JP2000310538A - Position detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the detecting accuracy during the stop of a position detecting apparatus which makes use of an artificial satellite. SOLUTION: At every computing timing, positioning position data Pg(i) which are found on the basis of received radio waves from a GPS satellite, a speed vector Vg(i) and a speed-error estimated value Vth are read out (S110). Estimated position data Pe(i) which is found at a previous computing timing and the positioning position data Pg(i) are weighted and averaged, and present- position data P(i) is found (S160). The speed vector Vg(i) is added to the present- position data P(i), and estimated position data Pe(i+1) at a next computing timing is found (S190). However, when the magnitude Vg(i) of the speed vector is smaller than the speed-error estimated value Vth (S180-Y), the estimated position data Pe(i) at this time is set as the estimated position data Pe(i+1) in the next time as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for receiving a radio wave from an artificial satellite and detecting the position of the receiving point.

[0002]

2. Description of the Related Art Conventionally, as this kind of device, GPS
(Global Positioning System) Using a plurality of artificial satellites (hereinafter referred to as “GPS satellites”) provided for the purpose of receiving radio waves simultaneously from three or four GPS satellites and transmitting a C / A code superimposed on the radio waves 2. Description of the Related Art There is known a GPS receiving apparatus that calculates a pseudo distance with each GPS satellite using the calculated distance and calculates a positioning based on the pseudo distance to obtain a current position.

[0003] The pseudorange is obtained by measuring the time required for a C / A code transmitted from a GPS satellite at a predetermined timing to reach a GPS receiver by a clock operating according to a GPS reference time. The measurement time can be easily obtained by multiplying the propagation time of the radio wave.

Incidentally, in GPS, in order to control the detection accuracy, accuracy deterioration (SA: Selective Availa
abilities) are introduced, and the frequency of the carrier wave is intentionally fluctuated within a certain range. Therefore, various measurement errors occur according to the fluctuations, and the positioning position obtained by the positioning calculation varies. Would.

[0005] As one of the methods for reducing the variation of the positioning positions, the latest positioning position is averaged by past positioning positions (for example, by averaging the previous positioning position and the current positioning position). However, when this method is applied, there is a problem that the measured position obtained by averaging is delayed in time from the actual position.

On the other hand, for example, Japanese Patent Application Laid-Open No. 8-686
No. 51 discloses not only a method of calculating a positioning position from a pseudo distance calculated based on a C / A code as in the past, but also a GP.
Using a Doppler shift generated in a carrier wave in accordance with a relative speed with respect to the S satellite, a speed vector indicating a moving speed and a moving direction of the GPS receiving device (or a moving body equipped with the device) is obtained, and this speed vector is used. Thus, a device that suppresses variations in the positioning position by GPS without causing a time delay is disclosed.

In this device, an estimated position at the next measurement timing is obtained based on the already calculated current position and the velocity vector, and a weighted average of the estimated position and the actually measured positioning position is obtained at the next measurement timing. The value is calculated as the current position.

In other words, the past (previous) measured position is not used as it is, but is used for calculating an estimated position, and averaging is performed between the estimated position and the actually measured position. There is no time lag unlike the conventional device, and the carrier wave in the GPS receiver is
Since the bit rate has a higher resolution than the C / A code of 1 Mbps, when the current position is obtained by combining the velocity vectors obtained by using the carrier, the current position is obtained only by the pseudo distance obtained by using the C / A code. Rather, the variation can be suppressed, and the measurement accuracy is improved.

[0009]

However, since the carrier frequency fluctuation due to SA cannot be distinguished from the frequency displacement due to Doppler shift, an error component corresponding to the magnitude of the fluctuation is superimposed on the velocity vector. I will.

[0010] When moving at high speed, the speed vector component generated by the movement is sufficiently large, so that the effect of the error component is small. The effect is greater because the distance is relatively large.

As a result, when the above-mentioned GPS receiver is applied to a navigation device for a vehicle, a speed vector is detected in spite of the fact that the vehicle is actually stopped, so that the speed vector is detected on a map. There is a problem that the current position constantly changes and the display is difficult to see. Also, for example, when the vehicle stops once at an intersection and starts moving again, if the current position during the stop varies due to an error component, the vehicle will start moving from a position different from the stopped position, as shown in FIG. Is displayed as if the vehicle is running on a cranked road. As a result, if the current position obtained by the GPS receiver is matched with the road on the map, there is a problem that the current position is displayed on an incorrect road in some cases.

Further, especially when traveling in an urban area, a multipath occurs in which radio waves reflected on buildings and the like are received. When this multipath occurs, the pseudorange to be detected becomes longer, so that correct positioning cannot be performed. However, if the vehicle is traveling, the surrounding conditions change in a short period of time, so the duration of the multipath state is short, and there is almost no effect. In such a case, since the multipath state continues, the influence is large, and there is a problem that the current position displayed on the map of the navigation device is greatly incorrect.

Accordingly, an object of the present invention is to improve the accuracy of a position detected during stoppage in a position detecting device using an artificial satellite in order to solve the above problems.

[0014]

According to a first aspect of the present invention, there is provided a position detecting apparatus for receiving radio waves from a plurality of artificial satellites, and receiving the received radio waves from the plurality of artificial satellites. Based on the superimposed timing information, the pseudo-range detecting means detects a pseudo-range with each of the artificial satellites, and further, the positioning calculating means determines the positioning at each predetermined calculation timing based on the detected pseudo-distance. Find the position repeatedly.

At the same time, the relative velocity detecting means detects the relative velocity between the device and each of the artificial satellites based on the frequency displacement of the radio wave received by the receiving means, and the velocity vector calculating means detects the relative velocity. Based on the speed, a speed vector indicating the moving speed and moving direction of the device is repeatedly obtained for each calculation timing. That is, the frequency of the radio wave is
Since the Doppler shift is performed according to the relative speed between the device and the artificial satellite, the relative speed can be obtained based on the frequency displacement caused by the Doppler shift.

The position estimating means obtains an estimated position of the device at the next calculation timing based on the speed vector obtained by the speed vector calculating means and the preset current position of the device. The current position updating means updates the current position with a weighted average value of the positioning position obtained by the positioning calculating means and the estimated position obtained by the position estimating means at the previous calculation timing.

However, if the stop determining means determines that the vehicle is in the stop state, the prohibiting means prohibits the update of the estimated position by the position estimating means, and replaces the estimated position used at the current calculation timing with the next time. Is set as the estimated position at the calculation timing. According to the position detection device of the present invention configured as described above, the current position is obtained based on the measured position obtained using the timing information and the estimated position obtained using the velocity vector. The accuracy of the current position can be improved without causing a time delay as in a conventional device that suppresses variations using the measured position.

In addition, according to the position detecting device of the present invention, the stop state is determined based on the moving speed of the device (or the moving body on which the device is mounted). Since the estimated position is not updated based on the speed vector, it is possible to reliably prevent the current position from fluctuating due to an error component of the speed vector that becomes relatively large when the vehicle is stopped or running at low speed.

The speed vector calculating means averages the speed vector obtained at the previous calculation timing and the speed vector obtained at the current calculation timing,
The velocity vector may be supplied to the position estimating means. In this case, when the speed vector is averaged, the value takes into account the acceleration of the speed vector, so that the estimated position can be obtained more accurately, and the current position can be obtained with higher accuracy.

When the stop state is judged by the stop judging means, specifically, the magnitude of the speed vector obtained by the speed vector calculating means is set in advance. The determination can be made by comparing with a determination threshold value. In this case, if the magnitude of the speed vector is smaller than the determination threshold, it may be determined that the vehicle is in the stopped state.

When the vehicle is traveling at a low speed such that the magnitude of the speed vector is equal to or smaller than the determination threshold value due to traffic congestion or the like, the estimated position is updated even though the vehicle is actually moving. Therefore, the estimated position is greatly different from the actual position, and as a result, the accuracy of the current position calculated based on the estimated position and the measured position may be reduced.

Therefore, in the position detecting device according to a third aspect of the present invention, when the measured position and the current position are separated from each other by a predetermined upper limit distance during the stop state for more than a predetermined upper limit time, The estimated position initialization means initializes the estimated position based on the measured position.

That is, if the device (moving body on which the device is mounted) is moving at a low speed equal to or less than the determination threshold, a state where the measured position is separated from the current position by the upper limit distance is once detected. This state continues unless movement at or above the determination threshold is started. For this reason, when continuing for more than the upper limit time, the apparatus considers that the low-speed movement is in the stopped state by initializing the estimated position based on the positioning position, assuming that the apparatus is actually moving at a low speed. The error caused by this is eliminated.

When a multipath occurs at the time of stoppage, the estimated position and the positioning position are also greatly different from each other. Paths are often eliminated. For this reason, if the upper limit time is set to a length long enough to increase the possibility that the multipath will be eliminated, the movement is restarted without the effect of the multipath being accumulated at the current position. At times, an accurate current position from which the influence of multipath has been eliminated can be obtained.

However, even if the radio waves from the satellites are normally received, the positioning positions individually obtained have relatively large errors, so that the estimated position initializing means sets the estimated position as the estimated position. When performing initialization, it is desirable to use a position obtained by averaging a plurality of positioning positions obtained during the stop state.

The averaging may be a simple averaging of the positioning positions within a certain period, a weighted averaging in a time series, or a weighted averaging according to the positioning accuracy at each time. . By the way, the accuracy of the positioning position changes variously depending on the combination of artificial satellites used for positioning and the variation in accuracy of the artificial satellite itself, and accordingly, the range in which the error of the velocity vector varies also changes. Further, even if the determination threshold value for determining whether or not the device is in the stopped state is set to be smaller than the variation in the error of the speed vector, an effective determination cannot be made.

Therefore, a determination threshold value setting means is provided, and the determination threshold value used by the stop determination means is variably set based on the accuracy information superimposed on the radio wave received by the receiving means. It is desirable to do. Thus, the optimum determination threshold can always be set according to the error that changes every moment depending on the combination and arrangement of the satellites used for positioning, so that the system performance can be maximized.

However, when the judgment threshold is variably set,
If this value is excessive, the update of the estimated position using the speed vector is not performed unless the speed is increased to a certain degree even though the movement is started, so that the update of the estimated position is started. If the current position suddenly changes and the current position is displayed on a map such as a navigation device based on the sudden change, the display of the current position moves unnaturally.

According to a sixth aspect of the present invention, when the determination threshold value is calculated by applying the accuracy information to a predetermined arithmetic expression, the determination threshold value setting means sets the calculated value to a predetermined upper limit value. If it is larger, it is desirable to limit the determination threshold to the upper limit.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating an overall configuration of a vehicular navigation device configured using the GPS receiver 2 of the present embodiment.

As shown in FIG. 1, the vehicular navigation device receives a radio wave from a GPS satellite and outputs a current position data P indicating the current position of the vehicle.
And a map data storage medium 4 for storing map data of a road map, and a current position of the vehicle centered on the basis of the map data from the map data storage medium 4 and the current position data P from the GPS receiver 2. The navigation unit 8 includes a navigation unit 8 that displays a road map of the traveling area of the vehicle on the display unit 6.

Here, the GPS receiver 2 of the present embodiment
An antenna 10 for receiving a radio wave from a PS satellite, and based on a signal received from the antenna 10, capture / track a satellite signal, extract a carrier, demodulate a C / A code, and spread a spectrum using a C / A code. A receiving circuit unit 12 for decoding decoded data, extracting a frequency displacement amount of a carrier wave, measuring a transmission time of a C / A code, and an arithmetic unit 14 including a microcomputer mainly including a CPU, a ROM, and a RAM.
And

FIG. 1 shows functional blocks of the operation unit 14, and as shown in FIG.
A speed error estimating unit 20 that extracts accuracy information from data decoded by the receiving circuit unit 12 and calculates an estimated speed error value Vth as a determination threshold based on the accuracy information.
And C measured by the receiving circuit unit 12 for each GPS satellite.
The pseudo distance between the vehicle equipped with the navigation device and each GPS satellite is determined based on the transmission time of the / A code,
A positioning operation unit 22 that calculates positioning position data Pg representing a positioning position of the vehicle based on the pseudo distance, and each GPS satellite used for positioning operation based on the frequency displacement amount of the carrier extracted by the receiving circuit unit 12 Vector calculation unit 2 for obtaining a relative speed between the vehicle and the vehicle and obtaining a speed vector Vg representing the moving speed and the moving direction of the vehicle based on the relative speed.
4 and a filtering unit 26 that calculates the current position data P based on the positioning position data Pg and the speed vector Vg obtained by the positioning calculation unit 22 and the speed vector calculation unit 24.

The speed error estimator 20 includes a user range accuracy (URA) included in detailed trajectory information (ephemeris) as accuracy information extracted from the decoded data.
And the accuracy degradation coefficient (DOP: Dilution Of Prec) determined by the arrangement of GPS satellites used for positioning calculation.
ision), the speed error estimated value Vth [m / s] is calculated according to the following equation (1).

Vth = k × PMura × PMhdop (1) Here, PMura is a parameter set based on URA, and as shown in [Table 1], an average value of a range corresponding to URA, for example, URA = 7 if PMura =
36 are used. PMhdop is a horizontal accuracy degradation coefficient (HDOP) obtained from the DOP, and k is a value obtained by converting the measurement error of the Doppler shift generated by the internal noise of the GPS receiver 2 into speed.

[0036]

[Table 1]

However, if the estimated speed error Vth calculated by the equation (1) is larger than the upper limit value (1 [m / s] in this embodiment), the speed error estimating unit 20 determines that the speed error The estimated value Vth is limited to this upper limit (that is, 0 <Vth ≦ 1), and the speed error estimated value Vth is repeatedly calculated every time the combination or arrangement of the GPS satellites used for the positioning calculation changes. It is configured as follows.

The positioning calculation unit 22 and the speed vector calculation unit 24 repeatedly calculate the positioning position data Pg and the speed vector Vg at the same timing based on the signals received by the reception circuit unit 12 at the same timing. Is configured. Next, the positioning calculation unit 22 simultaneously detects at least three (preferably four or more) pseudoranges with the GPS satellites, and applies the pseudorange to a known positioning calculation to convert the positioning position data Pg. calculate.

In the speed vector calculation unit 24,
Based on the north direction velocity Vn and the east direction velocity Ve obtained by using the equation (2), the velocity vector Vg is calculated by synthesizing these.

[0040]

(Equation 1)

Where Vu is the upward speed, VLF is the speed-converted value of the offset of the reference oscillator of the receiver, ni, ei, u
i is the north, east, and upward cosine of the unit vector heading for the GPS satellite i, and Vdui is the predicted value (calculated value) of the Doppler shift of the radio wave (carrier wave) from the satellite i and the carrier wave detected by the receiving circuit unit 12. The difference from the measured value of the frequency displacement is shown. Note that the speed vector calculation in the speed vector calculation unit 24 is a known one, similarly to the positioning calculation in the positioning calculation unit 22.

Here, the speed error estimated value Vth from the speed error estimating unit 20 and the positioning position data P from the positioning calculating unit 22
g, the filtering process performed by the calculation unit 14 based on the speed vector Vg from the speed vector calculation unit 24 will be described with reference to the flowchart shown in FIG.

This process is started periodically (1 [s] cycle in the present embodiment) repeatedly after the start of the operation of the vehicle. When this processing is started, first, in S110, the speed error estimating unit 2
0, the estimated speed error value Vth, the measured position data Pg, and the speed vector Vg are input from the positioning calculation unit 22 and the speed vector calculation unit 24. In the subsequent S120, the current start of this process is performed after the vehicle starts running. It is determined whether or not this is the first activation.

If it is determined that this is the first activation, the process proceeds to S130 to initialize the current position data P and the estimated position data Pe with the positioning position data Pg read in S110, and then to S140. Then, the parameter i representing the operation timing is initialized to zero (i ← 0), and the routine goes to S170.

Thereafter, assuming that the first activation of this processing is the 0th activation, the data read in S110 at the i-th activation of this processing (hereinafter referred to as the i-th computation timing) is P
g (i), Vg (i), and the current position data calculated at the same i-th calculation timing are P (i) and P (i).
Assume that the estimated position data used for the calculation of (i) is represented by Pe (i).

On the other hand, if it is determined in S120 that the current activation of this process is not the first activation, the process proceeds to S15.
Go to 0, and G is being captured by blocking radio waves by buildings, etc.
When the number of PS satellites becomes 2 or less, the positioning operation unit 22
Then, it is determined whether or not the calculation processing by the speed vector calculation unit 24 is interrupted.

If the positioning calculation has been performed without interruption, the flow shifts to S160 to calculate the current position data P (i) according to the following equation (3). That is, the positioning position data Pg (i) read in S120, and
At the previous calculation timing, S190, S240, S
After calculating the weighted average value with the estimated position data Pe (i) calculated in any of 250 and S260, the process proceeds to S170.

[0048]

(Equation 2)

Here, m> 0 and n> 0. For example, m
= 9, n = 1. Note that, as the value of m is larger than n, the variation in the calculated current position data P (i) becomes smaller. In the process of obtaining the weighted average value, the current position data P is updated by filtering the positioning position data Pg with the speed vector Vg so that the locus of the current position data P falls within a predetermined range defined by the speed vector Vg. Can be thought of as something to do.

Then, in S170, S130 or S1
The current position data P (i) set and calculated at 60 is
Output to the navigation operation unit 8. At this time, the navigation calculation unit 8
Based on the current position data P (i) from the GPS receiver 2, the display unit 6 displays the current position of the vehicle and a road map near the current position.

At S180, the estimated speed error value Vth read at S110 is used as a judgment threshold value.
The magnitude of the velocity vector read at 110 | Vg
(I) |, that is, the moving speed of the vehicle is the speed error estimated value Vth
It is determined whether it is smaller than. If it is determined that the magnitude | Vg (i) | of the speed vector is equal to or greater than the estimated speed error value Vth, the process proceeds to S190 assuming that the vehicle is moving, and the speed / speed of the moving vehicle is determined. Since the direction does not change rapidly in a short time, the current position data P (i) and the speed vector Vg are calculated as shown in the equation (4).
(I) is added to obtain estimated position data Pe (i + 1) at the next calculation timing.

Pe (i + 1) = P (i) + Vg (i) (4) On the other hand, at S180, the magnitude of the velocity vector | Vg
(I) If it is determined that | is smaller than the estimated speed error value Vth, the process proceeds to S200 assuming that the vehicle is stopped, and then the distance | Pg between the positioning position and the current position is determined.
(I) -P (i) | is determined to be greater than or equal to a preset upper limit distance Pth, and if a positive determination is made, that is,
The distance between the positioning position and the current position is within the allowable range (upper limit distance Pt).
If h) is exceeded, the process moves to S210.

At S210, a preset upper limit time T
judge whether the timer for measuring th has been started,
If the timer has not been started, the process proceeds to S220, and after the timer is started, the process proceeds to S250. However, the timer is S15
If a positive determination is made at 0 and if a negative determination is made at S180, the operation is stopped and the clock value is reset.

On the other hand, if it is determined in S210 that the timer has been started, the process proceeds to S230, and it is determined whether the timer has timed out. If so, the process proceeds to S240. Then, as shown in equation (5), the positioning position data Pg read in S110
(I) is set as the next estimated position data Pe (i + 1).

Pe (i + 1) = Pg (i) (5) In S200, the distance | Pg (i) −P (i) | between the measured position and the current position is equal to or smaller than the upper limit distance Pth (that is, allowable). If it is within the range), or if the timeout has not occurred even if it is greater than the upper limit distance Pth, the flow shifts to S250, and as shown in Expression (6), the estimated position data Pe ( i) is set as the estimated position data Pe (i + 1) at the next calculation timing.

Pe (i + 1) = Pe (i) (6) If it is determined in S150 that the positioning is suspended, the process proceeds to S260, and as shown in Expression (7). Then, the estimated position data Pe (i + 1) is calculated by adding the velocity vector Vg (i0) read last immediately before the positioning is interrupted to the current position data P (i).

Pe (i + 1) = P (i) + Vg (iO) (7) Here, i0 indicates a parameter indicating the time of last positioning. In other words, if the speed / azimuth of the vehicle does not change abruptly during the suspension of the positioning, the estimated position data Pe (i + 1) at the next and later calculation timings can be corrected to some extent based on the speed vector V (i0). And when the positioning is resumed, the estimated position data Pe
Thus, the current position can be corrected to some extent accurately.

Then, S190, S240, S250,
In any of S260, the next estimated position data Pe (i
When +1) is calculated, the flow shifts to S270, where the parameter i is incremented (i ← i + 1), and this processing ends. That is, in this processing, the read (S110) positioning position data Pg (i) at each calculation timing.
And the estimated position data P obtained at the previous calculation timing
The current position data P (i) is obtained from e (i) (S160).

In this processing, the calculation of the estimated position data Pe (i + 1) used at the next calculation timing is performed as follows, as the case may be. That is, when the vehicle is moving (S180-NO), the current position data P (i) and the speed vector Vg (i) are added assuming that the speed and direction of the vehicle do not change rapidly. To obtain the estimated position data Pe (i + 1) (S19).
0) On the other hand, when the vehicle is stopped (S180-YES), basically, the estimated position data Pe (i) is not updated and the next estimated position data Pe (i) is not updated. (i + 1)) (S250).

However, in this processing, whether the vehicle is stopped or not is determined based on whether the magnitude | Vg (i) | of the speed vector is smaller than the estimated speed error value Vth. Is determined to be stopped, the vehicle may actually be moving at a lower speed at a speed smaller than the estimated speed error value Vth.

In this case, since the estimated position data Pe is not updated, the current position data P (i) calculated based on the estimated position data Pe (i) and the positioning operation unit 2
The error from the positioning position data Pg (i) calculated in 2 increases with the passage of time.

Therefore, when this error, that is, the distance | Pg (i) -P (i) | between the current position and the measured position exceeds the allowable range (upper limit distance Pth) (S200-YES), The estimated position data Pe (i + 1) is converted to the positioning position data P
Reinitialization is performed using g (i) (S240) so that the error between the two data is reduced.

The distance | Pg between the current position and the measured position
A situation where (i) -P (i) |
It occurs not only when the vehicle moves at low speed but also when a multipath occurs. However, there is a high possibility that the multipath will be canceled after a certain period of time due to the movement of the GPS satellite.
Therefore, only when the above situation continues for the upper limit time Tth or more (S210-YES, S230-YES), the re-initialization (S2
By performing step 40), the influence of multipath is eliminated from the estimated position data Pe and, consequently, the current position data P.

FIG. 3 is an explanatory diagram showing how the current position data P (i) and the estimated position data Pe (i) obtained by the filtering process change. 3A to 3C, the calculation timing i
= 2 indicates a case where the vehicle is running at a speed equal to or higher than the estimated speed error value Vth.

At this time, the current position data P (i) calculated by the weighted average of the positioning position data Pg (i) and the estimated position data Pe (i) based on the speed vector Vg (i-1) having less variation. ) Indicates positioning position data Pg
(I) Variation is smaller than that of itself.

FIG. 3A shows a case where the vehicle is actually stopped after the calculation timing i = 3. In this case, the estimated position data Pe (i) is fixed and the speed vector Since there is no influence of the error included in Vg (i), the variation in the current position data P (i) is further reduced.

FIG. 3B shows a case in which the vehicle is traveling at a low speed at a speed smaller than the estimated speed error value Vth after the calculation timing i = 3. here,
When the calculation timing i = 4, the distance | Pg (4) −P (4) | between the current position and the measured position becomes larger than the upper limit distance Pth, and thereafter, the calculation timing i = X−1 after the upper limit time Tth has elapsed. At the time of, the estimated position data Pe is re-initialized.

As described above, if the low-speed running is determined to be in the stop state, the error between the positioning position data Pg (i) and the estimated position data Pe (i) increases. It can be seen that this error accumulated at the current position is eliminated. Further, FIG. 3C shows a case where the vehicle is actually stopped after the calculation timing i = 3, but a multipath occurs, and thereafter, the multipath is resolved at the calculation timing i = 6. ing. In other words, if the speed vector Vg is smaller than the estimated speed error value Vth, the estimated position data Pe is not updated. Therefore, even if a multipath occurs and the positioning position data Pg greatly changes, the positioning position data Pg follows the change. And the current position data P (6) calculated when the multipath is canceled is the current position data P (6) obtained before the occurrence of the multipath.
It returns to the vicinity of (2). That is, when the vehicle resumes running, the current position data P (i) in which the influence of the multipath is not accumulated is calculated.

The current position data P calculated in this manner is output to the navigation operation section 8 in S170 as described in the flowchart of FIG. Then, the current position of the vehicle is displayed on the display unit 6 together with a nearby road map. FIG. 4 shows a traveling locus of the current position when the vehicle actually travels. In the case of not performing the stop determination based on the conventional device shown in FIG. 5, that is, when the stop determination based on the estimated speed error value Vth is performed, the dispersion of the current position data P calculated when the vehicle stops is large. Make a stop decision,
When the update of the estimated position data Pe is prohibited when it is determined that the vehicle is in the stop state, it is understood that the variation in the current position data P at the time of the stop is greatly reduced, and the trajectory is stable.

As described above, according to the GPS receiver 2 of this embodiment, the estimated position data Pe () at the next calculation timing is calculated based on the current position data P (i) and the velocity vector Vg (i). i + 1) is calculated, and at the next calculation timing, based on the estimated position data Pe (i + 1) and the positioning position data Pg (i + 1), the current positioning position data Pg (i) is not used as it is, and the current position is determined. Since the data P (i + 1) is calculated, the current position data P can be calculated accurately without causing a time delay.

According to the GPS receiver 2 of the present embodiment, the magnitude | Vg (i) | of the velocity vector is equal to the estimated velocity error value V determined by the state of the GPS satellite used for positioning.
If it is smaller than th and the influence of the error component in the speed vector Vg is large, it is determined that the vehicle is stopped,
With the estimated position data Pe (i) fixed, the velocity vector Vg
Since the value is not updated according to (i),
Variations in the stopped current position data P (i) due to the error component of the speed vector Vg (i) can be reliably suppressed.

Further, in the GPS receiver 2 of the present embodiment, while the vehicle is stopped, the distance between the positioning position and the current position |
If Pg (i) -P (i) | is longer than the upper limit distance Pth for more than the upper limit time Tth, the estimated position data P (i + 1) at the next calculation timing is converted to the positioning position data Pg ( Re-initialization is performed in i).

For this reason, when the vehicle is actually moving at a low speed at a speed smaller than the estimated speed error value Vth, it is detected that the vehicle is moving at a low speed, although it is determined that the vehicle is stopped. In addition to eliminating the error caused by the above, even if a state in which the distance between the positioning position and the current position is longer than the upper limit distance due to the influence of multipath occurs, if the distance does not continue for the upper limit time Tth, the positioning position data Pg
Since the re-initialization of the current position data P (i) by (i) is not performed, the positioning position data Pg (i) by multipath is not used.
Can be prevented from being accumulated in the current position data P (i).

In the GPS receiver 2 of the present embodiment, the estimated speed error value Vth for determining whether or not the vehicle is stopped.
Is variably set, and the upper limit is limited. Therefore, the optimum speed error estimated value Vth can always be set according to the error that changes every moment depending on the combination and arrangement of the satellites used for positioning, so that the system performance can be maximized and the speed can be maximized. By setting the error estimation value Vth to a value larger than necessary,
It is possible to reliably prevent the display of the current position displayed on the map from becoming an unnatural movement, such as a situation in which the vehicle does not readily start moving even though it is starting to move.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist of the present invention. . For example, in the above embodiment, when calculating the current position data P (i) from the positioning position data Pg (i) and the estimated position data Pe (i), the weighting coefficients m and n of the weighted average are fixed and used. But, for example,
As the combination of GPS satellites used for positioning changes,
Each time the positioning accuracy changes, the weighting coefficients m and n may be changed according to the positioning accuracy. Specifically, when the positioning accuracy is high, the positioning position data Pg (i)
When the positioning accuracy is low, the weighting coefficient m of the estimated position data Pe (i) may be increased. In this case, the accuracy and stability of the current position data P (i) can be improved.

Further, since acceleration and rotation occur in the actual vehicle, the estimated position data Pe (i) is calculated in the above embodiment in which the motion of the vehicle is assumed to be constant and the estimated position data Pe (i) is calculated. An error occurs in i). Therefore, the movement amount of the vehicle deviating from the constant speed is estimated position data Pe (i).
If the weighting factors m and n for calculating the current position data P (i) are determined in consideration of the error of the current position data P (i), the current position data P (i) can be calculated more accurately.

In the above embodiment, in S190, the motion of the vehicle is modeled as a constant speed motion.
Although the estimated position data Pe (i + 1) is calculated using the expression (4), the estimated position data Pe (i + 1) may be calculated using the expression (8) in consideration of the acceleration motion.

Pe (i + 1) = P (i) + {V (i−1) + V (i)} / 2 (8) Further, in the above embodiment, in S240, the re-initialization of the estimated position data Pe (i + 1) is performed. When performing the conversion, the positioning position data Pg (i) is used as it is, but a plurality of positioning position data Pg read in S110 at each calculation timing from the start of the timer to the time-out.
The averaged positioning position data obtained based on g may be used. In this case, the averaging process may be simple averaging, weighted averaging according to a time series, or weighted averaging according to the positioning accuracy at each time.

In the above-described embodiment, the stop state is determined based on whether or not the magnitude of the speed vector is smaller than a predetermined value. Alternatively, the stop state may be directly determined based on a measurement signal or the like from another device.

In the above embodiment, the GPS receiver 2 is a position detecting device, the antenna 10 and the receiving circuit unit 12 are a receiving unit, the speed error estimating unit 20 is a determination threshold setting unit, and the positioning calculating unit 22 is a pseudo distance detecting unit. And speed calculation means 24, relative speed detection means and speed vector calculation means, S190 is position estimation means, S160 is current position update means, S180 is stop determination means, S250 is inhibition means, and S210 to S240 are estimation. It corresponds to position initialization means.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a navigation device configured using a GPS receiver according to an embodiment.

FIG. 2 is a flowchart illustrating the content of a filtering process performed by a filtering unit.

FIG. 3 is an explanatory diagram showing how the current position data and the estimated position data calculated by the filtering process change.

FIG. 4 is an explanatory diagram showing a locus of current position data displayed on a map.

FIG. 5 is an explanatory diagram showing a locus of current position data by a conventional device.

[Explanation of symbols]

2 ... GPS receiver 4 ... Map data storage medium
6 display unit 8 navigation operation unit 10 antenna 1
2 ... Receiving circuit unit 14 ... Calculation unit 20 ... Speed error estimation unit
22 positioning measurement unit 24 speed vector calculation unit 26 filtering unit

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 28, 1999 (1999.4.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

[0048]

(Equation 2)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshitaka Ozaki 1-1-1, Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 2C032 HB22 HC08 HD03 2F029 AA02 AB07 AC02 AC06 AC12 AC14 AD03 5H180 AA01 BB15 FF05 FF22 FF27 FF32 9A001 GG01 JJ78

Claims (6)

[Claims] 1. A receiving means for receiving radio waves from a plurality of artificial satellites, and a pseudo distance detecting means for detecting a pseudo distance to each of the artificial satellites based on timing information superimposed on the radio waves received by the receiving means. And, based on the pseudo distance detected by the pseudo distance detecting means,
Positioning calculation means for repeatedly obtaining a positioning position for each predetermined calculation timing; and relative speed detection means for detecting a relative speed between the device and the artificial satellite based on a frequency displacement of a radio wave received by the reception means. Based on the relative speed detected by the relative speed detection means,
Speed vector calculating means for repeatedly obtaining a speed vector indicating a moving speed and a moving direction of the device at each of the calculation timings; a speed vector obtained by the speed vector calculating means;
And a position estimating means for obtaining an estimated position of the device at the next calculation timing based on the preset current position of the device, and a positioning position obtained by the positioning calculation means, A current position updating means for updating the current position based on a weighted average value of the estimated position obtained by the position estimating means; and a stop determination for judging a stop state of the position detecting apparatus. Means, when it is determined that the stop state by the stop determination means,
Prohibiting means for prohibiting updating of the estimated position by the position estimating means. 2. The position detecting device according to claim 1, wherein said stop judging means stops when a magnitude of a speed vector obtained by said speed vector calculating means is smaller than a predetermined judgment threshold value. A position detecting device for determining a state. 3. The position detection device according to claim 1, wherein a state in which the positioning position and the current position are separated by a predetermined upper limit distance or more during the stop state is set in advance. A position detecting device provided with an estimated position initializing means for initializing the estimated position based on the measured position, when the estimated time has continued for a predetermined time or more. 4. The position detecting device according to claim 3, wherein the estimated position initializing means initializes the estimated position by a position obtained by averaging a plurality of positioning positions obtained during the stop state. A position detecting device. 5. The position detecting device according to claim 1, wherein a judgment threshold value used by said stop judging means is variable based on accuracy information superimposed on a radio wave received by said receiving means. A position detecting device provided with a judgment threshold value setting means for setting. 6. The position detecting device according to claim 5, wherein the determination threshold value setting means calculates a determination threshold value by applying the accuracy information to a predetermined arithmetic expression, and the calculated value is set in advance. The position detecting device, wherein, when the value is larger than the upper limit, the determination threshold is limited to the upper limit.