JP7534780B2 - Unmanned Aerial Vehicles - Google Patents

Description

The present invention relates to unmanned aerial vehicle technology.

The following patent document discloses an unmanned aerial vehicle that inspects the ceiling and wall surfaces of structures:

JP 2020-147231 A JP 2019-130974 A

In recent years, the use of multicopters (unmanned aerial vehicles) for structural inspection work has been considered. A multicopter uses multiple rotors to control the attitude and movement of the aircraft, and if the rotors come into contact with a structure or other object and their rotation is impeded, the aircraft will immediately crash. For example, in an environment surrounded by walls, such as inside a tunnel, even the slightest piloting error, external disturbance, or sensing error can cause a crash.

Due to the nature of rotorcraft such as multicopters, which float in the air by scraping the air with their rotors, it is more difficult to stabilize their position than moving objects placed on the ground. For example, to mount a structural inspection device on a multicopter and move it along the surface of the structure, extremely advanced piloting techniques and highly accurate sensors and control programs are required. The difficulty increases even more when the inspection surface is inclined or curved, such as the ceiling of an arched tunnel.

In view of the above problems, the problem that the present invention aims to solve is to improve the workability and safety of inspection work on structures using unmanned aerial vehicles.

To solve the above problems, the unmanned aerial vehicle of the present invention comprises multiple horizontal rotors, which are rotors with horizontal rotating wings, a mount for holding external equipment, and a support column for supporting the mount, the support column having a joint and a suspension mechanism, the joint allowing a portion of the support column to bend in any direction or in a specified direction, and the support column being extendable and retractable in its length direction by the suspension mechanism.

The mount that holds the external device is supported by an extendable support, and the holding angle of the mount and the external device can be changed by a joint, making it possible to adjust the orientation of the external device relative to the inclined or curved surface of a structure while keeping the aircraft horizontal.

In this case, it is preferable that the joint section be able to bend a part of the support section in any direction. This makes it possible to change the holding angle of the external device in any direction, and can accommodate structures of various shapes. It is also preferable that the joint section has a spherical bearing, but it is believed that a universal joint, for example, can also provide the same effect.

It is also preferable that the mount is supported by a plurality of the support columns. This makes it possible to further stabilize the orientation and posture of the mount (external device).

In addition, the restoring force of the suspension mechanism is preferably adjusted to such an extent that the support section is barely compressed by the weight of the external device and the mount section alone when the support section is set vertically, or such an extent that the support section is partially compressed by the weight. Furthermore, it is more preferable that the restoring force of the suspension mechanism is adjusted to such an extent that the support section is partially compressed by the weight of the external device and the mount section when the support section is set vertically. For example, when the external device or the mount section is pressed against the surface of a structure to adjust its angle to the shape of the structure, if the restoring force of the suspension mechanism is high, it is necessary to press them strongly against the structure, which causes excessive load on the horizontal rotor. By adjusting the restoring force of the suspension mechanism to such an extent that the support section is easily compressed against an external force, energy efficiency during operation is improved and a long flight time (continuous operation time) can be ensured.

In this case, the suspension mechanism uses a spring as an elastic member, and the total value of the restoring force of the suspension mechanism of one or more of the support pillars is preferably a maximum of 220 N or less, and the allowable deflection of the spring is preferably 30 mm or more. In addition, it is preferable that the overall spring constant of the suspension mechanism of one or more of the support pillars is 6 N/mm or less.

The unmanned aerial vehicle of the present invention further includes a vertical rotor, which is a rotor having vertical rotor blades, and the vertical rotor blades of the vertical rotor are preferably variable pitch propellers. In this case, it is more preferable that the vertical rotor functions as a pusher that propels the aircraft horizontally and as a tractor that pulls the aircraft horizontally by controlling the pitch angle. By providing a vertical rotor in addition to multiple horizontal rotors and using it as a pusher and tractor, the horizontal rotor can be dedicated to maintaining the horizontality and altitude of the aircraft, and it is possible to move the aircraft forward and backward without tilting it. Furthermore, by making the vertical rotor's vertical rotor a variable pitch propeller, it is possible to instantly switch the thrust direction (thrust/pulling) of the vertical rotor, improving maneuverability against disturbances.

In this case, it is more preferable that the mount or the external device has a contact portion that contacts a work surface, which is the ceiling or wall surface of a structure, and that the vertical rotor generates a thrust in a direction parallel to the work surface. In this case, it is preferable that the contact portion is a wheel. When the contact portion of the unmanned aerial vehicle abuts against a structure, the movement of the unmanned aerial vehicle is partially restricted by the structure. This also has the effect of suppressing the shaking of the aircraft due to external disturbances. In other words, when the contact portion abuts against a structure, the position of the aircraft becomes more stable. In this state, the horizontal rotor is dedicated to maintaining the horizontality and altitude of the aircraft, and the vertical rotor moves the aircraft forward and backward, so that the aircraft can be moved stably while maintaining the relative position between the work surface and the aircraft.

The unmanned aerial vehicle of the present invention further comprises a rotor arm, which is a rod-shaped part that supports the horizontal rotor, and a rotor guard, which is a protective device that protrudes laterally from the horizontal rotor and prevents the horizontal rotor from contacting a surrounding object by hitting the surrounding object before the horizontal rotor when the horizontal rotor approaches the surrounding object, and it is preferable that the rotor guard is supported by the rotor arm and that the position of the rotor guard can be changed along the length of the rotor arm. The provision of the rotor guard prevents the horizontal rotor from contacting the surrounding object. On the other hand, the rotor guard protruding to the side significantly increases the overall dimensions (occupied space) of the aircraft. By making the position of the rotor guard changeable along the length of the rotor arm, it is possible to improve space efficiency during storage and transportation of the aircraft. It also eliminates the need to remove the rotor guard each time the aircraft is stored or transported.

The unmanned aerial vehicle of the present invention further comprises a plurality of rotor arms, which are rod-shaped portions supporting the plurality of horizontal rotors, and a plurality of rotor guards, which are protective equipment that protrude laterally from each of the horizontal rotors and that, when the horizontal rotors approach a surrounding object, hit the surrounding object before the horizontal rotor, thereby preventing the horizontal rotors from contacting the surrounding object. The plurality of rotor guards are each supported by a separate rotor arm, and the rotor guards supported by a pair of adjacent rotor arms in a clockwise or counterclockwise direction in a plan view are supported by the rotor arms with their positions shifted from each other in the vertical direction, and at least one of the rotor guards is provided with a branch-like portion extending toward the other rotor guard, and at least one of the pair of rotor arms is preferably capable of rotating toward the other rotor arm. By providing the rotor guard, the horizontal rotor is prevented from contacting the surrounding object. In addition, if the rotor guard has a branch-like portion extending toward the adjacent rotor guard, the branch-like portion may be an obstacle when the rotor arm is horizontally rotated to fold the aircraft. With this configuration, adjacent rotor guards are positioned differently in the vertical direction, which prevents interference between the branch parts and allows the aircraft to be folded compactly.

As described above, the present invention can improve the workability and safety of structure inspection work using unmanned aerial vehicles.

FIG. 1 is a perspective view of a multicopter according to an embodiment. FIG. 2 is a right side view of the multicopter. FIG. 2 is a plan view of the multicopter. FIG. 4 is a partial plan view showing the folding structure of the rotor arm. FIG. FIG. 4 is a left side view of the support portion and the mount portion. This is a schematic diagram showing the inspection of the ceiling surface of a waterway tunnel using a multicopter. FIG. 2 is a block diagram showing the functional configuration of the multicopter. FIG. 2 is a schematic diagram showing sensing by each sensor inside a waterway tunnel. 13 is a flowchart showing a method for operating a multicopter when performing inspection work on a waterway tunnel.

The following describes an embodiment of the present invention with reference to the drawings. The embodiment described below is an example of inspecting the ceiling surface of a waterway tunnel using a multicopter 10, which is an unmanned aerial vehicle. In the following description, "up" and "down" refer to directions parallel to the Z axis of the coordinate system depicted in each drawing, with the Z1 side being up and the Z2 side being down. "Front" and "rear" refer to directions parallel to the X axis of the same coordinate system, with the X1 side being the front and the X2 side being the rear. "Right" and "left" refer to directions parallel to the Y axis of the same coordinate system, with the Y1 side being the right and the Y2 side being the left. "Horizontal" refers to a surface parallel to the XY plane of the same coordinate system, or the direction of that surface.

[Configuration Overview]
Fig. 1 to Fig. 3 are diagrams showing the external appearance of a multicopter 10 according to this embodiment. Fig. 1 is a perspective view of the multicopter 10, Fig. 2 is a right side view of the multicopter 10, and Fig. 3 is a plan view of the multicopter 10. Fig. 7 is a schematic diagram showing a state in which a work surface 90, which is the ceiling surface of a waterway tunnel, is inspected using the multicopter 10.

The multicopter 10 in this embodiment is a so-called hexacopter, and is equipped with six horizontal rotors 41, which are rotors with horizontal rotating wings. The body of the multicopter 10 is composed of a center frame 11 at its center, rotor arms 12, which are six rod-shaped parts extending radially from the center frame 11 in a plan view, and skids 13, which are landing gear (landing gear) arranged below the center frame 11. The center frame 11 in this embodiment is composed of two plates arranged side by side with their plate surfaces facing up and down, and a battery 18 is placed on the upper surface, and a control device 20, which constitutes a control unit (described later), and other components are placed between the plates.

The six horizontal rotors 41 are attached to the tip of each rotor arm 12. The horizontal rotors 41 are rotors with fixed pitch propellers attached to the output shafts of motors, and the multicopter 10 controls the rolling, pitching, and yawing of the aircraft by adjusting the rotation speed of each horizontal rotor 41, and moves the aircraft horizontally by utilizing the horizontal component of force when the aircraft (rotor rotation plane) is tilted.

The multicopter 10 of this embodiment further includes a vertical rotor 42, which is a rotor having vertical rotors. The vertical rotor 42 is fixed to the skid 13, and is arranged so that its center line of rotation overlaps with the front-rear direction of the multicopter 10. The vertical rotor 42 of this embodiment is a rotor having a variable pitch propeller. The vertical rotor 42 acts as a pusher that propels the aircraft horizontally and as a tractor that pulls the aircraft horizontally by switching its pitch angle. The multicopter 10 of this embodiment includes a vertical rotor 42 in addition to the multiple horizontal rotors 41, and by using this as a pusher and a tractor, the horizontal rotor 41 is dedicated to maintaining the horizontality and altitude of the aircraft, and the vertical rotor 42 can move the aircraft forward and backward without tilting it. In addition, since the propeller of the vertical rotor 42 is a variable pitch propeller, the thrust direction (thrust/pulling) of the vertical rotor 42 can be instantly switched. This improves the maneuverability of the multicopter 10 against disturbances.

The multicopter 10 supports an inspection device 53, which is an external device that inspects the working surface 90 of the waterway tunnel, on the top of its body. The inspection device 53 is placed on a mount 50, which is its holding member, and inspects the surface of the structure facing the upper surface of the inspection device 53. The mount 50 is supported by support columns 60, which are four pillars that are erected vertically on the upper surface of the center frame 11.

The mount unit 50 has front and rear wheels 51 and 52, which are wheels arranged in front and behind the inspection device 53. These front and rear wheels 51 and 52 are one form of the contact part of the present invention, and are pressed against the working surface 90 of the waterway tunnel and roll on the working surface 90. The front wheels 51 in this form are a pair of wheels with a drive source, and are arranged so that their rotation center line overlaps with the left and right direction of the multicopter 10. In other words, the front wheels 51 are arranged so that they rotate in the forward and backward directions. The rear wheels 52 in this form are single wheels. The rear wheels 52 are steering wheels that can be steered left and right by a servo. These front and rear wheels 51 and 52 protrude above the inspection device 53, which prevents the inspection device 53 from directly contacting the working surface 90, and the distance between the working surface 90 and the inspection device 53 can be kept constant.

In addition, when the front wheels 51 and rear wheels 52 are pressed against the work surface 90, the movement of the multicopter 10 is partially restricted by the work surface 90. This also has the effect of suppressing the shaking of the aircraft due to external disturbances. In other words, when the front wheels 51 and rear wheels 52 are pressed against the work surface 90, the position of the aircraft becomes more stable. In this state, the horizontal rotor 41 is dedicated to maintaining the horizontality and altitude of the aircraft, and the aircraft is moved parallel to the work surface 90 using the thrust of the vertical rotor 42, thereby stabilizing the attitude of the inspection device 53 during inspection work and the relative position between the work surface 90 and the inspection device 53. The front wheels 51 and rear wheels 52 can also be used as auxiliary means for horizontal movement of the aircraft.

The multicopter 10 in this embodiment is a hexacopter, but the number of horizontal rotors 41 is not limited to six, and can be changed as appropriate according to the required lift, for example, a quadcopter with four horizontal rotors, an octacopter with eight horizontal rotors, or a tricopter with three horizontal rotors. In addition, the contact parts of the present invention are not limited to the front wheels 51 and the rear wheels 52, and can be, for example, ball casters, caterpillar tracks, or a sled with low sliding resistance depending on the surface roughness of the work surface 90. The contact parts may be provided on the inspection device 53 instead of the mount 50. In addition, the specific function, purpose, configuration, and method of use of the inspection device 53 are not particularly limited. Furthermore, the external device held by the mount 50 is not limited to the inspection device 53, and can be any external device that can be held by the mount 50. In addition, the shape and structure of the mount 50 are not limited to a pedestal or frame as in this embodiment, and can be changed as appropriate according to the shape of the external device to be held. The mount portion 50 may simply be an adapter member that connects the support portion 60 and the inspection device 53, for example.

[Folding structure]
4 is a partial plan view showing the folding structure of the rotor arm 12. Hereinafter, the structure of the rotor guard 70 of this embodiment and the folding structure of the rotor arm 12 including this will be described with reference to FIGS.

Each horizontal rotor 41 of the multicopter 10 is attached so that the orientation of the output shaft of the horizontal rotor 41 adjacent to it in a clockwise or counterclockwise direction in a plan view is up-down opposite to each other. As a result, the rotation plane of each horizontal rotor 41 is misaligned in the up-down direction from the rotation plane of the adjacent horizontal rotor 41, and interference between adjacent horizontal rotors 41 can be avoided, for example, even if the rotor arm 12 is shortened to make the aircraft more compact. As shown in Figure 3, the horizontal rotors 41 of this embodiment are also arranged so that the rotation planes of adjacent horizontal rotors 41 partially overlap when viewed in a plan view.

The multicopter 10 has multiple rotor guards 70 supported by each rotor arm 12. The rotor guards 70 are protective gear that protrude laterally beyond the horizontal rotor 41 and abut against surrounding objects before the horizontal rotor 41 approaches the surrounding object, thereby preventing the horizontal rotor 41 from coming into contact with the surrounding object.

The rotor guard 70 of this embodiment is composed of a slide pole 71 fixed to the rotor arm 12, a horizontal branch portion 72 which is a branch portion that branches off from the tip of the slide pole 71 in a clockwise and counterclockwise direction in a plan view, and a vertical branch portion 73 which is a branch portion that branches off vertically upward or downward from the tip of the slide pole 71. Thin round pipe material of the same diameter is used for the slide pole 71, the horizontal branch portion 72, and the vertical branch portion 73. The slide pole 71 is clamped to the rotor arm 12 by a rotor guard clamp 79 which is a clamping mechanism, and its position can be changed along the length of the rotor arm 12 by loosening the rotor guard clamp 79.

As shown in Figures 1 and 2, the slide pole 71 is disposed below the rotor arm 12 for the rotor arm 12 on which the horizontal rotor 41 is supported with its output shaft facing upward, and is disposed above the rotor arm 12 for the rotor arm 12 on which the horizontal rotor 41 is supported with its output shaft facing downward. In other words, the slide pole 71 and horizontal branch portion 72 are vertically offset from their neighboring slide poles 71 and horizontal branch portions 72. In addition, the vertical branch portion 73 extends upward in the rotor guard 70 of the rotor arm 12 on which the horizontal rotor 41 is supported with its output shaft facing upward, and extends downward in the rotor guard 70 of the rotor arm 12 on which the horizontal rotor 41 is supported with its output shaft facing downward. In other words, the vertical branch portion 73 extends in a direction that covers the horizontal rotor 41 to be protected.

As shown in FIG. 4, when the six rotor arms 12 of the multicopter 10 of this embodiment are divided into three at the front of the aircraft and three at the rear of the aircraft, the movable arms 12b, which are rotor arms 12 on both sides of the fixed arms 12a, which are rotor arms 12 extending forward and backward of the aircraft, can be rotated horizontally toward the adjacent fixed arms 12a. The propellers equipped on the horizontal rotor 41 of this embodiment are so-called folding propellers 411.

In this way, the multicopter 10 of this embodiment can store the rotor guard 70 by sliding the slide pole 71 of the rotor guard 70 toward the center of the aircraft, and can fold the rotor arm 12 compactly while avoiding interference with the horizontal branch parts 72 of adjacent rotor guards 70. This improves space efficiency during storage and transportation of the aircraft, and also eliminates the need to remove the rotor guard 70 each time it is stored or transported. In the example of FIG. 4, the horizontal branch parts 72 of the two movable arms 12b interfere with each other, so when folding the rotor arm 12, the rotor guard 70 of the movable arm 12b is fixed by slightly rotating the slide pole 71 in the circumferential direction to shift the positions of the horizontal branch parts 72 from each other.

[Structure for following inclined and curved surfaces]
Figures 5 and 6 are diagrams showing the structure of the support column 60. Figure 5 is a front view of the support column 60 and the mount section 50, and Figure 6 is a left side view of the support column 60 and the mount section 50. The inclined surface/curved surface following structure of the mount section 50 will be described below with reference to Figures 5 and 6.

As mentioned above, the mount 50 that holds the inspection device 53 is supported by a number of support columns 60. The support columns 60 are expandable support members with a double-cylinder structure in which an inner cylinder 61 is inserted into an outer cylinder 62. The base end (lower end) of the support columns 60 is fixed to the upper surface of the center frame 11, and the tip end is connected to the mount 50.

The support column 60 in this embodiment has a ball joint 63 (spherical bearing) and a suspension mechanism 64. The ball joint 63 is a joint that allows the tip portion 65 of the support column 60 to bend in any direction. The cushioning function of the suspension mechanism 64 in this embodiment is achieved by a compression coil spring housed in the outer cylinder 62.

In this embodiment of the multicopter 10, the mount 50 that holds the inspection device 53 is supported by an extendable support 60, and the support angle of the mount 50 can be changed by a ball joint 63, making it possible to adjust the orientation of the inspection device 53 to an inclined or curved surface without tilting the aircraft. In particular, the joint of this embodiment uses a ball joint 63 that allows the tip 65 of the support 60 to bend in any direction, so that the orientation of the inspection device 53 can be adapted to work surfaces 90 of various shapes. It is considered that the ball joint 63 can be substituted with a universal joint, for example. It is also considered that when it is known that the direction in which the mount 50 is tilted is either forward/backward or left/right, the joint may be configured with a hinge that allows the tip 65 of the support 60 to bend only in a predetermined direction.

Here, the restoring force of the suspension mechanism 64 in this embodiment is adjusted to such an extent that when the support part 60 is set vertically, the support part 60 is partially compressed only by the weight of the inspection device 53 and the mount part 50 (including the front wheel 51 and the rear wheel 52). When the mount part 50 is pressed against the work surface 90 and its angle is adjusted to match the shape of the work surface 90, if the restoring force of the suspension mechanism 64 is high, the mount part 50 will continue to be pressed strongly against the work surface 90, and the load on a part of the horizontal rotor 41 will become excessive. In this embodiment, the restoring force of the multicopter 10 is adjusted to such an extent that the support part 60 is easily compressed against an external force, thereby improving the load and energy efficiency of the horizontal rotor 41 during operation. In other words, according to the multicopter 10 in this embodiment, it is possible to ensure a longer flight time (continuous operation time). The restoring force of the suspension mechanism 64 may be adjusted to such an extent that it is barely compressed only by the weight of the inspection device 53 and the mount part 50.

More specifically, the weight of the inspection device 53 and the mount unit 50 in this embodiment is about 5 kg, the composite spring constant of the suspension mechanisms 64 (compression coil springs) of the four support columns 60 is about 3 N/mm, and the total value of the restoring force (elastic force) of these suspension mechanisms 64 is about 220 N at maximum. The maximum extension length of the support columns 60 is about 60 mm. In order to inspect the ceiling and wall surfaces of a structure with energy efficiency using an unmanned aerial vehicle such as the multicopter 10 in this embodiment, it is desirable that the composite spring constant of the suspension mechanisms 64 is 6 N/mm or less, and the total value of the restoring force of these suspension mechanisms 64 is desirably 220 N or less at maximum. In addition, if the allowable deflection amount of the compression coil springs used in the suspension mechanisms 64 is at least 30 mm or more, it can accommodate inclined and curved surfaces to some extent.

In this embodiment, the mounting unit 50 is supported by four support pillars 60 to stabilize the orientation and posture of the mounting unit 50 and the inspection device 53, but the number of support pillars 60 is not limited to four and may be, for example, three, or even two depending on the shape and weight balance of the external device and the mounting unit. Furthermore, it is considered possible to support the mounting unit with a single support pillar by providing the joint with a holding force and a restoring force.

[Sensor configuration and control function]
Fig. 8 is a block diagram showing the functional configuration of the multicopter 10. Fig. 9 is a schematic diagram showing the sensing state by each sensor in a waterway tunnel. Hereinafter, the sensor configuration and control function of the multicopter 10 of this embodiment will be described mainly with reference to Figs. 8 and 9.

As shown in FIG. 8, the control function of the multicopter 10 in this embodiment is mainly composed of a flight controller 14, which is a control unit, a horizontal rotor 41, a vertical rotor 42, and a communication device 15 that communicates with the pilot (operator terminal 19).

The flight controller 14 has a control device 20, which is its central part. The control device 20 is a microcontroller that has a CPU and storage devices such as RAM, ROM, and flash memory. The control device 20 is not limited to a standalone microcontroller, and may be combined with a so-called companion computer. It is also possible to configure it with, for example, an FPGA (field-programmable gate array) or an ASIC (application specific integrated circuit).

The flight controller 14 further has a flight control sensor group 30 including an IMU 31 (Inertial Measurement Unit), a downward facing optical flow sensor 32, a barometric altitude sensor 33, a first laser ranging sensor 34 facing upward, a second laser ranging sensor 35 facing downward, a first LIDAR 36 facing to the right, a second LIDAR 37 facing to the left, and a Doppler sensor 38 facing upward, which are connected to the control device 20.

The IMU 31 is a sensor that detects the inclination of the multicopter 10 body, and is mainly composed of a three-axis acceleration sensor and a three-axis angular velocity sensor.

The optical flow sensor 32 is a sensor that detects the movement of the object being photographed or the camera itself from changes in state between two or more images taken in succession. For example, in places where GPS (GNSS) signals are difficult to reach, such as the waterway tunnel of this embodiment, an alternative position detection means is required. By providing the optical flow sensor 32, it is possible to detect changes in the horizontal position of the aircraft even in such places. In addition, the multicopter 10 of this embodiment is equipped with four LED lights 321 that illuminate the downward direction (the object being photographed by the optical flow sensor 32) (see Figure 1 or Figure 2). This improves the detection accuracy of the optical flow sensor 32 in dark places.

In addition, optical flow sensors mounted on unmanned aerial vehicles are generally directed downward to capture images of the ground or floor directly below the aircraft, but in an environment such as this embodiment where there are ceilings and walls around the multicopter 10 and liquid matter (water) below the aircraft, the optical flow sensor 32 may be directed upward.

The first laser distance measuring sensor 34 and the second laser distance measuring sensor 35 (hereinafter, these laser distance measuring sensors are also referred to as "laser distance measuring sensors 34, 35") are so-called laser range finders, and are optical parallax type distance meters using laser light. When flying the multicopter 10 in a structure with a ceiling surface, such as the waterway tunnel of this embodiment, attention must be paid not only to the altitude above the ground but also to the distance from the ceiling surface. The multicopter 10 of this embodiment has, as its altitude detection means, the second laser distance measuring sensor 35 (first distance measuring means) facing downward, as well as the first laser distance measuring sensor 34 (second distance measuring means) facing upward, which increases safety in the tunnel.

As shown in FIG. 3, the multicopter 10 of this embodiment has three first laser distance measuring sensors 34, which are distributed at approximately equal intervals around the inspection device 53. The first laser distance measuring sensors 34 of this embodiment not only measure the distance to the ceiling surface of the waterway tunnel, but also serve as a pressure detection means for monitoring the degree of pressure on the mount unit 50 during inspection of the work surface 90, as shown in FIG. 7. In this embodiment, the multicopter 10 supports the mount unit 50 that holds the inspection device 53 with an extendable support 60, and monitors the distance to the work surface 90 with three first laser distance measuring sensors 34 facing the work surface 90, thereby preventing the mount unit 50 from peeling off or falling off the work surface 90 or from being pressed against the work surface 90 too strongly. In other words, it is possible to keep the mount unit 50 pressed against the work surface 90 at a moderate level.

The Doppler sensor 38 is a reflective moving object detector that uses the Doppler effect of microwaves. In addition to the first laser distance sensor 34, the multicopter 10 of this embodiment is further equipped with a Doppler sensor 38 facing the work surface 90, so that the amount and speed of movement of the multicopter 10 relative to the work surface 90 can be determined more accurately.

The barometric altitude sensor 33 is an altitude sensor that calculates the altitude (altitude) of the multicopter 10 above sea level from the detected barometric altitude. In this embodiment, the multicopter 10 calculates the current position in the vertical direction from the detection values of the laser ranging sensors 34, 35 and the detection value of the barometric altitude sensor 33. The detection accuracy of the laser ranging sensors 34, 35 decreases in dusty or wet places. By combining these with the barometric altitude sensor 33, it becomes easier to identify noise from the laser ranging sensors 34, 35, and the vertical position of the multicopter 10 can be more stabilized.

The first lidar 36 and the second lidar 37 are solid-state lidars (LiDAR: Light Detection and Ranging). As mentioned above in relation to the optical flow sensor 32, an alternative position detection means is required in places where GPS signals are difficult to reach, such as the waterway tunnel of this embodiment. Also, in environments where it is difficult to use geomagnetism, such as inside structures that make extensive use of steel frames, an alternative heading (nose direction) determination means is also required. The first lidar 36 and the second lidar 37 determine the distance to surrounding objects and their shapes, and if necessary, compare this with premises map information, etc., to determine the coordinate position and nose direction of the multicopter 10 within the premises.

In addition, unlike general laser distance measuring sensors and ultrasonic distance measuring sensors, the first lidar 36 and the second lidar 37 can obtain not only the distance to the surrounding objects but also the three-dimensional shape of the surrounding objects over a relatively wide range. This makes it possible to recognize, for example, installations on the surface of a structure or local unevenness, and filter them out. In this embodiment of the multicopter 10, the nose direction is forward, and the first lidar 36 is arranged in a direction to scan the right side of the aircraft, and the second lidar 37 is arranged in a direction to scan the left side of the aircraft. When flying through a continuous passage such as the waterway tunnel of this embodiment, the distance to the left and right walls is more important than the front and rear to ensure safety. By having the first lidar 36 scan the right side of the aircraft and the second lidar 37 scan the left side of the aircraft, safety within such a structure can be increased.

In this way, the flight controller 14 of this embodiment can use these flight control sensors 30 to obtain not only the inclination and rotation of the aircraft, but also the coordinate position within the waterway tunnel, the relative position to surrounding objects, the nose direction, altitude, and travel speed.

The control device 20 has a flight control program 21, which is a program that controls the attitude and basic flight operations of the multicopter 10 when flying. The flight control program 21 adjusts the rotation speed of each horizontal rotor 41 and the pitch angle of the vertical rotor 42 based on information obtained from the flight control sensor group 30, and flies the multicopter 10 while correcting disturbances in the attitude and position of the aircraft.

The control device 20 further has an autonomous flight program 22, which is a program that causes the multicopter 10 to fly autonomously. The autonomous flight program 22 can register a flight plan 23, which is data that specifies information about the destination and waypoints of the multicopter 10, the altitude and speed during flight, specific operations for inspection work, and the like. The autonomous flight program 22 causes the multicopter 10 to fly autonomously in accordance with the flight plan 23, using instructions from the operator terminal 19, a specified time, and the like as start conditions.

In this way, the multicopter 10 of this embodiment is an unmanned aerial vehicle with advanced flight control functions. However, the unmanned aerial vehicle of the present invention is not limited to the form of the multicopter 10, and for example, an aircraft in which some sensors are omitted from the flight control sensor group 30, or an aircraft that does not have an autonomous flight function and can fly only by manual piloting can be used. Furthermore, the sensor configuration of the multicopter 10 of this embodiment, except for the function of the first laser distance measuring sensor 34 as a pressure detection means, is not limited to the multicopter 10 of this embodiment, but can be widely adopted as long as it is an unmanned aerial vehicle that flies indoors, and the same effects as this embodiment can be obtained.

[Mode switching function]
The flight control program 21 or the autonomous flight program 22 of this embodiment can switch between a first steering mode in which the horizontal rotor 41 tilts and moves the aircraft, and a second steering mode in which the horizontal rotor 41 maintains the horizontality and altitude of the aircraft while using the vertical rotor 42 for horizontal movement. This can be done manually, but by making the switching possible automatically according to preset conditions, it is possible to automate the work performed by the multicopter 10. It is also possible to eliminate the first steering mode itself from the multicopter 10 and make the multicopter 10 flyable only in the second steering mode.

[Inspection work flow]
Fig. 10 is a flowchart showing a method of operating the multicopter 10 when inspecting a waterway tunnel using the multicopter 10. The flow of the work will be described below in order with reference to Fig. 10. Note that the work procedure described below is assumed to be performed fully automatically by the autonomous flight program 22, but any step may be performed manually.

(S1: Takeoff process)
The multicopter 10 is taken off from a home position inside or outside the waterway tunnel.

(S2: Dispatch process)
Head to the site where inspection work will be carried out in the first steering mode.

(S3: Idling process)
When the multicopter 10 approaches within 1.5 m of the ceiling surface (work surface 90) at the site where the inspection work is performed, the pitch angle of the vertical rotor 42 is set to zero or approximately zero while remaining in the first steering mode to start idling the vertical rotor 42. It takes some time for the vertical rotor 42 to reach a sufficient rotation speed after starting. By idling the vertical rotor 42 before actually using it, the next process can be started smoothly. The idling of the vertical rotor 42 may be started simultaneously with the arming of the multicopter 10 or from the takeoff process (S1). In this embodiment, the timing to start using the vertical rotor 42 is known in advance, so that the power consumption of the vertical rotor 42 is reduced by starting idling (idling) the vertical rotor 42 a little before that.

(S4, S5: inspection process)
When the mount portion 50 (front wheels 51 and rear wheels 52) of the multicopter 10 comes into contact with the work surface 90, the multicopter 10 is switched from the first steering mode to the second steering mode, and inspection work of the work surface 90 is performed.

(S6, S7: Return process)
Once inspection of the work surface 90 is completed and the multicopter 10 is removed from the work surface 90, the multicopter 10 is switched back to the first steering mode and returned to the home position.

(S8: Landing process)
The multicopter 10 is landed at the home position. Note that the location where the multicopter 10 returns to is not limited to the home position (takeoff position) and may be another location.

The above describes an embodiment of the present invention, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

10: Multicopter (unmanned aerial vehicle), 11: Center frame, 12: Rotor arm, 12a: Fixed arm, 12b: Movable arm, 13: Skid, 14: Flight controller (control unit), 15: Communication device, 18: Battery, 19: Operator terminal, 20: Control device, 21: Flight control program, 22: Autonomous flight program, 23: Flight plan, 30: Flight control sensor group, 31: IMU, 32: Optical flow sensor, 321: LED light (lighting means), 33: Barometric altitude sensor, 34: First laser ranging sensor (first ranging means, altitude detection means, pressure detection means), 35: Second laser Laser distance sensor (second distance measuring means, altitude detection means), 36: first lidar, 37: second lidar, 38: Doppler sensor, 41: horizontal rotor, 411: folding propeller, 42: vertical rotor, 50: mount, 51: front wheel (wheel, contact part), 52: rear wheel (wheel, contact part), 53: inspection device (external device), 60: support part, 61: inner cylinder, 62: outer cylinder, 63: ball joint (spherical bearing, joint part), 64: suspension mechanism, 65: tip part (of support part), 70: rotor guard, 71: slide pole, 72: horizontal branch part, 73: vertical branch part, 79: rotor guard clamp, 90: working surface

Claims (15)

A plurality of horizontal rotors, each of which is a rotor having horizontal rotor blades;
a mount portion for holding an external device above the plurality of rotors ;
a support portion for supporting the mount portion,
The support column has a joint and a suspension mechanism,
the joint portion is disposed closer to the mount portion than the suspension mechanism,
The joint portion allows a part of the support portion to bend in an arbitrary direction or a predetermined direction,
the support column is extendable and contractible in its length direction by the suspension mechanism,
The mount portion or the external device has a contact portion that contacts a work surface which is a ceiling surface or a wall surface of a structure.
Unmanned aerial vehicle. The unmanned aerial vehicle according to claim 1, wherein the joint allows a portion of the support to bend in any direction. The unmanned aerial vehicle according to claim 2, wherein the joint has a spherical bearing. An unmanned aerial vehicle according to any one of claims 1 to 3, wherein the mount is supported by a plurality of the support columns. An unmanned aerial vehicle according to any one of claims 1 to 4, wherein the restoring force of the suspension mechanism is adjusted to such an extent that, when the support section is set vertically, the support section is barely compressed by the weight of the external device and the mount section alone, or the support section is partially compressed by said weight. The unmanned aerial vehicle according to claim 5, wherein the restoring force of the suspension mechanism is adjusted to such an extent that when the support section is set vertically, the support section is partially compressed by the weight of the external device and the mount section. An unmanned aerial vehicle according to claim 5 or 6, in which a spring is used as an elastic member in the suspension mechanism, and the total value of the restoring force of the suspension mechanism of one or more of the support members is a maximum of 220 N or less. An unmanned aerial vehicle according to any one of claims 5 to 7, in which a spring is used as an elastic member in the suspension mechanism, and the allowable deflection of the spring is 30 mm or more. An unmanned aerial vehicle according to any one of claims 5 to 8, wherein the suspension mechanism uses a spring as an elastic member, and the overall spring constant of the suspension mechanism of one or more of the support members is 6 N/mm or less. Further comprising a vertical rotor, the rotor having vertical rotor blades;
An unmanned aerial vehicle as described in any one of claims 1 to 9, wherein the vertical rotor's vertical rotor blades are controllable pitch propellers. The unmanned aerial vehicle described in claim 10, in which the vertical rotor acts as a pusher that propels the aircraft horizontally and as a tractor that pulls the aircraft horizontally by controlling the pitch angle. The unmanned aerial vehicle according to claim 10 or 11, wherein the vertical rotor generates thrust in a direction parallel to the work surface. The unmanned aerial vehicle according to claim 12, wherein the contact portion is a wheel. A plurality of horizontal rotors, each of which is a rotor having horizontal rotor blades;
A mount for holding an external device;
a support portion for supporting the mount portion,
The support column has a joint and a suspension mechanism,
The joint portion allows a part of the support portion to bend in an arbitrary direction or a predetermined direction,
the support column is extendable and contractible in its length direction by the suspension mechanism,
A rotor arm that is a rod-shaped portion that supports the horizontal rotor;
a rotor guard that is a protective device that protrudes laterally from the horizontal rotor and prevents the horizontal rotor from contacting the surrounding object by hitting the surrounding object before the horizontal rotor when the horizontal rotor approaches the surrounding object;
the rotor guard is supported by the rotor arm;
The rotor guard is movable along the length of the rotor arm.
Unmanned aerial vehicle . A plurality of horizontal rotors, each of which is a rotor having horizontal rotor blades;
A mount for holding an external device;
a support portion for supporting the mount portion,
The support column has a joint and a suspension mechanism,
The joint portion allows a part of the support portion to bend in an arbitrary direction or a predetermined direction,
the support column is extendable and contractible in its length direction by the suspension mechanism,
A plurality of rotor arms that are rod-shaped portions supporting the plurality of horizontal rotors;
a plurality of rotor guards that are protective devices protruding laterally from each of the horizontal rotors and that, when the horizontal rotors approach a surrounding object, abut against the surrounding object before the horizontal rotor, thereby preventing the horizontal rotors from contacting the surrounding object;
each of the rotor guards is supported by a respective rotor arm;
The rotor guards supported by a pair of rotor arms adjacent to each other in a clockwise or counterclockwise direction in a plan view are supported by the rotor arms with their positions shifted from each other in the up-down direction, and at least one of the rotor guards is provided with a branch-like portion extending toward the other rotor guard,
At least one of the pair of rotor arms is capable of rotating toward the other rotor arm.
Unmanned aerial vehicle .

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