EP3390221A1 - Low-vibration drone - Google Patents
Low-vibration droneInfo
- Publication number
- EP3390221A1 EP3390221A1 EP16815958.0A EP16815958A EP3390221A1 EP 3390221 A1 EP3390221 A1 EP 3390221A1 EP 16815958 A EP16815958 A EP 16815958A EP 3390221 A1 EP3390221 A1 EP 3390221A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- powertrain
- drone
- rotor
- universal joint
- housing structure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000013016 damping Methods 0.000 claims description 12
- 239000012528 membrane Substances 0.000 claims description 9
- 230000005284 excitation Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000004075 alteration Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000002028 premature Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 230000033001 locomotion Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/001—Vibration damping devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U50/00—Propulsion; Power supply
- B64U50/20—Transmission of mechanical power to rotors or propellers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/001—Vibration damping devices
- B64C2027/002—Vibration damping devices mounted between the rotor drive and the fuselage
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U10/00—Type of UAV
- B64U10/10—Rotorcrafts
- B64U10/13—Flying platforms
- B64U10/14—Flying platforms with four distinct rotor axes, e.g. quadcopters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U20/00—Constructional aspects of UAVs
- B64U20/60—UAVs characterised by the material
Definitions
- the present invention relates to a multirotors drone. It relates more particularly to a drone comprising a fuselage and a plurality of housing structures for a plurality of powertrains.
- MTOW mini drones multirotors.
- These rotary wing aircraft consist of several rotors (at least 3) whose different thrusts allow lift and control of the drone.
- the main advantage of this configuration compared to conventional helicopters, lies in its simplicity: just a few motors directly driving rotors, controlled by an inertial unit and controlled by a small computer, to fly almost any object .
- Vibrations are particularly harmful for the reliability and precision of drones.
- the inertial units which determine the position of the drone in space, are very sensitive to vibrations. These can cause drift and disorientation of the drone which then becomes uncontrollable.
- the vibrations may also be responsible for disengagement in flight of the drone, because of the loss of fastening screws or premature structural fatigue, for example.
- the vibrations transmitted to the on-board sensors for the mission can drastically reduce the accuracy of measurements.
- the "rolling shutter” phenomenon well known to photographers, and directly related to the vibrations of a camera, which is responsible for obvious geometric aberrations.
- the reduction of the vibration level is therefore an essential problem for the design of a professional drone.
- the strategy currently implemented by the bulk of UAV manufacturers consists of isolating only the sensor (camera or other) from the structure of the drone via silentblocs. Although functional, this strategy has two major drawbacks: the vibrations are transmitted to the inertial unit, thus disturbing the reading of the accelerometers and gyroscopes which condition the stability of the flight and the structure of the drone remains subjected to vibrations, which can thus lead to serious problems of reliability (disruption of the inertial unit, loss of screws in flight, premature structural fatigue, etc.).
- EP 2599718 discloses a disk-shaped drone comprising a body housing a plurality of horizontally oriented rotors driven by motors. Each of the rotors is connected to the body through a support arm. The body serves as anchor for the rotor support arms. The body is centrally disposed in the platform casing.
- the object of the invention is to provide a device for isolating in a particularly effective manner the vibrations from a multirotor drone powertrain, while transmitting the necessary efforts to control the drone.
- the invention provides a drone comprising a fuselage and a plurality of housing structures in which are arranged a plurality of powertrains, a mechanical link between each powertrain and each powertrain housing structure, said mechanical connection between each power train and each powertrain housing structure comprising a flexible connecting member connecting the power train to the powertrain housing structure, said mechanical linkage between each powertrain and each powertrain housing structure further comprising a joint universal arranged in the axis of rotation of the powertrain, opposite the rotor.
- the flexible connecting element is remote from said universal joint.
- the universal joint is advantageously anti-torque.
- the flexible connecting element is an elastomeric membrane fixed on the one hand to the upper portion of the powertrain, and on the other hand to the housing structure.
- the universal joint has the advantage of being inexpensive, durable and effective.
- the universal joint comprises a spiral membrane cooperating on the one hand with the housing structure and on the other hand with the powertrain and a multiaxial flexible connection in which a prominent portion of the powertrain is inserted.
- FIG 1A is a schematic view illustrating the main efforts to be taken into account in a drone multirotors architecture
- FIG 1B is a sectional view in the vertical plane of the powertrain housing and the powertrain, with a symbolic representation of the damping system according to the invention
- FIG. 1C is a perspective view of an example of a drone provided with a plurality of powertrain housing structures arranged at the end of arms carried by the fuselage of the drone;
- FIG. 2 is a sectional view in the vertical plane of an example of a housing structure of the powertrain and an example of implementation of a damping system
- FIG 3 is a top view of the housing structure of the powertrain to see the extreme positrons allowed by the damping system according to the invention
- FIGS. 4A and 4B illustrate an example of a joint or ball joint according to the invention
- FIGS. 5A and 5B illustrate two examples of flexible fastening according to the invention.
- drone 1 is meant a remotely piloted aircraft as defined in the decree of 1 April 2012 on “the design of civil aircraft that circulate without any person on board, the conditions of their employment and capabilities required by the people who use them. In short, it is any aircraft capable of unmanned flight on board, which is controlled either by a computer (on board or on the ground) or by an operator on the ground, used for recreational purposes, competitions , or professional.
- rotary wing means any drone whose lift in the air is obtained by means of at least one rotor 6, allowing the drone to hover.
- the invention relates preferentially to multirotor drones equipped with three to eight rotors.
- powertrain 4" powertrain which comprises a motor, a rotor with fixed pitch or variable pitch, and all the transmission elements between the motor and the rotor 6 (reducer, rotor head, axis of rotation 5, blade holders, etc.)
- MOW means "maximum take off weight”, that is to say, the maximum take-off weight of an aircraft, the mass beyond which an aircraft can take off without potentially harming flight safety.
- Rolling Shutter image acquisition technique on a digital sensor, which consists in recording line by line the image received by the sensor. This technique causes geometric aberrations, or image distortions, when moving objects are being acquired or when the sensor is subjected to vibrations.
- Figure 1A illustrates the key forces involved in a rotor arrangement.
- the latter must be able to transmit the traction force.
- the torque transmitted by the motor must be supported by the fixing means.
- the fixing assembly in addition to being adapted to the latter constraints, must be able to damp the vibrations as well as possible.
- FIG. 1C illustrates an example of a multirotor drone 1 comprising a plurality of housing structures 3 such as that illustrated in the example of FIG. 1B.
- the objective sought by vibration isolation is to modify the stiffness of the connection between the exciting element and its support in the direction of excitation, so that the cutoff frequency of this link is significantly lower than the excitation frequency.
- the exciting element is the powertrain 4, and more precisely the rotor 6 where most of the vibrations (unbalance, geometric defect, etc.).
- the direction of the excitation is the plane materialized by the rotor disk 6.
- the support of the exciting element is the structure of the drone.
- the connection between the exciting element and its support is the attachment of the powertrain 4 in the housing structure 3 of the powertrain.
- the objective is to change the stiffness of the maintenance of the powertrain 4 in the plane of the rotor 6, while transmitting the torque and traction provided by the powertrain as shown in the diagram of Figure 1A.
- the invention proposes a mounting, as shown diagrammatically in FIG.
- this architecture makes it possible to transmit the traction and torque forces of the powertrain to the structure via the universal joint, while isolating the motions of the powertrain 4 in the plane of the rotor 6 thanks to the flexible connection elements 20.
- Figure 3 illustrates the beneficial effect of this configuration, using a top view of a powertrain 4 arranged in a housing structure 3.
- the solid lines represent the initial position of the bearing ball 7 of the rotor axis.
- the dashed lines represent the powertrain 4 in maximum deflection position.
- the characteristic length is defined as the distance L between the universal joint 10 and the plane of the rotor. To maximize the efficiency of the invention, this characteristic length must be related to the diameter D of the rotor 6, and a characteristic length is preferably chosen in the following ranges: a range of extended characteristic length for which the distance L is greater than or equal to 0.5.D and lower or equal to 2.D. A first preferred characteristic length range for which the distance L is greater than or equal to 0.2. D and less than or equal to 1, 5.D. Finally, a second preferred characteristic length range for which the distance L is greater than or equal to 0.5. D and less than or equal to 1 .D.
- the concrete embodiment of a universal joint connection 10 is complicated by the restricted space and mass constraints imposed by a multirotor drone. Added to this is the need to transmit the traction force provided by the powertrain 4 to the structure.
- conventional solutions such as blade coupling, cardan joints or Rzeppa gasket do not take up, or fail, traction.
- the GMP comprises a protruding portion 1 1 which fits into a homothetic hole of the joint, and of larger dimensions, by the company of a flexible multiaxial connection 13 put implemented for example by an elastomeric piece which cooperates with the structure of the drone around the hole.
- a spiral membrane 12 is fixed in its center on the powertrain 4, for example using the fasteners 14, and at its ends on the structure of the drone 1. It transmits rigidly the torque of the powertrain 4 to the structure of the drone while the multiaxial flexible connection 13 transmits almost rigidly the traction of the powertrain 4, while leaving it "swivel" around the joint, thanks to local deformations of the elastomeric part.
- FIGS. 5A and 5B show two exemplary embodiments of a flexible connection element 20.
- FIG. 5A shows an exemplary interface between the upper zone of a hollow-axis GMP with a "brushless" motor with a rotating cage with the housing structure 3.
- the figure illustrates the rotor 5 and the stator 8, the latter serving as an attachment point for an inner fixation 21 of a flexible membrane 20, cooperating on the other hand with the housing structure 3 at the Figure 5B shows an example similar to that of Figure 5A, for a full-axis GMP.
- the figure illustrates the rotor 5 and the stator 8, the latter serving as an attachment point for an inner fixation 21 of a flexible membrane 20, cooperating on the other hand with the housing structure 3 by means of an external fastener 22 .
- the main difficulty in the choice of flexible connecting elements 20 lies in the fact that a rotor 6 must accelerate to reach a nominal speed. During this acceleration phase, the natural frequency of the device will be reached and exceeded. During the passage of this natural frequency, it is necessary to have a damping coefficient sufficient to avoid a phenomenon of divergent resonance and potentially destructive. However, this damping must not be too high to avoid canceling the insulating effect of the link beyond this natural frequency.
- the flexible connecting elements 20 are preferably made using elastomeric materials (rubbers, silicones, latex, etc.).
- elastomeric materials rubbers, silicones, latex, etc.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Aviation & Aerospace Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Vibration Prevention Devices (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1502625A FR3045569B1 (en) | 2015-12-17 | 2015-12-17 | DRONE WITH LOW VIBRATION LEVEL |
PCT/IB2016/057651 WO2017103837A1 (en) | 2015-12-17 | 2016-12-15 | Low-vibration drone |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3390221A1 true EP3390221A1 (en) | 2018-10-24 |
Family
ID=55451252
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16815958.0A Pending EP3390221A1 (en) | 2015-12-17 | 2016-12-15 | Low-vibration drone |
Country Status (4)
Country | Link |
---|---|
US (1) | US20200262548A1 (en) |
EP (1) | EP3390221A1 (en) |
FR (1) | FR3045569B1 (en) |
WO (1) | WO2017103837A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT201700018546A1 (en) * | 2017-02-20 | 2018-08-20 | Sab Heli Div S R L | RADIO CONTROLLED HELICOPTER |
DE202017006861U1 (en) | 2017-08-08 | 2018-08-09 | HAVEL metal foam GmbH | drone |
CN113284134B (en) * | 2021-06-17 | 2023-09-26 | 张清坡 | Unmanned aerial vehicle flight platform for geological survey |
US20240239481A1 (en) * | 2023-01-17 | 2024-07-18 | Beta Air, Llc | A system and a method of vibration mitigation for an propulsor and a boom in an electric aircraft |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101042200B1 (en) * | 2010-09-02 | 2011-06-16 | 드림스페이스월드주식회사 | Unmanned flying vehicle made with pcb |
DE102011119590A1 (en) * | 2011-11-29 | 2013-05-29 | Aibotix GmbH | Remote controllable flight platform |
CN203318680U (en) * | 2012-10-29 | 2013-12-04 | 深圳市哈博森科技有限公司 | Four-rotor aircraft |
-
2015
- 2015-12-17 FR FR1502625A patent/FR3045569B1/en not_active Expired - Fee Related
-
2016
- 2016-12-15 EP EP16815958.0A patent/EP3390221A1/en active Pending
- 2016-12-15 WO PCT/IB2016/057651 patent/WO2017103837A1/en active Application Filing
- 2016-12-15 US US16/062,794 patent/US20200262548A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
FR3045569A1 (en) | 2017-06-23 |
WO2017103837A1 (en) | 2017-06-22 |
US20200262548A1 (en) | 2020-08-20 |
FR3045569B1 (en) | 2017-12-08 |
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