JP7464113B2 - Position measuring device, position measuring method, and program - Google Patents

Description

The present invention relates to technology for measuring the position of a moving object with high precision.

In recent years, positioning using navigation satellite systems, such as the Global Navigation Satellite System (GNSS), has been used in a wide range of applications.

GNSS positioning methods include code based positioning, which provides a positioning accuracy of a few meters, and carrier phase based positioning, which provides centimeter-level positioning accuracy. For example, the real time kinematic method, which is also compatible with moving objects, is used as a carrier phase positioning method.

One application that uses GNSS positioning is positioning for autonomous vehicles. Autonomous driving requires absolute positioning accuracy of sub-meter (order of a few centimeters to a few tens of centimeters) that can determine the lane in which the vehicle is driving and the vehicle's position within the lane. For this reason, it is expected that the carrier phase positioning method will mainly be applied.

In GNSS positioning, not only does the convergence (fix) rate of the carrier phase positioning solution decrease in a reception environment called an urban canyon, where high-rise buildings and other structures exist around the reception position, but there is also the issue of the accuracy of the code positioning solution, which is used as an alternative when a carrier phase positioning solution cannot be obtained, deteriorating. In addition, when positioning a moving object such as a vehicle, there are environments where navigation satellite signals (hereinafter referred to as satellite signals) cannot be received temporarily, such as inside tunnels or under overpasses.

"High-precision vehicle position measurement algorithm integrating DGPS/INS/VMS", Hideo Kumagai, Yukihiro Kubo, et al., "Photogrammetry and Remote Sensing", Vol. 41, No. 4, 2002

In order to address the above issues, a composite positioning method for moving objects has been proposed that combines an absolute positioning means using GNSS positioning with a complementary relative positioning means such as an IMU (Inertial Measurement Unit). In conventional technology, when it is difficult to receive satellite signals or the reception state is judged to have deteriorated, the composite positioning method generally involves reactively switching from the absolute positioning means to the relative positioning means, or reactively increasing the weighting of the relative positioning means.

However, in the conventional method of reactively switching from absolute positioning means to relative positioning means when the satellite signal reception deteriorates, accurate absolute position coordinates cannot be obtained depending on the timing of the switch, and as a result, there was an issue that the positioning accuracy of the relative positioning means after the switch continues to deteriorate.

The present invention has been made in consideration of the above points, and aims to provide a technology for avoiding deterioration of positioning accuracy that occurs when switching from an absolute positioning means to a relative positioning means in a hybrid positioning method that combines an absolute positioning means and a relative positioning means.

According to the disclosed technique, there is provided a position measurement device for measuring the position of a moving object, comprising:
a positioning control unit that compares a first positioning result of the moving body obtained by an absolute position positioning unit with a second positioning result of the moving body obtained by a relative position positioning unit, determines whether or not a difference between the first positioning result and the second positioning result exceeds a first threshold, and, if the difference exceeds the first threshold, calculates a position coordinate of the moving body after the difference exceeded the first threshold based on the relative position of the moving body obtained by the relative position positioning unit and the position coordinate of the moving body obtained by the absolute position positioning unit prior to the point in time when the difference exceeded the first threshold,
The positioning control unit calculates the position coordinates of the moving object after the difference between the first positioning result and the second positioning result exceeds the first threshold, using the position coordinates of the moving object obtained by the absolute position positioning unit at a past time when the difference was equal to or smaller than a third threshold that is smaller than the first threshold.
A position measurement device is provided.

According to the disclosed technology, in a hybrid positioning method that combines an absolute positioning means and a relative positioning means, it is possible to avoid the deterioration of positioning accuracy that occurs when switching from an absolute positioning means to a relative positioning means.

1 is a functional configuration diagram of a position measurement device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a hardware configuration of a position measurement device. FIG. 11 is a diagram for explaining a reference operation. FIG. 2 is a diagram for explaining an operation according to an embodiment of the present invention. 4 is a flowchart of the operation of the position measurement device. FIG. 13 is a diagram illustrating an example of a displacement measurement period. FIG. 13 is a diagram illustrating a configuration example in which an absolute position measurement unit is located on a cloud.

Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

In the following embodiment, a vehicle traveling on a road is given as the moving object to be positioned, but this is just one example. The present invention can be applied to moving objects in general, not limited to vehicles traveling on roads.

(Device configuration)
1 shows a functional configuration diagram of a position measurement device 100 according to the present embodiment. As shown in FIG. 1, the position measurement device 100 according to the present embodiment includes an absolute position measurement unit 110, a relative position measurement unit 120, an output unit 130, a position measurement control unit 140, and a data storage unit 150.

The absolute positioning unit 110 is a GNSS carrier phase positioning receiver. However, depending on the application of the position measurement device 100, a satellite signal receiver using a method other than the carrier phase positioning method (such as a code positioning method) may be used as the absolute positioning unit 110. In addition, the absolute positioning unit 110 has a function of collecting observation data and position data of reference stations that are necessary to perform carrier phase positioning.

The relative position measurement unit 120 is a vehicle speed pulse measurement device, an IMU, an in-vehicle camera, LiDAR (Light Detection and Ranging), a GNSS Doppler shift measurement device, etc. The vehicle speed pulse measurement device determines the speed of the vehicle, that is, the distance traveled per unit time. The three-axis gyro and three-directional accelerometer mounted on the IMU determine three-dimensional angular velocity and acceleration. The relative position of the vehicle can be determined from the movement of an object in the image data captured by the in-vehicle camera. With LiDAR, a laser beam is scanned while irradiating the object and observing the scattered and reflected light, thereby measuring the distance to the object and determining the relative position of the vehicle. With the GNSS Doppler shift measurement device, the speed information is obtained by measuring the frequency change of the carrier wave of the received satellite signal, and the relative displacement of the vehicle position can be determined by integrating this information over time.

The relative position measurement unit 120 may be a plurality of positioning means among the positioning means such as a vehicle speed pulse measurement device, an IMU, an in-vehicle camera, LiDAR, a GNSS Doppler shift measurement device, etc., or may be a single positioning means. When the relative position measurement unit 120 has a plurality of positioning means, it may be provided with a mechanism for selecting and outputting the most accurate positioning result among the positioning results obtained by each of the plurality of positioning means, or may be provided with a mechanism for coupling all or part of the positioning results obtained by each of the plurality of positioning means using a Kalman filter or the like and outputting them.

In addition, the relative position positioning unit 120 is supplied with a high-precision clock signal obtained by time synchronization with the GNSS signal from the absolute position positioning unit 110, and during the time period when positioning is performed by the relative position positioning unit 120 (the time period when the reliability of the positioning results by the absolute position positioning unit 110 is low), the relative position positioning unit 120 is able to maintain the accuracy of the clock signal by holdover (self-running operation by an oscillator) without relying on time synchronization with the GNSS signal.

The positioning control unit 140 controls the processing of the procedures described below. The data storage unit 150 stores parameters used for positioning. For example, the displacement measurement period and various thresholds described below are examples of parameters. The data storage unit 150 also stores the positioning results (position, direction, displacement, etc.) for the period from the present to a certain point in the past, together with the exact time information (timestamp) at which positioning was performed for each of the absolute position positioning unit 110 and the relative position positioning unit 120.

The output unit 130 outputs the current position, which is the positioning solution obtained by the positioning control unit 140. The current position is expressed in three-dimensional coordinates (x, y, z), but the output information may be the three-dimensional coordinates themselves based on a geographic coordinate system or a projected coordinate system, or other information. For example, a control signal may be output to a control unit of an autonomous vehicle, or image information showing the position on a map may be output.

The position measurement device 100 may be a single, physically integrated device, or may be a device in which several functional units are physically separated and connected via a network. For example, the positioning control unit 140 may be a computer that operates according to a program, and the other functional units may be devices external to the position measurement device 100.

In addition, the position measurement device 100 may be entirely mounted on a mobile body for use, or some of its functions may be provided on a network (e.g., on the cloud) and the remaining functions may be mounted on a mobile body for use. For example, the positioning control unit 140 may be provided on the cloud and the remaining functions may be mounted on a mobile body for use.

In addition, for example, observation data (also called raw data) may be output from a GNSS carrier phase positioning receiver provided in a moving object, and the observation data may be transmitted to a carrier phase positioning calculation processing function unit provided in the cloud, thereby performing carrier phase positioning calculation on the cloud. In this case, the positioning calculation result is input from the carrier phase positioning calculation processing function unit on the cloud to the positioning control unit 140.

(Hardware configuration example)
Fig. 2 is a diagram showing an example of the hardware configuration of a computer that can be used as the position measurement device 100 in this embodiment or the positioning control unit 140 in the position measurement device 100. The computer in Fig. 2 has a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, and an output device 1008, which are all connected to each other by a bus B.

The program that realizes the processing on the computer is provided by a recording medium 1001, such as a CD-ROM or a memory card. When the recording medium 1001 storing the program is set in the drive device 1000, the program is installed from the recording medium 1001 via the drive device 1000 into the auxiliary storage device 1002. However, the program does not necessarily have to be installed from the recording medium 1001, but may be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files, data, etc.

When an instruction to start a program is received, the memory device 1003 reads out and stores the program from the auxiliary storage device 1002. The CPU 1004 realizes functions related to the position measurement device 100 or the positioning control unit 140, etc., in accordance with the program stored in the memory device 1003. The interface device 1005 is used as an interface for connecting to a network. The display device 1006 displays a GUI (Graphical User Interface) or the like according to a program. The input device 1007 is composed of a keyboard and mouse, buttons, a touch panel, etc., and is used to input various operational instructions. The output device 1008 outputs the results of calculations.

(Overview of Operation of Position Measurement Device 100)
An example of the operation of the position measurement device 100 when the position measurement device 100 is mounted on a vehicle as a moving body will be described below with reference to FIGS.

In order to make it easier to understand the effects of the technology of this embodiment, we will first use Figure 3 to explain the operation when the technology of this embodiment is not used.

The vehicle shown in Figure 3 is equipped with a conventional position measurement device that uses an absolute position measurement unit and a relative position measurement unit in a complementary manner and reactively switches between the two.

In Figure 3, the position measurement device measures its position using the absolute position measurement unit until the vehicle traveling diagonally upward to the right reaches the vicinity of point A. As the satellite signal reception deteriorates near point A, the position measurement device switches its positioning means from the absolute position measurement unit to the relative position measurement unit, and thereafter outputs, as the position solution, the position coordinates obtained from the relative position (relative displacement) measured by the relative position measurement unit from the position last measured by the absolute position measurement unit (B) (solid arrow in Figure 3).

As shown in Figure 3, in this conventional method, the error that occurs between the vehicle position at the time of switching (A) and the absolute positioning result at that time (B) is continuously carried over to the positioning results based on subsequent relative positioning, resulting in a continuous deterioration in positioning accuracy.

An example of operation of this embodiment, which solves the above problem, will be described with reference to Figure 4. The vehicle in Figure 4 is equipped with a position measurement device 100 according to this embodiment, so when referring to the vehicle, it will be referred to as the vehicle (position measurement device 100).

In this embodiment, the vehicle (position measuring device 100) does not use the absolute position measuring unit 110 and the relative position measuring unit 120 in a complementary manner, but rather improves positioning performance by actively operating both units at all times and monitoring each other.

A vehicle (position measurement device 100) traveling diagonally upward and to the right in Figure 4 is outputting positioning results by the absolute position measurement unit 110 below the position shown in C.

The absolute position measurement unit 110 and the relative position measurement unit 120 each measure the displacement of the vehicle (position measurement device 100) for a certain period (a displacement measurement period described below). The positioning control unit 140 compares the displacement measured by the absolute position measurement unit 110 with the displacement measured by the relative position measurement unit 120 for each displacement measurement period, and switches the positioning means used to output the results from the absolute position measurement unit 110 to the relative position measurement unit 120 at the timing when the difference between the two exceeds a predetermined threshold (here, "threshold TH1"). In the example of Figure 4, this timing occurs when the vehicle (position measurement device 100) is located at the point indicated by B.

After switching to the relative position measurement unit 120, the positioning control unit 140 goes back to the (e.g. last) time within the displacement measurement period where the difference in displacement is smaller than a predetermined threshold (here, "threshold TH3"; threshold TH3 < threshold TH1), and outputs as the positioning result the position coordinates of the absolute positioning result at that time plus the relative displacement measured by the relative position measurement unit 120 and stored in the data storage unit 150, starting from that position coordinate. In Figure 4, the position at that time (the going back time) is indicated by A, and the output of the positioning result based on the relative displacement from that position is indicated by a solid line.

By performing the above switching operation, the problem of continuing errors as shown in Figure 3 is resolved, and highly accurate positioning results can be obtained as shown in Figure 4. In other words, stable absolute positioning performance can be achieved without depending on the satellite signal reception state.

(Operation flow of the position measurement device 100)
Next, an example of the operation of the position measurement device 100 will be described in more detail with reference to the flowchart in Fig. 5. Note that, although a "variant example" will be described last, the example described before the description of the "variant example" will be referred to as a "basic example".

First, in S101, a displacement measurement period and thresholds (threshold TH1, threshold TH2, threshold TH3, etc.) are set in the position measurement device 100. The displacement measurement period and thresholds are stored in the data storage unit 150 and are referenced by the positioning control unit 140. The displacement measurement period and thresholds may be determined based on the accuracy of the relative position positioning unit 120, for example.

If the accuracy of the relative positioning unit 120 is high, the positioning result of the displacement measured by the relative positioning unit 120 has a small error even for displacement over a relatively long period of time, so the displacement measurement period for the same threshold setting value can be made longer than when the accuracy of the relative positioning unit 120 is low.

In the example of Figure 5, it is assumed that the reliability of the positioning by the absolute position measuring unit 110 is high in the initial state. In S102, both the absolute position measuring unit 110 and the relative position measuring unit 120 perform positioning. The positioning control unit 140 outputs the positioning result (vehicle position coordinates) of the absolute position measuring unit 110 to the output unit 130, and the output unit 130 outputs the positioning result of the absolute position measuring unit 110.

In addition, while both the absolute position measurement unit 110 and the relative position measurement unit 120 perform positioning, the positioning control unit 140 stores the respective positioning results in the data storage unit 150. Specifically, for the absolute position measurement unit 110, the coordinates of the absolute position and the measurement time are stored in the data storage unit 150, and for the relative position measurement unit 120, for example, the relative position (which may be called relative displacement) starting from the positioning result (vehicle position coordinates) of the absolute position measurement unit 110 at a certain measurement time and the measurement time of the relative position are stored in the data storage unit 150.

The above positioning results, for example, the positioning results of the absolute position measuring unit 110 and the relative position measuring unit 120 for each time period of the measurement period are stored in the data storage unit 150.

The absolute position measurement unit 110 and the relative position measurement unit 120 each also measure the displacement of the vehicle (position measurement device 100) for each displacement measurement period. The positioning control unit 140 also stores the displacements measured by the absolute position measurement unit 110 and the relative position measurement unit 120 in the data storage unit 150 for each displacement measurement period.

For example, if a displacement measurement period is from time t1 to time t2, and the position of the vehicle (position measuring device 100) measured at time t1 is Pt1, and the position of the vehicle (position measuring device 100) measured at time t2 is Pt2, then the displacement during that displacement measurement period is represented by a vector from Pt1 to Pt2, and this is stored.

In addition, data older than a predetermined period of time may be automatically deleted from the data storage unit 150.

In S103, the positioning control unit 140 compares the displacement measured by the absolute position positioning unit 110 during the most recent displacement measurement period with the displacement measured by the relative position positioning unit 120 during the same displacement measurement period. Specifically, the difference between the displacements is calculated.

For example, if the displacement measured by the absolute position measurement unit 110 is V1 = (x1, y1, z1) and the displacement measured by the relative position measurement unit 120 is V2 = (x2, y2, z2), the difference can be calculated as the magnitude of V1-V2, that is, ((x1-x2) ² + (y1-y2) ² + (z1-z2) ² ) ^1/2 .

In S104, the positioning control unit 140 determines whether "the difference in displacement within the displacement measurement period exceeds a preset threshold value TH1 and the reliability of the positioning result of the absolute position positioning unit 110 has decreased."

Whether the reliability of the positioning results of the absolute position positioning unit 110 has decreased may be determined based on the reception state of the satellite signals (radio signal strength, CNR (Carrier-to-Noise ratio), number of satellites that can be received well, etc.), or based on the convergence (fix) state of the carrier phase positioning, the occurrence status of cycle slips, etc.

In addition, among the judgment condition of S104 "The difference in displacement within the displacement measurement period exceeds the preset threshold value TH1, and the reliability of the positioning result of the absolute position positioning unit 110 has decreased", "The reliability of the positioning result of the absolute position positioning unit 110 has decreased" may be excluded from the condition. This is because if the reliability of the relative position positioning unit 120 is sufficiently high, it can be estimated that "The reliability of the positioning result of the absolute position positioning unit 110 has decreased" when "The difference in displacement within the displacement measurement period exceeds the preset threshold value TH1".

If the determination in S104 is Yes, proceed to S105. If the determination in S104 is No, return to S102. If returning to S102, the determination in S104 is executed in the next displacement measurement period. Note that with regard to the determination in S104, the process may proceed to S105 if the condition is satisfied in N consecutive displacement measurement periods (N is a predetermined integer of 1 or more).

In addition, if the absolute position measuring unit 110 is unable to receive a satellite signal or is unable to output a positioning result due to a malfunction of the absolute position measuring unit 110, the judgment in S104 will immediately become Yes.

If the process proceeds to S105 (i.e., if "the difference in displacement within the displacement measurement period exceeds the preset threshold TH1 and the reliability of the positioning result of the absolute position positioning unit 110 has decreased"), the positioning control unit 140 calculates the position coordinates by adding the relative displacement measured by the relative position positioning unit 120 from the time the position coordinates were measured to a certain time, to the position coordinates measured by the absolute position positioning unit 110 at, for example, the last time of a displacement measurement period prior to (past) the displacement measurement period (a displacement measurement period in which "the difference in displacement < threshold TH3"), as the position solution (vehicle position coordinates) at the time the relative displacement was measured (the above-mentioned "certain time").

After that, by integrating (adding) the relative displacements measured sequentially by the relative position measuring unit 120 over time, a positioning solution at that point in time can be obtained each time a positioning result is obtained by the relative position measuring unit 120.

For example, the displacement measurement period in which the displacement difference exceeded the threshold value TH1 is set as displacement measurement period 4, the displacement measurement period immediately before that is set as displacement measurement period 3, the displacement measurement period immediately before that is set as displacement measurement period 2, and the displacement measurement period immediately before that is set as displacement measurement period 1. Figure 6 shows displacement measurement periods 1 to 4.

As shown in Figure 6, displacement measurement period 1 is the period from time t1 to time t2, and the difference in displacement due to the positioning results in displacement measurement period 1 satisfies "difference in displacement < threshold value TH3". Neither displacement measurement period 2 nor displacement measurement period 3 satisfies "difference in displacement < threshold value TH3".

At this time, the positioning control unit 140 reads out the positioning result (vehicle position coordinates) by the absolute position measurement unit 110 at a time within the displacement measurement period 1 (here, time t2 is used as an example) from the data storage unit 150, and further reads out the relative displacement from time t2 to time t3 measured by the relative position positioning unit 120 from the data storage unit 150, and adds the relative displacement to the position coordinates to obtain the positioning result (vehicle position coordinates) at time t3.

The period from time t2 to time t3 above may be displacement measurement period 2, and time t3 may be a time within displacement measurement period 2, or may be any other time after t2. In any case, by accumulating and adding past relative displacements measured by the relative position measurement unit 120 stored in the data storage unit 150, and by adding relative displacements obtained sequentially in real time, it is possible to obtain a current positioning result (i.e., a positioning result at a time after the time when "difference > threshold TH1" was detected).

The threshold used in S106 in Figure 5 is threshold TH2. Threshold TH2 is equal to or less than threshold TH1. In S106, the positioning control unit 140 determines whether "the difference in displacement within the displacement measurement period is equal to or less than the preset threshold TH2, and the reliability of the positioning result of the absolute position positioning unit 110 is sufficiently high."

As described above, whether the positioning results of the absolute position positioning unit 110 are sufficiently reliable may be determined based on the satellite signal reception state (radio signal strength, CNR, number of satellites that can be received well, etc.), or based on the convergence (fix) state of carrier phase positioning, the occurrence status of cycle slips, etc.

In addition, among the judgment condition of S106 "The difference in displacement within the displacement measurement period is equal to or less than the preset threshold value TH2, and the reliability of the positioning result of the absolute position positioning unit 110 is sufficiently high", "The reliability of the positioning result of the absolute position positioning unit 110 is sufficiently high" may be excluded from the condition. This is because if the reliability of the relative position positioning unit 120 is sufficiently high, it can be estimated that "The reliability of the positioning result of the absolute position positioning unit 110 is sufficiently high" because "The difference in displacement within the displacement measurement period is equal to or less than the preset threshold value TH2".

If the determination in S106 is Yes, proceed to S102 and return to the mode in which the positioning solution of the absolute positioning unit 110 is output from the position measurement device 100. If the determination in S106 is No, return to S105 and continue in the mode in which the positioning solution of the relative positioning unit 120 is used.

In addition, with regard to the judgment in S106, if the condition is satisfied for M consecutive displacement measurement periods (M is a predetermined integer of 1 or more), the process may return to S102.

In addition, the thresholds TH1 and TH2 can each be set arbitrarily for purposes such as providing a protective buffer value to avoid operational instability due to switching back of both positioning means.

(Modification 1 (Modification of Operation))
The determination in steps S104 and S106 in FIG. 5 may be performed in the following manner.

In this example, the absolute positioning unit 110 of the position measurement device 100 has multiple GNSS receiver antennas (a pair of a GNSS receiver and a GNSS antenna). In a manner similar to the mobile base station method, the multiple GNSS receiver antennas perform carrier phase positioning, allowing the absolute positioning unit 110 to measure the relative positions between the GNSS antennas. For example, assuming there is a GNSS antenna 1 and a GNSS antenna 2, the relative position coordinates (x, y, z) of GNSS antenna 2 can be measured when the position coordinates of GNSS antenna 1 are (0, 0, 0).

Since GNSS antenna 1 and GNSS antenna 2 are fixed to the vehicle (position measurement device 100), the positioning control unit 140 can determine the orientation (direction of travel) of the vehicle (position measurement device 100) using the vector from GNSS antenna 1 to GNSS antenna 2.

In the judgment of S104 in FIG. 5 in the first modified example, and in the calculation of the positioning solution in S105, the threshold value TH4 and the threshold value TH6 (threshold value TH4>threshold value TH6) are used, respectively. In S104, the positioning control unit 140 compares the direction measured by the absolute position measuring unit 110 with the direction measured by the relative position measuring unit 120 (the directional component of the displacement), and if the difference (the difference in angle) exceeds the threshold value TH4, proceeds to S105. The processing in S105 is the same as the processing described above, and the positioning result can be obtained by adding the relative displacement obtained by the relative position measuring unit 120 to the position coordinates obtained by the absolute position measuring unit 110 at the time when the difference in the past direction is equal to or less than the threshold value TH6.

In the judgment of S104, the condition may be that "the difference (angle difference) exceeds the threshold value TH4 and the reliability of the positioning result of the absolute position measuring unit 110 has decreased."

In addition, if the absolute position measuring unit 110 is unable to receive a satellite signal or is unable to output a positioning result due to a malfunction of the absolute position measuring unit 110, the judgment in S104 will immediately become Yes.

In the judgment of S106 of the modified example, a threshold value TH5 (threshold value TH5≦threshold value TH4) is used. In S106, the positioning control unit 140 compares the direction measured by the absolute position measuring unit 110 with the direction measured by the relative position measuring unit 120 (directional component of displacement), and if the difference (angle difference) is less than or equal to the threshold value TH5, the process returns to S102. If the judgment of S106 is No, the process returns to S105.

In the judgment of S106, the condition may be that "the difference (angle difference) is less than or equal to threshold value TH5 and the reliability of the positioning result of the absolute position measuring unit 110 is sufficiently high."

In addition, in the judgments of S104 and S106, similar to the basic example based on the difference in displacement, the condition may be satisfied in multiple consecutive displacement measurement periods. In addition, the thresholds TH4 and TH5 can be set arbitrarily for the purpose of providing a protective buffer value to avoid operational instability due to the switching back of both positioning means.

In addition, it is also possible to make a judgment based on both the difference in displacement and the difference in orientation, and then make a condition judgment by ANDing or ORing the results of both judgments.

The absolute position positioning results obtained by the absolute position positioning unit 110 (e.g., a GNSS receiver) vary depending on the satellite signal reception environment, but the relative position positioning unit 120 has little dependency on the satellite signal reception environment, so measurements by the relative position positioning unit 120 are effective as a means of evaluating the validity of the measurement results obtained by the absolute position positioning unit 110.

In other words, in absolute positioning using GNSS in a moving object, the positioning results often tend to fluctuate discontinuously due to reflected and diffracted waves (multipath) of the satellite signal generated by surrounding buildings, whereas relative positioning using the relative positioning unit 120 (IMU, etc.) is less susceptible to such external environment effects. Similarly, in relative displacement positioning using speed measurement based on the Doppler shift of the satellite signal, the effects of reflected and diffracted waves from surrounding buildings are smaller than those of positioning using satellite signals.

In addition, the positioning control unit 140 may couple the positioning results by the absolute position positioning unit 110 and the relative position positioning unit 120 using an extended Kalman filter or the like. This makes it possible to output the positioning results with reduced (smoothed) discontinuous changes when switching from absolute positioning to relative positioning, or from relative positioning to absolute positioning. In addition, the positioning control unit 140 may be provided with a function of estimating (predicting) the output value of positioning at the current time or future time from the output value of past positioning results.

(Modification 2 (Modification of Configuration))
As described above, the carrier phase positioning calculation may be performed on the cloud. Fig. 7 shows an example of the system configuration in this case.

An absolute positioning device 200 is provided on the network 300. This absolute positioning device 200 is implemented, for example, on a virtual machine on the cloud.

The absolute positioning device 200 comprises an absolute positioning calculation unit 210, an observation data receiving unit 220, and a positioning result transmission unit 230. The observation data receiving unit 220 receives observation data obtained by observing satellite signals by the position measurement device 100. The absolute positioning calculation unit 210 performs positioning calculations using the observation data. The positioning result transmission unit 230 transmits the obtained positioning result to the position measurement device 100.

Compared to the configuration in Figure 1, the position measurement device 100 shown in Figure 7 does not have an absolute position measurement unit 110, but instead has an observation data acquisition and transmission unit 160 and a positioning result receiving unit 170. The observation data acquisition and transmission unit 160 observes satellite signals and transmits the observation data to the absolute position measurement device 200. The positioning result receiving unit 170 receives the positioning result from the absolute position measurement device 200 and passes the positioning result to the positioning control unit 140.

The processing contents other than the processing related to absolute positioning are the same as the processing contents described so far. The displacement obtained by absolute positioning may be measured by the absolute positioning device 200 on the cloud and transmitted to the position measurement device 100 together with the position measurement result, or the positioning control unit 140 of the position measurement device 100 may calculate the displacement from the absolute position. In addition, the absolute positioning device provided on the cloud may be referred to as the "absolute positioning unit."

As described above, the positioning control unit 140 may be provided on the cloud. For example, in the configuration of FIG. 7, the positioning control unit 140 may be provided in the absolute positioning device 200 instead of the positioning device 100, or the means for performing absolute positioning calculations may be left in the positioning device 100, and only the positioning control unit 140 may be provided on the cloud.

(Effects of the embodiment)
As described above, according to this embodiment, in a composite positioning method that combines an absolute positioning means and a relative positioning means, it is possible to avoid deterioration of positioning accuracy that occurs when switching from an absolute positioning means to a relative positioning means, thereby achieving stable absolute positioning performance that is not dependent on the reception state of satellite signals.

(Summary of the embodiment)
In the present embodiment, at least the position measuring device, the position measuring method, and the program described in the following items are provided.
(Section 1)
A position measurement device for measuring the position of a moving object,
a positioning control unit that compares a first positioning result of the moving body obtained by an absolute position positioning unit with a second positioning result of the moving body obtained by a relative position positioning unit, determines whether a difference between the first positioning result and the second positioning result exceeds a first threshold, and if the difference exceeds the first threshold, calculates the position coordinates of the moving body after the difference exceeded the first threshold based on the relative position of the moving body obtained by the relative position positioning unit and the position coordinates of the moving body obtained by the absolute position positioning unit prior to the point at which the difference exceeded the first threshold.
(Section 2)
2. The position measuring device according to claim 1, wherein the first positioning result is a displacement of the moving body obtained by the absolute position measuring unit during a predetermined displacement measurement period, and the second positioning result is a displacement of the moving body obtained by the relative position measuring unit during the displacement measurement period.
(Section 3)
3. The position measuring device according to claim 1, wherein the first positioning result is an orientation of the moving body obtained by the absolute position measuring unit, and the second positioning result is an orientation of the moving body obtained by the relative position measuring unit.
(Section 4)
The positioning control unit calculates the position coordinates of the moving body after the difference between the first positioning result and the second positioning result exceeds the first threshold, using the position coordinates of the moving body obtained by the absolute position positioning unit at a past time when the difference between the first positioning result and the second positioning result was equal to or less than a third threshold that is smaller than the first threshold.
(Section 5)
The position measuring device according to any one of claims 1 to 4, wherein the positioning control unit outputs the position coordinates of the moving body obtained by the absolute position measuring unit when it determines that the difference between the first positioning result and the second positioning result is equal to or less than a second threshold value after the difference exceeds the first threshold value.
(Section 6)
A position measurement method executed by a position measurement device that measures the position of a moving object, comprising:
A position measurement method comprising: comparing a first positioning result of the moving body obtained by an absolute position positioning unit with a second positioning result of the moving body obtained by a relative position positioning unit; determining whether a difference between the first positioning result and the second positioning result exceeds a first threshold; and, if the difference exceeds the first threshold, calculating the position coordinates of the moving body after the difference exceeded the first threshold based on the relative position of the moving body obtained by the relative position positioning unit and the position coordinates of the moving body obtained by the absolute position positioning unit prior to the point at which the difference exceeded the first threshold.
(Section 7)
A program for causing a computer to function as a positioning control unit in the position measurement device according to any one of claims 1 to 5.

Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

REFERENCE SIGNS LIST 100 Position measurement device 110 Absolute position measurement unit 120 Relative position measurement unit 130 Output unit 140 Position measurement control unit 150 Data storage unit 160 Observation data acquisition and transmission unit 170 Position measurement result reception unit 200 Absolute position measurement device 210 Absolute position measurement calculation unit 220 Observation data reception unit 230 Position measurement result transmission unit 300 Network 1000 Drive device 1001 Recording medium 1002 Auxiliary storage device 1003 Memory device 1004 CPU
1005 Interface device 1006 Display device 1007 Input device 1008 Output device

Claims (5)

A position measurement device for measuring the position of a moving object,
a positioning control unit that compares a first positioning result of the moving body obtained by an absolute position positioning unit with a second positioning result of the moving body obtained by a relative position positioning unit, determines whether or not a difference between the first positioning result and the second positioning result exceeds a first threshold, and, if the difference exceeds the first threshold, calculates a position coordinate of the moving body after the difference exceeded the first threshold based on the relative position of the moving body obtained by the relative position positioning unit and the position coordinate of the moving body obtained by the absolute position positioning unit prior to the point in time when the difference exceeded the first threshold,
The positioning control unit calculates the position coordinates of the moving body after the difference between the first positioning result and the second positioning result exceeds the first threshold, using the position coordinates of the moving body obtained by the absolute position positioning unit at a past time when the difference was equal to or smaller than a third threshold that is smaller than the first threshold. 2. The position measuring device according to claim 1, wherein the first positioning result is a displacement of the moving body obtained by the absolute position measuring unit during a predetermined displacement measurement period, and the second positioning result is a displacement of the moving body obtained by the relative position measuring unit during the displacement measurement period. The position measuring device according to claim 1 or 2, wherein the first positioning result is an orientation of the moving object obtained by the absolute position measuring unit, and the second positioning result is an orientation of the moving object obtained by the relative position measuring unit. A position measurement method executed by a position measurement device that measures the position of a moving object, comprising:
a positioning control step of comparing a first positioning result of the moving body obtained by an absolute position positioning unit with a second positioning result of the moving body obtained by a relative position positioning unit, determining whether or not a difference between the first positioning result and the second positioning result exceeds a first threshold, and, if the difference exceeds the first threshold, calculating a position coordinate of the moving body after the difference exceeded the first threshold based on the relative position of the moving body obtained by the relative position positioning unit and the position coordinate of the moving body obtained by the absolute position positioning unit prior to the point in time when the difference exceeded the first threshold,
the position measurement method, in the position measurement control step, calculating the position coordinates of the moving body after the difference between the first position measurement result and the second position measurement result exceeds the first threshold value by using the position coordinates of the moving body obtained by the absolute position measurement unit at a past time when the difference between the first position measurement result and the second position measurement result was equal to or smaller than a third threshold value that is smaller than the first threshold value. A program for causing a computer to function as a positioning control unit in the position measurement device according to any one of claims 1 to 3 .

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