阅读说明：本技术 一种无人机复飞装置及无人机 (Unmanned aerial vehicle device and unmanned aerial vehicle fly back ) 是由 岳焕印 廖小罕 叶虎平 于 2020-06-19 设计创作，主要内容包括：本发明涉及一种无人机复飞装置及无人机,当无人机在飞行时或/和当无人机在准备起飞返程时,若其旋翼发生损坏时,则通过电磁铁装置控制磁性弹片远离电机移动,使卡持电机的挂钩与电机完全脱离,并在弹簧的作用力下,使电机沿滑槽向下移动,在电机沿滑槽向下移动时,通过设置在折叠桨叶上的支撑件与旋翼相抵,使电机的转轴与旋翼完全分离,并在电机沿滑槽向下移动时,使折叠在连接件外侧的折叠桨叶连接在转轴上,并在离心力的作用下,使折叠桨叶展开,此时,折叠桨叶向无人机提供升力,以保证无人机能正常飞行或/和正常起飞,减少用户损失,且不会危及他人的生命安全。(The invention relates to an unmanned aerial vehicle re-flying device and an unmanned aerial vehicle, when the unmanned aerial vehicle flies or/and when the unmanned aerial vehicle is ready to take off and return, if the rotor wing of the unmanned aerial vehicle is damaged, the electromagnet device controls the magnetic elastic sheet to move away from the motor, so that the hook clamping the motor is completely separated from the motor, and the motor moves downwards along the sliding chute under the action of the spring, when the motor moves downwards along the sliding groove, the rotating shaft of the motor is completely separated from the rotor wing through the support piece arranged on the folding paddle to abut against the rotor wing, and when the motor moves downwards along the sliding chute, the folding paddle folded at the outer side of the connecting piece is connected on the rotating shaft, and under the action of centrifugal force, the folding blades are unfolded, at the moment, the folding blades provide lift force for the unmanned aerial vehicle, so as to ensure that the unmanned plane can normally fly or/and take off, reduce the loss of users and not endanger the life safety of other people.)

1. An unmanned aerial vehicle fly-back device is characterized by comprising a connecting piece (1), a motor (2), a rotor wing (3), an electromagnet device (4), a magnetic elastic piece (5) and at least two folding blades;

the bottom end of the connecting piece (1) is connected with the body of the unmanned aerial vehicle, a cylindrical magnetic elastic piece (6) is arranged in the connecting piece (1), a magnetic elastic piece (7) used for covering the magnetic elastic piece (6) is arranged at the top end of the connecting piece (1), and a first opening concentric with the axis of the magnetic elastic piece (6) is arranged on the magnetic elastic piece (7);

one end of each magnetic elastic sheet (5) is connected to the corresponding magnetic elastic sheet (7), the other end of each magnetic elastic sheet (5) is provided with a hook (8), the plurality of magnetic elastic sheets (5) are circumferentially arranged along the corresponding magnetic elastic sheet (6), and the plurality of electromagnet devices (4) are embedded in the corresponding connecting piece (1) and correspond to the plurality of magnetic elastic sheets (5) one by one;

a first clamping table (9) which is outwards convex along the radial direction is arranged at the bottom end of the motor (2), a spring (10) which is in a compression state is arranged between the first clamping table (9) and the magnetic elastic sheet (7), hook parts of the hooks (8) are positioned below the first clamping table (9) and clamp the motor (2), and a rotating shaft (11) of the motor (2) penetrates through the first opening and is connected with the rotor wing (3);

the folding blade is also provided with a supporting piece (12) which is used for abutting against the rotor wing (3) when the motor (2) moves downwards along the magnetic elastic sheet (6) so as to completely separate the rotating shaft (11) from the rotor wing (3);

electromagnet device (4) are used for when rotor (3) take place to damage, control magnetism shell fragment (5) are kept away from motor (2) remove, so that couple (8) with motor (2) break away from completely, and under the effort of spring (10), make motor (2) follow magnetism shell fragment (6) downstream, and make and fold and be in the connecting piece (1) outside folding paddle connects on pivot (11), and under the effect of centrifugal force, make folding paddle expandes.

2. An unmanned aerial vehicle missed approach device of claim 1, characterized in that, the folding paddle includes fixed part (13) and is used for the folding portion (14) that expandes under centrifugal force, set up support piece (12) on fixed part (13), be equipped with 90 degrees auto-lock articulated elements (15) between folding portion (14) and fixed part (13).

3. The unmanned aerial vehicle device that flies repeatedly of claim 2, characterized in that, be equipped with on pivot (11) that the cross section is polygonal second ka tai (16), be equipped with in rotor (3) with the second opening of second ka tai (16) adaptation, second ka tai (16) and second opening are used for carrying out the joint before motor (2) moves down along magnetism shell fragment (6), so that rotor (3) and pivot (11) carry out synchronous rotation.

4. The unmanned aerial vehicle device of claim 3, wherein the other end of the fixed part (13) is provided with a recess adapted to the second clamping table (16), and the second clamping table (16) and the recess are used for clamping when the motor (2) moves downwards along the magnetic elastic sheet (6).

5. An unmanned aerial vehicle missed approach device of claim 2 or 3, characterized in that, still be equipped with on the top of motor (2) with pivot (11) concentric bearing (17), be equipped with connecting rod (18) between bearing (17) and fixed part (13).

6. An unmanned aerial vehicle fly-back device according to any one of claims 1 to 4, further comprising a controller, wherein the controller is configured to acquire lift force of each rotor (3) of the unmanned aerial vehicle, compare the lift force of each rotor (3) with a preset lift force one by one, and determine whether the rotor (3) is damaged according to the comparison result; and determining whether to send an instruction for controlling the magnetic elastic sheet (5) to move away from the motor (2) to the electromagnet device (4) or not according to the damage result.

7. An unmanned aerial vehicle fly-back device according to claim 6, wherein a buckle (19) for preventing the folding part (14) from unfolding before the motor (2) moves downwards along the magnetic elastic sheet (6) is further arranged between the folding part (14) and the connecting piece (1).

8. An unmanned aerial vehicle, characterized in that, an unmanned aerial vehicle fly-back device of any one of claims 1 to 7 is adopted.

Technical Field

The invention relates to the technical field of unmanned aerial vehicles, in particular to an unmanned aerial vehicle missed-flight device and an unmanned aerial vehicle.

Background

Along with the development of unmanned aerial vehicle technique, unmanned aerial vehicle can play more and more important effect in the middle of each field of each trade at home and abroad, and at present, unmanned aerial vehicle often can run into following problem, specifically:

1) when the unmanned aerial vehicle flies, if the rotor wing of the unmanned aerial vehicle is damaged, the unmanned aerial vehicle is often crashed, loss is caused to a user, and meanwhile, the life safety of people in the crash place is endangered;

2) when unmanned aerial vehicle lands and carries out the operation in a certain place and finishes, then when preparing to take off and return journey, if the rotor takes place to damage, make unmanned aerial vehicle can not normally take off to make unmanned aerial vehicle can not normally return, cause the loss for the user.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides an unmanned aerial vehicle fly-back device and an unmanned aerial vehicle.

The technical scheme of the invention is as follows:

the foldable propeller comprises a connecting piece, a motor, a rotor wing, an electromagnet device, a magnetic elastic sheet and at least two foldable blades;

the bottom end of the connecting piece is connected with a body of the unmanned aerial vehicle, a cylindrical sliding groove is formed in the connecting piece, a cover plate used for covering the sliding groove is arranged at the top end of the connecting piece, and a first opening concentric with the axis of the sliding groove is formed in the cover plate;

one end of the magnetic elastic sheet is connected to the cover plate, the other end of the magnetic elastic sheet is provided with a hook, the magnetic elastic sheets are circumferentially arranged along the sliding groove, and the electromagnet devices are embedded in the connecting piece and correspond to the magnetic elastic sheets one by one;

a first clamping table protruding outwards along the radial direction is arranged at the bottom end of the motor, a spring in a compressed state is arranged between the first clamping table and the cover plate, hook parts of the hooks are located below the first clamping table and used for clamping the motor, and a rotating shaft of the motor penetrates through the first opening and is connected with the rotor wing;

the folding blade is also provided with a supporting piece which is used for abutting against the rotor wing when the motor moves downwards along the sliding chute so as to completely separate the rotating shaft from the rotor wing;

the electromagnet device is used for controlling the magnetic elastic sheet to be far away from the motor to move when the rotor wing is damaged, so that the hook is completely separated from the motor, the motor moves downwards along the sliding groove under the action force of the spring, the folding paddle outside the connecting piece is connected to the rotating shaft, and the folding paddle is unfolded under the action of centrifugal force.

The unmanned aerial vehicle missed-flight device has the following beneficial effects:

when unmanned aerial vehicle when flight or/and when unmanned aerial vehicle is preparing to take off when returning, if when its rotor takes place to damage, then keep away from the motor through electromagnet device control magnetism shell fragment and remove, make the couple that the motor was held to the card break away from completely with the motor, and under the effort of spring, make the motor along spout downstream, when the motor along spout downstream, support piece through setting up on folding paddle offsets with the rotor, make the pivot and the rotor of motor separate completely, and when the motor along spout downstream, make folding the folding paddle in the connecting piece outside connect in the pivot, and under the effect of centrifugal force, make folding paddle expand, at this moment, folding paddle provides lift to unmanned aerial vehicle, in order to guarantee that unmanned aerial vehicle can normally fly or normally take off, reduce the user loss, and can not endanger other people's life safety.

On the basis of the scheme, the unmanned aerial vehicle missed approach device can be further improved as follows.

Further, the folding paddle includes fixed part and the folding portion that is used for expanding under the centrifugal force effect, set up on the fixed part support piece, the folding portion with be equipped with 90 degrees auto-lock articulated elements between the fixed part.

The beneficial effect of adopting the further scheme is that: under the effect of centrifugal force, can expand the folded part completely through 90 degrees auto-lock articulated elements, make the folded part can not take place to rock to guarantee that unmanned aerial vehicle can steadily fly.

Further, be equipped with the cross section in the pivot and be polygonal second card platform, be equipped with in the rotor with the second opening of second card platform adaptation, second card platform and second opening are used for the motor is followed carry out the joint before the spout downstream, so that the rotor with the pivot carries out synchronous rotation.

The beneficial effect of adopting the further scheme is that: the motor is followed before the spout downstream, to the second card platform with the second opening carries out the joint, so that the rotor with the pivot carries out synchronous rotation.

Further, the other end of fixed part be equipped with the depressed part of second card platform looks adaptation, the second card platform with the depressed part is used for the motor is followed carry out the joint when spout downwardly moving.

The beneficial effect of adopting the further scheme is that: the motor is followed during spout downstream, through carrying out the joint to second card platform and depressed part, connect the fixed part in the pivot, guarantee that folding paddle can rotate along with the pivot of motor.

Further, a bearing concentric with the rotating shaft is further arranged at the top end of the motor, and a connecting rod is arranged between the bearing and the fixing portion.

The beneficial effect of adopting the further scheme is that: before the motor moves downwards along the sliding chute, the fixing part is fixed through the connecting rod; the fixing part is connected behind the rotating shaft and is used for ensuring that the folding blades and the rotating shaft synchronously rotate through the bearing.

The unmanned aerial vehicle further comprises a controller, wherein the controller is used for acquiring the lift force of each rotor of the unmanned aerial vehicle, comparing the lift force of each rotor with a preset lift force one by one, and determining whether the rotor is damaged or not according to the comparison result; and determining whether to send an instruction for controlling the magnetic elastic sheet to move away from the motor to the electromagnet device according to the damage result.

The beneficial effect of adopting the further scheme is that: by acquiring the lift force of each rotor wing of the unmanned aerial vehicle, judging the lift force of each rotor wing and the preset lift force one by one, and determining whether the rotor wing is damaged or not according to the comparison result; and determining whether to send an instruction to the electromagnet device according to the damage result, and is simple and convenient.

Further, a buckle for preventing the folding part from unfolding before the motor moves downwards along the sliding groove is arranged between the folding part and the connecting piece.

The beneficial effect of adopting the further scheme is that: the folding part is prevented from unfolding before the motor moves downwards along the sliding groove by arranging a buckle between the folding part and the connecting piece.

The technical scheme of the unmanned aerial vehicle provided by the invention is as follows: adopt above-mentioned any one unmanned aerial vehicle device that flies repeatedly.

The unmanned aerial vehicle has the following beneficial effects:

when unmanned aerial vehicle when flight or/and when unmanned aerial vehicle is preparing to take off when returning, if when its rotor takes place to damage, then keep away from the motor through electromagnet device control magnetism shell fragment and remove, make the couple that the motor was held to the card break away from completely with the motor, and under the effort of spring, make the motor along spout downstream, when the motor along spout downstream, support piece through setting up on folding paddle offsets with the rotor, make the pivot and the rotor of motor separate completely, and when the motor along spout downstream, make folding the folding paddle in the connecting piece outside connect in the pivot, and under the effect of centrifugal force, make folding paddle expand, at this moment, folding paddle provides lift to unmanned aerial vehicle, in order to guarantee that unmanned aerial vehicle can normally fly or normally take off, reduce the user loss, and can not endanger other people's life safety.

Drawings

Fig. 1 is a schematic structural diagram of an unmanned aerial vehicle missed approach device according to an embodiment of the present invention;

FIG. 2 is a top view of the second boss coupled to the shaft and the rotor, respectively;

FIG. 3 is a top view of the second boss in engagement with the recess;

Detailed Description

As shown in fig. 1, the unmanned aerial vehicle missed approach device of the embodiment of the present invention includes a connecting member 1, a motor 2, a rotor 3, an electromagnet device 4, a magnetic spring 5, and at least two folding blades;

the bottom end of the connecting piece 1 is connected with a body of the unmanned aerial vehicle, a cylindrical sliding groove 6 is arranged in the connecting piece 1, a cover plate 7 used for covering the sliding groove 6 is arranged at the top end of the connecting piece 1, and a first opening concentric with the axis of the sliding groove 6 is formed in the cover plate 7;

one end of the magnetic elastic sheet 5 is connected to the cover plate 7, the other end of the magnetic elastic sheet 5 is provided with a hook 8, the plurality of magnetic elastic sheets 5 are circumferentially arranged along the sliding groove 6, and the plurality of electromagnet devices 4 are embedded in the connecting piece 1 and correspond to the plurality of magnetic elastic sheets 5 one by one;

a first clamping table 9 protruding outwards along the radial direction is arranged at the bottom end of the motor 2, a spring 10 in a compressed state is arranged between the first clamping table 9 and the cover plate 7, hook portions of the hooks 8 are located below the first clamping table 9 and clamp the motor 2, and a rotating shaft 11 of the motor 2 penetrates through the first opening and is connected with the rotor 3;

a support 12 is also arranged on the folding blade for abutting against the rotor 3 when the motor 2 moves downwards along the chute 6 so as to completely separate the rotating shaft 11 from the rotor 3;

the electromagnet device 4 is used for controlling the magnetic elastic sheet 5 to be far away from the motor 2 to move when the rotor 3 is damaged, so that the hook 8 and the motor 2 are completely separated, the motor 2 moves downwards along the sliding groove 6 under the action force of the spring 10, the folding paddle blade which is folded at the outer side of the connecting piece 1 is connected to the rotating shaft 11, and the folding paddle blade is unfolded under the action of centrifugal force.

When the unmanned aerial vehicle flies or/and when the unmanned aerial vehicle is prepared to take off and return, if the rotor 3 is damaged, the magnetic elastic sheet 5 is controlled by the electromagnet device 4 to move away from the motor 2, the hook 8 for clamping the motor 2 is completely separated from the motor 2, and under the action of the spring 10, the motor 2 moves downwards along the chute 6, when the motor 2 moves downwards along the chute 6, the support piece 12 arranged on the folding blade is abutted against the rotor 3, the rotating shaft 11 of the motor 2 is completely separated from the rotor 3, and when the motor 2 moves downwards along the chute 6, the folding blade folded outside the connecting piece 1 is connected on the rotating shaft 11, and under the action of centrifugal force, the folding blade is unfolded, at the moment, the folding blade provides lifting force for the unmanned aerial vehicle, so as to ensure that the unmanned aerial vehicle can normally fly or/and normally take off, thereby reducing the loss of users, and does not endanger the life safety of others.

In the present application, the missed approach can be understood as follows:

1) when the unmanned aerial vehicle flies, if the rotor wing 3 of the unmanned aerial vehicle is damaged, the unmanned aerial vehicle re-flying device can keep a normal flying state, namely the unmanned aerial vehicle re-flying;

2) when unmanned aerial vehicle lands and carries out the operation in a certain place and finishes, then when preparing to take off and return, if rotor 3 takes place to damage, make unmanned aerial vehicle normally take off, make its normal taking off through the unmanned aerial vehicle device that flies again of this application, also can understand as making unmanned aerial vehicle fly again.

Wherein, unmanned aerial vehicle's body indicates: with rotor 3 on the unmanned aerial vehicle and the relevant part of connecting rotor 3 demolish the remaining part in back, connecting piece 1 accessible welding mode, threaded connection mode are connected with unmanned aerial vehicle's body.

The cover plate 7 and the connecting member 1 can be fixed by welding or screwing, and the cover plate 7 and the connecting member 1 can be integrally formed.

Wherein, the material of magnetic shrapnel 5 can be 304 stainless steel, 403 stainless steel, 410 stainless steel, 414 stainless steel, 416 stainless steel etc. still have certain elasticity when having magnetism, and can be by 2, 3, 4, 5 and more magnetic shrapnels 5 along 6 circumference of spout arrange, correspondingly, the quantity of magnetic shrapnel 5 also is 2, 3, 4, 5 and more, and all set up 1 magnetic shrapnel 5 with the corresponding position of every magnetic shrapnel 5 in connecting piece 1, and electromagnet device 4's structure is:

copper coils are wound on the iron core, and the acting force of the electromagnet device 4 and the magnetic shrapnel 5 can be accurately simulated and calculated through finite element software such as ANSYS or MAXWELL, so that current is input to the electromagnet device 4, and the hook 8 is ensured to be completely separated from the motor 2.

Wherein, the first clamping platform 9 can be in the following form:

1) the first clamping table 9 is in a ring shape protruding outwards along the radial direction of the motor 2, so that the hook part of the hook 8 can clamp the first clamping table 9;

2) the first clamping table 9 is a protrusion protruding outwards along the radial direction of the motor 2, and the number of the protrusions is the same as that of the magnetic spring pieces 5, that of the electromagnet devices 4 or that of the hooks 8, so that the hook part of each hook 8 can conveniently clamp each protrusion.

Wherein, the concrete structure of support 12 is: with the concentric annular post of the pivot 11 of motor 2, and the size relation between support piece 12 and the rotor 3 can be obtained through simple calculation, in order to guarantee motor 2 is followed when spout 6 moves down, support piece 12 offsets with rotor 3 so that pivot 11 with rotor 3 separates completely, and can set up a plurality of support piece 12.

Preferably, in the above technical solution, the folding blade includes a fixed portion 13 and a folding portion 14 for unfolding under the action of centrifugal force, the fixed portion 13 is provided with the support member 12, and a 90-degree self-locking hinge 15 is provided between the folding portion 14 and the fixed portion 13.

Wherein, 90 degrees auto-lock articulated elements 15 can refer to folding hinge, exert an effort centrifugal force promptly to folding portion 14, and this effort centrifugal force promptly is greater than folding hinge's hinge power when, just can make folding portion 14 expand completely and folding portion 14 can not take place to rock to guarantee that unmanned aerial vehicle can steadily fly.

The fixing portion 13 and the supporting portion 12 can be fixed by welding or screwing.

Preferably, in above-mentioned technical scheme, be equipped with the second ka tai 16 that the cross section is polygonal on the pivot 11, be equipped with in the rotor 3 with the second opening of second ka tai 16 adaptation, second ka tai 16 and second opening are used for being in motor 2 follows carry out the joint before spout 6 moves down, so that rotor 3 with pivot 11 carries out synchronous rotation.

Before motor 2 along spout 6 moves down, to second ka tai 16 with the second opening carries out the joint, so that rotor 3 with pivot 11 carries out synchronous rotation.

The polygon may be a quadrangle, a pentagon, a hexagon, etc., and the hexagon is taken as an example, as shown in fig. 2, specifically:

fix the cross section for hexagonal second ka tai 16 and motor 2's pivot 11 through the welding mode, and be equipped with on rotor 3 with the second opening of second ka tai 16 adaptation, at this moment, second open-ended cross section also for using the hexagon, then carry out the joint with second ka tai 16 and second opening through interference fit's mode, in order to guarantee motor 2 is followed before 6 downstream of spout, rotor 3 carries out synchronous rotation with pivot 11, guarantees unmanned aerial vehicle's normal flight.

Preferably, in the above technical solution, the other end of the fixing portion 13 is provided with a recessed portion adapted to the second clamping table 16, and the second clamping table 16 and the recessed portion are used for clamping when the motor 2 moves downwards along the sliding groove 6.

Follow at motor 2 during spout 6 downstream, through carrying out the joint to second ka tai 16 and depressed part, connect fixed part 13 on pivot 11, guarantee that folding paddle can rotate along with motor 2's pivot 11.

The second chuck 16 with a hexagonal cross section is taken as an example for illustration, specifically:

1) when the number of the folding blades is 2, each folding blade comprises 1 fixing part 13, and there are 2 depressed parts, as shown in fig. 3, at this time, one depressed part is a half hexagon, and two depressed parts form a complete hexagon, at this time, when the rotating shaft 11 rotates, the second clamping table 16 is driven to rotate, and when the second clamping table 16 rotates, the 2 depressed parts can automatically clamp the second clamping table 16 and rotate along with the second clamping table 16;

3) when the quantity of folding paddle is 3, this moment, a depressed part is 1/3 hexagons, and 3 depressed parts form a complete hexagon, and at this moment, when pivot 11 is when rotating, drive second ka tai 16 and rotate, when second ka tai 16 rotated, 3 depressed parts can automatic card hold second ka tai 16 to rotate along with second ka tai 16, when the quantity of folding paddle is more, analogizes with this.

It should be noted that: the distance that motor 2 moved down along spout 6 accessible calculation obtains to guarantee when motor 2 moved down along spout 6, offset with rotor 3 through support piece 12 that sets up on folding paddle, make motor 2's pivot 11 and rotor 3 separate completely, and make the folding paddle that folds in the connecting piece 1 outside connect in pivot 11.

Preferably, in the above technical solution, a bearing 17 concentric with the rotating shaft 11 is further disposed at the top end of the motor 2, and a connecting rod 18 is disposed between the bearing 17 and the fixing portion 13.

The bearing 17 can be fixed on the top end of the motor 2 in a welding mode, or the bearing 17 is embedded into the top end of the motor 2, two ends of the connecting rod 18 are respectively connected with the fixing part 13 and the bearing 17 in a welding mode or a threaded connection mode, and the fixing part 13 is fixed through the connecting rod 18 before the motor 2 moves downwards along the sliding chute 6; the fixing part 13 is connected behind the rotating shaft 11, and a bearing 17 is used for ensuring that the folding blades rotate synchronously with the rotating shaft 11.

Preferably, in the above technical solution, the unmanned aerial vehicle further includes a controller, the controller is configured to acquire a lift force of each rotor 3 of the unmanned aerial vehicle, compare the lift force of each rotor 3 with a preset lift force one by one, and determine whether the rotor 3 is damaged according to a comparison result; and determining whether to send an instruction for controlling the magnetic elastic sheet 5 to move away from the motor 2 to the electromagnet device 4 according to the damage result.

By acquiring the lift force of each rotor wing 3 of the unmanned aerial vehicle, judging the lift force of each rotor wing 3 and the preset lift force one by one, and determining whether the rotor wing 3 is damaged or not according to the comparison result; according to the damage result, whether to send the instruction to electromagnet device 4 is confirmed, and is simple and convenient, specifically:

1) when the lift force of at least one rotor wing 3 of the unmanned aerial vehicle is smaller than the preset lift force, determining that at least one rotor wing 3 is damaged, and sending a command for controlling the magnetic elastic sheet 5 to move away from the motor 2 to the electromagnet device 4 corresponding to the at least one rotor wing 3;

2) when the lift force of each rotor wing 3 of the unmanned aerial vehicle is greater than the preset lift force, it is determined that no rotor wing 3 is damaged, and at the moment, a command for controlling the magnetic elastic sheet 5 to move away from the motor 2 is not sent to the electromagnet device 4;

wherein, supposing that the unmanned aerial vehicle has 4 rotors 3, as is well known, when the resultant force of the lift forces of the 4 rotors 3 is greater than the gravity of the unmanned aerial vehicle, the unmanned aerial vehicle can take off, so that the lift force of each rotor 3 is G/4, wherein G represents the gravity of the unmanned aerial vehicle, and the preset lift force can be set to be G/4;

wherein, the lift of each rotor 3 can be obtained by arranging a pressure sensor on each connecting piece 1, specifically:

1) the piezoelectric sensor can be arranged on the folding blade, particularly the fixing part 13 of the folding blade, when the rotor 3 rotates, a downward acting force can be generated, at the moment, the acting force can enable the piezoelectric sensor to generate an electric signal, the lifting force of each rotor 3 can be obtained by analyzing the electric signal, before the piezoelectric sensor is applied, the functional relation between the electric signal returned by the pressure sensor and the lifting force can be accurately obtained through multiple comparison experiments, when the piezoelectric sensor is applied, the upgrading of each rotor 3 can be accurately obtained through the functional relation, and therefore, a more accurate comparison result can be obtained;

2) a high-precision pressure sensor can be arranged on the folding blade, particularly on the fixing part 13 of the folding blade, for example, the precision is +/-0.05% FS, +/-0.025% FS, etc., when the rotor 3 rotates, a downward acting force can be generated, and the lift force of each rotor 3 can be accurately obtained through the high-precision pressure sensor;

3) the lift of each rotor 3 can be calculated by monitoring the airflow through the drone rotors 3 using a light pressure sensor developed by AERS-Midwest.

Preferably, in the above technical solution, a buckle 19 is provided between the folding portion 14 and the connecting member 1 to prevent the folding portion 14 from unfolding before the motor 2 moves down along the chute 6, wherein the buckle 19 may be in the following form:

1) the buckle 19 is a long rod, one end of the long rod is connected with the folding part 14 in an interference fit mode, and one end of the long rod is fixedly connected with the connecting piece 1 in a threaded connection mode or a welding mode so as to prevent the folding part 14 from unfolding before the motor 2 moves downwards along the sliding groove 6;

when the motor 2 moves downwards along the sliding chute 6, the folding part 14 rotates, and centrifugal force is generated at the moment, so that the connection relation between the long rod and the folding part 14 is broken, and the folding part 14 can be unfolded normally;

it should be noted that: before the buckle 19 is applied, a plurality of comparison experiments are carried out to ensure that the connection relationship between the long rod and the folding part 14 can be broken under the action of centrifugal force, so that the folding part 14 can be normally unfolded;

2) the buckle 19 is a section of steel wire and a button, specifically, one end of the steel wire is fixedly connected with the connecting piece 1 in a welding mode, the other end of the steel wire is connected with the secondary end of the button in a welding mode, the female end of the button is arranged at the corresponding position of the folding part 14, and the folding part 14 is effectively prevented from unfolding before the motor 2 moves downwards along the chute 6 through the connection of the secondary end and the female end;

when the motor 2 moves downwards along the chute 6, the folding part 14 rotates, and centrifugal force is generated at the moment, so that the connection relation between the male end and the female end of the button is broken, and the folding part 14 can be unfolded normally;

it should be noted that: before the buckle 19 is applied, a plurality of comparison experiments should be performed to ensure that the connection relationship between the male end and the female end of the button can be broken under the action of centrifugal force, so that the folding part 14 can be normally unfolded.

The unmanned aerial vehicle provided by the embodiment of the invention adopts any one of the above mentioned flyback devices.

When the unmanned aerial vehicle flies or/and when the unmanned aerial vehicle is prepared to take off and return, if the rotor 3 is damaged, the magnetic elastic sheet 5 is controlled by the electromagnet device 4 to move away from the motor 2, the hook 8 for clamping the motor 2 is completely separated from the motor 2, and under the action of the spring 10, the motor 2 moves downwards along the chute 6, when the motor 2 moves downwards along the chute 6, the support piece 12 arranged on the folding blade is abutted against the rotor 3, the rotating shaft 11 of the motor 2 is completely separated from the rotor 3, and when the motor 2 moves downwards along the chute 6, the folding blade folded outside the connecting piece 1 is connected on the rotating shaft 11, and under the action of centrifugal force, the folding blade is unfolded, at the moment, the folding blade provides lifting force for the unmanned aerial vehicle, so as to ensure that the unmanned aerial vehicle can normally fly or/and normally take off, thereby reducing the loss of users, and does not endanger the life safety of others.

In the present invention, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.