an accelerometer sensor, or an ESC (Electronic Speed Controller); the data processing unit comprising a first input, Hardware or Software, for the microphone signal coming from said at least one microphone (5) and a second input, Hardware or Software, for the reference signal coming from said reference sensor; the data processing unit being configured to subtract said reference signal from the microphone signal, optionally to subtract, for each arm (2b), the reference signal of the reference sensor installed on said specific arm (2b) from the microphone signal of the microphone (5) positioned on said specific arm (2b). A method of searching for an audio signal source (200, 300), said method comprising: - an overflight phase of a predefined area of territory by means of a search drone (1), said overflight phase being performed at least by activating at least one engine (3) of the search drone (1); - an activation of at least a first microphone (5) of said search drone (1) during at least the overflight phase, following which the microphone (5) transmits a microphone signal towards a data processing unit (4) positioned at search drone board (1), - electronic signal processing, performed to locate the position of at least one audio signal source (200, 300), said electronic signal processing comprising at least one data processing step performed on the microphone signal produced at the output from the first microphone (5) , said data processing step determining a position of the source (200, 300) of audio signals in relation to the position assumed by the drone for search (1). 9. Method according to claim 8, comprising the activation of at least three microphones (5) of said search drone (1), in particular a second and a third microphone in addition to said first microphone (5), optionally positioned in positions mutually distinct on said search drone (1), and the step of locating the position of the at least one source (200, 300) of audio signals comprises at least one data processing step performed on the microphone signal produced at the output of each of said three microphones (5). 10. Method according to claim 9, wherein the electronic signal processing step comprises calculating an arrival time (TOA|) and power (SS,) of the microphone signal of each of said at least one first, second and third microphones (5) to obtain a first, second, third arrival time (TOAt , TOA2, TOA3), and a first, second, third strength of the microphone signal (SS1, SS2, SS3); the electronic signal processing step comprising a comparison between said first, second and third arrival times (TOA1, TOA2, TOA3) and said first, second, third power of the microphone signal (SS^ SS2, SS3) to determine electronically the position of said audio source (200, 300) with respect to the position assumed by said search drone (1).