Flight plan changing method and flight plan changing apparatus

A flight plan changing method performed by an apparatus includes reading a flight log of an unmanned aircraft that flies flight routes connecting multiple way points included in a flight plan and captures image data of an object located between the way points; identifying, based on the flight log, coordinates of a position of the unmanned aircraft at which the capturing of the image data of the object is interrupted; and generating a changed flight plan including way points that are newly determined based on the identified coordinates of the position.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based upon and claims priority to Japanese Patent Application No. 2018-045330, filed on Mar. 13, 2018, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of this disclosure relates to a flight plan changing method and a flight plan changing apparatus.

2. Description of the Related Art

There is a known inspection method where an object at a high altitude (e.g., a power line stretched between pylons) is inspected by capturing image data of the object using an unmanned aircraft such as a drone equipped with an imaging device. In such an inspection method, a flight plan including multiple way points is generated, and image data of the object is captured by automatically flying the unmanned aircraft along the object according to a flight route connecting the way points (see, for example, WO 2015/180133).

However, the flight distance between way points and the power consumption during flight may increase depending on the shape of an object whose image data is captured. Also, the power consumption during the flight may increase due to the influence of natural phenomena (e.g., wind and rain). As a result, the remaining battery power may become less than or equal to a predetermined value during the flight, and the flight according to the flight plan may be interrupted as a failsafe operation.

In the related-art technology, if the flight according to the flight plan is interrupted, a changed flight plan including way points before and after a position at which the flight is interrupted and unflown way points (way points to which the unmanned aircraft has not flown) is generated. With the changed flight plan, image data of the same portion of the object is repeatedly captured. Accordingly, compared with a case where the flight plan is not interrupted, the amount of captured image data increases, the time necessary to analyze the image data increases, and the inspection efficiency decreases.

SUMMARY OF THE INVENTION

In an aspect of this disclosure, there is provided a flight plan changing method performed by an apparatus. The flight plan changing method includes reading a flight log of an unmanned aircraft that flies flight routes connecting multiple way points included in a flight plan and captures image data of an object located between the way points; identifying, based on the flight log, coordinates of a position of the unmanned aircraft at which the capturing of the image data of the object is interrupted; and generating a changed flight plan including way points that are newly determined based on the identified coordinates of the position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An aspect of this disclosure provides a flight plan changing method and a flight plan changing apparatus that can improve inspection efficiency.

Embodiments of the present invention are described below with reference to the accompanying drawings. Throughout the specification and the drawings, the same reference number is assigned to components having substantially the same function and configuration, and repeated description of those components is omitted.

First Embodiment

<External Configuration and Functional Configuration of Unmanned Aircraft>

First, an unmanned aircraft (e.g., a drone) used to inspect an object (in an example of a first embodiment, a power line stretched between pylons) is described.FIG. 1Ais a drawing illustrating an example of an external configuration of an unmanned aircraft100, andFIG. 1Bis a drawing illustrating an example of a functional configuration of the unmanned aircraft100. As illustrated inFIG. 1A, the unmanned aircraft100includes an aircraft body110and an attachment120. Also, as illustrated inFIG. 1B, the aircraft body110includes a flight module130, a power supply140, and a control device150; and the attachment120includes an imager121.

The flight module130includes a mechanism (e.g., propellers and motors) that enables the unmanned aircraft100to fly. The power supply140includes a power source (e.g., a battery) for supplying power to the flight module130and the imager121.

The control device150controls the flight module130and the power supply140of the aircraft body110and the imager121of the attachment120. A control program is installed in the control device150and is executed to cause the control device150to function as a flight controller151, a power monitor152, and an imaging controller153.

The flight controller151controls the flight module130such that the unmanned aircraft100flies flight routes connecting multiple way points included in a set flight plan. More specifically, the flight controller151controls the flight module130such that the unmanned aircraft100flies a flight route between way points at a constant distance from a power line that is an object to be inspected. Also, when a failsafe operation is requested by the power monitor152, the flight controller151interrupts a flight according to a set flight plan, and controls the flight module130to cause the unmanned aircraft100to return to a home position (HP). Further, the flight controller151obtains the coordinates (latitude, longitude, and altitude) of positions of the unmanned aircraft100during flight, and stores the coordinates in association with time information in a flight log storage154.

The power monitor152monitors the amount of remaining power that can be supplied by the power supply140, and stores information indicating the state of the power supply140in association with time information in the flight log storage154. Also, when the amount of remaining power becomes less than or equal to a predetermined threshold, the power monitor152requests the flight controller151and the imaging controller153to perform a failsafe operation.

The imaging controller153controls the imager121to start and stop capturing image data, and stores the captured image data in association with time information in the flight log storage154. The imaging controller153controls the imager121to start capturing image data when a flight starts, and controls the imager121to stop capturing image data when the flight ends. Also, when a failsafe operation is requested by the power monitor152, the imaging controller153interrupts the capturing of image data by the imager121. The imager121of the attachment120captures image data of an object under the control of the imaging controller153. The imager121sends the captured image data to the imaging controller153.

<Hardware Configuration of Control Device of Unmanned Aircraft>

Next, a hardware configuration of control device150of the unmanned aircraft100is described.FIG. 2is a block diagram illustrating an example of a hardware configuration of the control device150of the unmanned aircraft100. As illustrated inFIG. 2, the control device150includes a central processing unit (CPU)201, a read-only memory (ROM)202, a random access memory (RAM)203, a secondary storage204, a display device205, an operating device206, and an interface (I/F) device207. These components of the control device150are connected to each other via a bus208.

The CPU201executes various programs (e.g., a control program) installed in the secondary storage204. The ROM202is a nonvolatile memory and functions as a main memory storing various programs and data that are necessary for the CPU201to execute the programs installed in the secondary storage204. The RAM203is a volatile memory such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). The RAM203functions as a main memory that provides a work area into which the programs installed in the secondary storage204are loaded when executed by the CPU201.

The secondary storage204is a secondary memory that stores various programs and information used when the programs are executed. For example, the flight log storage154is implemented by the secondary storage204.

The display device205is an output device that displays, for example, internal states of the control device150. The operating device206is an input device for inputting various instructions to the control device150. The I/F device207is a connection device for communications with a flight plan management apparatus (described later) that manages flight plans of the unmanned aircraft100.

Next, a flight plan set in the control device150of the unmanned aircraft100is described.FIG. 3Ais a table indicating an exemplary flight plan300. As illustrated inFIG. 3A, the flight plan300includes information items “point” and “latitude, longitude, altitude”.

The “point” stores a home position (HP) and way points (WP) in flight order. The example ofFIG. 3Aindicates that the unmanned aircraft100plans to fly in the flight order of “HP→WP1→WP2→WP3→WP4→HP”. The “latitude, longitude, altitude” stores information indicating the latitude, longitude, and altitude of each of the home position (HP) and the way points (WP).

FIG. 3Billustrates the positions of way points included in the flight plan300and flight routes based on the flight plan300. In the example ofFIG. 3B, WP1is located above and at a predetermined distance from a pylon310, and WP2is located near the top of the pylon310. Also in the example ofFIG. 3B, WP3is located near the top of a pylon320, and WP4is located above and at a predetermined distance from the pylon320.

As illustrated inFIG. 3B, according to the flight plan300, the unmanned aircraft100flies from HP to WP1(flight route341), and descends to WP2(flight route342). Then, the unmanned aircraft100flies between WP2and WP3at a constant distance from a power line330(flight route343). After reaching WP3, the unmanned aircraft100ascends to WP4(flight route344) and returns from WP4to HP (flight route345).

<Cases where Flight Distance and Power Consumption Increase>

There are cases where a flight distance and power consumption of the unmanned aircraft100flying a flight route between way points included in the flight plan300increase.FIGS. 4A through 4Dare drawings used to describe cases where a flight distance and power consumption increase.

FIGS. 4A and 4Bare used to describe a case where the flight distance between way points increases due to the shape of an object to be captured. In this case, although the distance between the pylon310and the pylon320inFIG. 4Ais the same as that inFIG. 4B, power lines401and402stretched between the pylon310and the pylon320inFIGS. 4A and 4Bhave different shapes.

More specifically, compared with the power line401inFIG. 4A, the power line402inFIG. 4Bhas a more curved shape. As described above, the unmanned aircraft100flies between WP2and WP3at a constant distance from the power line. For this reason, the flight distance inFIG. 4Bbecomes greater than that inFIG. 4A.

FIGS. 4C and 4Dare used to describe a case where the power consumption during a flight between way points increases due to the shape of an object to be captured. In this case, although the distance between the pylon310and the pylon320inFIG. 4Cis the same as that inFIG. 4D, power lines403and404stretched between the pylon310and the pylon320inFIGS. 4C and 4Dhave different shapes (symmetrical shapes). For this reason, in a flight between WP2and WP3inFIG. 4C, the distance of downward flight is longer than the distance of upward flight. On the other hand, in a flight between WP2and WP3inFIG. 4D, the distance of upward flight is longer than the distance of downward flight. As a result, the power consumption during the flight inFIG. 4Dbecomes greater than the power consumption during the flight inFIG. 4C.

Thus, even when way points are determined similarly, the flight distance and/or the power consumption during a flight may increase due to the shape of an object to be captured. As a result, the amount of remaining power may become less than or equal to a predetermined threshold during the flight, and the flight according to a flight plan may be interrupted as a failsafe operation. Although not illustrated inFIGS. 4A through 4D, the power consumption during a flight may also increase due to natural phenomena such as rain, snow, and head wind blowing in a direction opposite the flight direction of the unmanned aircraft100.

<Flight Routes Taken when Flight According to Flight Plan is Interrupted>

When the amount of remaining power becomes less than or equal to a predetermined threshold during a flight according to a flight plan due to an increase in the flight distance or the power consumption, a failsafe operation is requested and the flight is interrupted. Flight routes taken in such a case are described here.

FIG. 5Ais a table indicating an exemplary flight plan500. As indicated byFIG. 5A, the flight plan500includes five way points WP1through WP5.

FIG. 5Billustrates the positions of way points included in the flight plan500, flight routes (solid lines) based on the flight plan500, and actual flight routes (dotted lines). In the example ofFIG. 5B, WP1is located above and at a predetermined distance from a pylon510, and WP2is located near the top of the pylon510. Also in the example ofFIG. 5B, WP3is located near the top of a pylon520, WP4is located near the top of a pylon530, and WP5is located above and at a predetermined distance from the pylon530.

As illustrated inFIG. 5B, according to the flight plan500, the unmanned aircraft100flies from HP to WP1(flight route561), and descends to WP2(flight route562). Then, the unmanned aircraft100flies between WP2and WP3at a constant distance from a power line540(flight route563). After passing WP3, the unmanned aircraft100further flies between WP3and WP4at a constant distance from a power line550(flight route564). After reaching WP4, the unmanned aircraft100ascends to WP5(flight route565), and returns from WP5to HP (flight route566).

InFIG. 5B, it is assumed that the unmanned aircraft100actually flies as indicated by dotted lines571through575. As indicated by the dotted lines571through575, the unmanned aircraft100actually flies according to the flight plan500until the unmanned aircraft100passes WP3(dotted lines571through573). However, after passing WP3, the flight of the unmanned aircraft100according to the flight plan500is interrupted at a position580, and the unmanned aircraft100returns from the position580to HP (dotted lines574and575).

<Exemplary Flight Log Recorded when Flight According to Flight Plan is Interrupted>

Next, an exemplary flight log600is described with reference toFIG. 6. The flight log600is stored in the flight log storage154when a flight according to the flight plan500is interrupted.

As indicated byFIG. 6, the flight log600includes information items “point”, “time”, “latitude, longitude, altitude”, “power”, and “image data”. The “point” stores a home position (HP) and way points (WP) in flight order. The “time” stores time information obtained by the flight controller151during the flight.

In the example ofFIG. 6, it is assumed that the amount of remaining power of the unmanned aircraft100became less than or equal to a predetermined threshold, a failsafe operation was requested, and the capturing of image data was interrupted at a position indicated by La100, Lo100, and Al100 (latitude, longitude, and altitude).

Next, a flight plan changing method is described based on an assumption that a changed flight plan is generated for the unmanned aircraft100that has returned to HP due to an interruption of a flight according to the flight plan500. First, a changed flight plan generated according to a related-art flight plan changing method is described as a comparative example, and then a changed flight plan generated according to a flight plan changing method of the first embodiment is described.

(1) Changed Flight Plan Generated According to Related-Art Flight Plan Changing Method

FIG. 7Ais a table indicating a changed flight plan700generated according to a related-art flight plan changing method. As indicated byFIG. 7A, the flight plan700generated according to the related-art flight plan changing method includes way points WP3and WP4located before and after the position580at which the flight according to the flight plan500is interrupted and unflown way points WP4and WP5(way points to which the unmanned aircraft100has not flown).

FIG. 7Billustrates the positions of way points included in the flight plan700and flight routes based on the flight plan700. As illustrated inFIG. 7B, the unmanned aircraft100flies from HP to WP3′ (flight route701), and then descends to WP3(flight route702). Then, the unmanned aircraft100flies between WP3and WP4at a constant distance from the power line550(flight route564). After reaching WP4, the unmanned aircraft100ascends to WP5(flight route565) and returns from WP5to HP (flight route566).

Thus, according to the related-art flight plan changing method, the unmanned aircraft100flies the flight routes564through566. Here, a section of the flight route564between WP3and the position580(seeFIG. 5B) has already been flown in the flight based on the flight plan500(the dotted line574inFIG. 5B). Therefore, image data corresponding to the section between WP3and the position580is captured twice. Accordingly, with the related-art flight plan changing method, compared with a case where the flight according to the flight plan500is not interrupted, the amount of captured image data increases, the time necessary to analyze the image data increases, and the inspection efficiency decreases.

(2) Changed Flight Plan Generated According to Flight Plan Changing Method of First Embodiment

Next, a flight plan changing method according to the first embodiment is described.FIG. 8Ais a table indicating a changed flight plan800generated according to a flight plan changing method of the first embodiment. As indicated byFIG. 8A, according to the flight plan changing method of the first embodiment, the position580at which the flight based on the flight plan500is interrupted is set as a new way point WP7, a position that is located above and at a predetermined distance from the position580is set as a new way point WP6, and the flight plan800including the new way points WP6and WP7and the unflown way points WP4and WP5is generated.

FIG. 8Billustrates the positions of way points included in the flight plan800and flight routes based on the flight plan800. As illustrated inFIG. 8B, the unmanned aircraft100flies from HP to WP6′ (flight route801), and then descends to WP7(flight route802). Then, the unmanned aircraft100flies between WP7and WP4at a constant distance from the power line550(flight route803). After reaching WP4, the unmanned aircraft100ascends to WP5(flight route565) and returns from WP5to HP (flight route566).

Thus, with the changed flight plan800generated according to the flight plan changing method of the first embodiment, the unmanned aircraft100does not have to fly the section between WP3and the position580(seeFIG. 5B). This makes it possible to prevent image data corresponding to the section between WP3and the position580from being captured twice. Accordingly, even when a flight according to a flight plan is interrupted, the flight plan changing method of the first embodiment can prevent an increase in the amount of captured image data, prevent an increase in time necessary to analyze the image data, and improve the inspection efficiency.

<Functional Configuration of Flight Plan Management Apparatus>

Next, a functional configuration of a flight plan management apparatus900is described with reference toFIGS. 9A and 9B. The flight plan management apparatus900, for example, generates a flight plan, sets the generated flight plan, analyzes a flight log, changes the flight plan, and sets the changed flight plan.

FIG. 9Aillustrates a relationship between the unmanned aircraft100and the flight plan management apparatus900. As illustrated inFIG. 9A, the flight plan management apparatus900is an external apparatus provided outside of the unmanned aircraft100and wirelessly communicates with the unmanned aircraft100.

FIG. 9Bis a drawing illustrating a functional configuration of the flight plan management apparatus900. A flight plan management program is installed in the flight plan management apparatus900. The flight plan management apparatus900executes the flight plan management program and thereby functions as a flight plan generator901, a flight plan setter902, a flight log analyzer903, a flight plan changer904, and a changed flight plan setter905.

The flight plan generator901generates the flight plan500. The flight plan setter902sets the flight plan500generated by the flight plan generator901in the flight controller151(seeFIG. 1B).

The flight log analyzer903is an example of an identifier. The flight log analyzer903reads a flight log (e.g., flight log600) stored in the flight log storage154(seeFIG. 1B), and identifies actually-flown way points and unflown way points in the flight plan500based on the flight log. Also, based on the flight log600, the flight log analyzer903identifies the coordinates (latitude, longitude, altitude) of the position580of the unmanned aircraft100at which a failsafe operation is requested and the capturing of image data by the imager121is interrupted.

The flight plan changer904is an example of a changer. The flight plan changer904generates a changed flight plan800. As described above, the changed flight plan800includes the way point WP7corresponding to the position identified by the flight log analyzer903(i.e., the position580at which the flight plan500is interrupted), the way point WP6that is located above and at a predetermined distance from the position580, and the unflown way points WP4and WP5. The changed flight plan setter905sets the changed flight plan800generated by the flight plan changer904in the flight controller151.

<Hardware Configuration of Flight Plan Management Apparatus>

Next, a hardware configuration of the flight plan management apparatus900is described.FIG. 10is a block diagram illustrating an example of a hardware configuration of the flight plan management apparatus900. As illustrated inFIG. 10, the flight plan management apparatus900includes a CPU1001, a ROM1002, a RAM1003, a secondary storage1004, a display device1005, an operating device1006, and an I/F device1007. These components of the flight plan management apparatus900are connected to each other via a bus1008.

The CPU1001executes various programs (e.g., a flight plan management program) installed in the secondary storage1004. The ROM1002is a nonvolatile memory and functions as a main memory storing various programs and data that are necessary for the CPU1001to execute the programs installed in the secondary storage1004. The RAM1003is a volatile memory such as a DRAM or an SRAM and functions as a main memory that provides a work area into which the programs installed in the secondary storage1004are loaded when executed by the CPU1001.

The secondary storage1004is a secondary memory that stores various programs and information used when the programs are executed. The display device1005is an output device that displays, for example, internal states of the flight plan management apparatus900. The operating device1006is an input device for inputting various instructions to the flight plan management apparatus900. The I/F device1007is a connection device for communications with the unmanned aircraft100.

Next, a flight plan changing process performed by the flight plan management apparatus900is described.FIG. 11is a flowchart illustrating a flight plan changing process. When the unmanned aircraft100, in which the flight plan500is set, starts a flight from HP and returns to HP, the flight plan management apparatus900wirelessly connects to the unmanned aircraft100and starts the process illustrated byFIG. 11.

At step S1101, the flight log analyzer903reads the flight log600from the flight log storage154. At step S1102, the flight log analyzer903determines whether the amount of remaining power became less than or equal to a predetermined threshold and a failsafe operation was requested during the flight. When it is determined at step S1102that the failsafe operation was not requested (NO at step S1102), the flight plan changing process ends.

When it is determined at step S1102that the failsafe operation was requested (YES at step S1102), the flight plan changing process proceeds to step S1103. At step S1103, based on the read flight log600, the flight log analyzer903identifies the coordinates (latitude, longitude, altitude) of the position580of the unmanned aircraft100at which the failsafe operation was requested and the capturing of image data by the imager121was interrupted.

At step S1104, the flight plan changer904determines new way points. Specifically, the flight plan changer904determines the identified position580and a position located above and at a predetermined distance from the position580as new way points.

At step S1105, the flight plan changer904generates, as a changed flight plan, the flight plan800that includes the determined new way points and unflown way points.

At step S1106, the changed flight plan setter905sets the generated flight plan800in the flight controller151. Then, the flight plan changing process ends.

<Flight Log of Flight According to Changed Flight Plan>

Next, a flight log1200of a flight of the unmanned aircraft100according to the changed flight plan800set by the changed flight plan setter905is described with reference toFIG. 12.

As indicated byFIG. 12, according to the flight log1200, the unmanned aircraft100started the flight from HP, passed WP6, WP7, WP4, and WP5, and returned to HP. Accordingly, any portion of image data with a file name “IM2” does not overlap the image data with the file name “IM1” that was captured during the flight according to the original flight plan500.

SUMMARY

As described above, the flight plan changing method of the first embodiment includes reading a flight log from an unmanned aircraft that flies flight routes connecting multiple way points included in a flight plan and captures image data of an object located between the way points; identifying coordinates of a position of the unmanned aircraft at which the capturing of the image data of the object is interrupted; and generating a changed flight plan including way points that are newly determined based on the identified coordinates of the position.

Thus, even when a flight according to a flight plan is interrupted, the flight plan changing method of the first embodiment can prevent image data of the same portion of an object from being repeatedly captured, thereby prevent an increase in the amount of captured image data, and prevent an increase in time necessary to analyze the image data. That is, the flight plan changing method of the first embodiment can generate a flight plan that can improve the inspection efficiency.

Second Embodiment

In the first embodiment, the flight plan management apparatus900is provided outside of the unmanned aircraft100as an external apparatus. However, in a second embodiment, all or some of the functions (the flight plan generator901through the changed flight plan setter905) of the flight plan management apparatus900may be implemented by the control device150of the unmanned aircraft100.

Also in the first embodiment, the flight plan management apparatus900includes the flight plan generator901, the flight plan setter902, the flight log analyzer903, the flight plan changer904, and the changed flight plan setter905. However, these functions of the flight plan management apparatus900may be implemented by multiple apparatuses. For example, these functions of the flight plan management apparatus900may be implemented by a flight plan generating apparatus including the flight plan generator901and the flight plan setter902, and a flight plan changing apparatus including the flight log analyzer903, the flight plan changer904, and the changed flight plan setter905.

OTHER EMBODIMENTS

In the first and second embodiments, the position580of the unmanned aircraft100, at which a failsafe operation is requested and the capturing of image data by the imager121is interrupted, is determined as a new way point. However, a new way point may also be determined in a different manner. For example, a position near the position580may be determined as a new way point.

Also in the first and second embodiments, the position580of the unmanned aircraft100is described as a position at which the capturing of image data by the imager121is interrupted. Here, the capturing of image data by the imager121is interrupted when a failsafe operation is requested. Therefore, the position580of the unmanned aircraft100may be defined as a position at which a failsafe operation is requested. Also, the position580may be defined as a position at which the amount of remaining power that can be supplied becomes less than or equal to a predetermined threshold. Further, the position580may be defined as a position at which a failsafe operation is requested and a flight according to the flight plan500is interrupted.

In the first and second embodiments, a failsafe operation is requested when the amount of remaining power becomes less than or equal to a predetermined threshold. However, a failsafe operation may be requested in response to other events.

In the first and second embodiments, a power line stretched between pylons is used as an example of an object. However, any other object at a high altitude may be inspected using the unmanned aircraft100.

In the first and second embodiments, the capturing of image data is started when a flight starts and is stopped when the flight ends. However, the capturing of image data may be started and stopped at other timings. For example, the capturing of image data may be started when the unmanned aircraft100reaches WP2or WP7and stopped when the unmanned aircraft100reaches WP4.

A flight plan changing method and a flight plan changing apparatus according to embodiments of the present invention are described above. However, the present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.