US20220153413A1

US20220153413A1 - Flight Control System For Unmanned Aerial Vehicle And Topography Measuring System

Info

Publication number: US20220153413A1
Application number: US17/599,128
Authority: US
Inventors: Loti Riccardo; Kaoru Kumagai
Original assignee: Tierra SpA; Topcon Corp
Current assignee: Tierra SpA; Topcon Corp
Priority date: 2019-03-29
Filing date: 2020-03-26
Publication date: 2022-05-19
Also published as: WO2021112158A1; EP4071049A1; WO2020204116A1; JP2020203664A; EP3947147A1; EP3947147A4; EP4071049A4; US20230010931A1; US11999480B2; JPWO2021112158A1

Abstract

A flight control system for an unmanned aerial vehicle comprises an unmanned aerial vehicle on which a reflector is mounted and a total station for tracking the reflector and for acquiring measurement data including three-dimensional coordinates of the reflector, wherein the total station comprises a tracking module for tracking the reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of the tracking module and for emitting a data transmitting light, and a TS-arithmetic control module, wherein the unmanned aerial vehicle has a photodetector for receiving the data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of the unmanned aerial vehicle, and wherein the TS-arithmetic control module is configured to superimpose the measurement data on the data transmitting light, and the UAV-arithmetic control module is configured to separate the measurement data from the photodetecting signal and obtains a flight position of the unmanned aerial vehicle in real time.

Description

TECHNICAL FIELD

The present invention relates to a flight control system for an unmanned aerial vehicle for transmitting a flight position of an unmanned aerial vehicle to the unmanned aerial vehicle in real time, and to a topography measuring system in which a shape measuring instrument is mounted on the unmanned aerial vehicle and which performs a topography measurement from the sky.

BACKGROUND ART

Recently, an unmanned aerial vehicle has become common and developed, and a photography, a small freight transport and the like are carried out using the unmanned aerial vehicle. The unmanned aerial vehicle is remotely operated in a visible state, or a position of the unmanned aerial vehicle is obtained by using a GPS and the unmanned flight is performed in accordance with a program as set. In this case, a real-time flight position of the unmanned aerial vehicle is not highly accurately required.
Further, a photogrammetry is widely carried out based on aerial photographs for a topography measurement. Further, recently, a method, in which a camera is mounted on an unmanned aerial vehicle, the ground is photographed from the sky by the camera, and the aerial photographs are acquired, has become widespread.
Further, in a case where a camera is mounted on an unmanned aerial vehicle, and the ground is photographed from the sky by the camera, there is a method is which a reflector is disposed on the unmanned aerial vehicle, this reflector is tracked by a total station, a position of the unmanned aerial vehicle is measured, a photographing position of the unmanned aerial vehicle is identified based on a measurement result and a topography measurement is performed based on the photographing position and the images.
Conventionally, positional data of an unmanned aerial vehicle is stored in a total station, photography data and after the end of the measurement, the positional data of the unmanned aerial vehicle are collated with each other, and then a topography measurement result is calculated. Therefore, measurement data cannot be seen in real time, and a judgment of a measurement state is made after a completion of a photographing by the unmanned aerial vehicle and after a position-measurement by the total station. For this reason, in a case where the measurement state is judged insufficient and a remeasurement is required, a measurement work must be again performed from the beginning, which results in a considerable loss of time.
Further, conventionally, since the positional data of the unmanned aerial vehicle is stored in the total station, a position measuring instrument is additionally required in order that the unmanned aerial vehicle itself to recognize its flight position in real time, and as a result, a configuration of a system is complicated.

CITATION LIST

Patent Literature

PTL1: Patent 2015-1450
PTL2: Patent 2015-145784

SUMMARY OF INVENTION

Technical Problem

In the present invention, in a total station and a flight control system for an unmanned aerial vehicle or a topography measuring system using the unmanned aerial vehicle, a system which enables to transmit a flight position of the unmanned aerial vehicle measured by the total station to the unmanned aerial vehicle in real time is provided.

Solution to Problem

The present invention relates to a flight control system for an unmanned aerial vehicle comprises an unmanned aerial vehicle on which a reflector is mounted and a total station for tracking the reflector and for acquiring measurement data including three-dimensional coordinates of the reflector, wherein the total station comprises a tracking module for tracking the reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of the tracking module and for emitting a data transmitting light, and a TS-arithmetic control module, wherein the unmanned aerial vehicle has a photodetector for receiving the data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of the unmanned aerial vehicle, and wherein the TS-arithmetic control module is configured to superimpose the measurement data on the data transmitting light, and the UAV-arithmetic control module is configured to separate the measurement data from the photodetecting signal and to obtain a flight position of the unmanned aerial vehicle in real time.
Further, the present invention relates to the flight control system for an unmanned aerial vehicle, wherein the tracking module is configured to pulse-emit a tracking light in a predetermined cycle and to emit the data transmitting light in a time period of each emission interval in such a manner that the data transmitting light does not interfere with the tracking light and a reflected tracking light.
Further, the present invention relates to the flight control system for an unmanned aerial vehicle, wherein the tracking module is also used as a data transmitting module, and the tracking module is configured to emit the tracking light as the data transmitting light in the time period of each emission interval.
Further, the present invention relates to the flight control system for an unmanned aerial vehicle, wherein the photodetector includes the reflector and has a reflective film formed on a reflection surface of the reflector and for transmitting a part of a light, and a photodetection element for receiving the data transmitting light through the reflective film.
Further, the present invention relates to a topography measuring system comprises an unmanned aerial vehicle, on which a reflector and a shape measuring instrument provided at a position known to the reflector are mounted, and a total station for tracking the reflector and for acquiring measurement data including three-dimensional coordinates of the reflector,

wherein the total station comprises a tracking module for tracking the reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of the tracking module and for emitting a data transmitting light, and a TS-arithmetic control module,
wherein the unmanned aerial vehicle has a photodetector for receiving the data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of the unmanned aerial vehicle, and
wherein the TS-arithmetic control module is configured to superimpose the measurement data on the data transmitting light, the UAV-arithmetic control module is configured to acquire topographical shape data by the shape measuring instrument, and the UAV-arithmetic control module is configured to separate the measurement data from the photodetecting signal, to obtain a position of the shape measuring instrument in real time, to associate the position of the shape measuring instrument with the topographical shape data, and to obtain three-dimensional coordinates of the shape measuring instrument at the time of acquiring the topographical shape data.

Further, the present invention relates to the topography measurement system, wherein the tracking module is configured to pulse-emit a tracking light in a predetermined cycle and to emit the data transmitting light in a time period of each emission interval in such a manner that the data transmitting light does not interfere with the tracking light and a reflected tracking light.
Further, the present invention relates to the topography measurement system, wherein the tracking module is also used as a data transmitting module, and the tracking module is configured to emit the tracking light as the data transmitting light in the time period of each emission interval.
Further, the present invention relates to the topography measurement system, wherein the photodetector includes the reflector and has a reflective film formed on a reflection surface of the reflector and for transmitting a part of a light, and a photodetection element for receiving the data transmitting light through the reflective film.
Further, the present invention relates to the topography measurement system, wherein the total station has a TS-GNSS device, the unmanned aerial vehicle has a UAV-GNSS device, wherein the TS-arithmetic control module is configured to obtain a GNSS time at the time of acquiring the measurement data by the TS-GNSS device and to associate the GNSS time with the measurement data, and wherein the UAV-arithmetic control module is configured to obtain a GNSS time at the time of acquiring shape data by the UAV-GNSS device, to associate the GNSS time with the shape data, and to associate the measurement data with the shape data through the GNSS time.
Further, the present invention relates to the topography measurement system, wherein the shape measuring instrument is a camera for photographing a ground surface, and the UAV-arithmetic control module is configured to perform a photogrammetry based on image data acquired by the camera and on three-dimensional coordinates, as obtained from the data transmitting light, of the camera at the time of acquiring an image.
Furthermore, the present invention relates to the topography measurement system, wherein the shape measuring instrument is a laser scanner for acquiring point cloud data, and the UAV-arithmetic control module is configured to convert the point cloud data into three-dimensional data of a ground surface system based on the point cloud data acquired by the laser scanner and on three-dimensional coordinates, as obtained from the data transmitting light, of the laser scanner at the time of acquiring the point cloud data.

Advantageous Effects of Invention

According to the present invention, the flight control system for an unmanned aerial vehicle comprises an unmanned aerial vehicle on which a reflector is mounted and a total station for tracking the reflector and for acquiring measurement data including three-dimensional coordinates of the reflector, wherein the total station comprises a tracking module for tracking the reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of the tracking module and for emitting a data transmitting light, and a TS-arithmetic control module, wherein the unmanned aerial vehicle has a photodetector for receiving the data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of the unmanned aerial vehicle, and wherein the TS-arithmetic control module is configured to superimpose the measurement data on the data transmitting light, and the UAV-arithmetic control module is configured to separate the measurement data from the photodetecting signal and to obtain a flight position of the unmanned aerial vehicle in real time. As a result, the unmanned aerial vehicle is capable of flying based on a highly accurate positional information measured by the total station while flying.
Further, according to the present invention, the topography measuring system comprises an unmanned aerial vehicle, on which a reflector and a shape measuring instrument provided at a position known to the reflector are mounted, and a total station for tracking the reflector and for acquiring measurement data including three-dimensional coordinates of the reflector,

wherein the total station comprises a tracking module for tracking the reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of the tracking module and for emitting a data transmitting light, and a TS-arithmetic control module,
wherein the unmanned aerial vehicle has a photodetector for receiving the data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of the unmanned aerial vehicle, and
wherein the TS-arithmetic control module is configured to superimpose the measurement data on the data transmitting light, the UAV-arithmetic control module is configured to acquire topographical shape data by the shape measuring instrument, and the UAV-arithmetic control module is configured to separate the measurement data from the photodetecting signal, to obtain a position of the shape measuring instrument in real time, to associate the position of the shape measuring instrument with the topographical shape data, and to obtain three-dimensional coordinates of the shape measuring instrument at the time of acquiring the topographical shape data. As a result, it is possible for the unmanned aerial vehicle to obtain a highly accurate positional information measured by the total station while flying, and it is possible to exert an excellent effect that a topography measurement is performed with high accuracy based on this positional information.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A schematical block diagram of an embodiment of the present invention.

FIG. 2 A schematical block diagram of a total station used in the present embodiment.

FIG. 3 A schematical block diagram of a UAV used in the present embodiment.

FIG. 4 A block diagram of an example of a photodetector.

FIG. 5 An explanatory drawing to show light emission timings of a distance measuring light, a tracking light and a data transmitting light, an operation timing of a photodetection shutter and a photodetection timing of the photodetector.

DESCRIPTION OF EMBODIMENTS

A description will be given below on an embodiment of the present invention by referring to the attached drawings.
FIG. 1 is a schematical drawing of an aerial photogrammetry system using a data transmission method according to the present invention.
An aerial photogrammetry system 1 constituted of a surveying instrument with a tracking function and an unmanned aerial vehicle (UAV 3).
In the following description, a total station is used as a surveying instrument 2 with a tracking function.
The total station 2 is provided at a known point (point at which three-dimensional coordinates are known). The total station 2 has a telescope module 5, which is rotatable in a horizontal direction and a vertical direction, and is capable of sighting an object to be measured and performing an electro-optical distance measurement. Further, a vertical angle and a horizontal angle of the telescope module 5 are detected by a vertical angle detector and a horizontal angle detector respectively, and three-dimensional coordinates of the object to be measured can be determined based on the detected vertical angle and horizontal angle and a distance measurement result.
Further, the telescope module 5 has a tracking function and is capable of measuring the object to be measured while tracking an object to be measured with retroreflective characteristics (for instance, a prism 7). Further, since the object to be measured is measured by the total station 2, an obtained measurement result (three-dimensional coordinates) is highly accurate.
The UAV 3 is capable of performing a flight based on a remote operation or an unmanned flight (autonomous flight) and has a camera 6 for performing a photogrammetry. In this case, the camera 6 functions as a shape measuring instrument.
The camera 6 has an image pickup optical axis which becomes vertical when the UAV 3 is in a horizontal attitude. Alternatively, the camera 6 is provided on the UAV 3 via a gimbal mechanism and set in such a manner that the image pickup optical axis always becomes vertical irrespective of an attitude of the UAV 3. As the camera 6, a camera or a video camera, which enables to acquire digital images, is used, and the camera 6 enables to acquire still images and continuous images.
Further, a retro-reflector as an object to be measured is provided on a lower surface of the UAV 3. As the retro-reflector, an omnidirectional prism 7 is preferably used. A relationship between an optical reference position of the prism 7 and an optical reference position of the camera 6 is fixed, and the positional relationship is known. Further, a reference optical axis of the prism 7 is parallel to the image pickup optical axis of the camera 6.
In FIG. 2, a description will be given on an outline of the total station 2.
The total station 2 mainly comprises a TS-arithmetic control module 11, a TS-storage module 12, a distance measuring module 13, a tracking module 14, a data transmitting module 15, an angle measuring module 16 and a TS-GNSS device 17.
The distance measuring module 13 functions as an electronic distance meter, projects a distance measuring light 21 toward the object to be measured, receives the distance measuring light 21 reflected on the object to be measured and measures a distance to the object to be measured based on a time difference between a projection timing and a photodetection timing and on a light velocity. Further, the distance measuring module 13 is controlled by the TS-arithmetic control module 11, and a measurement result obtained by the distance measuring module 13 is input to the TS-arithmetic control module 11. It is to be noted that, as the distance measuring light 21, a pulsed light is used.
As the TS-arithmetic control module 11, a CPU specialized for this instrument or a general-purpose CPU is used. A photodetecting signal is input to the TS-arithmetic control module 11 from the TS-GNSS device 17, and the TS-arithmetic control module 11 obtains a time signal (GNSS time) from the photodetecting signal. Further, the TS-arithmetic control module 11 associates the distance measurement result with the GNSS time in the distance measurement.
The tracking module 14 has an optical axis (tracking optical axis) which is parallel or approximately parallel to an optical axis (distance measuring optical axis) of the distance measuring module 13 and irradiates a tracking light 22 to an object to be tracked (that is, the object to be measured) at a timing which is the same as or approximately the same as a timing of irradiating the distance measuring light 21. It is to be noted that, as the tracking light 22, a pulsed light is used.
Further, the tracking module 14 has a photodetecting module (not shown) for receiving the tracking light 22 reflected on the object to be tracked. A deviation from a reference position of the photodetecting module is obtained based on a position of a reflected tracking light on the photodetecting module, a photodetection result of the photodetecting module is input to the TS-arithmetic control module 11, and the TS-arithmetic control module 11 controls the vertical angle and the horizontal angle of the telescope module 5 in such a manner that a photodetecting position coincides with the reference position.
Further, the photodetecting signal of the photodetecting module of the distance measuring module 13 and the photodetecting signal or the tracking module 14 are optically separated by changing their wavelengths so that the photodetecting signals do not interfere with each other. For instance, a red light is used as the distance measuring light 21 and an infrared light is used as the tracking light 22, lights having different wavelengths are used as the distance measuring light 21 and the tracking light 22, and the distance measuring light 21 and the tracking light 22 are separated from each other by a wavelength selecting film or a wavelength selecting filter.
The data transmitting module 15 has an optical axis (transmitting optical axis), which is parallel or approximately parallel to the distance measuring optical axis or the tracking optical axis, emits a data transmitting light 23 in a time period during which the distance measuring light 21 and the tracking light 22 are not emitted, and irradiates the data transmitting light 23 on the transmitting optical axis. That is, the data transmitting light 23 is emitted in a time period during which the photodetections of the distance measuring module 13 and the photodetecting module of the tracking module 14 are limited or prohibited by a shutter in such a manner that the distance measuring light 21, a reflected light of the distance measuring light 21, the tracking light 22, a reflected light of the tracking light 22 and the data transmitting light 23 do not interfere with each other. Further, the wavelengths of the distance measuring light 21 and the tracking light 22 are changed, and the interference of both the reflected lights is prevented.
The TS-arithmetic control module 11 controls the emission of the data transmitting light 23 in such a manner that measurement data measured by the total station 2 is superimposed on the data transmitting light 23. As a method for superimposing the measurement data on the data transmitting light 23, the data transmitting light 23 is optically modulated, or the data transmitting light 23 is pulse-emitted, and the measurement data is superimposed by an ON/OFF control over the pulsed light.
It is to be noted that the GNSS time is associated with the distance measurement data which is to be superimposed on the data transmitting light 23.
The angle measuring module 16 has a vertical angle detector 18 and a horizontal angle detector 19 and detects a sighting direction of the telescope module 5, that is, a vertical angle and a horizontal angle of the distance measuring optical axis. It is to be noted that a synthesized angle of the vertical angle and the horizontal angle will be referred to as a directional angle, which indicates a direction of the distance measuring optical axis.
The vertical angle and the horizontal angle are input to the TS-arithmetic control module 11, and the TS-arithmetic control module 11 determines three-dimensional coordinates of the object to be measured or a measuring point based on the vertical angle, the horizontal angle and on a distance measurement result of the distance measuring module 13.
As the TS-storage module 12, a magnetic storage device such as an FDD or an HDD, an optical recording device such as a CD, a DVD or an MO, a semiconductor storage device such as a memory card or a USB memory or the like is used.
In the TS-storage module 12, various kinds of programs are stored. These programs include a control program configured to control the distance measuring module 13, the tracking module 14 and the data transmitting module 15 respectively or configured to synchronously control the distance measuring module 13, the tracking module 14 and the data transmitting module 15, and further include a distance measurement program configured to make the distance measuring module 13 carry out a distance measurement, a tracking program configured to make the tracking module 14 carry out a tracking, a data transmission program configured to make the data transmitting module 15 transmit data, an angle measurement program configured to make the angle measuring module 16 carry out an angle measurement, a calculation program configured to calculate the three-dimensional coordinates based on distance measurement data acquired by the distance measuring module 13 and angle measurement data acquired by the angle measuring module 16, a program configured to associate the distance measurement data, the angle measurement data and a GNSS time acquired from the TS-GNSS device with each other and other programs.
Further, in the TS-storage module 12 are stored the distance measurement data acquired by the distance measuring module 13, the angle measurement data acquired by the angle measuring module 16 and three-dimensional data of the measuring point or the object to be measured. The distance measurement data, the angle measurement data and the three-dimensional coordinate data will be generally referred to as measurement data hereinafter. Therefore, the measurement data is associated with the GNSS time.
FIG. 3 shows an outline of the UAV 3.
The UAV 3 mainly comprises a UAV-arithmetic control module 25, a UAV-storage module 26, a UAV-GNSS device 27, a photodetector 28, a flight control module 29 and an image pickup control module 30.
Further, the UAV 3 has the necessary number of flight motors 31 (four flight motors 31 a, 31 b, 31 c and 31 d are shown in the drawing) controlled by the flight control module 29 and the propellers 32 rotated by the flight motors 31 respectively. Further, the UAV 3 has the camera 6 of which photographing operation is controlled by the image pickup control module 30.
As the UAV-arithmetic control module 25, a CPU specialized for this instrument or a general-purpose CPU is used, and the UAV-arithmetic control module 25 carries out various kinds of programs stored in the UAV-storage module 26, performs the various kinds of calculations or performs an integral control over the fight control module 29 and the image pickup control module 30.
It is to be noted that a part of the functions of the UAV-arithmetic control module 25 may be assigned to the flight control module 29 and the image pickup control module 30.
As the UAV-storage module 26, a magnetic storage device such as an FDD or an HDD, an optical recording device such as a CD, a DVD or an MO, a semiconductor storage device such as a memory card or a USB memory or the like is used.
In the UAV-storage module 26, various kinds of programs are stored. These programs include a flight control program configured to control the flight, a flight plan program configured to autonomously flight, a calculation program configured to carry out the photogrammetry, an image pickup control program configured to control the image pickup control module 30, a program configured to obtain the GNSS time from the UAV-GNSS device 27 and identify each photographed image and a photographing time of the camera 6 by the GNSS time, a program configured to associate the distance measurement data transmitted from the data transmitting module 15 with each image acquired by the camera 6 based on the GNSS time, a program configured to perform the photogrammetry based on each image and the measurement data and perform the topography and other programs.
By referring to FIG. 4, a description will be given on the photodetector 28.
The photodetector 28 mainly has a prism module 35 and an amplifier 36.
The prism module 35 has a prism 7 for retro-reflecting an incident beam and photodetection elements 37 provided on reflection surfaces of the prism 7. The prism 7 has a plurality of reflection surfaces, and the incident beam is generally reflected on the plurality of reflection surfaces more than once. The example in the drawing shows a state where the incident beam is reflected on the two reflection surfaces twice and retro-reflected. Further, in the example in the drawing, partially transparent reflective films 38 are formed on the two reflection surfaces respectively, and the photodetection elements 37 are provided on the reflection surfaces respectively. Each of the reflective films 38 has the optical characteristics which reflect a greater part of the incident beam and through which transmit a very small part of the incident beam, for instance, optical characteristics through which transmit 10% of the incident beam and which reflect 90% of the incident beam.
Therefore, when a beam enters the prism module 35, 90% of the beam is retro-reflected, and 10% of the beam is transmitted through the reflective films 38 and detected by the photodetection elements 37. Each of the photodetection elements 37 outputs a photodetecting signal, and each of the photodetecting signals is amplified by the amplifier 36 and input to the UAV-arithmetic control module 25. It is to be noted that the amplification of the photodetecting signals may be performed in the UAV-arithmetic control module 25. It is to be noted that the reflective film 38 and the photodetection element 37 may be provided on only one reflection surface in such a manner that the photodetecting signal can be obtained from the one reflection surface.
A description will be given below on actions by referring to FIG. 5.
The prism 7 is sighted by the telescope module 5, the distance measuring light 21 is irradiated, the distance measuring light 21 is retro-reflected by the prism 7, the reflected distance measuring light is received by the distance measuring module 13, and the distance measurement and the angle measurement are carried out. Further, the tracking light 22 and the data transmitting light 23 are irradiated. Since the tracking light 22, the data transmitting light 23 and the distance measuring light 21 have the same optical axis or approximately the same optical axis, both the tracking light 22 and the data transmitting light 23 enter the prism 7.
The tracking light 22 is retro-reflected by the prism 7, the reflected tracking light is received by the tracking module 14, and the prism 7 is tracked, that is, the UAV 3 is tracked.
As shown in FIG. 5, both the distance measuring light 21 and the tracking light 22 are pulsed lights and emitted at the same timing. An emission cycle of the pulsed lights is, for instance, 50 Hz. Further, a shutter provided to the tracking module 14 is opened for a predetermined time “t1” from the emission timing of the tracking light 22, and the photodetecting module of the tracking module 14 can receive the reflected light of the tracking light 22. The distance measuring light 21 does not interfere with the tracking light 22 since the distance measuring light 21 has a different wavelength, and the distance measuring light 21 is received by the distance measuring module 13 after a predetermined time from the emission timing of the distance measuring light 21. As described above, since the reflected lights of the distance measuring light 21 and the tracking light 22 are optically separated from each other, there arises no problem even if the reflected lights are received at the same timing.
The predetermined time “t1” is set longer than a round-trip time from when the tracking light 22 is emitted to when the tracking light 22, as reflected by the prism 7 (object to be measured), returns.
The data transmitting light 23 is emitted in a time period from when a time “t2” (>“t1”) elapses from the emission timing to when a next pulsed light is emitted. On this data transmitting light 23, the measurement data obtained by measuring in a previous time period is superimposed. For instance, on the data transmitting light 23 emitted in a period “P2” in FIG. 5, the measurement data measured by the distance measuring light emitted in a period “P1” is superimposed.
It is to be noted that the emission cycle of the pulsed lights is determined by a processing speed (reaction speed) of the photodetection elements. For instance, regarding the tracking module 14, as a photodetection element used in the photodetecting module of the tracking module 14, a CCD or a CMOS, which is an aggregate of pixels, is used, however since outputs of the pixels are sequentially checked one by one in the detection of the reflected tracking light, the next pulsed light cannot be received until the check of all the pixels is completed. Therefore, the emission cycle of the pulsed lights is determined by a response performance of the photodetection element. When a general photodetection sensor used in a commercially available digital camera or video camera is used, the emission cycle of the pulsed light is approximately 50 Hz. It is to be noted that, in the present embodiment, the emission cycle of approximately 50 Hz brings about a sufficient effect.
Since the data transmitting light 23 is emitted in the time period during which the shutter is closed, even if a reflected data transmitting light reflected by the prism 7 enters the tracking module 14, the reflected data transmitting light does not interfere with a tracking photodetecting signal.
A part of the data transmitting light 23, which enters the prism 7, is transmitted through the reflective films 38 and received by the photodetection elements 37. The photodetecting signal output from each photodetection element 37 is amplified by the amplifier 36 and input to the UAV-arithmetic control module 25.
Here, the distance measuring light 21 and the tracking light 22 also enter the photodetection elements 37, but since a waveform of the photodetecting signals output from the photodetection element 37 differs from the waveforms of the distance measuring light 21, the tracking light 22 and the data transmitting light 23 and the photodetecting signals are separated from the distance measuring light 21, the tracking light 22 and the data transmitting light 23 in terms of the time, the photodetecting signals can be easily identified. Further, characteristics of the reflective films 38 can be selected in such a manner that only the tracking light can be transmitted therethrough.
The UAV-arithmetic control module 25 separates the superimposed measurement data from the photodetecting signal. The measurement data is data of the three-dimensional coordinates of the prism 7, that is, the camera 6, and the measurement data is associated with the GNSS time. Further, the separated measurement data is stored in the UAV-storage module 26.
The image pickup control module 30 acquires images of the ground by the camera 6 at a predetermined time interval during the flight of the UAV 3. Further, the UAV-arithmetic control module 25 acquires a GNSS time at the time of acquiring the images from the UAV-GNSS device 27, identifies a time of photographing of the camera 6 by the GNSS time and associates the acquired images with the GNSS time. Further, the three-dimensional coordinates of the prism 7 determined by the total station 2, that is, the three-dimensional coordinates of the UAV 3, are transmitted to the UAV 3 in real time, and the three-dimensional coordinates are linked (associated) with the GNSS time.
Image data associated with the GNSS time is stored in the UAV storage module 26. The UAV-arithmetic control module 25 carries out the photogrammetry based on the image data and the measurement data stored in the UAV-storage module 26 and on the positional data transmitted from the total station 2.
Based on the GNSS time at which the image data is acquired, the UAV-arithmetic control module 25 retrieves the positional data, as transmitted from the total station, which matches with the GNSS time and identifies the three-dimensional coordinates at which the image data is acquired. Therefore, each of the image data becomes data with three-dimensional coordinates, and the UAV-arithmetic control module 25 carries out the photogrammetry based on the image data. A result of the photogrammetry is stored in the UAV-storage module 26.
While carrying out the photogrammetry, the UAV-arithmetic control module 25 judges whether the result of the photogrammetry has an abnormality at the same time. Therefore, the judgment on the abnormality in the photogrammetry can be made in real time.
In a case where the abnormality in the result of the photogrammetry is judged, with respect to a position (region) where the abnormality is judged, a photographing and a measuring by the total station 2 are carried out again. Therefore, the remeasurement can be carried out in a minimum time.
Further, since the photogrammetry is carried out while flying, the acquisition of necessary data is completed when the UAV 3 finishes a planned flight, and the measurement can be efficiently performed.
Further, since the three-dimensional coordinates of the prism 7 determined by the total station 2, that is, the three-dimensional coordinates of the UAV 3, are transmitted to the UAV 3 in real time, the UAV 3 can recognize its own flight position in real time.
Therefore, when a flight plan, a surveying plan and others are stored in the UAV-storage module 26 in advance, an autonomous flight can be performed in accordance with the flight plan and the surveying plane. A surveying can be performed without remotely operating.
It is to be noted that when it is configured in such a manner that the pulsed light of the distance measuring light 21 transmitted from the total station 2, or the pulsed light of the tracking light 22 or the data transmitting light 23 is received by the photodetection elements 37 and the photographing is performed by the camera 6 with the use of the photodetecting signal emitted from the photodetection element 37 as a trigger, it enables to identify an image pickup position without using the GNSS time.
In the embodiment as described above, the photodetector 28 has the prism module 35 and the amplifier 36, and the prism module 35 is constituted of the prism 7, the reflective films 38 and the photodetection elements 37 which are provided on the reflection surfaces of the prism 7, but a partial reflection mirror which reflects a part of the data transmitting light 23 may be provided on an optical path of the data transmitting light 23, and it may be so designed that the reflected light is detected by the photodetection elements.
Further, the photodetector 28 may be separated from the prism 7. That is, an optical system which receives only the data transmitting light 23 may be provided, and the data transmitting light 23 may be received by the photodetection elements 37 through the optical system.
Further, in the embodiment as described above, the data transmitting module 15 is provided separately from the tracking module 14, but a data transmitting function may be added to the tracking module 14, and the data transmitting module 15 may be omitted.
As the tracking light required for tracking, the pulsed light emitted in a predetermined cycle can suffice, and thus the tracking light is continuously emitted in each time period between the pulsed lights, and the measurement data is superimposed on the tracking light. That is, the tracking light is emitted in each time period where the data transmitting light as described above is emitted, and the tracking light is used as the data transmitting light.
Further, in the embodiment as described above, the camera is used as a shape measuring instrument which measures a shape of the ground, but a laser scanner may be used as the shape measuring instrument instead of the camera. In a case where the laser scanner is used, point cloud data is acquired as data for measuring the shape of the ground.
By obtaining a position of the laser scanner at the time of acquiring the point cloud data from the data transmitting light 23, it enables to convert the point cloud data into three-dimensional coordinates of a ground surface system (with reference to the total station 2).
Furthermore, in the prevent invention, the shape measuring instrument may be omitted, and a system, which transmits an accurate flight position of the UAV 3 measured by the total station from the total station to the UAV 3 in real time and enables the autonomous flight of the UAV 3, may be configured.
In this case, a distance which the light reaches is 1 km or more, and the autonomous flight in a wide area is possible. Further, as the structures required for the data transmission, the structures comprised in the total station can be used, and the system configuration is simple.

REFERENCE SIGNS LIST

1 Aerial photogrammetry system
2 Total station
3 UAV
5 Telescope module
6 Camera
7 Prism
11 TS-arithmetic control module
13 Distance measuring module
14 Tracking module
15 Data transmitting module
16 Angle measuring module
21 Distance measuring light
22 Tracking light
23 Data transmitting light
25 UAV-arithmetic control module
27 UAV-GNSS device
28 Photodetector
29 Flight control module
30 Image pickup control module

Claims

1. A flight control system for an unmanned aerial vehicle comprising an unmanned aerial vehicle on which a reflector is mounted and a total station for tracking said reflector and for acquiring measurement data including three-dimensional coordinates of said reflector,

wherein said total station comprises a tracking module for tracking said reflector, a data transmitting module having an optical axis parallel or approximately parallel to a tracking optical axis of said tracking module and for emitting a data transmitting light, and a TS-arithmetic control module,

wherein said unmanned aerial vehicle has a photodetector for receiving said data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of said unmanned aerial vehicle, and wherein said TS-arithmetic control module is configured to superimpose said measurement data on said data transmitting light, and said UAV-arithmetic control module is configured to separate said measurement data from said photodetecting signal and to obtain a flight position of said unmanned aerial vehicle in real time.

2. The flight control system for an unmanned aerial vehicle according to claim 1, wherein said tracking module is configured to pulse-emit a tracking light in a predetermined cycle and to emit said data transmitting light in a time period of each emission interval in such a manner that said data transmitting light does not interfere with the tracking light and a reflected tracking light.

3. The flight control system for an unmanned aerial vehicle according to claim 2, wherein said tracking module is also used as a data transmitting module, and said tracking module is configured to emit the tracking light as said data transmitting light in the time period of each emission interval.

4. The flight control system for an unmanned aerial vehicle according to claim 1, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

5. A topography measuring system comprising an unmanned aerial vehicle, on which a reflector and a shape measuring instrument provided at a position known to said reflector are mounted, and a total station for tracking said reflector and for acquiring measurement data including three-dimensional coordinates of said reflector,

wherein said unmanned aerial vehicle has a photodetector for receiving said data transmitting light and for emitting a photodetecting signal and a UAV-arithmetic control module for controlling a flight of said unmanned aerial vehicle,

and wherein said TS-arithmetic control module is configured to superimpose said measurement data on said data transmitting light, said UAV-arithmetic control module is configured to acquire topographical shape data by said shape measuring instrument, and said UAV-arithmetic control module is configured to separate said measurement data from said photodetecting signal, to obtain a position of said shape measuring instrument in real time, to associate the position of said shape measuring instrument with said topographical shape data, and to obtain three-dimensional coordinates of said shape measuring instrument at the time of acquiring said topographical shape data.

6. The topography measuring system according to claim 5, wherein said tracking module is configured to pulse-emit a tracking light in a predetermined cycle and to emit said data transmitting light in a time period of each emission interval in such a manner that said data transmitting light does not interfere with the tracking light and a reflected tracking light.

7. The topography measuring system according to claim 6, wherein said tracking module is also used as a data transmitting module, and said tracking module is configured to emit the tracking light as said data transmitting light in the time period of each emission interval.

8. The topography measuring system according to claim 5, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

9. The topography measuring system according to claim 5, wherein said total station has a TS-GNSS device, said unmanned aerial vehicle has a UAV-GNSS device, wherein said TS-arithmetic control module is configured to obtain a GNSS time at the time of acquiring said measurement data by said TS-GNSS device and to associate said GNSS time with said measurement data, and wherein said UAV-arithmetic control module is configured to obtain a GNSS time at the time of acquiring shape data by said UAV-GNSS device, to associate said GNSS time with said shape data, and to associate said measurement data with said shape data through said GNSS time.

10. The topography measuring system according to claim 5, wherein said shape measuring instrument is a camera for photographing a ground surface, and said UAV-arithmetic control module is configured to perform a photogrammetry based on image data acquired by said camera and on three-dimensional coordinates, as obtained from said data transmitting light, of said camera at the time of acquiring an image.

11. The topography measuring system according to claim 5, wherein said shape measuring instrument is a laser scanner for acquiring point cloud data, and said UAV-arithmetic control module is configured to convert said point cloud data into three-dimensional data of a ground surface system based on said point cloud data acquired by said laser scanner and on three-dimensional coordinates, as obtained from said data transmitting light, of said laser scanner at the time of acquiring said point cloud data.

12. The flight control system for an unmanned aerial vehicle according to claim 2, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

13. The flight control system for an unmanned aerial vehicle according to claim 3, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

14. The topography measuring system according to claim 6, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

15. The topography measuring system according to claim 7, wherein said photodetector includes said reflector and has a reflective film formed on a reflection surface of said reflector and for transmitting a part of a light, and a photodetection element for receiving said data transmitting light through said reflective film.

16. The topography measuring system according to claim 9, wherein said shape measuring instrument is a camera for photographing a ground surface, and said UAV-arithmetic control module is configured to perform a photogrammetry based on image data acquired by said camera and on three-dimensional coordinates, as obtained from said data transmitting light, of said camera at the time of acquiring an image.

17. The topography measuring system according to claim 9, wherein said shape measuring instrument is a laser scanner for acquiring point cloud data, and said UAV-arithmetic control module is configured to convert said point cloud data into three-dimensional data of a ground surface system based on said point cloud data acquired by said laser scanner and on three-dimensional coordinates, as obtained from said data transmitting light, of said laser scanner at the time of acquiring said point cloud data.