JPH0660935B2 - Moving position measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention In the present invention, the absolute position of a moving body is obtained by navigation radio waves, and the relative position is obtained by integrating the moving distance and direction of the moving body. The present invention relates to a moving position measuring device in which one calculated position is selected as a position of a moving body according to a reception state.

<Background of the Invention> A device described in Japanese Patent Application No. 60-135817 is known as this type of device, and the conventional device is not able to receive the navigation radio wave normally because the navigation radio wave is weak. When it is detected that it has disappeared, the absolute position at that time is used as the starting point of the relative position calculation, and the relative position calculation is performed thereafter to be the current position.

However, in this conventional device, when the deterioration of the reception state of the navigation radio wave is detected, the absolute position at that time is used as the starting point of the relative position calculation, so that the reception state is deteriorated and the absolute position detection accuracy is large. The absolute position in the state that the error is included will be used as the starting point for the relative position calculation, and the relative position obtained after that will contain a large error, which makes it impossible to accurately measure the position of the moving body. There was a problem.

<Purpose of the Invention> The present invention has been made in view of the above conventional problems,
It is an object of the present invention to provide a moving position measuring device capable of accurately measuring the current position of a moving body when the reception state deteriorates.

<< Constitution of the Invention >> In order to achieve the above object, the present invention provides an absolute position calculating means for obtaining an absolute position of a moving body using a navigation radio wave, and a moving body with respect to a reference position by integration processing of a moving distance and a direction of the moving body. Relative position calculation means for determining the relative position of the navigation signal, reception state determination means for determining the reception state of the navigation radio wave based on the received signal, and the reception state determination means for determining the reception state of the navigation radio wave as a good first reception level. In this case, the reference position of the relative position calculating means is updated to the absolute position of the moving body, and the absolute position is selected as the moving position of the moving body, and the receiving state determining means. When it is determined by the navigation signal that the reception state of the navigation radio wave is the second reception level that is worse than the first reception level, the updating of the reference position of the relative position calculation means is stopped and The second position selecting means for selecting the absolute position as the moving position of the moving body and the reception state judging means discriminates that the reception state of the navigation radio wave is the third reception level which is further deteriorated than the second reception level. In this case, a third position selecting unit that stops updating the reference position of the relative position calculating unit and selects the relative position as the moving position of the moving body is provided.

<< Embodiment of the Invention >> Hereinafter, a preferred embodiment of an apparatus according to the present invention will be described with reference to the drawings.

The device shown in FIG. 1 is installed in a vehicle, and the present traveling position of the vehicle is measured by this device.

The receiving circuit 10 receives the Loran C radio wave, which is a navigation radio wave, via the antenna 12, and the received signal indicating the radio wave arrival time difference is supplied to the reception position calculation circuit 14.

The reception position calculation circuit 14 uses the reception signal of the reception circuit 10 to obtain position data (x _L , y _L ) indicating the absolute current traveling position of the vehicle. And latitude.

Further, the traveling direction and the traveling distance of the vehicle are respectively detected by the geomagnetic sensor 16 and the distance sensor 18, and the detection signals thereof are sampled by the estimated position calculation circuit 20 at predetermined intervals.

Then, the estimated position calculation circuit 20 obtains the amount of movement of the vehicle during the sampling interval based on the sampling values, and the absolute position given from the reception position calculation circuit 14 is initialized to perform an integration process of the amount of movement. There is.

As a result, position data (x _D , y _D ) indicating the current traveling position of the vehicle relative to the absolute position of the reception position calculation circuit 14 is obtained.

Here, the binarized reception signal of the reception circuit 10 is supplied to the SN detection circuit 22, and the SN ratio detection circuit 22 synchronously adds the reception signals as shown in Japanese Patent Application No. 58-105540. The SN ratio of the received signal is stochastically calculated by.

The SN ratio detection signal of the SN ratio detection circuit 22 is supplied to the reception level judgment circuit 24, and the judgment characteristics of the reception level judgment circuit 24 are shown in FIG.

In the reception level determination circuit 24, when the SN ratio of the received signal exceeds the set SN ratio C ₁ (for example, −10 dB), it is determined that the reception state is good (level 1), and the SN ratio is the set SN ratio C ₁ Below, the set SN ratio C ₂ (for example, −26
It is determined that the reception state has deteriorated (level 2) when it is equal to or higher than dB), and that the reception state has significantly deteriorated (level 3) when the SN ratio is equal to or less than the set SN ratio C ₂ . .

As can be seen from FIG. 2, hysteresis is added to the characteristic 100 to prevent chattering in determination.

This is because when selecting the absolute position by the navigation radio wave or when selecting the relative position by the reception position calculation circuit 14,
The detected SN ratio varies depending on the sample time, and when the absolute position by the navigation radio wave is selected or the relative position by the reception position calculation circuit 14 is selected, the detected current position does not settle near a certain value. is there.

Therefore, in the present embodiment, a hysteresis is provided to prevent this, and as shown in FIG. 2, when going from level 1 to level 2, route a, when going from level 2 to level 3, route b, level. Route 3 is selected when going from level 3 to level 2, and route d is selected when going from level 2 to level 1.

The judgment signal obtained by the reception level judgment circuit 24 is supplied to the estimated position calculation circuit 20 and the calculation position selection circuit 26.

In the estimated position calculation circuit 20, when the SN ratio of the received signal is equal to or higher than the set SN ratio C ₁ and the reception state is good (level 1), the position data (x _D , y _D ) is reset and the position data (x _L , Y _L ) is being performed, and the position data (x _D , y _D ) is reset and updated when the SN ratio of the received signal is less than the set SN ratio C ₁ and the reception state deteriorates slightly. Stopped at (Level 2).

Therefore, when the SN ratio of the Loran C radio wave becomes slightly low (level 2), the actual operation of the estimated position calculation circuit 20 is started, and thereafter the position data (x _D , y obtained by the estimated position calculation circuit 20 is obtained. _D ) indicates the relative current traveling position of the vehicle with the position data (x _L , y _L ) obtained by the reception position calculation circuit 14 at that time as the reference position (x _O , y _O ).

On the other hand, in the calculation position selection circuit 26, the reception level determination circuit 24
Position data (x _L , y _L ) according to the determination signal of
When any of (x _D , y _D ) is selected as the data (x _i , y _i ) indicating the current traveling position of the vehicle and the SN ratio of the received signal is equal to or higher than the set SN ratio C ₂ (level 1 or The position data (x _L , y _L ) is at level 2), and the position data (x _L , y _L ) is at the time when the SN ratio of the received signal is less than the set SN ratio C ₂ and radio wave reception is impossible (level 3). _D ,
y _D ) are respectively selected as the position data (x _i , y _i ).

The operation of the present embodiment is described by a flow chart in FIG. 3. In this FIG. 3, the latitude direction is determined by using the detection signals of the geomagnetic sensor 16 and the distance sensor 18 sampled at fixed time intervals or at intervals of distance. Data indicating the distance traveled by the vehicle in the longitudinal direction (Δx,
First, the estimated position calculation circuit 20 obtains Δy) (step 200).

Then the distance data (Δx, Δy) is it the position data which has been determined by (x _{D, y D)} each summed position data indicating the relative current running position of the vehicle by the (x _D, y _{D 2} ) is calculated by the estimated position calculation circuit 20 (step 202).

Then, when the position data (x _L , y _L ) indicating the absolute current traveling position of the vehicle is obtained by the reception position calculation circuit 14 using the reception signal of the reception circuit 10 (step 204), the SN ratio of the reception signal is calculated. Whether the set SN ratio C ₁ or more is S or not
The reception level determination circuit 24 uses the detection signal of the N ratio detection circuit 22 (step 205).

At that time, the SN ratio of the received signal is equal to or more than the set SN ratio C ₁ , the reception state of the Loran C radio wave is good, and the reception position calculation circuit 14
If the absolute current traveling position of the vehicle indicated by the position data (x _L , y _L ) is accurate (affirmative determination in step 205), the position data (x _D , y _D ) is reset (step 206), and the initial position data (x _O , y _O ) indicating the reference position is forced to the position data (x _L , y _L ) of the reception position calculation circuit 14. Is changed to (Step 20
8).

As a result, only the position data (x _L , y _L ) is given to the calculation position selection circuit 26 from the reception position calculation circuit 14, and the position data (x _L , y _L ) indicates the current traveling position of the vehicle. It is selected as the indicated data (x _i , y _i ) (step 210).

When accurate position data (x _L , y _L ) with a high SN ratio of the received signal (level 1) is obtained, the absolute position indicated by this is selected as the current traveling position of the vehicle.

When the SN ratio of the received signal is less than the set SN ratio C ₁ and more than the set SN ratio C ₂ and the reception state is slightly deteriorated (affirmative determination in step 212), the position data (x _L , Y _L ) is calculated as position data (x _i , y _i ) indicating the current traveling position of the vehicle.
In is selected (step 210), the forced change of the reset (step 206) and the initial position data _(x O, _{y O)} of the estimated position calculating circuit 20 in the position data _(x D, _{y D)} (step 208) Be stopped.

Therefore, immediately before the reception state deteriorates, the reception position calculation circuit 14
Indicated by the position data obtained in _(x L, _{y L)} position data, based on the _{(x D, y} D) is determined by the estimated position calculation circuit 20 and thus its position data _{(x D, y} D) The relative position is accurate with respect to the actual current traveling position.

Further, when the SN ratio of the received signal becomes less than the set SN ratio C ₂ and the reception state significantly deteriorates (negative determination in step 212), radio wave reception becomes impossible and accurate position data (x _L , y _L). ) Cannot be obtained, the position data (x _D , y _D ) obtained by the estimated position calculation circuit 20 is used as position data (x _i , y _i ) indicating the current traveling position of the vehicle. Selected in step 26 (step 21)
4).

The position data (x _D , y _D ) is obtained on the basis of the accurate position data (x _L , y _L ) obtained when the SN ratio of the received signal is high as described above. According to the embodiment, it is possible to measure the current traveling position of the vehicle with high accuracy regardless of the radio wave reception state.

In the present embodiment, the absolute current traveling position of the vehicle is obtained using the Loran C radio wave, but Decca, Omega,
It is also preferable to configure the device so as to obtain its position using radio waves such as NNSS and GPS.

When the absolute position is calculated by GPS or the like, the device can be configured to measure the HDOP, GDOP, the arrangement position of the receiving satellite, and the like to monitor the reception state of radio waves.

Here, DOP indicates a lateral error, and the higher the accuracy, the smaller the value. And HDOP is a lateral position error using only the x, y coordinate (two-dimensional) data of the GPS satellite, and GDOP is the x, y, z, coordinate (3
Dimension) data and lateral position error using positioning time difference data t are shown.

Therefore, instead of the S / N ratio used in the above example, the above D
As in the case of the above embodiment, the absolute value using the GPS satellite or the relative position using this absolute position as the reference position is used by the level discrimination (level 1 to level 3) of the reception state by using the OP value and a certain threshold value. It is intended to select a position.

<Effects of the Invention> As described above, according to the present invention, when the reception state of the navigation radio wave is deteriorated, the relative position based on the absolute position accurately obtained using the radio wave when the reception state is good When the navigation signal reception condition deteriorates significantly after that, the relative position is selected as the current position of the moving body instead of the absolute position. It is possible to measure the current position with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of the apparatus according to the present invention, FIG. 2 is an explanatory view of the judgment characteristic of the reception level judgment circuit in FIG. 1, and FIG. 3 is a description of the operation of the embodiment of FIG. It is a flowchart to do. 10 ... Reception circuit 12 ... Antenna 14 ... Reception position calculation circuit 16 ... Geomagnetic sensor 18 ... Distance sensor 20 ... Estimated position calculation circuit 22 ... SN ratio detection circuit 24 ... Reception level determination circuit 26 ... Calculation position selection circuit

Claims (1)

[Claims] 1. An absolute position calculating means for obtaining an absolute position of a moving body using navigation radio waves, and a relative position calculating means for obtaining a relative position of the moving body with respect to a reference position by integrating processing of a moving distance and a direction of the moving body, In the case where the receiving state determining means determines the receiving state of the navigation radio wave based on the received signal and the receiving state determining means determines that the receiving state of the navigation radio wave is the first reception level with a good reception level, the relative position calculating means First position selecting means for updating the reference position to the absolute position of the moving body and selecting the absolute position as the moving position of the moving body, and the reception state of the navigation radio wave by the reception state judging means for the first position. When it is determined that the second reception level is worse than the reception level, the updating of the reference position of the relative position calculating means is stopped and the absolute position is selected as the moving position of the moving body. If the reception state of the navigation radio wave is determined to be the third reception level which is further deteriorated than the second reception level by the second position selection means and the reception state determination means, the relative position calculation means And a third position selecting unit that stops updating the reference position and selects the relative position as the moving position of the moving body.