Drone and Drone Control Device

Abstract

To provide a drone capable of restoring a posture after a collision and a control device for a drone.SOLUTION: A drone 1 includes: a propeller 2 including a first bent portion disposed between a center portion and a tip portion, a first strain gauge 26 embedded in the first bent portion and detecting strain; a motor 27 for rotating the propeller 2; a state calculation unit 312 for calculating fall speed and fall distance of a machine body when the first strain gage 26 detects the strain; and a control signal output unit 313 for outputting a signal for returning altitude of the machine body by drop distance to the motor 27 based on the fall speed and the fall distance of the machine body calculated by the state calculation unit 312.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a drone and a control device for the drone.

Background Art

[0002] A drone is a type of moving body that flies in the air by rotating blades. Drones with sizes and flight performances corresponding to their applications are used for transporting loads, spraying pesticides, taking images from above, etc. The position, speed, attitude, etc. of the drone are controlled by an operator who operates a remote controller or by a program executed by the control unit of the drone.

[0003] Normally, the drone is controlled so as not to collide with other objects. However, depending on the situation where the drone is placed, a collision with other objects may occur. Even in the case of a collision, the drone performs control to minimize damage.

[0004] For example, Patent Document 1 describes a drone that uses artificial intelligence to recognize an object from an image and performs control to prevent a collision, with collision prevention means for preventing a collision.

[0005] Also, Patent Document 2 describes a propeller that is easy to return to its original shape even if it is deformed during rotation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the drone described in Patent Document 1, depending on the quality or quantity of information accumulated to recognize an object, there is a problem that it cannot respond to a rapid fall of the drone after a collision and it is difficult to return to its original attitude.

[0008] Also, in a drone that does not perform control considering the impact caused by a collision even with the propeller described in Patent Document 2, there is a problem that it is difficult to return to its original attitude after a collision.

[0009] In view of the above problems, an object of the present invention is to provide a drone and a control device for the drone that can return to its original attitude after a collision.

Means for Solving the Problems

[0010] To achieve the above object, a drone according to one aspect of the present invention is disposed between a central portion and a tip portion and is more flexible and bendable than the central portion and the tip portion a propeller including a first bending portion and a first strain gauge embedded in the first bending portion for detecting strain of the first bending portion, a motor for rotating the propeller, a state calculation unit for calculating a falling speed and a falling distance of the aircraft when the first strain gauge detects the strain, and a control signal output unit for outputting to the motor a signal for returning the altitude of the aircraft by the falling distance based on the falling speed and the falling distance of the aircraft calculated by the state calculation unit.

[0011] The drone according to the present invention is disposed between a main body portion of the aircraft and an arm connecting the motor and is more flexible and bendable than the main body portion and the arm including a second bending portion and a second strain gauge embedded in the second bending portion for detecting strain of the second bending portion, the state calculation unit calculates a collision model including the speed of an object that caused the strain when the second strain gauge detects the strain, and the control signal output unit may output to the motor a signal for moving the aircraft to a position where it does not collide with the object based on the collision model.

[0012] When the magnitude of the distortion exceeds a threshold value, the state calculation unit of the drone according to the present invention may determine that the distortion has been detected.

[0013] A control device for a drone according to another aspect of the present invention is disposed between the central portion and the tip portion and is more flexible and bendable than the central portion and the tip portion a propeller including a first bending portion and a first strain gauge embedded in the first bending portion for detecting strain, a motor for rotating the propeller, in a drone equipped with when the first strain gauge detects the strain, calculate the falling speed and falling distance of the aircraft, Based on the calculated falling speed and falling distance of the aircraft, output a signal to the motor to return the altitude of the aircraft by the falling distance.

Advantages of the Invention

[0014] According to the present invention, there is provided a drone and a control device for a drone that can return to the original posture after a collision.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0016] (Embodiment) Hereinafter, with reference to the drawings, the drone 1 according to one embodiment of the present invention will be described.

[0017] (Overall Configuration of Drone 1) As shown in FIG. 1, the drone 1 includes four propellers 2, a control unit 31 that controls the rotation speed of each propeller 2, a main body unit 3 that stores a battery 32 that supplies power to the control unit 31, etc., and four arms 4 that extend outward from the main body unit 3 in four different directions by 90 degrees in the same plane and connect the main body unit 3 and each propeller 2. The drone 1 does not include a cage that covers the periphery of the propeller 2. The drone 1 is an example of an airframe.

[0018] More specifically, the propeller 2 is divided into, for example, a propeller 2A that rotates counterclockwise when the drone 1 ascends, and a propeller 2B that rotates in the direction opposite to the propeller 2A, for example, clockwise. The propeller 2A and the propeller 2B have a symmetrical structure and are formed of the same material. Therefore, hereinafter, the propeller 2A will be described as the propeller 2, and the description of the propeller 2B will be omitted.

[0019] (Propeller 2) As shown in FIG. 2(A), the propeller 2 includes a hub 21 which is a rotatable central portion, a blade portion 22 including a pair of blades extending outward from the hub 21, a bent portion 23 that bendably connects the hub 21 and the blade portion 22, a deformable edge 24 provided at the edge of the blade portion 22, a plurality of fibrous tendons 25 embedded in the bent portion 23 to connect the hub 21 and the blade portion 22, and a strain gauge 26 embedded in the bent portion 23 to detect the strain of the bent portion 23.

[0020] The hub 21 is disposed at the center of the propeller 2. The hub 21 is a central portion that couples the rotation axis of the propeller 2 to other members of the propeller 2. At the center of the hub 21, a hole H for connection to the rotation axis of a motor M (not shown) is threaded in the Z direction. The hub 21 includes an annular ring R and a transition portion T formed to continuously and smoothly project radially outward from the annular ring R. At one end of the transition portion T, the hub 21 is connected to the bent portion 23. The hub 21 includes a high-rigidity hard plastic material, for example, an ABS resin, a PLA (polylactic acid) resin.

[0021] The blade portion 22, like the hub 21, includes a high-rigidity hard plastic material. The blade portion 22 is formed in a shape that functions as a rotating blade of the propeller 2 integrally with the deformable edge 24 described later. Note that the specific shape of the propeller 2 may be calculated theoretically or by simulation and is not limited to the shape shown in FIG. 2(A).

[0022] The bent portion 23 is made of a material with higher flexibility than the hub 21 and the wing portion 22, for example, silicone rubber. Also, the rigidity of the bent portion 23 is lower than the rigidity of the hub 21 and the wing portion 22. The bent portion 23 is disposed between the hub 21 and the wing portion 22 and is formed in a continuously changing shape that smoothly connects the transition portion T located outside the hub 21 and the inside of the wing portion 22. When the bent portion 23 bends, the wing portion 22 can be displaced in the vertical direction and the rotational direction. The bent portion 23 is an example of a first bent portion.

[0023] The deformable edge 24 is an example of a leading edge portion provided at the edge of the wing portion 22 in the rotational direction D. The rotational direction D is counterclockwise in the propeller 2. Similar to the bent portion 23, the deformable edge 24 is made of a material with higher flexibility than the hub 21 and the wing portion 22, for example, silicone rubber. The rigidity of the deformable edge 24 is lower than the rigidity of the hub 21 and the wing portion 22.

[0024] The tendon 25 is a filamentous member made of a flexible and high-strength fiber material, for example, nylon fiber. As shown by the dashed line, a plurality of tendons 25 are stretched between the hub 21 and the wing portion 22, and their surroundings are covered by the bent portion 23. The rigidity of the tendon 25 is lower than the rigidity of the bent portion 23, and the flexibility of the tendon 25 is higher than the flexibility of the bent portion 23.

[0025] The strain gauge 26 is formed in a rectangular flat plate shape and is a sensor embedded in the bent portion 23. When the bent portion 23 is strained, the strain gauge 26 is also strained, so its resistance value changes. The control unit 31 described later is connected to the strain gauge 26 via the plus and minus lead wires 26P and 26N. Therefore, the control unit 31 measures the change in the resistance value of the strain gauge 26 and detects the presence or absence and degree of strain of the propeller 2. The strain gauge 26 is an example of a first strain gauge.

[0026] The propeller 2 shown in Fig. 2(B) is directly attached to the shaft of the motor 27 without passing through gears, chains, etc. Therefore, the rotational speed of the propeller 2 can be adjusted by adjusting the rotational speed of the motor 27.

[0027] The lower right part of Fig. 2(B) is an enlarged view of the connection part between the propeller 2, which has collided with an obstacle and distorted the bent part 23, and the motor 27. This enlarged view is a side view of the propeller 2 in the middle of being inserted into the shaft without fixing the propeller 2 to the motor 27 for easy understanding. On the upper part of the motor 27, there is a contactor 41 which is a copper protrusion formed in a smooth shape. Two contactors 41 are arranged on the upper part of the motor 27, one is electrically connected to the lead wire 26P, and the other is electrically connected to the lead wire 26N respectively. On the side of the hub 21 facing the motor 27, two copper rings 42 are pasted. These copper rings 42 have the same center, but the diameter of one copper ring 42 is larger than that of the other copper ring 42. The outer copper ring 42 is electrically connected to the lead wire 26P, and the inner copper ring 42 is electrically connected to the lead wire 26N.

[0028] The contactor 41 is arranged at a position in contact with the copper ring 42. Therefore, even when the propeller 2 rotates, the contactor 41 continues to maintain an electrical connection with the copper ring 42. Therefore, even when the propeller 2 rotates, the lead wire 26P maintains an electrical connection with the lead wire 46P through the contactor 41 and the copper ring 42, and the lead wire 26N also maintains an electrical connection with the lead wire 46N through another contactor 41 and another copper ring 42.

[0029] (Main body part 3) Returning to Fig. 1, the main body part 3 includes a control part 31 for controlling flight and a battery 32 for supplying power to the control part 31, the motor 27 of the propeller 2, etc.

[0030] (Arm 4) The drone 1 is provided with four arms 4. As shown in Fig. 2(C), the arm 4 includes a base end portion 43, a bent portion 44, and a tip end portion 45 in order from the main body portion 3 side toward the propeller 2. Three strain gauges 46 are embedded in the bent portion 44.

[0031] The bent portion 44 includes a material with higher flexibility than the base end portion 43 and the tip end portion 45, for example, silicone rubber. The bent portion 44 has a hardness that maintains the structure of the drone 1. A motor 27 is fixed to the tip end portion 45. On the surface of the arm 4, in addition to the lead wires 26P, 26N, 46P, 46N, a cable or the like for supplying power to the motor 27 is arranged. The bent portion 44 is an example of a second bent portion.

[0032] Each strain gauge 46 is equivalent to the strain gauge 26 described above, and the plus and minus lead wires 46P, 46N are connected. These three strain gauges 46 are connected to the control unit 31 via the lead wires 46P, 46N. The control unit 31 is arranged at a position where it can independently detect the strain of the bent portion 44 in three directions perpendicular to each other. Therefore, the control unit 31 can detect whether the bent portion 44 is strained, the direction of the strain, and the degree thereof. The strain gauge 46 is an example of a second strain gauge.

[0033] (Control unit 31) The control unit 31 includes, for example, a flight controller that executes operations for controlling the flight of the drone 1. The control unit 31 further includes a receiver that receives the operation of the remote controller and transmits it to the flight controller, and an amplifier 34 that amplifies the calculation result by the flight controller using the power supplied from the battery 32 and outputs it to the motor 27.

[0034] The control unit 31 of the main body 3 shown in FIG. 3 includes a sensor information acquisition unit 311 that acquires sensor information including information such as the strain of the strain gauge 26, the position, acceleration, and time of the drone 1 via a sensor interface 33 connected to the strain gauge 26 and the sensor 35, a state calculation unit 312 that calculates the state of the drone 1 such as its attitude and speed, and a control signal output unit 313 that outputs a control signal to the motor 27 via the amplifier 34 based on the state of the drone 1 calculated by the state calculation unit 312.

[0035] The sensor interface 33 includes, for example, a circuit that applies a voltage supplied from the battery 32 between the lead wires 26P and 26N of each strain gauge 26 and measures the flowing current. The sensor information acquisition unit 311 obtains, for example, the resistance value of the strain gauge 26 from the ratio of the applied voltage to the flowing current, and calculates the presence or absence and the degree of the strain occurring in the strain gauge 26. Connected to the sensor interface 33 is a sensor 35 including a gyroscope, an accelerometer, a barometer, a GPS receiver, an infrared sensor, and the like.

[0036] The amplifier 34 receives power supply from the battery 32, for example, amplifies the control signal output from the control signal output unit 313, and supplies the amplified signal to each motor 27 to rotate each propeller 2.

[0037] (Overview of Control) Referring to FIG. 4, the control for continuing flight when the drone 1 collides with an object during flight will be described. Since the environment in which the drone 1 flies is various, the control suitable for stably continuing flight differs depending on when and where the object collides. Therefore, the control content will be described while dividing the cases below.

[0038] First, the state calculation unit 312 detects a collision of an object with the drone 1 based on the sensor information acquired via the sensor information acquisition unit 311 (S11).

[0039] When the state calculation unit 312 detects that an object has collided with the propeller (S11; Yes: P1), it calculates the falling speed and falling distance of the drone 1 (S12).

[0040] Subsequently, based on the falling speed and falling distance calculated in step S12, the state calculation unit 312 stabilizes the flight of the drone 1 (S13).

[0041] On the other hand, when the state calculation unit 312 detects that an object has collided with the arm (S11; Yes: P2), it calculates a collision model (S14).

[0042] Next, based on the collision model calculated in step S14, the state calculation unit 312 reacts to the collision (S15). Specifically, for example, the state calculation unit 312 determines the position of the object included in the calculated collision model and performs control such as moving the drone 1 away from that position.

[0043] Subsequently, the state calculation unit 312 replans the flight path to reach the destination without colliding with the object (S16). Specifically, for example, the state calculation unit 312 replans the flight path so that it does not pass through the position of the object assumed from the collision model.

[0044] If step S13 or S16 is executed, the state calculation unit 312 further detects a collision (S17).

[0045] If no collision with an object is detected (S11; No), the state calculation unit 312 repeats step S11.

[0046] When the state calculation unit 312 detects a collision (S17; Yes), it calculates a collision map (S18). Specifically, for example, the state calculation unit 312 detects a collision and sequentially determines that a collision has occurred, and calculates data such as the coordinates, time, speed, and attitude at which the object collided.

[0047] After calculating the conflict map, when the state operation unit 312 detects a collision with the propeller (P1), it proceeds to step S12, and when it detects a collision with the arm (P2), it proceeds to step S14, respectively.

[0048] In step S17, when no collision is detected (S17; No), the state operation unit 312 performs a recovery flight including moving the drone 1 to a position where it does not collide with an object based on, for example, a collision model (S19).

[0049] When ending the flight (S20; Yes), the state operation unit 312 returns, and when not ending the flight (S20; No), it returns to step S11 and continues the subsequent steps of the determination. For example, when the state operation unit 312 detects that the drone 1 has reached the destination, the remaining amount of the battery 32 has fallen below the threshold for continuing the flight, etc., the end of the flight is determined.

[0050] By repeating steps S11 to S20 described above, even if a collision occurs, the drone 1 can continue stable flight.

[0051] (Step of determining the presence or absence of a collision) In step S11 described above, the state operation unit 312 shown in FIG. 3 determines the presence or absence of a collision and the target from the sensor information such as the strain gauge 26 and the sensor 35 acquired by the sensor information acquisition unit 311.

[0052] The details of step S11 will be described with reference to a specific example of the sensor information shown in FIG. 5. The sensor information is, for example, an ID (Identifier) that uniquely identifies the strain gauge 26, a group indicating whether the strain gauge 26 is attached to the propeller 2 or the arm 4, and the x, y, and z coordinates indicating the position of the strain gauge 26 defined with the center of gravity of the drone 1 as the origin, and the strain numerical values are associated with each other. Also, there are three strain gauges 26 attached to the arm 4, and since each of them detects strain in different directions in the x, y, and z directions, the values identifying these directions are also associated with the ID.

[0053] When the group only contains "propeller" and does not contain "arm", the state calculation unit 312 determines that an object has collided with the propeller 2. When the group only contains "arm" and does not contain "propeller", the state calculation unit 312 determines that an object has collided with the arm 4.

[0054] When the group contains both "propeller" and "arm", the state calculation unit 312 determines that an object has collided with both the propeller 2 and the arm 4. The state calculation unit 312 may perform the same processing as when an object collides with the propeller 2.

[0055] When there is no strain gauge 26 among all the strain gauges 26 whose strain exceeds the threshold value, the state calculation unit 312 does not detect a collision. The state calculation unit 312 is configured to detect a collision when the strain value of each strain gauge 26 exceeds the threshold value, and to determine that no collision is detected otherwise.

[0056] For collision detection, instead of the raw strain value DVr acquired by the sensor information acquisition unit 311 from the strain gauge 26, the scaled strain value DVs considering the offset value DVo described below is used. DVs = ABS(DVr - DVo)

[0057] Here, ABS represents the absolute value. The scaled strain value DVs is the absolute value of the value obtained by subtracting the offset value DVo for the strain from the raw strain value DVr.

[0058] The offset value DVo is, for example, a value for considering the strain caused by the rotation of the propeller 2. The offset value DVo is calculated, for example, as the strain value acquired by the sensor information acquisition unit 311 from the strain gauge 26 when the propeller 2 and the arm 4 of the drone 1 are not in contact with an object while maintaining the rotation speed of the propeller 2 constant.

[0059] The offset value DVo may be a constant. For example, when the rotation speed of the propeller 2 is relatively small, it may be a value proportional to the rotation speed, and when the rotation speed of the propeller 2 is large enough to exceed the threshold value of the rotation speed, it may be a constant. Also, the offset value DVo may be a value actually acquired by the sensor information acquisition unit 311 from the strain gauge 26 by varying the rotation speed of the propeller 2 in various ways.

[0060] For ease of understanding, the strain value described below is assumed to be the scaled strain value DVs. As an example, assuming the threshold value is 5%, since only the strain gauge 26 with an ID of "2" has a strain value exceeding 5%, in step S11, the state calculation unit 312 determines that the object has collided with the propeller 2.

[0061] The threshold value for the propeller used for collision detection and the threshold value for the arm may be different from each other. As another example, assuming the threshold value for the propeller is 5% and the threshold value for the arm is 2%, there is no strain gauge 26 exceeding the propeller threshold value, and only the strain gauge 26 attached to the arm with an ID of "5" exceeds the arm threshold value. Therefore, in step S11, the state calculation unit 312 determines that the object has collided with the arm. Also, since the strain gauge 26 with an ID of "5" detects the strain in the "x" direction, the state calculation unit 312 determines that the object moving in the x direction has collided with the arm.

[0062] (Steps for calculating the falling speed and falling distance) In step S12 shown in FIG. 4, the state calculation unit 312 calculates the falling speed Vfall and the falling distance Lfall of the drone 1 based on the information acquired by the sensor information acquisition unit 311 from sensors such as a GPS sensor and an acceleration sensor. Specifically, the state calculation unit 312 acquires the speed of the drone 1 from the sensor information acquisition unit 311, and obtains, for example, the speed in the z direction as the falling speed Vfall. Further, the state calculation unit 312 obtains the falling distance Lfall by multiplying the falling speed Vfall by time.

[0063] (Steps for calculating the collision model) In step S14 shown in FIG. 4, the state calculation unit 312 calculates the collision model of the drone 1. The collision model is data including the speed of the object that caused the distortion of the strain gauge 26 upon collision. For example, the state calculation unit 312 calculates the speed of the collided object from the time of collision with the object, the coordinates of the strain gauge 26 whose strain exceeded the threshold value, and the direction in which the collision was detected.

[0064] (Steps for calculating the collision map) In step S18 shown in FIG. 4, the state calculation unit 312 calculates the collision map of the drone 1. The collision map is data including the history of collisions. The collision map shown in FIG. 6 is data associating the ID of the strain gauge 26, the time when the collision was detected, the coordinates at that time, and the speed.

[0065] Since the collision map includes data on time, position, and speed, the state calculation unit 312 can calculate the position and movement path of the collided object. For example, assuming that the collided object maintains a constant speed v = (vx, vy, vz), the state calculation unit 312 calculates the x coordinate of the object T seconds after the current time from the following formula. x0 + vxT

[0066] The state calculation unit 312 calculates the y coordinate and the z coordinate in the same way as the x coordinate, respectively, y0 + vyT z0 + vzT using the following calculation formulas. Here, x0, y0, and z0 represent the x, y, and z coordinates at the time when the collision is detected.

[0067] (Steps of recovery flight) When the step S13 or S16 shown in FIG. 4 is executed, the control signal output unit 313 calculates a virtual attractive force (VAF) to return to the original altitude from the falling distance in step S19, and outputs a signal for controlling the motor 27 of each propeller 2 from the calculated attractive force.

[0068] When the step S15 shown in FIG. 4 is executed, the control signal output unit 313 outputs a signal for performing control to avoid an object that is an obstacle in step S17. Specifically, it moves to coordinates where there is no collision. When the target is another flying object moving at a constant speed V, control is performed to increase or decrease the altitude.

[0069] When the step S16 shown in FIG. 4 is executed, the control signal output unit 313 outputs a signal for performing control to avoid an object that is an obstacle while maintaining flight in step S17. In the collision map shown in FIG. 6, when the current time is 04:55, the control signal output unit 313 controls a signal to detour in the Y direction or the Z direction assuming that there is an obstacle in the X direction, for example, from the coordinate and speed information at times "04:54:059", "05:53:341", and "04:53:218".

[0070] (Hardware configuration) The control unit 31 can be realized by an information arithmetic device 800 having the hardware configuration illustrated in FIG. 7. The information processing device 800 includes a processor 101 that performs various arithmetic processes, an input / output interface 102 that communicates with other devices such as an input device 120 and an output device 130, a main memory device 103 such as a DRAM (Dynamic Random Access Memory) and an SRAM (Static Random Access Memory) that temporarily stores information, an auxiliary storage device 104 such as a hard disk drive (HDD), a solid state drive (SSD), and a non-volatile memory that permanently stores information, and a bus 105 that is a path for information exchanged between the processor 101, the input / output interface 102, the main memory device 103, or the auxiliary storage device 104.

[0071] The input device 120 is a device that receives input of data from the outside. The input device 120 is, for example, a strain gauge 26. Note that the input device 120 may be a reception interface such as a parallel bus or a serial bus, which is a device that detects a signal transmitted by another device. The output device 130 is a device that outputs data to the outside.

[0072] (First Experiment) An experiment in which the drone 1 described above was flown and collided with an object will be described. The first experiment examined the difference in the behavior after the collision between the case where the drone 1 was controlled to perform a recovery flight based on the calculated falling speed and falling distance and the case where it was not. Specifically, with the drone 1 hovering at a height of about 2 m from the floor indoors, it was made to collide with a cylindrical polyurethane resin with a diameter of about 5 cm and a height of about 10 cm, and the behavior of the drone 1 was examined for several seconds thereafter.

[0073] Figure 8(A) is an image capturing the behavior of the drone 1 when the control for performing the recovery flight was not performed, and Figure 8(B) is an image capturing the behavior of the drone 1 when the control for performing the recovery flight was performed.

[0074] Below each image included in FIGS. 8(A) and (B), the elapsed time from the reference time was shown in units of milliseconds. Also, the uppermost part of FIGS. 8(A) and (B) is the one taken immediately after the drone 1 collided with the object.

[0075] As shown in FIG. 8(A), when the control for making the recovery flight was not performed, the drone 1 tilted and continued to fall without recovering its attitude even after several hundred milliseconds had elapsed since the collision.

[0076] On the other hand, as shown in FIG. 8(B), when the control for making the recovery flight was performed, the drone 1 descended while tilted for about 700 milliseconds after the collision, but did not fall to the floor. Also, it began to regain altitude at about 700 milliseconds after the collision, and resumed hovering at almost the altitude before the collision after about 2300 milliseconds had elapsed.

[0077] (Second Experiment) The second experiment measured the temporal changes in the pitch (forward tilt angle) and altitude of the drone 1 when the control for making the recovery flight was performed. FIG. 9 shows graphs of the position, altitude, and pitch in the y direction of the drone 1 at the same time. The upper graph shows the change in the position in the y direction, the middle graph shows the change in altitude, and the lower graph shows the change in pitch. In this figure, the unit of the horizontal axis is minutes. For example, "1:05" represents 1 minute and 5 seconds. The position, pitch, and altitude in the y direction are all shown as estimated values because they were calculated and estimated from the information obtained from the sensor. The coordinate values shown in FIG. 9 are the values in the coordinate system set in the environment including the drone 1 shown in FIG. 10. For example, the vertically upward direction is set as the -z direction.

[0078] First, as shown in the estimated values of the middle graph in FIG. 9, at 1 minute and 27 seconds, the drone 1 is at a relatively large altitude, specifically about 0.3 m, and is descending. Also, as shown in the estimated values of the lower graph in FIG. 9, at the same time of 1 minute and 27 seconds, the drone 1 is fluctuating relatively violently, specifically about 5 degrees up and down respectively around the set value in terms of pitch. This indicates that at 1 minute and 27 seconds, the drone 1 collided with an obstacle. In addition, during the period before 1 minute and 27 seconds, specifically from 1 minute and 24 seconds to 1 minute and 27 seconds, as shown in the estimated values of the upper and lower graphs in FIG. 9, the position and pitch of the drone 1 in the y direction fluctuated relatively greatly. This is due to the control of moving the drone 1 in the y direction in order to make it collide with a fixed obstacle, and it is not a phenomenon indicating the result of the collision.

[0079] Next, as shown in the estimated values of the middle graph in FIG. 9, it can be understood that the altitude of the drone 1, which was -1.9 m at the moment of the collision at 1 minute and 27 seconds, dropped to -1.6 m during the subsequent unstable phase of about 2 seconds. This means that due to the collision with the obstacle, the drone 1 dropped by about 0.3 m. After that, after going through the recovery stage from 1 minute and 29 seconds to 1 minute and 32 seconds, the altitude of the drone 1 returned to about -2.0 m, which is the set value.

[0080] As shown in the estimated values of the lower graph in FIG. 9, after the collision, the pitch of the drone 1 deviated up to a maximum of 4 degrees positive and up to a maximum of 6 degrees negative with respect to the set value of -1 degree. During the subsequent recovery stage, the deviation of the pitch was limited to a maximum of about 4 degrees from the set value.

[0081] As described with reference to FIG. 9, both the altitude and pitch of the drone 1 deviated from the set value during the unstable phase that lasted about 1 to 2 seconds from the moment of the collision. This is presumably because the state calculation unit 312 was in the middle of calculating the falling speed and falling distance of the drone 1, and the control signal output unit 313 did not output a control signal for the recovery flight. In the recovery phase that follows the unstable phase and approximately two seconds have elapsed since the moment of collision, both the altitude and pitch of drone 1 rapidly approach the set values. This is presumably because the state calculation unit 312 has finished calculating the falling speed and falling distance of drone 1, and the control signal output unit 313 is outputting a control signal for recovery flight.

[0082] From the results of the first and second experiments, it is understood that according to drone 1, even if propeller 2 collides with an obstacle, stable flight can be continued.

[0083] (Modified Example) Drone 10 according to the modified example shown in FIG. 11 detects distortion using hall sensor 55 instead of strain gauge 26 of drone 1. Hereinafter, the description will focus on the parts different from drone 1.

[0084] Propeller 12 of drone 10 has a magnet 54 embedded inside the bent portion 53. A hall sensor 55 is arranged between propeller 12 and motor 27. Specifically, two hall sensors 55 are arranged on the fixing portion 13 and at a position outside the circle centered on the shaft. The fixing portion 13 is provided opposite to propeller 12 on motor 27 arranged at the tip of arm 14.

[0085] Since magnet 54 generates a magnetic field, hall sensor 55 detects the magnetic field generated by magnet 54. Also, when propeller 12 rotates, magnet 54 moves and the magnetic field changes, so hall sensor 55 detects the change in the magnetic field. And when distortion occurs in bent portion 53, the magnetic field changes compared to the case where there is no distortion. Therefore, for example, the state calculation unit 312 calculates the magnitude of the force applied to bent portion 53 from the maximum value of the magnitude of the magnetic field detected by hall sensor 55.

[0086] When an object collides with the propeller 12 and the bent portion 53 is distorted, a shift occurs in the position of the magnet 54. Therefore, the state calculation unit 312 calculates the distortion of the bent portion 53 from the shift in the magnetic field detected by the Hall sensor 55.

[0087] Note that the drone 10 equipped with the Hall sensor 55 instead of the strain gauge 26 performs flight control in the same flow as shown in FIG. 4.

[0088] By using the Hall sensor 55, the distortion of the bent portion 53 can be detected more precisely than when using the strain gauge 26.

[0089] Note that the method described in the above embodiment can be written as a program executable by a computer in a storage medium such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and applied to various devices. The computer that realizes the present disclosure reads the program stored in the storage medium and executes the above-described processing by being controlled by this program. Further, the present invention is not limited to the examples of the above-described embodiments, and can be implemented in other aspects by making appropriate changes.

[0090] The present invention can be implemented in various embodiments and modifications without departing from the broad spirit and scope of the present invention. Further, the above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims rather than the embodiments. And various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are regarded as being within the scope of the present invention.

Explanation of Reference Numerals

[0091] 1, 10 Drone 2, 2A, 2B, 12 Propeller 3 Main body portion 4, 14 Arm 13 Fixed portion 21 Hub 22 Wing part 23, 44, 53 Bending part 24 Deformable edge 25 Tendon 26, 46 Strain gauge 26P, 26N, 46P, 46N Lead wire 27 Motor 31 Control unit 32 Battery 33 Sensor interface 34 Amplifier 35 Sensor 41 Contact 42 Copper ring 43 Base end part 45 Tip end part 54 Magnet 55 Hall sensor 101 Processor 102 Input / output interface 103 Main memory device 104 Auxiliary memory device 105 Bus 120 Input device 130 Output device 311 Sensor information acquisition part 312 State calculation part 313 Control signal output part 800 Information calculation device

Claims

1. A propeller including a first bending portion disposed between a central portion and a tip portion, being more flexible and bendable than the central portion and the tip portion, and a first strain gauge embedded in the first bending portion for detecting strain of the first bending portion; A motor for rotating the propeller; A state calculation unit for calculating a falling speed and a falling distance of the aircraft when the first strain gauge detects the strain; A control signal output unit for outputting to the motor a signal for returning the altitude of the aircraft by the falling distance based on the falling speed and the falling distance of the aircraft calculated by the state calculation unit. A drone.

2. Including a second bending portion disposed between a main body portion of the aircraft and an arm connecting the motor, being more flexible and bendable than the main body portion and the arm, and a second strain gauge embedded in the second bending portion for detecting strain of the second bending portion; The state calculation unit calculates a collision model including the speed of an object that caused the strain when the second strain gauge detects the strain; The control signal output unit outputs to the motor a signal for moving the aircraft to a position where it does not collide with the object based on the collision model. The drone according to Claim 1.

3. The state calculation unit determines that the strain has been detected when the magnitude of the strain exceeds a threshold value. The drone according to Claim 1 or 2.

4. A propeller including a first bending portion disposed between a central portion and a tip portion, being more flexible and bendable than the central portion and the tip portion, and a first strain gauge embedded in the first bending portion for detecting strain; A motor for rotating the propeller; In a drone comprising: When the first strain gauge detects the strain, causing calculation of a falling speed and a falling distance of the aircraft; Based on the calculated falling speed and falling distance of the aircraft, causing output to the motor of a signal for returning the altitude of the aircraft by the falling distance. A control device for a drone.

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