JP7639248B2 - Positioning device - Google Patents

Description

The present invention relates to a positioning device.

Conventionally, there have been work vehicles equipped with a positioning unit that measures the carrier phase of transmission signals sent from multiple satellites, a relative displacement calculation unit that uses the carrier phase output from the positioning unit to determine the relative positional displacement of the vehicle body from a specific position that has been determined in advance, and an automatic driving control unit that controls the driving state of the vehicle body based on the calculation results of the relative displacement calculation unit so that the vehicle body drives along a predetermined linear target route (see, for example, Patent Document 1).

JP 2019-201612 A

Conventional work vehicle relative displacement calculation units have limited positioning accuracy because they do not use satellite information observed at reference stations (observation stations) or location information indicating the exact location of the reference stations. It is also possible to obtain observation data from multiple positioning satellites and perform positioning using RTK-GNSS (Real Time Kinematic-Global Navigation Satellite System) using information from observation stations whose exact installation positions are known. Such observation stations include electronic reference points installed by the Geospatial Information Authority of Japan.

However, if the observation stations are far away or if the observation data is updated at long intervals and a long time has passed since the last update, the positioning accuracy decreases because the fixed state cannot be obtained and the system goes into a floating state.

The objective of the present invention is to provide a positioning device that can improve positioning accuracy even when the observation station is far away or when the observation data is updated at long intervals and a long time has passed since the last update.

The positioning device according to an embodiment of the present invention is mounted on a moving body and uses RTK-GNSS to position the position of the moving body at each predetermined positioning cycle. The positioning device includes an observation data receiving unit that acquires observation data for a plurality of positioning satellites and receives the observation data from an observation station whose installation position is known, a positioning signal receiving unit that receives positioning signals from the plurality of positioning satellites, a positioning unit that uses the observation data received by the observation data receiving unit and the positioning signal received by the positioning signal receiving unit to position the position of the moving body by relative positioning with the installation position as a reference position, and a state determination unit that determines whether the moving body was in a fixed state or a floating state when the positioning unit positioned the position of the moving body. When the state determination unit determines that the moving body was in the floating state, the positioning unit determines the position of the moving body by relative positioning using the position of the moving body measured in the positioning cycle in which it was last determined to be in the fixed state as the reference position instead of the installation position, and outputs the position of the moving body as data representing the position of the moving body.

It is possible to provide a positioning device that can improve positioning accuracy even when the observation stations are far away or when the observation data is updated at long intervals and a long time has passed since the last update.

1 is a diagram showing a positioning system 1 including a positioning device 100 according to an embodiment. FIG. 1 illustrates an example of a configuration of a positioning device 100. FIG. 4 is a flowchart showing the process executed by the control device 130. FIG. 13 is a diagram showing an example of a horizontal error of a position estimation result.

The following describes an embodiment in which the positioning device of the present invention is applied.

<Embodiment>
FIG. 1 is a diagram showing a positioning system 1 including a positioning device 100 according to an embodiment. In FIG. 1, the horizontal axis represents the time axis. Here, as an example, a form in which the positioning device 100 is mounted on a drone 20 as an example of a moving body will be described. The positioning system 1 enables highly accurate position measurement by RTK-GNSS (Real Time Kinematic-Global Navigation Satellite System). In positioning by RTK-GNSS, a positioning signal output from a positioning satellite 5 is received by an observation station 10 and a positioning device 100 mounted on a drone 20, the distance between the positioning satellite 5 and the positioning device 100 is measured, and the three-dimensional coordinates of the positioning device 100 are calculated by solving simultaneous equations for a plurality of positioning satellites 5.

Here, we will explain a form that uses GPS (Global Positioning System), which is an example of GNSS, so the positioning signal output from the positioning satellite 5 is a GPS signal. However, the GNSS is not limited to GPS, and three-dimensional coordinates may be calculated using GLONASS, Beidou (BeiDou-2, Compass), Gallileo, or other GNSS.

In RTK-GNSS, the positioning device 100 uses the observation data received from the observation station 10 and the positioning signal received from the positioning satellite 5 to determine the position of the positioning device 100 by relative positioning with the installation position of the observation station 10 as the reference position. Here, the position of the positioning device 100 is synonymous with the position of the drone 20.

The observation station 10 knows its exact installation location (coordinates representing latitude, longitude, and altitude), and receives (acquires) GPS radio waves from multiple positioning satellites 5 to measure the distance to each positioning satellite 5. The observation station 10 constantly outputs observation data including position data representing its installation location and distance data representing the distance to each positioning satellite 5. The distance data included in the observation data is updated at regular intervals. This is because the positional relationship between the observation station 10 and the multiple positioning satellites 5 changes. Such an observation station 10 may include an electronic reference point of the Geospatial Information Authority of Japan.

The drone 20 is an example of a moving body, and is equipped with a positioning device 100. As an example, the drone 20 is equipped with a navigation control device that controls the navigation of the drone 20 based on the coordinates of the drone 20 determined by the positioning device 100.

When calculating the three-dimensional coordinates of the positioning device 100, the positioning device 100 determines whether it is in a fixed state where a fixed solution can be obtained, or a floating state where a fixed solution cannot be obtained. For example, even if it is in a fixed state at time t-1 shown in FIG. 1, it may change to a floating state at time t, which is the next positioning cycle.

Generally, in a fixed state, RTK-GNSS achieves high positioning accuracy of about several centimeters by performing positioning based on observation data from the observation station 10. However, in a floating state, the positioning accuracy may deteriorate to about several meters due to factors such as the long distance to the observation station 10 and the long time that has passed since the observation data was last updated. The positioning device 100 of the embodiment improves the positioning accuracy in a floating state to about several centimeters.

<Configuration of positioning device 100>
2 is a diagram showing an example of the configuration of the positioning device 100. The positioning device 100 includes an observation data receiving unit 110, a positioning signal receiving unit 120, and a control device 130. The observation data receiving unit 110 is a receiver that receives observation data from the observation station 10 via a mobile phone line. The positioning signal receiving unit 120 is a GPS receiver that receives positioning signals output from at least four or more positioning satellites 5.

As an example, the positioning device 100 employs single-frequency RTK, which is a method of receiving a single-frequency positioning signal (GPS signal), receiving observation data from the observation station 10 via a mobile phone line, and locating the position of the positioning device 100 based on the received positioning signal (GPS signal) and the received observation data.

To position the position of the drone 20 using RTK-GNSS for each positioning period, the positioning device 100 cancels out the error contained in the positioning signal based on the received positioning signal and the received observation data, determines the relative position of the positioning device 100 to the installation position of the observation station 10 based on the positioning signal with the error canceled out, and determines the position of the positioning device 100 based on the determined relative position and the installation position of the observation station 10.

The control device 130 has a main control unit 131, a positioning unit 132, a status determination unit 133, and a memory 134. The control device 130 is realized by a computer or microcomputer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an input/output interface, and an internal bus. The main control unit 131, the positioning unit 132, and the status determination unit 133 are functional blocks showing the functions of the programs executed by the control device 130. The memory 134 is a functional representation of the memory of the control device 130.

The main control unit 131 is a processing unit that controls the processing of the control device 130, and executes processing other than that executed by the positioning unit 132 and the state determination unit 133. For example, the main control unit 131 outputs a command to the observation data receiving unit 110 to receive observation data, and outputs a command to the positioning signal receiving unit 120 to receive a positioning signal.

The positioning unit 132 uses the observation data received by the observation data receiving unit 110 and the positioning signal received by the positioning signal receiving unit 120 to determine the position of the positioning device 100 by relative positioning using the installation position of the observation station 10 as the reference position.

In addition, when the state determination unit 133 determines that the positioning device 100 is in a floating state, the positioning unit 132 determines the position of the positioning device 100 by relative positioning using the position of the positioning device 100 determined in the positioning cycle in which the positioning device 100 was last determined to be in a fixed state as a reference position instead of the installation position of the observation station 10, and outputs the position of the positioning device 100 as data representing its position.

More specifically, when the state determination unit 133 determines that the positioning device 100 is in a floating state, the positioning unit 132 cancels out the error contained in the positioning signal based on the observation data received by the observation station 10 in the current positioning cycle and the positioning signal received by the positioning signal receiving unit 120 in the current positioning cycle in the relative positioning that uses the position of the positioning device 100 measured in the last positioning cycle determined to be in a fixed state as the reference position instead of the installation position of the observation station 10, and obtains the position of the positioning device 100 relative to the reference position using the positioning signal with the error canceled, and measures the position of the positioning device 100 based on the reference position and the position of the positioning device 100 relative to the reference position. The measured position of the positioning device 100 can be obtained by adding the difference in coordinates representing the position of the positioning device 100 relative to the reference position to the coordinates of the reference position. The positioning unit 132 outputs the measured position as data representing the position of the positioning device 100.

In addition, when the state determination unit 133 determines that the positioning unit 132 is in a fixed state, the positioning unit 132 uses the observation data received by the observation data receiving unit 110 and the positioning signal received by the positioning signal receiving unit 120 to output the position of the positioning device 100 determined by relative positioning using the installation position of the observation station 10 as the reference position, as data representing the position of the positioning device 100.

More specifically, when the state determination unit 133 determines that the positioning unit 132 is in a fixed state, the positioning unit 132 cancels out the error contained in the positioning signal using the observation data received by the observation data receiving unit 110 and the positioning signal received by the positioning signal receiving unit 120, obtains the position of the positioning device 100 relative to a reference position using the positioning signal with the error canceled, and determines the position of the positioning device 100 based on the reference position and the position of the positioning device 100 relative to the reference position. The determined position of the positioning device 100 can be determined by adding the difference in coordinates representing the position of the positioning device 100 relative to the reference position to the coordinates of the reference position. The positioning unit 132 outputs the determined position of the positioning device 100 as data representing the position. The reference position in this case is the installation position of the observation station 10.

The state determination unit 133 determines whether the state was fixed or floated when the positioning unit 132 located the position (three-dimensional coordinates) of the positioning device 100. Depending on whether a fix solution was obtained when the positioning device 100 was located, the state determination unit 133 determines whether the state was fixed, in which a fix solution can be obtained, or float, in which a fix solution cannot be obtained.

The memory 134 stores programs and data used by the main control unit 131, the positioning unit 132, and the state determination unit 133 when executing the above-mentioned processes, and also temporarily stores the positioning signals and observation data received by the observation data receiving unit 110 and the positioning signal receiving unit 120.

<Processing Executed by the Control Device 130 of the Positioning Device 100>
FIG. 3 is a flowchart showing the process executed by the control device 130. As shown in FIG.

When the flow starts, the main control unit 131 outputs a command to the observation data receiving unit 110 to receive observation data (step S1). This causes the observation data receiving unit 110 to receive the observation data.

The main control unit 131 outputs a command to the positioning signal receiving unit 120 to receive the positioning signal (step S2). This causes the positioning signal receiving unit 120 to receive the positioning signal. The distance to the positioning satellite 5 included in the observation data received by the command output in step S1 and the distance to the positioning satellite 5 obtained by the positioning signal received by the command output in step S2 are distances obtained based on the positioning signals received at the same time by the observation data receiving unit 110 and the positioning signal receiving unit 120.

The positioning unit 132 uses the observation data received by the observation data receiving unit 110 and the positioning signal received by the positioning signal receiving unit 120 to determine the position of the positioning device 100 by relative positioning using the installation position of the observation station 10 as the reference position (step S3). The positioning in step S3 is a process performed by RTK-GNSS, and the position determined in this manner represents the estimated position of the positioning device 100 estimated using the observation data and the positioning signal.

The state determination unit 133 determines whether the positioning device 100 was in a fixed state or a floating state when the positioning unit 132 determined the position (three-dimensional coordinates) of the positioning device 100 in step S3 (step S4).

If the state determination unit 133 determines in step S4 that the state is fixed, the positioning unit 132 outputs data representing the position of the positioning device 100 determined in step S3 as data representing the current position of the positioning device 100 (step S5).

On the other hand, if the state determination unit 133 determines in step S4 that the positioning device 100 was in a floating state, the positioning unit 132 determines the position of the positioning device 100 by relative positioning using the position of the positioning device 100 determined in the last positioning cycle in which it was determined that the positioning device 100 was in a fixed state as a reference position instead of the installation position of the observation station 10, and outputs the position as data representing the position of the positioning device 100 (step S6). The positioning in step S6 is a process performed by RTK-GNSS using the position of the positioning device 100 determined in the last positioning cycle in which it was determined that the positioning device 100 was in a fixed state as a reference position, and the position determined in this manner represents the estimated position of the positioning device 100 estimated from the observation data and the positioning signal.

When the processing of step S5 or S6 is completed, the main control unit 131 determines whether or not to end the series of processes (step S7). The series of processes is ended, for example, when the power of the drone 20 is turned off. When the main control unit 131 determines that the series of processes is not to be ended, the flow returns to step S1. Furthermore, when the power of the drone 20 is turned off, the main control unit 131 ends the series of processes (end).

<Horizontal error of position estimation result>
4A and 4B are diagrams showing an example of horizontal error in the position estimation result. Fig. 4A shows the result of estimating the position of the positioning device 100 by fixing the position of the positioning device 100 and performing positioning for 5 minutes. The positioning period is 1 second as an example. As shown in Fig. 4A, the standard deviation of the horizontal error is 1.98 cm.

For comparison, FIG. 4(B) shows the results of a comparative example in which the reference position for positioning is fixed to the installation position of the observation station 10, the position of the positioning device is fixed, positioning is performed for 5 minutes, and the position of the positioning device is estimated. The positioning period is 1 second as an example. As shown in FIG. 4(B), the standard deviation of the horizontal error was 14.86 cm.

In this way, when the positioning device 100 becomes floating, it determines its position by relative positioning, using the position of the positioning device 100 determined in the last positioning cycle in which it was determined to be in a fixed state as the reference position instead of the installation position of the observation station 10. This makes it possible to reduce the horizontal error of the position estimation result to approximately 13.3% compared to when the reference position is fixed to the installation position of the observation station 10.

In the comparative positioning device, when the observation station 10 is far away or when the device becomes floating due to the passage of time since the observation data update time, the reference position is fixed to the installation position of the observation station 10, resulting in a large measurement error. In contrast, when the positioning device 100 becomes floating, the position of the positioning device 100 measured in the positioning cycle in which it was last determined to be in a fixed state is used as the reference position instead of the installation position of the observation station 10, which is thought to be the reason for the above-mentioned difference.

Therefore, it is possible to provide a positioning device 100 that can improve positioning accuracy even when the observation station 10 is far away or when the observation data is updated at long intervals and a long time has passed since the update.

In addition, when the positioning device 100 is in a floating state, it is possible to use the measurement values of a gyro sensor, acceleration sensor, etc. to estimate the current position of the positioning device 100 with high accuracy, but the positioning device 100 can improve the positioning accuracy without using the measurement values of a gyro sensor, acceleration sensor, etc.

In addition, mounting a measuring device such as a gyro sensor or acceleration sensor on a moving body such as the drone 20 can cause problems such as increased weight, securing space for mounting, and difficulty in mounting the device itself when the moving body is small. In contrast, when the positioning device 100 is installed on a moving body such as the drone 20, there is no need to mount a measuring device such as a gyro sensor or acceleration sensor, and therefore the various problems described above do not occur, and the device can be realized at low cost.

The above describes an exemplary embodiment of a positioning device according to the present invention, but the present invention is not limited to the specifically disclosed embodiment, and various modifications and variations are possible without departing from the scope of the claims.

REFERENCE SIGNS LIST 1 Positioning system 5 Positioning satellite 10 Observation station 20 Drone 100 Positioning device 110 Observation data receiving unit 120 Positioning signal receiving unit 130 Control device 131 Main control unit 132 Positioning unit 133 State determination unit 134 Memory

Claims (5)

A positioning device that is mounted on a moving object and measures a position of the moving object by an RTK-GNSS at a predetermined positioning period,
an observation data receiving unit that acquires observation data about a plurality of positioning satellites and receives the observation data from an observation station whose installation position is known;
a positioning signal receiving unit that receives positioning signals from the plurality of positioning satellites;
a positioning unit that uses the observation data received by the observation data receiving unit and the positioning signal received by the positioning signal receiving unit to measure the position of the moving object by relative positioning with the installation position as a reference position;
a state determination unit that determines whether the moving object was in a fixed state or a floating state when the positioning unit determined the position of the moving object,
When the state determination unit determines that the moving body was in the floating state, the positioning unit determines the position of the moving body by relative positioning, using the position of the moving body determined in the positioning cycle in which the moving body was last determined to be in the fixed state as the reference position instead of the installation position, and outputs the positioning device as data representing the position of the moving body. 2. The positioning device according to claim 1, wherein when the state determination unit determines that the fixed state has been established, the positioning unit uses the observation data received by the observation data receiving unit and the positioning signal received by the positioning signal receiving unit to output the position of the moving body determined by the relative positioning using the installation position as a reference position as data representing the position of the moving body. 3. The positioning device according to claim 1, wherein, when the state determination unit determines that the positioning unit is in the fixed state, the positioning unit cancels out an error contained in the positioning signal using the observation data received by the observation data receiving unit and the positioning signal received by the positioning signal receiving unit, and uses the positioning signal in which the error has been canceled out to output the position of the moving body determined by the relative positioning with the installation position as a reference position as data representing the position of the moving body. 4. The positioning device according to claim 1, wherein, when the state determination unit determines that the moving body was in the float state, in the relative positioning in which the position of the moving body measured in the positioning cycle in which the moving body was last determined to be in the fixed state is used as the reference position instead of the installation position, the positioning unit cancels out an error contained in the positioning signal based on the observation data received by the observation data receiving unit and the positioning signal received by the positioning signal receiving unit, determines the position of the moving body using the positioning signal in which the error has been canceled, and outputs the positioning signal as data representing the position of the moving body. The positioning device according to any one of claims 1 to 4, wherein the positioning unit measures the position of the moving object using single-frequency RTK.

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