JPH0792389B2 - Gyro offset correction device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset correction device used in a device such as an optical fiber gyro, a mechanical gyro, a vibration gyro, or a gas rate gyro for detecting the direction of a vehicle based on the output of the gyro. is there.

[0002]

2. Description of the Related Art Conventionally, a gyro has been widely applied to a vehicle to detect a predetermined direction such as a traveling direction of the vehicle. Appropriate processing is applied to the output signal from this gyro, and the amount of change in direction Δ that accompanies the traveling of the vehicle
θ is obtained for each predetermined sampling cycle, and the current heading data of the vehicle is created by integrating the heading change amount Δθ. That is, the current azimuth θ of the vehicle is obtained as θ = θ ₀ + Δθ 2 using the azimuth θ ₀ obtained at the time of sampling one time before and the current azimuth change amount Δθ.

The current azimuth θ thus obtained is used for calculating the current position of the vehicle. For example, in the vehicle, the east-west direction component Δx (= ΔL × cos θ) and the north-south direction component Δy (=) of the traveling amount of the vehicle are calculated based on the traveling distance ΔL obtained from the output of the vehicle speed sensor for each predetermined time and the current heading θ. ΔL × sin θ) is obtained. Each component of the traveling amount of this vehicle is converted into the previous vehicle position data (P
The current vehicle position data (Px, Py) is obtained by adding each component of x ', Py'). Such vehicle position detection technology is called dead reckoning navigation.

However, the gyro tends to generate some offset output due to the influence of temperature and humidity even when the sensor output should be zero, such as when the gyro is stopped or running straight. When this offset output is accumulated, the detected current azimuth θ includes a large error, which makes the detection of the current vehicle position inaccurate.

In order to solve this problem, it has been conventionally proposed to subtract the offset output from the sensor output to detect the current azimuth θ. For example, Japanese Patent Publication Sho 58-3
Japanese Patent No. 9360 discloses a technique utilizing the fact that the output of the gyro during the period when the vehicle is stopped by a signal or the like is the offset itself. That is, offset correction is realized by detecting an offset from the output of the gyro while the vehicle is stopped and subtracting the detected offset from the output of the gyro during running.

However, the gyro offset is
It has the property of drifting due to changes in temperature and humidity regardless of whether the vehicle is stopped or running. Therefore, even if the gyro output during traveling is corrected by the constant offset value obtained while the vehicle is stopped, the offset-corrected azimuth will include an error due to the drift.

[0007] The above problem is relatively small because the vehicle can be stopped frequently or can be corrected while the drift is small and the offset is small. In addition, when the time from the start of the vehicle to the stop is long, the drift becomes large, the accuracy of the direction detection is extremely deteriorated, and the detection of the current position of the vehicle becomes inaccurate. .

Therefore, for example, Japanese Patent Laid-Open No. 63-182519
In the publication, using the output of the gyro while running straight,
Techniques for performing similar offset correction are disclosed. In the disclosed technology, it is identified from the road map data that the road on which the vehicle is traveling is a straight road, and the offset is detected based on the gyro output during traveling on the straight road. Therefore, since the drift value can be calculated and corrected in the traveling state without stopping for a long time, the position detection error can be reduced.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the technology of Japanese Patent No. 82519, the map information is read out, the road currently traveling is specified, whether or not the road is a straight road having a certain distance or more is determined, and if it is determined that the road is a straight road, the offset is corrected. I was giving a signal to permit. But,
When traveling on a road with a lot of bends such as a mountain road for a long time, there is a drawback that the gyro offset cannot be corrected during traveling.

Further, in reality, it is doubtful whether the error in the gyro output during traveling is due solely to the offset, and there is a possibility that the error in the gyro output may occur due to the inclusion of noise, for example. In this case, if the offset is corrected, the azimuth error increases. Therefore, an object of the present invention is to solve the above-mentioned technical problems and to provide an offset correction device that can perform gyro offset correction satisfactorily and enable accurate azimuth detection.

[0011]

Means and Actions for Solving the Problems The structure and action of the offset correcting apparatus according to the first aspect will be described with reference to FIG. This offset correction device is installed in an azimuth detection device, and includes a gyro 1 for detecting a turning angular velocity of a vehicle, and an offset correction means 2 for correcting an offset included in the output of the gyro 1. Cage,
The estimated azimuth of the vehicle is detected based on the cumulative output of the offset correction means 2 (Σ).

For map matching and offset value correction, a map memory 3 is provided for each link that stores a link azimuth, which is the azimuth unique to the link when the vehicle travels along the link. . The map matching means 4 determines that the locus of the detected position is in the matching state when there is a predetermined correlation with any of the links stored in the map memory 3. That is, when the detected current position and the link in the map data are well matched, it is determined as the matching state.

The map matching means 4 detects the current position of the vehicle by an arbitrary method. For example, the output of the gyro 1 is offset-corrected by the offset correction means 2 and a speed sensor for detecting the speed of the vehicle. It may be performed by so-called dead reckoning based on the output such as. Alternatively, the current position of the vehicle may be detected by measuring the propagation delay time of radio waves from a GPS (Grobal Positioning System) satellite.

Then, the link orientation of the link corresponding to the current position at the time when the matching state is determined based on the current position information detected by the map matching means 4,
The difference from the gyro accumulated azimuth (after offset correction if offset correction has been made) is taken and collected and stored as azimuth difference data (5). After that, the correction value Δθ of the direction is determined based on the collected direction difference data, and the direction of the vehicle is corrected based on the correction value Δθ (6).

Further, it is checked whether the azimuth correction value Δθ has the same polarity or different polarity as the previous azimuth correction value Δθ (7). If they match, the azimuth correction value Δθ is considered to have occurred based on the gyro offset, and the gyro offset is corrected (8). If they do not match, the gyro offset is not corrected.

[0016]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 2 is a block diagram showing the basic configuration of a navigation device including an offset correction device. This navigation device is mounted on a vehicle and is used. A gyro 21 that detects the turning angular velocity of the vehicle and a vehicle speed sensor 22 that detects the vehicle speed by detecting the rotational speed of wheels and the like.
The position detection unit 23, which has the following outputs and has these outputs, estimates the current position of the vehicle by so-called dead reckoning. An offset memory 31 for storing an offset value included in the output of the gyro 21 is connected to the position detecting section 23, and a value corrected by subtracting the offset value from the output of the gyro 21 is used to estimate the current position. Is used. The position detection unit 23 includes a CPU (not shown) and the like, and stores the memory 23a (which stores the azimuth difference data, the azimuth correction value Δθ, etc.) that functions as a work area, and the continuous running time of the vehicle. It has a continuous running counter 23b for measuring. As the gyro 21, various types such as an optical fiber gyro, a mechanical gyro, a vibration gyro, and a gas rate gyro can be used.

Estimated position data representing the current position detected by the position detection unit 23 is given to a control unit 24 composed of a CPU (central processing unit) or the like. The control unit 24 is a CD
A road map of the area corresponding to the estimated position data is read from the road map memory 25 composed of ROM or the like via the memory drive 26, and the estimated position is displayed on the display unit 27 such as a CRT together with the road map. A console 28 having a key input unit and the like is provided in association with the display unit 27, and various instruction input operations can be performed. From the position detection unit 23, direction data representing the traveling direction of the vehicle (hereinafter referred to as "vehicle direction") is given to the control unit 24 together with the estimated position data, and the display unit 27 is provided.
Then the direction of the vehicle is also displayed at the same time.

The position detection unit 23 detects the position of the dead reckoning navigation map and the estimated position obtained by the dead reckoning navigation and the road map read from the road map memory 25 via the memory drive 26. It is carried out in combination with a matching method (Japanese Patent Laid-Open Nos. 63-148115 and 64).
-53112). This map matching method uses the fact that the current position of the vehicle is always one point on the road,
This is a technique for correcting the estimated position to a position on the road map.

The road map memory 25 stores road data and the like consisting of combinations of nodes and links.
A node is a predetermined coordinate position on a road map, and is set at a branch point, a road bending point, or the like. Further, the link corresponds to the road connecting the nodes, and in principle, the vehicle can take only the coordinate position on this link. Road data consists of node data and link data. The node data consists of the node number and the address of the link connected to the node. The link data is the link number, the start and end node addresses of the link, the link distance, and the link when the vehicle passes through the link. It consists of direction and road type. In the present embodiment, the gyro 21 is used by using the link direction described above.
An offset value for offset correction is appropriately determined.

In the following, the detection of the azimuth of the vehicle by the position detector 23 will be described in detail. The detection of the direction of the vehicle is performed based on the output of the gyro 21, as described above. The output of the gyro 21 includes an offset which is an output when the turning angular velocity of the vehicle is zero. This offset value is stored in the offset memory 31, and the position detection unit 23 performs offset correction by subtracting the offset stored in the offset memory 31 from the output of the gyro 21, and the value obtained as a result of this offset correction. Is accumulated to detect the direction change amount of the vehicle. Therefore, the direction of the vehicle is detected by giving the initial direction from the console 28 or the like.

On the other hand, since the offset value has the property of drifting due to changes in temperature and humidity, if the constant offset value stored in the offset memory 31 is always used, the error due to the drift is accumulated. As a result, a large error occurs in the detection direction. Therefore, it is necessary to appropriately detect a correct offset value in which the drift amount is corrected, and perform the offset correction with this new offset value. Such offset value correction is preferably performed at the shortest possible time interval, and if a constant offset value is used for a long time, a large error may occur in the detection direction.

When the vehicle stops due to a signal or the like, the true turning angular velocity during the stop is zero. Therefore, the value obtained by correcting the output of the gyro 21 during the stop with the previous offset value is the offset drift amount. It becomes itself. For this reason,
The position detection unit 23 detects the offset drift amount based on the output of the gyro 21 that is offset-corrected each time the vehicle is stopped, obtains a new offset value in which the offset drift amount is corrected, and stores the value in the offset memory 31. To a new offset value.

On the other hand, when the vehicle is traveling on a highway or in a mountainous area, the continuous traveling time of the vehicle becomes long. Therefore, it is necessary to correct the offset value to a new value even while the vehicle is traveling. Therefore, the correction of the offset value is realized by the following software processing. 3 to 5 are flowcharts for explaining the process for correcting the offset value. This processing is performed by interruption every predetermined time (for example, 0.1 seconds). In steps S1-4,
The data of the gyro 21 and the data of the vehicle speed sensor 22 are fetched and integrated to obtain the azimuth and the traveling distance.

In step S5, it is determined whether or not the traveling distance has advanced by 2 m, and every time the traveling distance is advanced by 2 m, position detection processing (step S6), orientation difference collection processing (step S7) and orientation correction processing (step S8) are performed. In the position detection process (step S6), the degree of correlation between the trajectory of the estimated position of the vehicle detected by dead reckoning and the like and the links in the vicinity of the estimated position is calculated. Then, there is a link having a predetermined correlation, and therefore, it is determined whether or not there is a matching state in which the link and the trajectory of the estimated position are well matched.

In the direction difference collecting process in step S7, the process shown in FIG.
If it is determined that it is in the matching state (step S71), if it is in the matching state, in step S72, the orientation θ ^l _i of the link on the map at the time of the interruption and the gyro 21 integrated orientation the difference between theta _i is checked whether less than the upper limit value theta _1, was collected as a direction difference data only if less than the upper limit value theta _1, taking the average of the past misorientation data (θ _i -θ ^l _i) in step S73 Register it as Δθ _i . The reason why the link azimuth θ ^l _i and the gyro integrated azimuth θ _i are compared and averaged as described above is that the link azimuth θ ^l _i on the map may be rough and have an error. That is, link direction θ
If the difference between ^l _i and the gyro 21 integrated azimuth θ _i is too large, it is not used as data, and even if it is used as data, the average value is obtained in order to suppress variations as much as possible.

Even if it is determined in step S71 that the state is not the matching state, the average value of the orientation difference data is not calculated and registered. This is because if there is no matching state, there is no point in obtaining the link direction. In the azimuth correction process of step S8, as shown in FIGS. 5 and 6, it is checked whether or not the azimuth difference data is registered (step S81), and YE
If S, the average value Δθ _{i of} the misorientation data registered,
It is determined whether the difference between Δθ _j is less than the upper limit value θ2 (step S82). The reason for making such a determination is to check whether or not the orientation difference itself has a variation. If the variation is small, the average value Δθ _i of the orientation difference data is further averaged in step S83. Then, the gyro integration direction is corrected using this new average value Δθ (step S84).

In step S85, it is checked whether the azimuth correction value Δθ and the previous azimuth correction value Δθ have the same polarity. FIG. 7A shows the azimuth correction value Δθ _i and the previous azimuth correction value Δθ _i-1.
7 and 8 have the same sign, FIG. 7B shows the case where the azimuth correction value Δθ _i and the previous azimuth correction value Δθ _i-1 have different signs. If the sign is the same, it means that the error of the gyro accumulated direction shows the same tendency, and it can be inferred that it is based on the offset.If the sign is different, the error of the gyro accumulated direction is based on other noise. I can guess that there is.

Therefore, in step S86, the offset correction value Δω is obtained only when the difference between the azimuth correction value Δθ _i and the previous azimuth correction value Δθ _{i- 1} has the same sign (step S8).
6). The correction value Δω is obtained by dividing the azimuth correction value Δθ by the correction time interval. Then, this correction value Δω is added to the angular velocity output ω of the gyro 21 (step S8).
7). Then return.

As described above, according to the present embodiment, the azimuth correction is performed based on the azimuth difference data between the azimuth of the gyro and the azimuth of the link corresponding to the current position of the vehicle at the time of determining the map matching state. The gyro offset is corrected only when the polarities of the azimuth correction value Δθ and the previous azimuth correction value Δθ are matched, and the gyro offset is corrected only when they match. Fluctuations in the cumulative azimuth will not be mistaken for offset fluctuations.

Further, when the azimuth difference data, which is the difference between the gyro azimuth and the link azimuth, is used, an excessive amount of plural azimuth difference data collected in the past is excluded or an average operation is performed. Even if the above link azimuth is not sufficiently accurate, the gyro offset can be corrected well. It should be noted that in the above-mentioned embodiment, whether or not the polarities of the azimuth correction value Δθ and the previous azimuth correction value Δθ are matched is checked. The offset variation may be appropriately detected based on the above case, and the previous offset value may be corrected to the correct offset value. In general, the offset may be corrected by checking the matching of the polarity with the azimuth correction value Δθ of the past n times to detect the variation of the offset.

[0031]

As described above, according to the offset correction device of the first aspect, the direction difference data between the direction of the link corresponding to the current position of the vehicle at the time when the map matching state is determined and the integrated direction of the gyro. Based on, the azimuth correction is performed, and it is checked whether the azimuth correction value Δθ and the previous azimuth correction value Δθ have the same polarity, and the gyro offset is corrected only when they match. .

Therefore, even if the vehicle continues to run continuously for a long time, the link azimuth is used to appropriately detect the variation in the offset included in the output of the gyro, and the previous offset value is corrected to the correct offset. It can be corrected to a value. In addition, by checking whether the polarities of the azimuth correction value Δθ and the previous azimuth correction value Δθ match, it is determined whether the azimuth error is based on the offset deviation, and based on the offset deviation. The gyro offset correction is satisfactorily performed only when the gyro is detected, so that the direction detection accuracy can be significantly improved.

Further, according to the offset correction apparatus of the second aspect, when the azimuth difference data, which is the difference between the gyro azimuth and the link azimuth, is used, each of the plurality of azimuth difference data collected in the past has an upper limit. Since only those with a value of θ ₁ or less are collected and the average value of them is calculated to detect the fluctuation of the offset included in the output of the gyro,
Even if the link direction on the map is not sufficiently accurate, the gyro offset can be corrected well.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an offset correction device of the present invention.

FIG. 2 is a block diagram showing a basic configuration of a navigation device to which an offset correction method according to an embodiment of the present invention is applied.

FIG. 3 is a basic flowchart for explaining an operation for correcting an offset value.

FIG. 4 is a flowchart (a part of FIG. 4) for explaining an operation for correcting an offset value.

FIG. 5 is a flowchart (a part of FIG. 4) for explaining an operation for correcting an offset value.

FIG. 6 is a flowchart (continuation of FIG. 5) for explaining an operation for correcting an offset value.

FIG. 7 is a diagram illustrating the meaning of polarity determination in the offset correction processing of the present invention, where (a) is an error caused by the offset, and (b) is an error caused by a cause other than the offset. Indicates.

[Explanation of symbols]

 21 gyro (gyro) 22 vehicle speed sensor 23 position detection unit 23a memory 23b continuous running counter 24 control unit 25 road map memory 31 offset memory

Claims (2)

[Claims] 1. A gyro for detecting a turning angular velocity of a vehicle (1)
It is used to detect the direction of the vehicle based on the output of, and the route that the vehicle can travel is stored by a node that is a predetermined coordinate position on the route and a link that connects the nodes,
A map memory (3) that stores the link direction, which is the direction when the vehicle travels along the link, for each link, and the current position of the vehicle is detected, and the locus of the detected position and the map memory are stored. A means (4) for determining that the vehicle is in the matching state when the linking of any one of the links has a predetermined correlation, and corresponds to the current position of the vehicle when it is determined that the vehicle is in the matching state. Means (5) for collecting and storing bearing difference data which is a difference between the link bearing and the gyro integrated bearing, means for correcting the bearing of the vehicle based on the stored bearing difference data (6), and the bearing difference A means (7) for determining whether the polarity of the data and the polarity of the previously obtained azimuth difference data are equal, and a means for correcting the offset value of the gyro (1) based on the azimuth difference data when the polarities are equal. (2) and Offset correction device which comprises. 2. The azimuth difference data is a plurality of azimuth difference data collected in the past, and an average value of the azimuth difference data each having an upper limit value θ ₁ or less is stored.
The offset correction device described.