JP7114265B2 - Unmanned aerial vehicle gimbal mechanism - Google Patents

Description

The present invention relates to a gimbal mechanism for a laser scanner or camera mounted on an unmanned aerial vehicle.

A technique using an unmanned aerial vehicle (UAV (Unmanned Aerial Vehicle)) for surveying is known. In this technology, a UAV is equipped with a laser scanner and acquires laser scan data from the air. Also known is a technique for carrying out aerial photogrammetry by mounting a camera on a UAV. In the technology of mounting a sensor on a UAV, there is known a structure in which a gimbal mechanism is used to direct the sensor in a certain direction even if the aircraft is tilted (see Patent Document 1, for example).

Japanese Patent No. 6228679

A UAV is equipped with a GNSS positioning device (so-called GPS receiver) for identifying its own position, and flies while identifying its own position. By the way, when a UAV is equipped with a laser scanner or a camera, the object to be measured is not limited to the ground surface, and may be the side of a building or the underside of a bridge. For this reason, a degree of freedom is required in setting the directions of the laser scanner and camera.

Against this background, the present invention relates to a structure for mounting a laser scanner and a camera on a UAV, which maintains the attitude of the laser scanner and camera regardless of the attitude of the UAV, and enables setting with a higher degree of freedom. The purpose is to provide a

The present invention relates to a gimbal mechanism for an unmanned aerial vehicle, which is mounted on an unmanned aerial vehicle, and includes a frame-shaped base portion having an opening, a frame-shaped base portion capable of moving up and down inside the opening, and a gimbal mechanism capable of moving upward and downward from the base portion. An installation section that can be moved downward and installed with a laser scanner or a camera, a vertical position adjustment mechanism that can adjust the position of the installation section in the vertical direction with respect to the unmanned aerial vehicle, and a roll direction of the installation section. an angle adjustment mechanism capable of adjusting the angle of and the pitch direction of the installation section; an orientation detection section that detects the orientation of the installation section; and the pitch direction and the roll direction of the installation section based on signals from the orientation detection section. an angle driving unit that controls the angle of the , a storage unit that stores the positional relationship between the GNSS antenna facing upward and/or the reflecting prism facing downward, and the installation portion and the GNSS antenna and/or the reflecting prism; and the angle adjustment mechanism includes a roll axis rotation member rotatably supported by a horizontal support member, and a support member provided at an end of the roll axis rotation member rotatably supported in the pitch direction. and the mounting portion positioned adjacent to the support member .

The invention according to claim 3 is the invention according to claim 2, wherein the pitch direction and the roll direction of the installation section are determined based on the attitude of the unmanned aerial vehicle and the attitude of the installation section detected by the attitude detection section. It is characterized by further comprising a control unit that performs control to maintain the angle of direction in a predetermined direction.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein an optical surveying instrument is installed in the installation section, and the optical surveying instrument has a GNSS antenna and/or a reflecting prism. is fixed.

According to the present invention, it is possible to deal with various degrees of freedom regarding the structure for mounting a laser scanner and a camera on a UAV. Further, according to the present invention, the pitch direction (angular position around the pitch axis) and roll direction (angular position around the roll axis) of the installation table on which the equipment is mounted are maintained without being affected by the attitude of the UAV. . According to this function, it is possible to maintain the attitude of the laser scanner or camera in a specific direction without being affected by the attitude of the UAV. Further, according to the present invention, since a device such as a laser scanner is mounted in the central portion of the UAV, the weight balance is good and the flight stability of the UAV is obtained.

1 is a perspective view of an embodiment UAV; FIG. 4A and 4B are perspective views of the gimbal mechanism of the embodiment; FIG. 1 is a perspective view of a gimbal mechanism of an embodiment; FIG. 1 is a perspective view of a gimbal mechanism of an embodiment; FIG. 1 is a block diagram of an embodiment; FIG. 6 is a flow chart showing an example of a procedure of processing in the embodiment; It is the perspective view (A) and (B) which shows an example of a laser scanner. It is the perspective view (A) and side view (B) which show an example of a laser scanner.

(Overview)
A gimbal mechanism 200 for an unmanned aerial vehicle that can carry a laser scanner or camera is shown in FIGS. The gimbal mechanism 200 has a rotating member 205 around the pitch axis that functions as an installation section on which a laser scanner or camera is installed. The pitch-axis rotating member 205 can be electrically rotated about the pitch axis, and can also be vertically moved and electrically rotated about the roll axis.

In addition, the gimbal mechanism 200 outputs signals from attitude detection units (the vertical position measurement sensor 602, the pitch angle measurement sensor 603, and the roll angle measurement sensor 604 in FIG. 5) that detect the attitude of the rotating member 205 around the pitch axis, which is an installation unit. is provided with an angle drive unit (pitch angle control motor 606 and roll angle control motor 607) that controls the angles in the pitch and roll directions of the laser scanner or camera based on the above.

(UAV)
A UAV 100 is shown in FIG. The UAV 100 has base portions 101 and 102 that constitute the body. The base portions 101 and 102 have a rectangular frame shape with an opening in the center, and the gimbal mechanism 200 is arranged in the central opening.

Four horizontally extending struts are fixed to the base portions 101 and 102, and a propeller 103 for causing the UAV 100 to fly is attached to each tip of the four struts.

UAV 100 is equipped with GNSS equipment and an inertial navigation measurement unit (IMU) to obtain its own three-dimensional position and attitude during flight. In addition, the UAV 100 includes a motor for driving the propeller 103, a battery, a flight control device, a storage unit for storing flight plans and flight logs, etc., but these are the same as those of a normal UAV, so descriptions thereof will be omitted.

(Gimbal mechanism)
A gimbal mechanism 200 is shown in FIGS. Although not shown, the gimbal mechanism 200 also includes base portions 101 and 102 that constitute the main body of the UAV 100 . Also, the gimbal mechanism 200 may include various driving mechanisms represented by the pitch angle control motor 606, a GNSS antenna, a reflecting prism, and the like. In addition, the gimbal mechanism 200 may include various electronic circuits such as a control section, a driving relation, a storage section, and the like. The gimbal mechanism 200 is fixed to the bases 101, 102 of the UAV 100 shown in FIG. The gimbal mechanism 200 includes struts 201 and 202 , a horizontal support member 203 , a roll axis rotation member 204 and a pitch axis rotation member 205 .

Supports 201 and 202 extend vertically and are fixed to base portions 101 and 102 of UAV 100 . Moreover, the support|pillar protrudes and extends in the up-down direction of the base parts 101 and 102. As shown in FIG. The horizontal support member 203 is attached to the struts 201 and 202 so as to be vertically movable. The position in the vertical direction is detected by the vertical position measurement sensor 602 shown in FIG. 5, and the position is adjusted by the vertical position control motor 608. FIG.

The roll axis rotation member 204 is attached to the horizontal support member 203 so as to be rotatable about the roll axis. This rotation is performed by the roll angle control motor 607 shown in FIG. As the motor, for example, a brushless motor or a stepping motor is used. This is the same for other motors (eg, pitch angle control motor 606 in FIG. 2).

The rotating member 205 around the pitch axis functions as an installation section (installation table) on which an optical surveying instrument such as a laser scanner or camera is mounted. The pitch axis rotation member 205 rotates with respect to the roll axis rotation member 204 together with the support member 206 . This rotation is performed by the pitch angle control motor 606 shown in FIGS.

In addition, the pitch-axis rotation member 205 is offset-rotated with respect to the support member 206 about the pitch axis. Offset rotation is performed by a pitch offset setting motor 610 (see FIG. 5), not shown in FIG. FIG. 2B shows a state in which the pitch axis rotation member 205 is offset-rotated with respect to the support member 206 about the pitch axis. The support member 206 and the pitch axis rotation member 205 rotate integrally in pitch while the pitch axis rotation member 205 is offset rotated about the pitch axis with respect to the support member 206 .

The supporting member 206 constitutes a pitch offset section together with the rotating member 205 around the pitch axis. It is also possible to manually set the offset angle about the pitch axis.

Detection of the rotational position of the roll axis rotation member 204 about the roll axis is performed by a roll angle measurement sensor 604 shown in FIG. The rotation position of the pitch axis rotation member 205 about the pitch axis is detected by a pitch angle measurement sensor 603 shown in FIG. The angle is detected by a rotary encoder, but it is also possible to detect the number of pulses sent to the motor.

As the roll-axis rotating member 204 rotates about the roll axis, the pitch-axis rotating member 205 rotates about the roll axis. That is, the pitch-axis rotating member 205 can rotate about the roll axis and can also rotate about the pitch axis.

FIG. 4 shows a state in which the GNSS antenna 207 and the reflecting prism 208 are fixed to the support member 206. As shown in FIG. The reflecting prism 208 is a target for reflecting positioning laser light from a positioning device using laser light, such as a total station.

Here, since navigation signals from GNSS navigation satellites are propagated from the sky, the GNSS antenna 207 is arranged above. On the other hand, since the positioning laser light is emitted from the ground, the reflecting prism 208 is arranged below. It is also possible to prepare a plurality of installation candidates for the GNSS antenna and the reflecting prism, and to select the installation position from among them.

The relationship between the position (optical center position) of the optical survey instrument (camera or laser scanner) held on the rotating member 205 around the pitch axis, the position of the GNSS antenna 207 and the position of the reflecting prism 208 (position of the reflection center) is It is stored in the offset storage device 605 shown in FIG. Note that a configuration including only one of the GNSS antenna 207 and the reflecting prism 208 is also possible.

When the above positional relationship changes due to a change in vertical position, roll rotation, or pitch rotation, the above positional relationship is checked in advance for each vertical position and angular position, and the data is stored in the offset storage device 605. Keep

In the gimbal mechanism 200, by adjusting the vertical position of the horizontal support member 203, the pointing direction of the optical surveying instrument installed on the rotating member 205 around the pitch axis can be oriented downward, upward, or horizontally. be able to. For this reason, a wide survey range and high versatility can be obtained.

In particular, the horizontal support member 203 (rotating member 205 around the pitch axis) can be vertically moved inside the opening of the base portion 101 . Therefore, the pitch axis rotating member 205 and the optical surveying device such as a camera or laser scanner installed on the pitch axis rotating member 205 can be positioned above or below the base unit 101. A large downward field of view can be secured.

(control part)
The UAV 100 is equipped with a control section 600 shown in FIG. The controller 600 is included in the gimbal mechanism 200, but is omitted from FIG. A structure in which part of the control unit 600 (for example, the processing unit 609) is arranged at a position away from the structure that constitutes the gimbal mechanism 200 (usually at some part of the UAV 100) is also possible. .

The control unit 600 includes a three-axis gyro sensor 601, a vertical position measurement sensor 602, a pitch angle measurement sensor 603, a roll angle measurement sensor 604, an offset storage device 605, a pitch angle control motor 606, a roll angle control motor 607, and a vertical position control motor. 608 , a processing unit 609 and a pitch angle offset setting motor 610 .

The control unit 600 detects the attitudes of the UAV 100 and the optical surveying instrument mounted on the rotating member 205 around the pitch axis, and maintains the intended attitude of the optical surveying instrument even if the attitude of the UAV 100 changes. , the pitch angle and roll angle of the rotation member 205 around the pitch axis are controlled.

The 3-axis gyro sensor 601 detects angles of the UAV 100 about 3 axes (two horizontal axes orthogonal to the vertical axis). As the 3-axis gyro sensor 601, a 3-axis gyro function of an IMU (inertial measurement unit) included in the UAV 100 may be used. The vertical position measurement sensor 602 detects the vertical position of the horizontal support member 203 on the columns 201 and 202 . A pitch angle measurement sensor 603 detects the angular position of the pitch axis rotating member 205 about the pitch axis. A roll angle measurement sensor 604 detects the angular position of the roll axis rotating member 204 about the roll axis.

The offset storage device 605 stores the relative positional relationship between the position of the optical surveying instrument mounted on the rotating member 205 around the pitch axis and the positions of the GNSS antenna 207 and the mirror 208 in FIG. The pitch angle control motor 606 rotates the pitch axis rotating member 205 about the pitch axis. The roll angle control motor 607 rotates the roll axis rotation member 204 about the roll axis. A vertical position control motor 608 vertically moves the horizontal support member 203 with respect to the columns 201 and 202 . A processing unit 609 is a computer having a CPU, a memory, and various interfaces, and executes the processing in FIG. A pitch angle offset setting motor 610 offset-rotates the pitch axis rotating member 205 about the pitch axis to set an offset angle about the pitch axis with respect to the supporting member 206 .

(Example of processing)
FIG. 6 shows an example of the procedure of processing performed by the processing unit 609 in FIG. A program for executing the processing in FIG. 6 is stored in the memory in the processing unit 609 or other suitable storage device or storage medium, read from there and executed by the CPU provided in the processing unit 609 . It is also possible to store this program in an appropriate storage medium, storage server, or the like and acquire it from there.

Prior to the processing, the attitude in the absolute coordinate system of the optical survey instrument (laser scanner or camera) held by the gimbal mechanism 200 is specified in advance. The attitude of this optical surveying instrument is not limited to a fixed one, and can be changed in accordance with the position of the UAV 100, changed over time, adjusted to an attitude instructed by the operator of the UAV 100, or the like. be. Note that the absolute coordinate system is a coordinate system used in GNSS. In an absolute coordinate system, positions are specified by latitude, longitude, and altitude above mean sea level. Also, the attitude in the absolute coordinate system is described, for example, in polar coordinates in a three-dimensional coordinate system in which the X-axis is the east direction, the Y-axis is the north direction, and the Z-axis is the vertical direction.

When the process starts, the initial values are set first. This process is performed before the UAV 100 starts flying. In this process, first, the position and attitude of the UAV 100 on the absolute coordinate system are determined, and then the vertical position of the horizontal support member 203 is moved to the designated vertical position and fixed there (step S101). Next, the rotating member 205 around the pitch axis is offset-rotated to a designated pitch position (pitch angle) and fixed there (step S102). Next, the rotating member 204 around the roll axis is offset-rotated to a specified roll position (roll angle) and fixed there (step S103).

Next, the vertical position of the horizontal support member 203 is measured (step S104), the pitch position (pitch angle) of the rotating member 205 around the pitch axis is measured (step S105), and the roll position (roll angle) of the rotating member 204 around the roll axis is measured. is measured (step S106).

Next, based on the offset information stored in the offset storage device 605 and the measurement results of steps S104 to S106, the positions of the GNSS antenna 207 and the reflecting prism 208 with respect to the UAV 100 are obtained (steps S107 and S108).

Next, the parameters obtained in steps S104 to S109 and the offset information stored in the offset storage device 605 are obtained (step S109). In this state, the optical surveying instrument placed on the rotating member 205 around the pitch axis is set in a predetermined posture. However, since the attitude of the UAV 100 changes when the flight starts, the attitude control of the optical survey instrument does not consider the attitude of the UAV 100 at this stage. Attitude control of the optical survey instrument taking into account the attitude of the UAV 100 is performed in the following steps S110 and subsequent steps.

After step S109, the output of the 3-axis gyro sensor 601, the GNSS data, and the position of the reflecting prism are obtained (step S110), and the pitch angle and roll angle of the gimbal mechanism 200 are determined based on the content thereof and the content obtained in step S109. Control is performed (step S111). If the flight is not started, the data acquired in S110 is the same as the initial value, so the control of S111 is not performed, and the gimbal mechanism 200 maintains the stationary state before the start of flight.

In step S111, the processing unit 609 performs the following processing. First, from the result of step S109, the attitude of the optical survey instrument (the camera or laser scanner held by the gimbal mechanism 200) in the coordinate system fixed to the UAV 100 is obtained. On the other hand, the attitude of the UAV 100 in the absolute coordinate system, the position of the GNSS antenna, and the position of the reflecting prism are obtained from the result of step S110. This results in the attitude of the optical survey instrument, the position of the GNSS antenna and the reflector prism in the absolute coordinate system. By knowing the attitude of the optical survey instrument held by the gimbal mechanism 200 in the absolute coordinate system, the positions of the GNSS antenna and the reflecting prism, the difference between the actual values of these parameters and the initial values (values to be maintained) can be calculated. I understand. A signal for controlling the pitch angle and roll angle of the gimbal mechanism 200 is generated so as to eliminate this difference, and the attitude of the optical surveying instrument installed on the rotation member 205 around the pitch axis is controlled.

Through the above processing, even if the attitude of the UAV 100 changes, real-time control is performed so that the attitude in the absolute coordinate system of the optical surveying instrument held by the gimbal mechanism 200 is a predetermined one.

(Other 1)
In step S111, it is also possible to adjust the vertical position of the horizontal support member 203 (pitch axis rotation member 205) at the same time as the posture (roll angle and pitch angle) of the pitch axis rotation member 205 is adjusted. In this case, the position of the UAV 100 based on the laser positioning information of the GNSS device and the reflecting prism 208 provided in the UAV 100 and the positional relationship between the survey target (imaging target and laser scanning target) are determined. Find the position as the target position. Then, the vertical position of the rotating member 205 around the pitch axis is adjusted so that the optical surveying instrument is positioned at the target position.

For example, consider laser scanning a bridge from a flying UAV. At this time, it is assumed that laser scanning is first performed from above the bridge, and then laser scanning is performed on the back side (lower side) of the bridge by crawling under the bridge. In this case, first, the position of the rotating member 205 around the pitch axis is lowered below the base portion 102, and laser scanning is performed downward as viewed from the UAV 100. FIG. Next, the position of the rotating member 205 around the pitch axis is raised above the base portion 101, and laser scanning is performed upward as seen from the UAV 100. FIG. By doing so, a wide laser scanning range can be ensured.

(Other 2)
It is also possible to fix the GNSS antenna and/or reflector prism to an optical survey instrument such as a camera or laser scanner.

FIGS. 7A and 7B are perspective views of the laser scanner 300 fixed on the rotating member 205 around the pitch axis, which serves as an installation table. The laser scanner 300 includes an optical unit 301 that irradiates and receives scan laser light. Scanning laser light is emitted from the optical unit 301 to the outside, and reflected light from the object is received by the optical unit 301 .

The type of laser scanner is not particularly limited. Laser scanners are described in, for example, Japanese Patent No. 5466807 and Japanese Patent Application Laid-Open No. 2012-132917.

FIG. 7A shows an example in which the reflecting prism 230 and the GNSS antenna 107 are fixed to the laser scanner 300. FIG. The reflecting prism 230 has an optical characteristic of reversing the direction of incident light by 180 degrees and reflecting it. By performing tracking and ranging using a TS (total station) with the reflecting prism 230 as a target, tracking and positioning by the TS of an optical survey instrument (camera or laser scanner) mounted on the UAV 100 are performed. TS is described, for example, in JP-A-2015-145784.

In the case of FIG. 7A, the laser scanner 300 is fixed on the rotating member 205 around the pitch axis in FIG. 2 so that the GNSS antenna 107 is positioned vertically above and the reflecting prism 230 is positioned vertically below. At this time, an opening is provided in the rotating member 205 around the pitch axis, and the reflecting prism 230 is projected downward from the opening.

FIG. 7B shows another example in which the reflecting prism 230 and the GNSS antenna 107 are fixed to the laser scanner 300. FIG. In this case, the GNSS antenna 107 is fixed to the side of the laser scanner 300 and the reflecting prism 230 is fixed to the opposite side. The laser scanner 300 is fixed on the rotating member 205 around the pitch axis so that the GNSS antenna 107 is positioned vertically above and the reflecting prism 230 is positioned vertically below. Here, the laser scanner 300 is fixed to the rotating member 205 around the pitch axis in a state in which the reflecting prism 230 protrudes downward from an opening provided in the rotating member 205 around the pitch axis.

FIG. 7A shows a case where the laser scanner 300 is placed upright, and FIG. 7B shows a case where the laser scanner 300 is placed horizontally. Either of these two arrangement structures can be selected according to the scanning target and the scanning direction. In either case, in the basic state, the positional relationship is such that the GNSS antenna 107 is positioned above and the reflecting prism 230 is positioned below.

A laser scanner 500 is shown in FIGS. 8(A) and (B). The laser scanner 500 performs a conical laser scan centering on the axial direction from the optical unit 501 . In FIG. 8A, the reflecting prism 230 is fixed on the scanning light irradiation direction side, and the GNSS antenna 107 is fixed on the opposite side to the scanning light irradiation direction. Here, the reflecting prism 230 is fixed to the body of the laser scanner 500 via an arm 502 fixed to the body of the laser scanner 500 . Also, the GNSS antenna 107 is directly fixed to the main body of the laser scanner 500 .

In the case of FIG. 8A, an opening is provided in the rotating member 205 around the pitch axis shown in FIG. 2, and the laser scanner 500 is fixed to the rotating member 205 around the pitch axis so that the optical unit 501 protrudes downward from the opening. . In this case, laser scanning is performed mainly vertically downward.

FIG. 8B shows an example in which the GNSS antenna 107 is fixed to one side of the laser scanner 500 and the reflecting prism 230 is fixed to the other side. In this case, the laser scanner 500 is fixed to the rotating member 205 around the pitch axis so that the GNSS antenna 107 is vertically upward and the reflecting prism 230 is vertically downward. In this structure, the laser scan is centered in the horizontal direction.

In the configuration shown in FIGS. 7 and 8, the GNSS antenna and reflector prism are fixed rigidly, either directly or not directly, to the laser scanner. Therefore, the relationship between the position of the scanning origin of the laser scanner, the position of the GNSS antenna, and the position of the reflecting prism is less likely to change due to vibration or deformation of the member, and high stability can be obtained.

DESCRIPTION OF SYMBOLS 100... UAV, 101, 102... Base part, 103... Propeller, 107... GNSS antenna, 200... Gimbal mechanism, 201, 202... Strut, 203... Horizontal support member, 204... Rotating member around roll axis, 205... Around pitch axis Rotating member 206 Supporting member 207 GNSS antenna 208 Reflecting prism 230 Reflecting prism 300 Laser scanner 301 Optical section 500 Laser scanner 501 Optical section 502 Arm.

Claims (4)

An unmanned aerial vehicle gimbal mechanism mounted on an unmanned aerial vehicle,
a frame-shaped base having an opening;
an installation section that can move up and down inside the opening and can be moved upward and downward from the base section and on which a laser scanner or a camera is installed;
a vertical position adjustment mechanism capable of adjusting the position of the installation portion in the vertical direction with respect to the unmanned aerial vehicle;
an angle adjustment mechanism capable of adjusting the roll direction angle and the pitch direction angle of the installation portion;
an orientation detection unit that detects the orientation of the installation unit;
an angle driving unit that controls angles of the installation unit in the pitch direction and the roll direction based on signals from the attitude detection unit ;
an upward facing GNSS antenna and/or a downward facing reflector prism;
a storage unit that stores the positional relationship between the installation unit and the GNSS antenna and/or the reflecting prism;
with
The angle adjustment mechanism includes a roll axis rotation member rotatably supported by a horizontal support member, and the roll axis rotation member rotatably supported in the pitch direction by a support member provided at an end of the roll axis rotation member. and an installation part,
The gimbal mechanism for an unmanned aerial vehicle, wherein the installation section is arranged close to the support member . 2. The gimbal mechanism for an unmanned aerial vehicle according to claim 1 , wherein the axis of said GNSS antenna and said reflecting prism are aligned . A control unit that performs control to maintain the angles of the installation unit in the pitch direction and the roll direction in predetermined directions based on the attitude of the unmanned aerial vehicle and the attitude of the installation unit detected by the attitude detection unit. The gimbal mechanism for an unmanned aerial vehicle according to claim 1 or 2 . An optical survey instrument is installed in the installation section,
The gimbal mechanism for an unmanned aerial vehicle according to any one of claims 1 to 3, wherein a GNSS antenna and/or a reflecting prism are fixed to said optical survey instrument .

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