JP7547192B2 - Transmission source positioning device and transmission source positioning program - Google Patents

Description

This disclosure relates to technology for locating the position of a transmission source.

Technologies for locating the position of a transmitting source are disclosed in Patent Documents 1 and 2, etc. In Patent Documents 1 and 2, the position of a transmitting source is located so that the actual measured value of the arrival direction of the received wave from the transmitting source matches the predicted value of the arrival direction of the received wave from the transmitting source using a Kalman filter or the like (calculated based on the position of the mobile body equipped with the positioning system and the previous location position of the transmitting source).

Patent No. 5730473 specification Patent No. 5730506 specification

Figure 1 shows the problems associated with the movement of the true position of the transmitting source in the prior art. Here, the convergence index of the location position of the transmitting source is the size of the radius of a circle that is centered on the location position of the transmitting source and in which the true position of the transmitting source is highly likely to exist (hereinafter referred to as the "location index" of the transmitting source). The location index of the transmitting source gradually becomes smaller from the initial location stage to the position convergence stage, but does not become larger again (except when the location process is operating abnormally).

In Figure 1, the true position of the transmitting source is moving. However, because data on the movement of the transmitting source cannot be obtained, the true position of the transmitting source is treated as a fixed point. First, in the initial location stage when the location index of the transmitting source is large, the amount of correction from the previous value to the current value of the location position of the transmitting source can be made large, and the location position of the transmitting source can be made to follow the true position of the moving transmitting source. Finally, in the location convergence stage when the location index of the transmitting source is small, the amount of correction from the previous value to the current value of the location position of the transmitting source cannot be made large, and the location position of the transmitting source cannot be made to follow the true position of the moving transmitting source. Therefore, when the true position of the transmitting source moves for a long time, a location error occurs between the location position of the transmitting source and the true position of the moving transmitting source.

Figure 2 shows the problem associated with disturbance in the direction of arrival of received waves in the conventional technology. Here, depending on the attitude change of the mobile body on which the positioning system is mounted, multipath or the like occurs in the arrival path of the received waves between the transmission source and the mobile body, causing disturbance in the direction of arrival of the received waves between the transmission source and the mobile body.

In FIG. 2, the true position of the transmitting source does not move. First, in the initial stage (mobile body position (1)) when the moving body moves almost in a straight line, there is no disturbance in the direction of arrival of the received wave between the transmitting source and the moving body, so the location position of the transmitting source can be fixed near the true position of the non-moving transmitting source (location position (1)). Then, in the middle stage (mobile body position (2)) when the moving body turns 180 degrees, blind spots etc. occur due to the relationship between the attitude of the transmitting source and the moving body, so there is a jump in the location position of the transmitting source, and the location position of the transmitting source cannot be fixed near the true position of the non-moving transmitting source (location position (2)). Finally, in the final stage (mobile body position (3)) when the moving body moves in a straight line again, even if there is no disturbance in the direction of arrival of the received wave between the transmitting source and the moving body, the location position of the transmitting source cannot be easily returned to the vicinity of the true position of the non-moving transmitting source (location position (3)). Therefore, even a single disturbance in the direction of arrival will result in a location error between the location of the transmitting source and the true position of a stationary transmitting source (or the true position of a moving transmitting source).

In order to solve the above problem, the present disclosure aims to reduce the location error between the location of the transmission source and the true position of the transmission source when the true position of the transmission source moves or when the attitude of a mobile body equipped with a position location system changes, etc., when locating the position of the transmission source.

To solve the above problem, the location of the transmitting source is selected each time the variance value of the located transmitting source position reaches a minimum value. Here, a small variance value of the located transmitting source position is an indication that the located transmitting source position is close to the true position of the transmitting source. Then, based on the selected transmitting source position, the moving direction and moving speed of the transmitting source from the past to the present are calculated, and the moving direction and moving speed of the transmitting source from the present to the future are predicted. Furthermore, when predicting the transmitting source position from the present to the future based on the moving direction and moving speed of the transmitting source from the present to the future and outputting it as a final output, the predicted transmitting source positions are linearly and continuously connected through the position location process. Then, based on the finally output transmitting source position, the transmitting source motion model (fixed point or linear movement, etc.) for locating the transmitting source position is updated.

Specifically, the present disclosure provides a position location unit that locates the position of a transmission source such that an actual measurement value of the direction of arrival of a received wave from the transmission source coincides with a predicted value of the direction of arrival of a received wave from the transmission source; a position selection unit that selects the located position of the transmission source each time a variance value of the located position of the transmission source reaches a minimum value after location of the position of the transmission source has begun; and a position selection unit that selects the position of the transmission source predicted to be selected next time by extrapolating a line segment connecting the position of the transmission source predicted to be selected last time and the position of the transmission source selected this time from the position of the transmission source predicted to be selected this time. This transmitting source position locating device is characterized by comprising: a position prediction unit that calculates the direction of the transmitting source position and interpolates the position of the transmitting source until the next time the transmitting source position is selected; a position output unit that outputs the calculation result of the direction of the transmitting source position predicted to be selected each time and the interpolation result of the transmitting source position until the transmitting source position is selected each time as the final output of the transmitting source position; and a model update unit that updates a transmitting source motion model for locating the transmitting source position based on the transmitting source position finally output by the position output unit.

The present disclosure also provides a position location step for locationing the position of the transmitting source such that an actual measurement value of the direction of arrival of the received wave from the transmitting source coincides with a predicted value of the direction of arrival of the received wave from the transmitting source; a position selection step for selecting the located position of the transmitting source each time a variance value of the located position of the transmitting source reaches a minimum value after location of the position of the transmitting source has started; and a position selection step for selecting the position of the transmitting source predicted to be selected next time by extrapolating a line segment connecting the position of the transmitting source predicted to be selected last time and the position of the transmitting source selected this time from the position of the transmitting source predicted to be selected this time. This is a transmission source position location program that causes a computer to execute, in sequence, a position prediction step in which the direction is calculated and the position of the transmission source is interpolated until the next time the position of the transmission source is selected; a position output step in which the calculation result of the direction of the transmission source position predicted to be selected each time and the interpolation result of the transmission source position until the transmission source position is selected each time are used as the final output of the position of the transmission source; and a model update step in which the transmission source motion model for locating the position of the transmission source is updated based on the transmission source position finally output in the position output step.

With these configurations, when the true position of the transmitting source moves, the transmitting source motion model for locating the position of the transmitting source is updated, thereby reducing the output error between the output position of the transmitting source and the true position of the transmitting source. Furthermore, when a moving body equipped with a position locating system undergoes a change in attitude, etc., the predicted positions of the transmitting source are linearly and continuously connected, thereby reducing the output error between the output position of the transmitting source and the true position of the transmitting source.

To solve the above problem, the location of the located transmission source is selected when the variance value of the located transmission source position becomes smaller than a predetermined variance value for the first time, and each time a predetermined time interval has elapsed thereafter (the variance value is usually small). Here, a small variance value of the located transmission source position is an indication that the located transmission source position is close to the true position of the transmission source. Then, based on the selected transmission source position, the moving direction and moving speed of the transmission source from the past to the present are calculated, and the moving direction and moving speed of the transmission source from the present to the future are predicted. Furthermore, when predicting the position of the transmission source from the present to the future based on the moving direction and moving speed of the transmission source from the present to the future and outputting it as a final output, the predicted transmission source positions are linearly and continuously connected through the position location process. Then, based on the finally output transmission source position, the transmission source motion model (fixed point or linear movement, etc.) for locating the transmission source position is updated.

Specifically, the present disclosure provides a position location unit that determines the position of a transmission source such that an actual measurement value of the direction of arrival of a received wave from the transmission source coincides with a predicted value of the direction of arrival of a received wave from the transmission source; a position selection unit that selects the determined position of the transmission source when a variance value of the determined position of the transmission source becomes smaller than a predetermined variance value for the first time after the start of location of the position of the transmission source, and each time a predetermined time interval has elapsed thereafter; and extrapolating a line segment connecting the previously predicted position of the transmission source to the currently selected position of the transmission source from the currently predicted position of the transmission source. This transmitting source position locating device is characterized by comprising: a position prediction unit that calculates the position of the transmitting source predicted to be selected next time and interpolates the position of the transmitting source until the position of the transmitting source is selected next time; a position output unit that outputs the calculation result of the position of the transmitting source predicted to be selected each time and the interpolation result of the position of the transmitting source until the position of the transmitting source is selected each time as the final output of the position of the transmitting source; and a model update unit that updates a transmitting source motion model for locating the position of the transmitting source based on the transmitting source position finally output by the position output unit.

According to this configuration, when the true position of the transmitting source moves, the transmitting source motion model for locating the position of the transmitting source is updated, thereby reducing the output error between the output position of the transmitting source and the true position of the transmitting source. Furthermore, when a moving body equipped with a position locating system undergoes a change in attitude, etc., the predicted positions of the transmitting source are linearly and continuously connected, thereby reducing the output error between the output position of the transmitting source and the true position of the transmitting source.

The present disclosure also provides a transmission source position locating device, characterized in that the model update unit starts applying the updated transmission source motion model before the position of the transmission source located using the transmission source motion model before the update converges to a predetermined degree.

With this configuration, by starting to apply the updated transmission source motion model before complete convergence based on the transmission source motion model before the update, it is possible to avoid delaying the start of application of the updated transmission source motion model, and since the number of data points for the output positions based on the transmission source motion model before the update is sufficient, the construction accuracy of the updated transmission source motion model can be improved.

The present disclosure also provides a transmission source position locating device, characterized in that the model update unit applies the transmission source motion model before and after the update in parallel, and after the position of the transmission source located using the updated transmission source motion model converges to the predetermined degree, starts adopting the position of the transmission source finally output using the updated transmission source motion model instead of the position of the transmission source finally output using the transmission source motion model before the update.

According to this configuration, after complete convergence based on the updated transmission source motion model, application of the pre-update transmission source motion model is terminated and switching is made to the updated transmission source motion model, thereby effectively increasing the variance value of the located transmission source position again and allowing the position location process to continue to high-precision processing based on the updated transmission source motion model.

In this way, when locating the position of a transmission source, the present disclosure can reduce the location error between the location of the transmission source and the true position of the transmission source when the true position of the transmission source moves or when the attitude of a mobile body equipped with a position location system changes, etc.

FIG. 1 illustrates the problems associated with moving the true location of a transmitting source in the prior art. FIG. 1 is a diagram showing a problem associated with disturbance in the arrival direction of received waves in the prior art. FIG. 1 is a diagram showing a configuration of a positioning system according to the present disclosure. FIG. 2 is a diagram showing a procedure of a first position location process of the present disclosure. FIG. 2 is a diagram showing the contents of a first position location process of the present disclosure. FIG. 11 is a diagram showing a procedure of a second position location process of the present disclosure. FIG. 11 is a diagram showing the contents of a second position location process according to the present disclosure. FIG. 1 is a diagram illustrating an overview of a model update process according to the present disclosure. FIG. 1 illustrates an improvement to the model updating process of the present disclosure. FIG. 13 is a diagram illustrating a procedure of a model update process according to the present disclosure. FIG. 13 is a diagram illustrating a procedure of a model update process according to the present disclosure. FIG. 1 illustrates a solution to moving the true position of a transmitting source according to the present disclosure. FIG. 13 is a diagram showing a solution to the disturbance in the direction of arrival of received waves according to the present disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementations of the present disclosure, and the present disclosure is not limited to the following embodiments.

(Overview of the positioning system of the present disclosure)
The configuration of the positioning system of the present disclosure is shown in Fig. 3. The positioning system P is composed of an arrival direction measuring device 1 and a transmission source positioning device 2. The transmission source positioning device 2 is composed of a position locating section 21, a position selecting section 22, a position predicting section 23, a position output section 24 and a model updating section 25. The transmission source positioning device 2 is realized by installing the transmission source positioning programs shown in Figs. 4, 6, 10 and 11 in a computer.

The direction of arrival measuring device 1 acquires the received waves from the transmission source received by the antenna mounted on the mobile body, calculates the spectrum of the direction of arrival of the received waves from the transmission source, and calculates the direction of arrival of the received waves from the transmission source based on the direction of arrival spectrum result. Here, the spectrum of the direction of arrival of the received waves from the transmission source can be a MUSIC (Multiple Signal Classification) spectrum or the like. After calculating the MUSIC spectrum, the direction of arrival measuring device 1 acquires information on the reception phase difference between the antennas, information on the mounting position of each antenna, and information on the transmission frequency of the transmission source in order to calculate the direction of arrival of the received waves from the transmission source based on the MUSIC spectrum result.

The positioning unit 21 locates the position of the transmission source so that the actual measured value of the direction of arrival of the received wave from the transmission source matches the predicted value of the direction of arrival of the received wave from the transmission source (calculated based on the position of the mobile body equipped with the positioning system P and the previous location of the transmission source). Here, the positioning unit 21 may be a Kalman filter or the like, and the state equation of the Kalman filter or the like may be a fixed point model (the transmission source is fixed) or a linear movement model (the transmission source moves linearly), and the observation equation of the Kalman filter or the like may be a triangulation equation. Then, in order to locate the position of the transmission source, the positioning unit 21 acquires information on the direction of arrival of the received wave from the transmission source, information on the position and attitude of the mobile body, and information on the previous location of the transmission source.

The position selection unit 22, the position prediction unit 23, and the position output unit 24 will be described using Figs. 4 to 7. The model update unit 25 will be described using Figs. 8 to 13.

(First position location process of the present disclosure)
The procedure and contents of the first position location process of the present disclosure are shown in Fig. 4 and Fig. 5. The position selection unit 22 selects the position of the located transmission source every time the variance value (location index) of the located transmission source position reaches a minimum value. Here, a small variance value (location index) of the located transmission source position is an indication that the located transmission source position is close to the true position of the transmission source.

The position prediction unit 23 calculates the moving direction and moving speed of the transmission source from the past to the present based on the position of the selected transmission source, and predicts the moving direction and moving speed of the transmission source from the present to the future. Then, when predicting the position of the transmission source from the present to the future based on the moving direction and moving speed of the transmission source from the present to the future and providing the final output, the predicted positions of the transmission source are linearly and continuously connected through the position location process. This is explained in detail below.

The positioning unit 21 locates _the position of the transmission _source so that the actual measured value of the arrival direction of the received wave from the transmission source coincides with the predicted value of the arrival direction of the received wave from the transmission source (calculated based on the position of the mobile body equipped with the positioning system P and the previous located position of the transmission source) at equal time intervals from before time t1 to after time t4 (step S1).

Before time _t1 , the variance value (location index) of the located transmission source position is still greater than the predetermined variance value after the start of location of the transmission source position (step S2, NO). Therefore, the position selection unit 22 selects the located transmission source position as it is, like a Kalman filter, etc. (step S3). Then, the position output unit 24 sets the located transmission source position as the final output of the transmission source position (step S7).

Even before time _t1 , the variance value (location index) of the located transmission source position becomes smaller than the predetermined variance value for the first time after the start of location of the transmission source position (step S2, YES), but does not reach the minimum value (step S4, NO). Therefore, the position selection unit 22 selects the located transmission source position as it is, as in the Kalman filter, etc. (step S5). Then, the position output unit 24 sets the located transmission source position as the final output of the transmission source position (step S7).

At time _t1 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and reaches a minimum value (step S4, YES). Therefore, the position selection unit 22 selects the located transmission source position (black circle at time _t1 in FIG. 5) (step S6). Then, the position output unit 24 sets the located transmission source position (black circle at time _t1 in FIG. 5) as the final output of the transmission source position (step S7).

From time _t1 to time _t2 , the variance value (location index) of the located transmission source position is smaller than a predetermined variance value (step S2, YES) and does not reach a minimum value (step S4, NO). Therefore, the position selection unit 22 selects the located transmission source position as it is, similar to a Kalman filter, etc. (step S5). Then, the position output unit 24 sets the located transmission source position as the final output of the transmission source position (step S7).

At time _t2 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has reached a minimum value (step S4, YES). Therefore, the location selection unit 22 selects the located transmission source position (black circle at time _t2 in FIG. 5) (step S6). Then, the location prediction unit 23 calculates the direction of the transmission source position predicted to be selected at time _t3 when the location index reaches a minimum value next time ₍ the direction to the white circle at time _t3 in FIG. 5) by extrapolating the line segment connecting the transmission source positions selected at time _t1 and time _t2 from the transmission source position selected at time t2 (step S6). Furthermore, the location output unit 24 sets the direction of the transmission source position predicted to be selected at time _t3 when the location index reaches a minimum value next time (the direction to the white circle at time _t3 in FIG. 5) as the final output of the transmission source position (step S7).

From time _t2 to time _t3 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has not reached the minimum value (step S4, NO). Therefore, the location selection unit 22 does not select the located transmission source position (step S5). Then, the location prediction unit 23 interpolates _the transmission source position until the transmission source position is selected at time _t3 when the location index reaches the minimum value next time based on the length and direction of the line segment connecting the transmission source positions selected at time _t1 and time t2 (step S5). Furthermore, the location output unit 24 outputs the interpolation result of the transmission source position until the transmission source position is selected at time _t3 when the location index reaches the minimum value next time as the final output of the transmission source position (step S7).

At time _t3 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has reached a minimum value (step S4, YES). Therefore, the location selection unit 22 selects the located transmission source position (black circle at time _t3 in FIG. 5) (step S6). Then, the location prediction unit 23 calculates the direction of the transmission source position predicted to be selected at time _t4 when the location index reaches a minimum value next time (the direction _of the white circle at time t4 in FIG. 5) by extrapolating the line segment connecting the transmission source positions selected at time t2 and time _t3 from the transmission source position predicted to be selected at time _t3 (step S6). Furthermore, the location output unit 24 sets the direction of the transmission source position predicted to be selected at time _t4 when the location index reaches a minimum value next _time (the direction of the white circle at time _t4 in FIG. 5) as the final output of the transmission source position (step S7).

From time _t3 to time _t4 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has not reached the minimum value (step S4, NO). Therefore, the location selection unit 22 does not select the located transmission source position (step S5). Then, the location prediction unit 23 interpolates _the transmission source position until the transmission source position is selected at time _t4 when the location index reaches the minimum value next time based on the length and direction of the line segment connecting the transmission source positions selected at time _t2 and time t3 (step S5). Furthermore, the location output unit 24 outputs the interpolation result of the transmission source position until the transmission source position is selected at time _t4 when the location index reaches the minimum value next time as the final output of the transmission source position (step S7).

At time _t4 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has reached the minimum value (step S4, YES). Therefore, the location selection unit 22 selects the located transmission source position (black circle at time _t4 in FIG. 5) (step S6). Then, the location prediction unit 23 calculates the direction of the transmission source position predicted to be selected at time _t5 when the location index reaches the minimum _value next time (the direction of the white circle at time t5 in FIG. ₅ ) by extrapolating the line segment connecting the transmission source position predicted to be selected at time t3 and the transmission source position selected at time _t4 from the transmission source position predicted to be selected at time _t4 (step S6). Furthermore, the location output unit 24 sets the direction of the transmission source position predicted to be selected at time _t5 when the location index reaches the minimum value next time (the direction of the white circle at time _t5 in FIG. 5) as the final output of the transmission source position (step S7).

From time _t4 to time _t5 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S2, YES) and has not reached the minimum value (step S4, NO). Therefore, the location selection unit 22 does not select the located transmission source position (step S5). Then, the location prediction unit 23 interpolates the transmission source position until the transmission source position is selected at time _t5 when the location index reaches the minimum value next time based on the length and direction of the line segment connecting the transmission source position predicted to be selected at time _t3 and the transmission source position selected at time _t4 (step S5). Furthermore, the location output unit 24 outputs the interpolation result of the transmission source position until the transmission source position is selected at time _t5 when the location index reaches the minimum value next time as the final output of the transmission source position (step S7).

Even if the variance value (location index) of the located transmission source position temporarily becomes larger than the specified variance value, the final output position can move smoothly and not deviate significantly from the true position, based on the predicted movement direction and movement speed of the transmission source when the variance value (location index) of the located transmission source position was previously smaller than the specified variance value.

(Second position location process of the present disclosure)
The procedure and contents of the second position location process of the present disclosure are shown in Fig. 6 and Fig. 7. The position selection unit 22 selects the position of the located transmission source when the variance value (location index) of the located transmission source position becomes smaller than a predetermined variance value for the first time, and each time a predetermined time interval has elapsed thereafter (the location index is usually small). Here, a small variance value (location index) of the located transmission source position is an indication that the located transmission source position is close to the true position of the transmission source.

The position prediction unit 23 calculates the moving direction and moving speed of the transmission source from the past to the present based on the position of the selected transmission source, and predicts the moving direction and moving speed of the transmission source from the present to the future. Then, when predicting the position of the transmission source from the present to the future based on the moving direction and moving speed of the transmission source from the present to the future and providing the final output, the predicted positions of the transmission source are linearly and continuously connected through the position location process. This is explained in detail below.

The positioning unit 21 locates _the position of the transmission _source so that the actual measured value of the arrival direction of the received wave from the transmission source coincides with the predicted value of the arrival direction of the received wave from the transmission source (calculated based on the position of the mobile body equipped with the positioning system P and the previous located position of the transmission source) at equal time intervals from before time t1 to after time t4 (step S11).

Before time _t1 , the variance value (location index) of the located transmission source position is still greater than the predetermined variance value after the start of location of the transmission source position (step S12, NO). Therefore, the position selection unit 22 selects the located transmission source position as it is, like a Kalman filter, etc. (step S13). Then, the position output unit 24 sets the located transmission source position as the final output of the transmission source position (step S19).

At time _t1 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value for the first time after the start of location of the transmission source position (step S12, YES), and the position prediction process has not started (step S14, NO). Therefore, the position selection unit 22 selects the located transmission source position (black circle at time _t1 in FIG. 7) (step S15). Then, the position output unit 24 sets the located transmission source position (black circle at time _t1 in FIG. 7) as the final output of the transmission source position (step S19).

From time _t1 to time _t2 , the variance value (location index) of the located transmission source position is smaller than a predetermined variance value (step S12, YES), the position prediction process is started (step S14, YES), and a predetermined time interval (longer than the location location interval) has not elapsed since time _t1 (step S16, NO). Therefore, the position selection unit 22 selects the located transmission source position as it is, similar to the Kalman filter, etc. (step S17). Then, the position output unit 24 sets the located transmission source position as the final output of the transmission source position (step S19).

At time _t2 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process is started (step S14, YES), and a predetermined time interval (longer than the location location interval) has passed since time _t1 (step S16, YES). Therefore, the position selection unit 22 selects the located transmission source position (black circle at time _t2 in FIG. 7) (step S18). Then, the position prediction unit 23 calculates the transmission source position (white circle at time _t3 in FIG. ₇ ) predicted to be selected at the next time when the predetermined time interval has passed by extrapolating the line segment connecting the transmission source positions selected at time _t1 and time _t2 from the transmission source position selected at time _t2 (step S18). Furthermore, the position output unit 24 outputs the position of the transmission source predicted to be selected at the next time _t3 when the predetermined time interval has elapsed (the white circle at time _t3 in FIG. 7) as the final output of the position of the transmission source (step S19).

From time _t2 to time _t3 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process has started (step S14, YES), and a predetermined time interval (longer than the location location interval) has not elapsed _since time _t2 (step S16, NO). Therefore, the position selection unit 22 does not select the located transmission source position (step S17). Then, the position prediction unit 23 interpolates the transmission source position until the transmission source position is selected at time _t3 when the predetermined time interval elapses next time based on the length and direction of the line segment connecting the transmission source positions selected at time _t1 and time t2 (step S17). Furthermore, the position output unit 24 sets the interpolation result of the transmission source position until the transmission source position is selected at time _t3 when the predetermined time interval elapses next time as the final output of the transmission source position (step S19).

At time _t3 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process is started (step S14, YES), and a predetermined time interval (longer than the location location interval) has passed since time _t2 (step S16, YES). Therefore, the position selection unit 22 selects the located transmission source position (black circle at time _t3 in FIG. 7) (step S18). Then, the position prediction unit 23 calculates _the transmission source position predicted to be selected at time _t4 when the next predetermined time interval has passed (white circle at time _t4 in FIG. 7) by extrapolating the line segment connecting the transmission source positions selected at time _t2 and time _t3 from the transmission source position predicted to be selected at time t3 (step S18). Furthermore, the position output unit 24 outputs the position of the transmission source predicted to be selected at the next time _t4 when the predetermined time interval has elapsed (the white circle at time _t4 in FIG. 7) as the final output of the position of the transmission source (step S19).

From time _t3 to time _t4 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process has started (step S14, YES), and a predetermined time interval (longer than the location location interval) has not elapsed _since time _t3 (step S16, NO). Therefore, the position selection unit 22 does not select the located transmission source position (step S17). Then, the position prediction unit 23 interpolates the transmission source position until the transmission source position is selected at time _t4 when the next predetermined time interval has elapsed based on the length and direction of the line segment connecting the transmission source positions selected at time _t2 and time t3 (step S17). Furthermore, the position output unit 24 sets the interpolation result of the transmission source position until the transmission source position is selected at time _t4 when the next predetermined time interval has elapsed as the final output of the transmission source position (step S19).

At time _t4 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process is started (step S14, YES), and a predetermined time interval (longer than the location location interval) has passed since time _t3 (step S16, YES). Therefore, the position selection unit 22 selects the located transmission source position (black circle at time _t4 in FIG. 7) (step S18). Then, the position prediction unit 23 calculates the transmission source position predicted to be selected at time _t5 when the next predetermined time interval has passed (white circle at time t5 in FIG _. 7) by extrapolating the line segment connecting the transmission source position predicted to be selected at time _t3 and the transmission source position selected at time _t4 from the transmission source position predicted to be selected at time _t4 (step S18). Furthermore, the position output unit 24 outputs the position of the transmission source predicted to be selected at the next time _t5 when the predetermined time interval has elapsed (white circle at time _t5 in FIG. 7) as the final output of the position of the transmission source (step S19).

From time _t4 to time _t5 , the variance value (location index) of the located transmission source position is smaller than the predetermined variance value (step S12, YES), the position prediction process has started (step S14, YES), and a predetermined time interval (longer than the location location interval) has not elapsed since time _t4 (step S16, NO). Therefore, the position selection unit 22 does not select the located transmission source position (step S17). Then, the position prediction unit 23 interpolates the transmission source position until the transmission source position is selected at time _t5 when the next predetermined time interval has elapsed based on the length and direction of the line segment connecting the transmission source position predicted to be selected at time _t3 and the transmission source position selected at time _t4 (step S17). Furthermore, the position output unit 24 sets the interpolation result of the transmission source position until the transmission source position is selected at time _t5 when the next predetermined time interval has elapsed as the final output of the transmission source position (step S19).

Even if the variance value (location index) of the located transmission source position temporarily becomes larger than the specified variance value, the final output position can move smoothly and not deviate significantly from the true position based on the predicted movement direction and movement speed of the transmission source when the variance value (location index) of the located transmission source position was previously smaller than the specified variance value.

Alternatively, even if the variance value (location index) of the located transmission source position temporarily becomes larger than a predetermined variance value, it is possible to finally output an output position that moves smoothly and does not deviate significantly from the true position based on the calculation results of the movement direction and movement speed of the transmission source until the variance value (location index) of the transmission source position transitions from a state smaller than the predetermined variance value to a state larger than the predetermined variance value.

When the variance value (location index) of the located transmission source position again becomes smaller than the predetermined variance value, an output position that moves smoothly and does not deviate significantly from the true position can be finally output based on the calculation results of the movement direction and movement speed of the transmission source after the variance value (location index) of the transmission source position transitions from a state larger than the predetermined variance value to a state smaller than the predetermined variance value.

(Model Update Process of the Present Disclosure)
An overview of the model updating process of the present disclosure is shown in Fig. 8. The model updating unit 25 updates a transmission source motion model (such as a fixed point model or a linear motion model) for locating the position of the transmission source based on the position of the transmission source finally output by the position output unit 24.

On the left side of Fig. 8, the position output unit 24 finally outputs the output positions of the transmission source at times _t1 to _t4 based on a fixed point model as the transmission source motion model before the update. Then, the model update unit 25 constructs a linear motion model as the updated transmission source motion model based on the output positions of the transmission source at times _t1 to _t4 . On the right side of Fig. 8, the position output unit 24 finally outputs the output positions of the transmission source at times _t4 to _t7 based on a linear motion model as the updated transmission source motion model. Then, the model update unit 25 constructs a new linear motion model as the further updated transmission source motion model based on the output positions of the transmission source at times _t4 to _t7 .

The model update unit 25 can update the transmission source motion model every time or every few times when the variance value (location index) of the located transmission source position reaches a minimum value. The model update unit 25 can also update the transmission source motion model every time or every few times when a predetermined time interval has elapsed after the variance value (location index) of the located transmission source position becomes smaller than a predetermined variance value for the first time.

In this way, by updating the transmission source motion model for locating the position of the transmission source when the true position of the transmission source moves, the output error between the output position of the transmission source and the true position of the transmission source can be reduced. Furthermore, by linearly and continuously connecting the predicted positions of the transmission source when the mobile body equipped with the position location system P changes its attitude, etc., the output error between the output position of the transmission source and the true position of the transmission source can be reduced.

The improvement of the model update process of the present disclosure is shown in FIG. 9. The model update unit 25 starts applying the updated transmission source motion model (e.g., linear motion model) before the position of the transmission source located using the transmission source motion model before the update (e.g., fixed point model) converges to a predetermined degree.

In the left column of FIG. 9, the model update unit 25 further sequentially applies the transmission source motion models before and after the update, and starts to adopt the transmission source position finally output using the updated transmission source motion model in place of the transmission source position finally output using the transmission source motion model before the update, before the transmission source position determined using the transmission source motion model before the update converges to a predetermined degree.

In this way, by starting to apply the updated transmission source motion model before complete convergence based on the transmission source motion model before the update, it is possible to avoid delaying the start of application of the updated transmission source motion model, and since the number of data points for the output positions based on the transmission source motion model before the update is sufficient, the construction accuracy of the updated transmission source motion model can be improved.

In the right column of FIG. 9, the model update unit 25 further applies the transmission source motion models before and after the update in parallel, and after the position of the transmission source located using the updated transmission source motion model converges to a predetermined degree, starts to adopt the position of the transmission source finally output using the updated transmission source motion model instead of the position of the transmission source finally output using the transmission source motion model before the update.

In this way, after complete convergence based on the updated transmission source motion model, application of the pre-update transmission source motion model is terminated and switching to the updated transmission source motion model is performed, thereby effectively increasing the variance value of the located transmission source position again and allowing the position location process to continue to high-precision processing based on the updated transmission source motion model.

The steps of the model update process of the present disclosure are shown in Figures 10 and 11. Below, the model update process shown in the right column of Figure 9 will be described. However, the model update process shown in the left column of Figure 9 is also included in the present disclosure. This is because the model update process shown in the left column of Figure 9 also exhibits superior effects compared to conventional technology, just like the model update process shown in the right column of Figure 9.

The model application start process will be described with reference to FIG. 10. The model update unit 25 causes the position location unit 21 to start applying the first motion model (step S21). Here, the motion direction and speed of the transmission source have not yet been determined, and the first motion model is a fixed point model. Then, the model update unit 25 determines whether the first location has converged to a degree that does not completely converge (step S22). Here, when the model update unit 25 determines NO in step S22, it stops the model application start process for a while until it determines YES in step S22.

On the other hand, when the model update unit 25 judges YES in step S22, it constructs a second motion model based on the first final output position (step S23). Here, the motion direction and speed of the transmission source have been determined, and the second motion model is a linear motion model (or a curved motion model). Then, the model update unit 25 causes the position location unit 21 to start applying the second motion model (step S24). Then, the model update unit 25 judges whether the second location has converged to a degree that does not converge completely (step S25). Here, when the model update unit 25 judges NO in step S25, it stops the model application start process for a while until it judges YES in step S25.

On the other hand, when the model update unit 25 judges YES in step S25, it constructs a third motion model based on the second final output position (step S26). Here, the motion direction and speed of the transmission source have been determined, and the third motion model is a linear motion model (or a curved motion model). Then, the model update unit 25 causes the position location unit 21 to start applying the third motion model (step S27). Then, the model update unit 25 judges whether the third location position has converged to an extent that it does not converge completely (step S28). Here, when the model update unit 25 judges NO in step S28, it stops the model application start processing for a while until it judges YES in step S28. For the fourth and subsequent motion models, the model application start processing is executed in the same manner as for the first to third motion models.

In FIG. 11, the position adoption start process will be described. The model update unit 25 starts adopting the first final output position (step S31). Then, the model update unit 25 judges whether the second location position has converged to a degree that completely converges (step S32). Here, when the model update unit 25 judges NO in step S32, it stops the position adoption start process for a while until it judges YES in step S32. On the other hand, when the model update unit 25 judges YES in step S32, it judges whether the second final output position is almost the same as the first final output position (step S33). Here, when the model update unit 25 judges YES in step S33, it starts adopting the second final output position instead of the first final output position (step S34). On the other hand, if the model update unit 25 determines NO in step S33, it discards the second final output position and continues to adopt the first final output position so that there is no jump in the adopted position (step S35).

The case where step S34 is executed will be described. The model update unit 25 judges whether the third location position has converged to a degree where it is completely converged (step S36). Here, when the model update unit 25 judges NO in step S36, it stops the position adoption start processing for a while until it judges YES in step S36. On the other hand, when the model update unit 25 judges YES in step S36, it judges whether the third final output position is almost the same as the second final output position (step S37). Here, when the model update unit 25 judges YES in step S37, it starts adopting the third final output position instead of the second final output position (step S38). On the other hand, when the model update unit 25 judges NO in step S37, it discards the third final output position so that there is no jump in the adopted position, and continues adopting the second final output position (step S39).

The case where step S35 is executed will be described. The model update unit 25 determines whether the third location position has converged to a degree where it is completely converged (step S40). Here, when the model update unit 25 determines NO in step S40, it stops the position adoption start process for a while until it determines YES in step S40. On the other hand, when the model update unit 25 determines YES in step S40, it determines whether the third final output position is almost the same as the first final output position (step S41). Here, when the model update unit 25 determines YES in step S41, it starts adopting the third final output position instead of the first final output position (step S42). On the other hand, when the model update unit 25 determines NO in step S41, it discards the third final output position so that there is no jump in the adopted position, and continues adopting the first final output position (step S43). For the fourth and subsequent motion models, the position adoption start process is executed in the same way as for the first to third motion models.

The solution to the movement of the true position of the transmitting source according to the present disclosure is shown in FIG. 12. In FIG. 12, the true position of the transmitting source moves as in FIG. 1. First, the true position of the transmitting source is treated as a fixed point because data on the movement of the transmitting source cannot be obtained. However, in the initial stage of location where the location index of the transmitting source is large, the amount of correction of the location position of the transmitting source from the previous value to the current value can be increased, so the output position of the transmitting source can be made to follow the true position of the moving transmitting source. Finally, the true position of the transmitting source is treated as a moving point because data on the movement of the transmitting source can be obtained. Then, in the position convergence stage where the location index of the transmitting source is small, even if the amount of correction of the location position of the transmitting source from the previous value to the current value cannot be increased, the output position of the transmitting source can be made to follow the true position of the moving transmitting source. Therefore, even when the true position of the transmitting source moves for a long time, no output error occurs between the output position of the transmitting source and the true position of the moving transmitting source.

The solution to the disturbance in the direction of arrival of the received wave of the present disclosure is shown in FIG. 13. In FIG. 13, as in FIG. 2, the true position of the transmission source does not move. First, in the initial stage (mobile body position (1)) in which the moving body moves almost linearly, there is no disturbance in the direction of arrival of the received wave between the transmission source and the moving body, so the output position of the transmission source can be fixed in the vicinity of the true position of the non-moving transmission source (output position of (1)). Then, in the middle stage (mobile body position (2)) in which the moving body turns 180°, blinds, etc. occur due to the relationship between the posture of the transmission source and the moving body, and disturbance occurs in the direction of arrival of the received wave between the transmission source and the moving body, but in order to optimize the motion model, the output position of the transmission source can be fixed in the vicinity of the true position of the non-moving transmission source (output position of (2)). Finally, in the final stage (mobile body position (3)) when the mobile body moves in a straight line again, there is no disturbance in the direction of arrival of the received wave between the transmission source and the mobile body, so the output position of the transmission source can be fixed near the true position of the stationary transmission source (output position (3)). Therefore, even when the direction of arrival is disturbed, no output error occurs between the output position of the transmission source and the true position of the stationary transmission source (or the true position of a moving transmission source) in any of the initial, middle, and final stages.

The transmitter position locating device and transmitter position locating program disclosed herein can reduce the location error between the location of the transmitter and the true position of the transmitter when the true position of the transmitter moves or when the attitude of a mobile body equipped with a position locating system changes.

P: Positioning system 1: Direction of arrival measuring device 2: Source positioning device 21: Positioning section 22: Position selection section 23: Position prediction section 24: Position output section 25: Model update section

Claims (5)

a position locating unit that locates the position of the transmission source so that an actual measurement value of the arrival direction of the received wave from the transmission source coincides with a predicted value of the arrival direction of the received wave from the transmission source;
a position selection unit that selects the located position of the transmission source every time a variance value of the located position of the transmission source reaches a minimum value after starting the location of the position of the transmission source;
a position prediction unit that calculates a direction of the position of the transmission source predicted to be selected next by extrapolating a line segment connecting the position of the transmission source predicted to be previously selected and the position of the transmission source selected currently from the position of the transmission source predicted to be selected currently, and that interpolates the positions of the transmission source until the position of the transmission source is selected next time;
a position output unit that outputs, as a final output of the position of the transmission source, a calculation result of the direction of the position of the transmission source predicted to be selected each time and an interpolation result of the position of the transmission source until the position of the transmission source is selected each time;
a model updating unit that updates a transmission source motion model for locating the position of the transmission source based on the position of the transmission source finally output by the position output unit;
A transmission source position locating device comprising: a position locating unit that locates the position of the transmission source so that an actual measurement value of the arrival direction of the received wave from the transmission source coincides with a predicted value of the arrival direction of the received wave from the transmission source;
a location selection unit that selects the location of the transmission source when a variance value of the location of the transmission source becomes smaller than a predetermined variance value for the first time after the start of location of the location of the transmission source, and each time a predetermined time interval has elapsed thereafter;
a position prediction unit that calculates a position of the transmission source predicted to be selected next time by extrapolating a line segment connecting a position of the transmission source predicted to be previously selected and a position of the transmission source selected currently from the position of the transmission source predicted to be selected currently, and that interpolates the positions of the transmission source until the position of the transmission source is selected next time;
a position output unit that outputs a calculation result of the position of the transmission source predicted to be selected each time and an interpolation result of the position of the transmission source until the position of the transmission source is selected each time as a final output of the position of the transmission source;
a model updating unit that updates a transmission source motion model for locating the position of the transmission source based on the position of the transmission source finally output by the position output unit;
A transmission source position locating device comprising: The transmission source position locating device according to claim 1 or 2, characterized in that the model update unit starts applying the updated transmission source motion model before the position of the transmission source located using the transmission source motion model before the update converges to a predetermined degree. The transmission source position locating device of claim 3, characterized in that the model update unit applies the transmission source motion model before and after the update in parallel, and after the position of the transmission source located using the updated transmission source motion model converges to the predetermined degree, starts to adopt the position of the transmission source finally output using the updated transmission source motion model instead of the position of the transmission source finally output using the transmission source motion model before the update. a position locating step of locating a position of the transmitting source such that an actual measured value of an arrival direction of a received wave from the transmitting source coincides with a predicted value of an arrival direction of the received wave from the transmitting source;
a position selection step of selecting the located position of the transmitting source each time a variance value of the located position of the transmitting source reaches a minimum value after starting the location of the position of the transmitting source;
a position prediction step of calculating a direction of the position of the transmission source predicted to be selected next time by extrapolating a line segment connecting the position of the transmission source predicted to be previously selected and the position of the transmission source selected currently from the position of the transmission source predicted to be selected currently, and interpolating the positions of the transmission source until the position of the transmission source is selected next time;
a position output step of outputting the calculated direction of the position of the transmitting source predicted to be selected each time and the interpolated result of the position of the transmitting source until the position of the transmitting source is selected each time as a final output of the position of the transmitting source;
a model updating step of updating a transmission source motion model for locating the position of the transmission source based on the position of the transmission source finally output in the position output step;
A transmission source location program for causing a computer to execute the above steps in sequence.

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