JP2797681B2 - Position detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for detecting a current position of a moving object such as a vehicle.

<Conventional technology> Conventionally, a display device such as a CRT or the like displays the current position of a vehicle together with a road map in order to assist in reaching a destination when traveling in an unfamiliar area by a vehicle or when driving at night. The navigation device is displayed on a vehicle and used. For the detection of the current position of the vehicle, so-called dead reckoning which calculates an estimated position of the vehicle based on each output of a distance sensor such as a vehicle speed sensor and a direction sensor such as a geomagnetic sensor or a gyro, or the above-mentioned dead reckoning calculated by this dead reckoning A map matching method that performs a comparison operation between a GPS estimating device and a road map has been applied, but recently, positioning technology using radio waves from a GPS (global positioning system) satellite has been used as a navigation device for vehicles. It is also being applied to.

This positioning technology using GPS satellites is a technology for performing positioning by measuring the propagation delay time of radio waves generated by artificial satellites orbiting in a predetermined orbit, and receives radio waves from four different satellites. Thus, three-dimensional positioning is possible, and if radio waves from three different satellites can be received, two-dimensional positioning is possible. In the detection of the current position of the vehicle, the above-described two-dimensional positioning is generally applied since the position can be detected using the altitude of the vehicle as a known amount.

As is well known, positioning by radio waves that are open to civilian use among radio waves generated from GPS satellites is intentionally deteriorated in accuracy for reasons of U.S. national defense,
An error of about several tens of meters occurs. Therefore, in order to reduce this error, the positioning result obtained by the radio wave from the satellite and the previous positioning data are averaged, this average value is used as the current positioning data, and the positioning error is calculated by the average value calculation. It has been proposed to reduce it.

That is, when the vehicle travels along the locus L1 shown in FIG. 4, the position coordinates s1 to s7 obtained from the propagation delay time of the radio wave from the satellite indicated by “x” are not used as the positioning data as they are, For example, the previous positioning data D0 and position coordinates s1
And the average value of this positioning data D1 and the next position coordinate s2 as the positioning data D2, and the average value of the positioning data D2 and the position coordinate s3 as the new positioning data. D3. Similarly, an average value is calculated for the position coordinates s4 to s7 obtained from the propagation delay time, and positioning data D4 to D7 are calculated. The positioning data D1 to D7 thus obtained are used as data representing the current position of the vehicle, and the display device displays the current position of the vehicle on the basis of the positioning data D1 to D7.

<Problems to be Solved by the Invention> However, in order to enable positioning using GPS satellites, radio waves from three satellites must be received simultaneously as described above, so that high-rise buildings and tunnels There is a possibility that positioning cannot be performed while the vehicle is traveling. If the period during which positioning is impossible continues for a long time, the above-mentioned position coordinates obtained in a state where positioning can be performed thereafter and the latest positioning data may greatly differ from each other. In this case, a larger error is caused than when the average value calculation is not performed. In such a case, even if the positioning can be performed, a large positioning error occurs due to the adverse effect of the above average value calculation.

Therefore, an object of the present invention is to solve the above-described technical problem and to provide a position detection device capable of reliably obtaining highly accurate positioning data.

<Means for Solving the Problems> A position detecting device of the present invention for achieving the above object is mounted on a moving body and detects a position of the moving body based on radio waves radiated from an artificial satellite. A detecting device, comprising: detecting means for detecting a position of the moving body from a propagation delay time of radio waves from the artificial satellite; and positioning data creating means for performing an average value calculation on an output of the detecting means to obtain positioning data. And if the position detection by the detection means cannot be continuously performed over a first predetermined time and the position detection by the detection means can be continuously performed over a second predetermined time thereafter, The output of the positioning data from the positioning data creating means is prohibited during the second predetermined time period, and the output of the positioning data from the positioning data creating means is disabled after the lapse of the second predetermined time period. And means for permitting.

<Operation> According to the above configuration, the detecting means detects the position of the moving object from the propagation delay time of the radio wave from the artificial satellite, and the result of this detection is subjected to an average value calculation by the positioning data creating means, thereby obtaining an error. Is obtained with reduced positioning data.

If position detection by the detecting means cannot be performed continuously for the first predetermined time due to deterioration of the reception condition of the radio wave from the artificial satellite, even if the position detection by the detecting means becomes possible thereafter, The output of the positioning data from the positioning data generating means is not permitted unless the state in which the position detection is possible continues for the second predetermined time.

This is because when a long time elapses after the position detection by the detection means cannot be performed and the state returns to the state where the position detection can be performed by the detection means thereafter, the positioning data generation means performs processing on the data which is greatly separated in time. This is because the average value calculation is performed, and thus it is impossible to output accurate positioning data for a while. On the other hand, at the point in time when the second predetermined time has elapsed after returning to the state where the position detection by the detection means is possible, the output of the detection means after the return is replaced with the positioning data output by the positioning data creation means. Since it is largely reflected, accurate positioning data can be obtained, and output of this accurate positioning data is allowed.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a basic configuration of a navigation device to which a position detecting device according to one embodiment of the present invention is applied. This navigation device is used by being mounted on a vehicle which is a moving body, and displays a current position of the vehicle on a display unit 1 constituted by a CRT or the like together with a road map read from a map memory 2 constituted by a CD-ROM or the like. This is displayed. The detection of the current position of the vehicle is performed using GPS satellites 11, 12, and 13, taking into account cases such as when traveling in high-rise buildings or in tunnels where radio waves cannot be received. So-called dead reckoning navigation is also used.

The detection of the position of the vehicle by dead reckoning is based on the outputs of a distance sensor 3 such as a vehicle speed sensor, an azimuth sensor 4 such as a magnetic sensor, and a turning angle sensor 5 for detecting the turning angle of the vehicle. The detection is performed by the detection unit 6 so as to integrate the movement amount of the vehicle. The self-contained position detecting section 6 also calculates the position by the dead reckoning navigation method described above in order to prevent the accumulation of errors that each of the sensors 3, 4, and 5 inevitably has and to enable highly accurate position detection. Estimated position,
The current position of the vehicle is detected using a so-called map matching method for performing a comparison operation with a road map read from the map memory 2 via the memory driver 8.

To detect the position of the vehicle using radio waves from the GPS satellites 11 to 13, the radio waves from the satellites 11 to 13 are received by the antenna 14, and the propagation delay time of the received radio waves is detected by the detection unit 2 of the GPS receiver 15.
The detection is performed in step 1. The detecting unit 21 calculates the position coordinates of the vehicle from the above propagation delay time, and gives the position coordinates to the positioning data creating unit 22. The positioning data creation unit 22 performs an average value calculation on the position coordinates provided from the detection unit 21 to create positioning data.

The average value calculation is the same as the calculation shown in FIG. 4 described above. The average value calculation is performed by averaging the previous positioning data and the position coordinates given from the detection unit 21 to obtain the current positioning data. is there. As a result of such a calculation, for example, the output of the current detection unit 21 contributes only 1/2 to the current positioning data, the output of the previous detection unit 21 contributes 1/4 to the current positioning data, and The output of the detection unit 21 is 1 /
8 will be contributed. By this average value calculation, positioning data with reduced errors in the position coordinates detected by the detection unit 21 can be obtained.

Positioning based on radio waves from GPS satellites is possible only when radio waves from three satellites can be received simultaneously.
A state where only radio waves from less than or equal to (including 0) satellites can be received (hereinafter, such a state is referred to as a “severed state”)
If positioning is not possible, the detection unit
21 does not output the position coordinates, and therefore, the positioning data creation unit 22 does not output the positioning data.

The positioning data created as described above is
To the position detection control unit 24 of the position detection unit 16. The position detection control unit 24 provides the display control unit 7 with one of the estimated position data from the self-contained position detection unit 6 and the above-described positioning data as position data that gives the current position of the vehicle.

The display control unit 7 causes the display unit 1 to display the current position of the vehicle together with the road map read from the map memory 2 via the memory driver 8 based on the given position data.
An input unit 9 includes key input means and the like, and is used for scrolling a road map displayed on the display unit 1 and selecting various functions.

The position detection unit 16 is supplied with a reception state signal indicating whether or not the above-mentioned disconnection state is present via a line 25 from the detection unit 21 of the GPS receiver 15. The reception state signal is received by the reception unit 26, and the reception unit 26 controls a continuous reception counter 27 that measures the continuous time of the position in which positioning is possible, and a positioning impossible counter 28 that measures the continuous time of the disconnected state. . That is,
When the reception state signal from the line 25 indicates the disconnection state, a signal for causing the line 30 to increment the count value C1 of the positioning impossible counter 28 and clear the continuous reception counter 27 is derived. On the other hand, when the reception status signal from the line 25 indicates that the connection is not in the disconnected state, the count value C2 of the continuous reception counter 27 is incremented, and a signal for clearing the positioning impossible counter 28 is derived to the line 29.

The count values C2 and C1 of the continuous reception counter 27 and the positioning impossible counter 28 are given to the position detection control unit 24. The position detection control unit 24 determines that the disconnection state has occurred when the count value C1 of the positioning impossible counter 28 exceeds a predetermined value k1 corresponding to a first predetermined time ΔT1 (for example, 30 seconds),
During the disconnected state, the estimated position data from the self-contained position detection unit 6 is provided to the display control unit 7. Further, by returning from the disconnected state to the state where positioning is possible, the counting operation of the continuous reception counter 27 is started, and the count value C2 of the continuous reception counter 27 is changed to the second predetermined time ΔT2 (for example, 5 seconds). Also, the estimated position data from the self-contained position detecting unit 6 is employed in a period until the predetermined value k2 or more corresponding to is obtained. Then, when the count value C2 of the continuous reception counter 237 is equal to or more than the predetermined value k2, the positioning data from the line 23 is adopted, and this positioning data is given to the display control unit 7 as position data.

The operation of the position detector 16 is shown in more detail in the flowchart of FIG. That is, with the power-on, in step n0, the disconnection flag F1 for determining whether to use the estimated position data from the self-contained position detection unit 6 or the positioning data from the GPS receiver 15 is set. After that, in step n1, the receiving unit 26
It is determined whether the reception state signal from 25 indicates the disconnection state. In the disconnected state, the continuous reception counter 27 is cleared by the signal derived from the reception unit 26 to the line 29 in step n2, and the count value C1 of the positioning impossible counter 28 is incremented in step n3.

In step n4, the position detection control unit 24 determines whether the count value C1 of the positioning impossible counter 28 is equal to or greater than the predetermined value k1, and when the count value C1 is equal to or greater than the predetermined value k1,
In step n5, the disconnection flag 1 indicating the insulated state is set, and the process proceeds to step n6. Positioning impossible counter 28
When the count value C1 is less than the predetermined value k1, the disconnection flag
Proceed to step n6 without setting F1.

In step n6, the position detection control unit 24 sets the disconnection flag F1
Is determined, and when it is set, the estimated position data from the self-contained position detector 6 is adopted and given to the display controller 7 in step n7. On the other hand, when the disconnection flag F1 is reset, the positioning data provided from the GPF receiver 15 is adopted in step n8, and is provided to the display control unit 7 as position data. The subsequent operation returns to step n1.

If it is determined in step n1 that it is not in the disconnected state, the receiving unit
In step n9, the count value C2 of the continuous reception counter 27 is incremented by a signal derived from the line 30 to the line 30, and the positioning impossible counter 28 is cleared in step n10.

In step n11, the position detection control unit 24 determines whether or not the count value C2 of the continuous reception counter 27 is equal to or greater than the predetermined value k2.If the count value C2 is equal to or greater than the predetermined value k2, the disconnection flag F1 is reset in step n12. And proceed to step n6. When the count value C2 is less than the predetermined value k2, the disconnection flag
Proceed to step n6 without resetting F1.

By the above-described processing, the disconnection flag F1 is first reset when positioning by radio waves from the GPS satellites 11 to 13 can be continuously performed for a second predetermined time ΔT2 after the power is turned on. Therefore, during the period up to that time, the current position of the vehicle is obtained by dead reckoning navigation and the map matching method. Further, the disconnection flag F1 is set when the disconnection state continues for the first predetermined time ΔT1, and after returning from the insulating state to the state where positioning can be performed, the GPS satellite is set for the second predetermined time ΔT2. Reset when positioning by radio waves from 11 to 13 is possible. Therefore, when the disconnected state continues for the predetermined time ΔT1, position detection is performed by dead reckoning navigation and the map matching method, and the positioning is continuously performed for the predetermined time ΔT2 even after returning to the state where positioning is possible. Only after the possible states continue, the positioning data from the GPS receiver 15 is adopted.

For example, as shown in FIG. 3, a vehicle equipped with the navigation device moves from a start point q0 to a tunnel 41.
It is assumed that the vehicle travels along a route l1 passing through the route. At the start point q0, the operator operates the input unit 9 while the road map is displayed on the display unit 1, and inputs the position of the start point q0. The input of the start point q0 does not always have to be performed.

If the vehicle is started before the predetermined time ΔT2 elapses after the power is turned on, since the disconnection flag F1 is set, the position coordinates of the start point q0 are not changed until the flag F1 is reset. Based on the dead reckoning navigation, the current position is detected.

For example, if the above-mentioned predetermined time ΔT2 elapses after the power is turned on at the point q1, and it is possible to perform positioning by radio waves from the three GPS satellites 11 to 13 during this period, instead of the estimated position data by dead reckoning, etc. Then, the positioning data from the GPS receiver 15 is adopted. The positioning data adopted at this point q1 is data obtained by performing an average value calculation for a predetermined period ΔT2 on the position coordinates detected by the detecting unit 21 of the GPS receiver 15 in the positioning data creating unit 22, This positioning data does not include a large error.

When the vehicle travels along the route l1 and enters the tunnel 41, the radio waves from the satellites 11 to 13 cannot be received.
In 21, the position coordinates cannot be detected. If this state continues for the predetermined time ΔT1, the disconnection flag F1
Is set, and the estimated position data from the self-contained position detection unit 6 is adopted. The estimated position data in the self-contained position detection unit 6 is calibrated as needed based on the positioning data from the GPS receiver 15, so that errors in the distance sensor 3, the direction sensor 4, and the like are not excessively accumulated. Since the amount of movement of the vehicle can be actually detected by the self-contained position detection unit 6, it is necessary to provide an initial coordinate position for position detection. It may be provided by data, or may be provided by input from the input unit 9 as described above.

When the disconnection flag F1 is set by traveling in the tunnel 41, the positioning data from the GPS receiver 15 is not adopted during the period of the above-described predetermined time ΔT2 even after leaving the tunnel 41,
Estimated position data based on dead reckoning is adopted. After exiting tunnel 4, the GP
For the first time at the point q2 where it is detected that the state where positioning is possible in the detection unit 21 of the S receiver 15 has been detected, the GPS receiver 1
Positioning data from 5 is adopted.

The output of the positioning data creation unit 22 immediately after leaving the tunnel 41 is an average value of the positioning data created before entering the tunnel 41 and the output of the detection unit 21 at the time of exiting the tunnel 41, and the average value calculation is performed. Therefore, it contains a large error. This error is reduced as the positioning in the detecting unit 21 is performed a plurality of times after leaving the tunnel 41 and the contribution of the output of the detecting unit 21 during the period after leaving the tunnel 41 to the positioning data increases. In the present embodiment, the positioning data from the GPS receiver 15 is not used during the predetermined time ΔT2 during which the positioning data including a large error is output even after exiting the tunnel 41. Is not given.

Similar processing is performed not only when traveling through the tunnel 41 but also when radio waves from three satellites cannot be received, such as in a high-rise building.

As described above, according to the navigation device described above, when the positioning data output by the GPS receiver 15 includes a large error due to deterioration of the reception state, the positioning data is not adopted, and dead reckoning and The estimated position data obtained by the map matching method is adopted. Therefore, of the positioning data from the GPS receiver 15, only high-precision positioning data is adopted. This allows
In any period, the position of the vehicle can be detected with a high degree of accuracy, and the traveling of the vehicle by the navigation device can be significantly improved.

Note that the present invention is not limited to the above embodiment. For example, the average value calculation in the positioning data creation unit 22 is not limited to the above, and for example, a moving average of several continuously detected position coordinates may be obtained. Various other design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, according to the position detection device of the present invention, positioning can be performed when positioning cannot be performed by the detection means for a relatively long period due to deterioration of the reception state. Even after returning to the state, the output of the positioning data is not immediately permitted, and when the positioning can be continuously performed for the second predetermined time, the output of the positioning data from the positioning data creating means is permitted. Is done. As a result, the output positioning data becomes data that greatly contributes to the output of the detection unit after the positioning unit returns to a state where positioning by the detection unit is possible. Therefore, highly accurate positioning data in which the influence of the data detected before the positioning becomes impossible is sufficiently reduced is reliably output.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a navigation device to which a position detecting device according to an embodiment of the present invention is applied, FIG. 2 is a flowchart for explaining the operation thereof, and FIG. FIG. 4 is a diagram for explaining a position detection operation, and FIG. 4 is a diagram for explaining a method of creating positioning data. 11, 12, 13: GPS satellites, 14: Antenna, 15: GPS receiver, 16: Position detector, 21: Detector, 22: Positioning data generator, 24: Position detection controller , 27 …… Continuous reception counter, 28 …… Positioning impossible counter

Claims (1)

(57) [Claims] 1. A position detecting device mounted on a moving body and detecting a position of the moving body based on radio waves radiated from an artificial satellite, wherein the position detecting device detects the position of the moving object based on a propagation delay time of a radio wave from the artificial satellite. Detecting means for detecting the position of the body; positioning data generating means for performing an average value operation on the output of the detecting means to obtain positioning data; and detecting the position by the detecting means continuously for a first predetermined time. And when the position detection by the detection means is possible continuously for a second predetermined time thereafter, during the second predetermined time period, the position data from the positioning data generation means Means for prohibiting output and permitting output of positioning data from the positioning data creating means after a lapse of the second predetermined time period.