JP7086554B2 - Unmanned aerial vehicle control method and unmanned aerial vehicle control program - Google Patents

Description

The present invention relates to a control technique for an unmanned aerial vehicle.

A technique for tracking a UAV (Unmanned Aerial Vehicle) (unmanned aerial vehicle) with a TS (total station) is known (see, for example, Patent Document 1).

US2014 / 0210663 Gazette

During a UAV flight, the UAV may have to return or land in a safe place in a hurry due to problems such as equipment failure or malfunction, low battery power, or sudden changes in the weather. In particular, if there is a problem with the remaining battery power, it is necessary to return by flying the shortest distance possible in order to avoid a crash due to a dead battery.

At this time, if there is no obstacle, the UAV may be returned by the shortest flight, but if there is an obstacle such as a building, it is necessary to return the UAV by a route considering the existence of the obstacle. Further, it is desired that the above-mentioned emergency return is performed by automatic control. This is because there is a concern that an accident may occur due to an erroneous operation when the operator returns by maneuvering in an emergency.

Against this background, it is an object of the present invention to provide a technique for effectively avoiding obstacles and returning during an emergency return of a UAV in flight.

The present invention is a method for controlling an unmanned aircraft by a total station equipped with a laser scanner, and is a range centered on the unmanned aircraft flying by the laser scanner while tracking the unmanned aircraft flying by the laser beam of the total station. Based on the laser scan, a three-dimensional map of the space including the flight path of the unmanned aircraft is created, and based on the three-dimensional map, the flight at the time of returning to a predetermined specific point is performed. It is a control method for unmanned aircraft to be controlled.

The present invention is a program for causing a computer to control an unmanned aircraft by a total station equipped with a laser scanner, wherein the computer tracks an unmanned aircraft flying by the laser beam of the total station, and the laser scanner flies. A laser scan of a range centered on an unmanned aircraft, a three-dimensional map of the space including the flight path of the unmanned aircraft based on the laser scan, and a predetermined specific point based on the three-dimensional map. It is a program for controlling an unmanned aircraft that controls flight at the time of return .

According to the present invention, it is possible to obtain a technique for effectively avoiding obstacles and returning during an emergency return of a UAV in flight.

It is a schematic diagram of an embodiment. It is a block diagram of TS (total station). It is a block diagram of a route setting device. It is an image diagram explaining the selection of a route. It is a flowchart which shows an example of the processing procedure.

1. 1. First Embodiment (Overview)
FIG. 1 shows a state in which a flying UAV200 is tracked by a TS100. The flight of the UAV 200 may be along a predetermined flight path, or may be a manual operation in which the operator operates the controller. In the airspace where the UAV200 flies, there is a standing tree 110 that is an obstacle to the flight of the UAV200. Obstacles may be buildings, towers, utility poles, cliffs, hills, mountains and the like.

The TS100 has a laser scan function, performs laser scan around the UAV200 while tracking and positioning the flying UAV200, and acquires three-dimensional point cloud data around the flying UAV200. Then, a three-dimensional map is created based on the three-dimensional point cloud data. For example, if the UAV 200 flies near the standing tree 110, a three-dimensional map containing a three-dimensional model of the standing tree 110 is created on the TS100 side.

When the UAV200 must be returned to a predetermined ground position for some reason, the return route of the UAV200 is determined based on the three-dimensional map acquired by the TS100, and flight control is performed along this return route.

In an emergency, it is desirable to return by the shortest route possible, but contact with obstacles and collisions should be avoided. By setting the return route using the above three-dimensional map, it is possible to return in the shortest distance while avoiding interference and collision with obstacles.

(UAV200)
The UAV200 is a commercially available ordinary one equipped with a reflection prism 201. The selection of the UAV 200 is free, and the user of the present invention can freely select it. However, the UAV 200 needs to have a function of flying by receiving a control signal from the outside.

The UAV200 is equipped with a reflection prism 201 that is a target for tracking and ranging from the TS100. The reflection prism 201 has an optical characteristic of reflecting incident light by changing the direction by 180 °. The TS100 captures and tracks the UAV 200 by capturing the reflection prism 201 with the tracking light, and positions the UAV 200 by measuring the position of the reflection prism 201 with the ranging light.

(TS (total station))
Hereinafter, the TS100 will be described. FIG. 2 is a block diagram of the TS100. The TS100 includes a range-finding light emitting unit 101, a range-finding light receiving unit 102, a range-finding unit 103, a horizontal / vertical angle detection unit 104, a horizontal / vertical angle drive unit 105, a three-dimensional position calculation unit 106, a tracking unit 107, and a laser. It is equipped with a scanner 108 and a route selection device 109. The TS (total station) is described in Japanese Patent Application Laid-Open No. 2009-229192, Japanese Patent Application Laid-Open No. 2012-202821, Japanese Patent No. 5124391, and the like.

The range-finding light irradiation unit 101 irradiates the range-finding light toward the reflection prism 201 of the UAV 200. The ranging light is applied to the reflecting prism 201 via an optical system (not shown). The ranging light receiving unit 102 receives the reflected light of the ranging light reflected by the reflecting prism 201 via an optical system (not shown).

The distance measuring unit 103 calculates the distance from the TS 100 to the reflecting prism 201 based on the flight time of the distance measuring light. Specifically, an optical path for reference light is provided inside the TS100, and the distance from the phase difference between the reference light and the ranging light received by the ranging light receiving unit 102 to the reflecting prism 201 is calculated.

The TS100 has a main body capable of horizontal rotation. A movable part capable of vertical rotation (rotation control of elevation angle and depression angle) is attached to this main body. The optical system of the distance measuring light irradiation unit 101, the distance measuring light receiving unit 102, and the optical system of the tracking unit 107 are fixed to this movable portion. By shaking this movable part up, down, left and right, the horizontal and vertical irradiation directions of the tracking light and the ranging light are controlled. The laser scanner 108 is fixed to the main body instead of the movable part. Of course, a structure in which the laser scanner 108 is provided in the movable portion is also possible.

The horizontal / vertical angle detection unit 104 detects the horizontal angle (angle in the horizontal direction) and the vertical angle (elevation angle or depression angle) of the movable portion (main body). Angle detection is performed by a rotary encoder. In the angle measurement, for example, in the horizontal angle, the north direction is 0 ° and the clockwise angle is measured, and in the vertical angle, the horizontal is 0 ° and the elevation angle is + and the depression angle is-. The TS100 is installed at a known position on the map coordinate system (absolute coordinate system). The map coordinate system is a global coordinate system used in GNSS.

The horizontal / vertical right angle drive unit 105 performs horizontal rotational drive and vertical rotational drive of the movable portion. The horizontal / vertical right-angle drive unit 105 includes a motor and a drive circuit for performing the above-mentioned drive. By controlling the horizontal angle and the vertical angle of the movable portion, the irradiation directions of the tracking light and the ranging light are controlled.

The three-dimensional position calculation unit 106 is the three-dimensional coordinates of the reflection prism 201 from the distance to the reflection prism 201 calculated by the distance measurement unit 103 and the direction of the optical axis of the distance measurement light detected by the horizontal / vertical right angle detection unit 104. Calculate the value. This three-dimensional coordinate value is acquired on the TS coordinate system with the TS100 as the origin. Examples of the TS coordinate system include an XYZ coordinate system in which the east direction is the X axis, the north direction is the Y axis, and the vertically upward direction is the Z axis. Since the position of the TS100 on the map coordinate system is known, the position of the reflection prism positioned by the TS100 can be described on the map coordinate system by the coordinate transformation of the translation.

The tracking unit 107 tracks the UAV 200 flying by the tracking light. By tracking the UAV200 by the tracking unit 107, the optical axis of the distance measuring light is controlled to be directed to the UAV200. Specifically, the horizontal / vertical right-angle drive unit 105 operates so that the reflection prism 201 included in the UAV 200 is supplemented by the tracking light, and the optical axis of the TS100 is directed so that the optical axis of the ranging light faces the reflection prism 201. Control is done. The tracking of the reflecting prism using the tracking light is described in, for example, Japanese Patent No. 512439.

The laser scanner 108 performs a laser scan in a range centered on the optical axis of the ranging light, and acquires three-dimensional laser scan data in the range. The laser scanner is described in, for example, Japanese Patent Application Laid-Open No. 2010-151682, Japanese Patent Application Laid-Open No. 2008-268004, Japanese Patent No. 8767190, and Japanese Patent No. 7969558. Further, Japanese Patent Application Laid-Open No. US2015 / 0293224 describes a laser scanner in a form of electronically scanning without utilizing the rotation or reciprocating motion of the optical system. This electronic scan form is also available.

The route selection device 109 creates a three-dimensional map from the scan data obtained by the laser scanner 108. Then, using this 3D map, the obstacles to the flight of the UAV200 are extracted, and the places where the extracted obstacles exist or the places where the situation is unknown without laser scanning are avoided. Select a return route.

(Configuration of route selection device)
FIG. 3 is a block diagram of the route selection device 109. The route selection device 109 includes a landing position information reception unit 201, an aircraft position information reception unit 202, a scan data reception unit 203, a scan map creation unit 204, a flight prohibited location extraction unit 205, a route selection unit 206, and an aircraft control signal generation unit 207. , A flight distance calculation unit 208, a battery consumption calculation unit 209, a landing possible point search unit 210, and an externally created map reception unit 211.

Each functional unit of the control device 105 shown in FIG. 3 includes, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device) represented by an FPGA (Field Programmable Gate Array), or the like. It is composed of electronic circuits. It is also possible to configure some functions with dedicated hardware and some others with general-purpose microcomputers.

Whether each functional unit is configured with dedicated hardware or software-like configuration by executing a program on the CPU is determined in consideration of the required calculation speed, cost, power consumption, and the like. It should be noted that configuring the functional unit with dedicated hardware and configuring it as software are equivalent from the viewpoint of realizing a specific function.

It is also possible to prepare the route setting device 109 as an external device separate from the TS100. At this time, the route setting device 109 can be configured by a PC (personal computer) or a tablet PC.

The landing position information receiving unit 201 receives the position information of the point where the UAV 200 is to be returned or is to be landed. The received position information is not limited to one, and may be plural. In the initial setting, the starting point is set as the position to be returned.

The aircraft position information receiving unit 202 receives the position information of the UAV200 positioned by the TS100. It is also possible to receive the position information of the UAV200 specified by the GNSS position specifying device mounted on the UAV200. The scan data receiving unit 203 acquires the laser scan data scanned by the laser scanner 108.

The scan map creation unit 204 creates a three-dimensional map from the laser scan data received by the scan data reception unit 203. The created three-dimensional map may be a schematic map. As a three-dimensional map created from the terrain of FIG. 1, for example, the example of FIG. 4 can be mentioned. The three-dimensional map is a three-dimensional space represented by the (x, y, z) component, and the measured object has its maximum width and maximum height in the range visible from the TS100, respectively (x, y, z). ) It is expressed by the component. Therefore, the measured object is approximated as a plane visible from the TS100 of the rectangular parallelepiped 111 in the three-dimensional space. Here, the rectangular parallelepiped 111 is a three-dimensional model in which the three-dimensional information of the standing tree 110 obtained by laser scanning is approximated by a rectangular parallelepiped.

In the three-dimensional map created by the scan map creation unit 204, the flight prohibited part extraction unit 205 is a space where an obstacle that obstructs the flight of the UAV 200 exists, a space behind the obstacle as seen from the TS, and a laser. The space that was not scanned is extracted as a flight prohibited area. In the space behind the rectangular parallelepiped 111 seen from the TS100, the laser scan data from the TS100 cannot be obtained, and the three-dimensional information of the space is unknown. Therefore, the space is treated as a prohibited flight area to prevent accidents from occurring. In addition, since the three-dimensional information is unknown in the space where the laser scanner was not performed, the flight is prohibited in order to prevent accidents.

The route selection unit 206 searches for one or a plurality of routes capable of avoiding obstacles and flying, and selects the optimum route from the one or a plurality of routes. The search for one or more routes capable of avoiding obstacles and flying is performed based on the three-dimensional map created by the scan map creating unit 204 and the obstacles extracted by the obstacle extracting unit 205. The route candidates may be set in advance, but since shorter routes may be extracted, a return route search using a three-dimensional map is performed at the stage when feedback is required. Further, for the preset path, the interference with the obstacle is determined based on the three-dimensional map obtained by the laser scan. Here, if interference with an obstacle is expected, a new route candidate for avoiding the obstacle is searched for. If there are multiple routes that can be searched, select a route that is advantageous in terms of flight distance and power consumption from the routes that can avoid the extracted obstacles. For example, the route with the lowest power consumption is selected from a plurality of routes.

Examples of the route selection include the following methods. First, the scan map creation unit 204 sets a three-dimensional map (x, y, z) = (100,100,100) consisting of 100 unit spaces (x, y, z) = (1,1,1). The width, depth, and height of obstacles and prohibited areas where the situation is unknown are expressed as integers for each value of (x, y, z), and the position is also (x, y, z). Then, if it is expressed by 1 ≦ x, y, z, ≦ 100, it is possible to know in which unit space on the three-dimensional map the flight prohibited part exists.

Similarly, if the position of the UAV200 and the position of the return point are also expressed by 1 ≤ x, y, z, ≤ 100 using (x, y, z), the position of the UAV200 and the return point on the three-dimensional map can be expressed. The position of is also specified. The position of the UAV200 and the position of the return point specified on the three-dimensional map correspond to any one of the 100 unit spaces.

Therefore, the unit space corresponding to the position of the UAV200 is set as the start point, the unit space corresponding to the position of the return point is set as the goal point, the unit space with obstacles and the unit space where the situation is unknown without scan data are set as flight prohibited points. Search for a route that passes only through a unit space that is not a restricted area from the start point to the goal point. As a result, a route that can avoid (detour) obstacles and return is obtained. Further, in order to select the shortest route, the route having the smallest number of unit spaces may be selected from the searched routes.

The scale of one side of the unit space can be variable. For example, if the flight is up to 100m, the unit space is set to 1m x 1m x 1m, and when 100m is exceeded, it is set to 2m x 2m x 2m, and then the scale of one side of the unit space is set according to the flight distance. By changing, it is possible to respond to various flight distances. However, the larger the scale, the larger the unit space where obstacles are considered to occur. Therefore, when the flight distance becomes long, the number of unit spaces constituting the three-dimensional map is increased in advance so that the scale does not need to be increased too much.

The aircraft control signal generation unit 207 generates a signal for making the UAV 200 fly the route selected by the route selection unit 206. The maneuvering signal generated by the aircraft maneuvering signal generation unit 207 is transmitted to the UAV200, and the flight control of the UAV200 is performed by this maneuvering signal.

The flight distance calculation unit 208 calculates the flight distance of the selected return route. The battery consumption calculation unit 209 calculates the battery consumption required for the above-selected feedback route based on the calculation result of the flight distance calculation unit 208. At this time, the power consumption is calculated in consideration of factors such as turning and climbing. The landable point search unit 210 searches for a landable point when it is estimated that the battery does not have up to the initially set landing point. As the landable point, there is an embodiment in which a point without obstacles is selected from the three-dimensional map created on the side of the TS100. The externally created map reception unit 211 receives information on a separately prepared three-dimensional map or a three-dimensional map acquired by other means. It is also possible to accept point cloud data instead of a three-dimensional map.

(Example of processing)
An example of the processing in this embodiment is shown in FIG. First, the UAV 200 receives the position information of the return or landing point. The timing of receiving the position information may be before the start of the flight of the UAV200 or during the flight, but it is necessary to receive the position information by step S104 described later (step S101).

When the flight of the UAV200 is started, the tracking and positioning of the UAV200 by the TS100 are started. Further, a laser scan is performed by a laser scanner 108 centered on the UAV 200. The range of the laser scan is, for example, a range of a radius of 25 m centered on the UAV200. During the flight, the position of the UAV 200 is received by the aircraft position information receiving unit 202, and the laser scan data is received by the laser scan data receiving unit 203 (step S102). After receiving the scan data, the scan map creation unit 204 creates a three-dimensional map (step S103).

Then, when the UAV200 has an opportunity to return, the process proceeds from step S104 to step S105, and the current position of the UAV200 and the position of the return point on the three-dimensional map are collated. Here, the trigger for the UAV 200 to return is an instruction from the operator, a decrease in the battery amount, a malfunction of the device, or the like. If there is no opportunity for the UAV200 to return, the processes of steps S102 and S103 are repeated.

If the determination in step S104 is YES, it is determined based on the three-dimensional map created in step S103 whether or not the flight prohibited portion exists at the ground position on the straight line connecting the current position and the return position of the UAV200 (step S106). ). Here, if the flight prohibited portion does not exist on the straight line, a straight line connecting the current position of the UAV 200 and the return position in a straight line is selected as the return route (step S107). In step S105, if the flight prohibited portion exists on the straight line, it is determined whether the altitude of the flight prohibited portion is lower than the current position of the UAV 200 (step S108). Here, if there are multiple flight prohibited points, the one with the highest altitude is the comparison target.

If the altitude of the prohibited flight point is lower than the current position of the UAV200, a route for flying over the return position while maintaining the altitude and descending to the return point is selected (step S109). If the altitude of the prohibited flight point is higher than the current position of the UAV200, a route to the return point is selected in the shortest time by detouring to avoid obstacles (step S110). Finally, a signal for flying the determined route to the UAV200 is generated, and the process ends (step S111).

In this embodiment, a straight route connecting the current position of the UAV 200 and the return position in a straight line, a route of flying to the sky above the return position and descending to the return point while maintaining the altitude, and a detour to avoid a flight prohibited point are the shortest. The three flight routes (operations) of the route to the return point are set by the route selection unit 206 when the return is determined.

(Modification example)
You may search for a route that can avoid the prohibited flight points, calculate the battery consumption for the obtained route, and select the route with the lowest battery consumption.

2. 2. Second embodiment (overview)
When an opportunity to return to an unmanned aerial vehicle such as a UAV occurs, the point of takeoff is often set as the return point. However, it is conceivable that the battery installed will be low and it will not be possible to return to the takeoff point. Therefore, a mode is shown in which a route is selected with a landing point other than the takeoff point as the final point.

(Constitution)
In this case, the route selection device 109 includes a landable point search unit 210. The landable point search unit 210 searches for a landable point by the UAV 200 from the three-dimensional map created by the scan map creation unit 204. As a search for a landable point, a point where Z = 0 is selected as a landable point which is a flat land on a three-dimensional map which is a three-dimensional space represented by the (x, y, z) component.

Here, the point where Z = 0 may not be land but the water surface of a river or the like. Therefore, if the points where Z = 0 are long and narrow, it is determined that those points are rivers, and the points are excluded from the landable points. That is, the characteristics of the terrain where the risk of submersion or the like may occur when landing are defined in advance, and the places having the characteristics defined at the time of searching for the landable points are excluded. As a landable point, it is preferable to select a place where Z = 0 and the area is equal to or larger than the threshold value (for example, 5 m × 5 m or more). Further, in this case, it is also effective to select a place where Z = constant (or a place which can be regarded as constant) as a flat land even if Z = 0.

(Modification example)
The landing position information reception unit 201 may not accept the landing point, but may extract and determine the route with the landable point searched by the landing possible point search unit 210 as the final point. However, if the landable point search unit 210 cannot search for a landable point, it takes a risk and takes measures such as landing on the spot.

(others)
It is also possible to prepare a laser scanner separately from the TS100. In this case, calibration is performed in advance so that the three-dimensional point cloud data obtained by the laser scanner having a different configuration can be handled in the coordinate system with the TS as the origin.

The present invention can be used to route an unmanned aerial vehicle to a return or landing point.

100 ... TS (total station), 110 ... standing tree, 111 ... rectangular parallelepiped image when standing tree is treated as an obstacle, 200 ... UAV, 201 ... camera, 202 ... reflective prism.

Claims (2)

It is a method of controlling an unmanned aerial vehicle by a total station equipped with a laser scanner.
While tracking the unmanned aerial vehicle flying by the laser beam of the total station, the laser scanner performs a laser scan in a range centered on the flying unmanned aerial vehicle.
Based on the laser scan, a three-dimensional map of the space including the flight path of the unmanned aerial vehicle was created.
A control method for an unmanned aerial vehicle that controls flight when returning to a predetermined specific point based on the three-dimensional map. A program that allows a computer to control an unmanned aerial vehicle with a total station equipped with a laser scanner.
On the computer
While tracking the unmanned aerial vehicle flying by the laser beam of the total station, the laser scanner performs a laser scan in a range centered on the flying unmanned aerial vehicle.
Based on the laser scan, the creation of a three-dimensional map of the space including the flight path of the unmanned aerial vehicle,
Based on the 3D map, control of flight when returning to a predetermined specific point
A program for controlling unmanned aerial vehicles to execute .

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