JPH05288558A - Travel direction detecting device - Google Patents

Abstract

PURPOSE:To improve the precision of the direction sensor of a navigation system mounted on an automobile. CONSTITUTION:A vehicle travel direction correcting device having a geomagnetism sensor 11 for outputting the direction is provided with a rate sensor 12 outputting the direction added with the rotational angle to the reference direction, a measuring vehicle travel direction calculating means 2 weight-averaging the direction outputted from the geomagnetism sensor 11 and the direction outputted from the rate sensor 12 and outputting the measuring vehicle travel direction, a vehicle travel corrected direction outputting means 3 outputting the vehicle travel corrected direction from the outside, a correcting means 4 weight-averaging the measured vehicle travel direction and the vehicle travel corrected direction from the outside to guide the final corrected direction, and a vehicle travel corrected direction validity judging means 5 judging whether the vehicle travel corrected direction from the outside of the vehicle travel corrected direction outputting means 3 is valid and selectively outputting the measured vehicle travel direction or the final corrected direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction sensor for a navigation system mounted on an automobile or the like. In particular, the present invention aims to improve the accuracy of the azimuth sensor that uses both the geomagnetic sensor and the rate-type azimuth sensor that detects the rotational speed to obtain the azimuth.

[0002]

2. Description of the Related Art In recent years, a device called a navigation system has been used which assists a driver by calculating a route traveled by a moving object such as an automobile and displaying a current traveling point on a map on a display device. It is supposed to be done. Such a device includes a sensor for detecting a traveling direction and a distance sensor for detecting a moving distance, and calculates a traveling point from the detected traveling direction and moving distance. In such a device, it is necessary to detect the absolute azimuth corresponding to the direction on the map by the azimuth sensor used.

As a field of such a technology, there is a vehicle navigation system device described in Japanese Patent Laid-Open No. 64-35314. This device uses a geomagnetic sensor as a direction sensor. This detects the geomagnetism on the earth and outputs the absolute azimuth, but the horizontal component of the geomagnetism is about 0.3 G (gauss), which is very weak.
Disturbances may also be affected by the vehicle, such as the magnetic field due to the magnetization of the vehicle body, the magnetic field due to electronic devices inside the vehicle, etc.
Geomagnetism is disturbed by buildings, elevated roads, tunnels, and even other vehicles. Therefore, although a method of correcting an error factor due to disturbance has been taken, it is currently difficult to obtain sufficient accuracy. However, this geomagnetic sensor is characterized in that errors do not accumulate as compared with a rate sensor which detects a rotational speed and calculates an azimuth, which will be described later. In this way, the removal of the magnetic influence itself as a disturbance other than the earth magnetism is described in, for example, JP-A-61-272618 and JP-A-62-1.
There is one described in Japanese Patent Publication No. 91713. Since the removal of the disturbance magnetism itself does not matter in the present invention, the above description is omitted.

Other direction sensors include a vibration gyro,
There is an azimuth sensor called a rate type azimuth sensor that detects the azimuth by detecting the rotation speed of an optical fiber gyro, a gas rate sensor, etc., and calculating the rotation angle from the reference azimuth and adding it to the reference angle. These orientation sensors
Although a highly accurate detection result can be obtained, there is a problem that the error becomes large.

As the azimuth sensor of the navigation system for automobiles, a satellite system or a road beacon may be used. However, an error occurs depending on the reception condition.

[0006]

In the above-mentioned conventional traveling azimuth detecting device, a method of avoiding the accumulation of errors by using the rate type azimuth sensor for occasional correction to solve the above problem is used. In this correction method 1, there is a method for the driver to correct, but it is necessary for the driver to perform complicated work.
There is a problem in reliability due to individual differences among drivers.

Since it is necessary to detect the absolute azimuth for correction, it is preferable to use a geomagnetic sensor. However, since the geomagnetic sensor has an error due to the disturbance as described above, if the output of the geomagnetic sensor is directly corrected, the error increases. Therefore, in view of the above problems, the present invention provides a rate sensor, a geomagnetic sensor,
It is an object of the present invention to realize an azimuth sensor that can obtain highly accurate detection results for a long time by mutually complementing the problems of satellite systems, road beacons, and the like.

[0008]

In order to solve the above-mentioned problems, the present invention provides a vehicle heading compensating device having a geomagnetic sensor for detecting geomagnetism and outputting a heading calculated from the direction of the detected geomagnetism. A rate sensor, a measured vehicle traveling azimuth calculating means, a vehicle traveling corrected azimuth output means, a correcting means, and a vehicle traveling corrected azimuth valid determining means are provided. The rate sensor detects the rotation speed, calculates the rotation angle from the reference azimuth, and outputs the azimuth obtained by adding the rotation angle to the reference azimuth. The measurement vehicle traveling azimuth calculating means outputs a measurement vehicle traveling azimuth by weighted averaging the azimuth output by the geomagnetic sensor and the azimuth output by the rate sensor. The vehicle traveling correction azimuth output means outputs a vehicle traveling correction azimuth from the outside. The correction means derives a final corrected azimuth by weighted averaging the measured vehicle traveling azimuth from the measured vehicle traveling azimuth calculating means and the corrected azimuth from the vehicle traveling corrected azimuth output means. The vehicle traveling correction azimuth validity determining means determines whether the vehicle traveling correction azimuth from the outside of the vehicle traveling correction azimuth output means is valid and selectively outputs the measured vehicle traveling azimuth or the final corrected azimuth.

Further, in place of the vehicle traveling correction azimuth validity determining means, a correction for setting the weighted average of the weighted average in the correcting means as a function of the validity of the vehicle traveling azimuth from outside the vehicle traveling correction azimuth output means. You may make it provide a direction effectiveness detection means. The reference azimuth of the rate sensor may be updated with the final corrected azimuth of the correction means.

[0010]

According to the traveling direction detecting device of the present invention, the geomagnetism is detected in order to output the direction calculated from the direction of the geomagnetism detected by the geomagnetic sensor. The rotation speed is detected by the rate sensor, the rotation angle from the reference azimuth is calculated, the rotation angle is added to the reference azimuth, and the azimuth is output. The measurement vehicle traveling azimuth calculating means outputs a measurement vehicle traveling azimuth by weighted averaging the azimuth output by the geomagnetic sensor and the azimuth output by the rate sensor. The vehicle traveling correction azimuth output means outputs the vehicle traveling correction azimuth from the outside. The correction means derives a final corrected azimuth obtained by weighted averaging the measured vehicle traveling azimuth from the measured vehicle traveling azimuth calculating means and the corrected azimuth from the vehicle traveling corrected azimuth output means. The vehicle traveling correction azimuth validity determining means determines whether the vehicle traveling correction azimuth from the outside of the vehicle traveling correction azimuth output means is valid and selectively outputs the measured vehicle traveling azimuth or the final corrected azimuth. Therefore, for example, GSP (Global Ps
ition system), road beacons, and map matching can be used to correct the vehicle heading correction heading, thus reducing heading errors.

Further, the weighted average of the weighted averages in the correction means is detected by the corrected azimuth effectiveness detection means in place of the vehicle travel corrected azimuth validity determination means, and the effectiveness of the vehicle travel azimuth from outside the vehicle travel corrected azimuth output means is determined. Is set as a function. Therefore, flexibility can be obtained in the above configuration. Further, by updating the reference azimuth of the rate sensor with the final correction azimuth of the correction means, the rate sensor can be initialized also by the correction azimuth from the outside,
Furthermore, the error in the traveling direction can be reduced.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a vehicle signal bearing correction device according to a first embodiment of the present invention. The traveling direction detection device shown in this figure detects the rotational speed of a geomagnetic sensor, a vibration gyro, an optical fiber gyro, a gas rate sensor, etc. that detects the geomagnetism on the earth and outputs the absolute direction, and the rotation angle from the reference direction. Azimuth sensor 1 including a rate sensor or the like for calculating the azimuth by calculating
And a measurement vehicle traveling direction calculating means 2 for calculating the measurement vehicle traveling direction from the geomagnetic sensor and the rate sensor of the various direction sensors 1, and from the outside, for example, a GSP (Global Position).
System), on-road beacon, vehicle advancing correction orientation output means 3 for outputting vehicle advancing orientation from map matching,
From the measured vehicle traveling azimuth data θm from the measured vehicle traveling azimuth calculation means 2 and the azimuth data θc from the vehicle traveling corrected azimuth output means 3, a final corrected azimuth θm1 is obtained, θm1 = k · θc + (1-k) · θm (0 ≦ k ≦ 1) ... (1) as a correction means 4 which is derived by a weighted average, and a vehicle travel correction azimuth validity determination means 5 which determines whether the azimuth data θc of the vehicle travel correction azimuth output means 3 is valid. A switch 6-1 for selectively outputting the azimuth data θm from the measurement vehicle traveling azimuth calculating means 2 or the final correction azimuth θm1 from the correcting means 4 to the navigation system body by the vehicle traveling corrected azimuth validity determining means 5. And 6-2.

Next, the measuring vehicle traveling direction calculation means 2 will be described. When the digital output signal of the rate sensor in the various direction sensors 1 is Δθ and the direction by the rate sensor is θi, the following formula is established. θi = θi-1 + Δθ (2) The above equation θi-1 is initialized to the measured vehicle signal direction θm described later every predetermined time. Next, the digital output signal from the geomagnetic sensor is set to θm0, and θi from the rate sensor is weighted average to perform the signal processing to obtain the following measured vehicle signal direction θm.

Θm = k1 · θm0 + (1−k1) · θi; (0 ≦ k1 ≦ 1) (3) Here, the weighting factor k1 will be described. Immediately after the rate sensor is initialized by the above equation, the weighting factor k1 is increased, and the weighting factor k1 is decreased over time. As described above, this is because the rate sensor can detect with very high accuracy in a short time, so initially increase the weighting factor k1,
During this time, the influence of the error of the geomagnetic sensor can be reduced. When the operation time becomes long and the error of the rate sensor becomes large, the weighting factor k1 is gradually decreased to reduce the influence of the rate sensor.

As described above, the geomagnetic sensor has a large error due to disturbances caused by the magnetization of the vehicle body, bridges, elevated roads, railways, large structures, etc., but it was previously investigated whether these structures or their affected areas were affected. However, the stability of each region is stored in advance on the map of the navigation system body. Then, the weighting factor k1 is obtained from the stability of the running area. In other words, this weighting factor k1 is stable in areas where the geomagnetic sensor detection results are stable and the error is small. If the contribution ratio of the geomagnetic sensor is increased and is unstable, the contribution ratio of the geomagnetic sensor is decreased and the contribution ratio of the lator sensor is increased. Thus, the error due to the disturbance due to the magnetization of the vehicle body can be reduced.

Next, the vehicle traveling correction direction output means 3 will be described. The vehicle traveling corrected azimuth output means 3 includes a GSP receiver including a GSP antenna, a radio frequency unit (RF), a decoder unit, and the like when the corrected azimuth input from outside is GSP. Further, when the corrected heading input is a road beacon or a sign post, the vehicle traveling corrected heading output means 3 may include a beacon composed of an antenna, a radio frequency section (RF), a decoder section, and a sign post receiver.

In the case of road map data as the corrected azimuth input, the vehicle traveling corrected azimuth output means 3 is a set of devices such as road map data, a road map data reading device, and a device for identifying the road currently traveling from the road map data. , That is, a part of the location system using map matching may be included. Next, the vehicle traveling correction azimuth validity determining means 5 will be described. When the correction direction input from the outside is GSP, the vehicle travel correction direction validity determining means 5 determines the correction degree from parameters such as the effective reception number of GSP satellites and the geometric position error (PDOP value) of the GSP satellites. To do.

In the case of a road beacon or a sign post,
The correction effectiveness is determined from parameters such as reception intensity and reception error rate. In the case of road map data, the correction effectiveness is determined from parameters such as the length (linearity) of the identified road and the certainty of identifying the road. The vehicle traveling correction azimuth validity determining means 5 outputs the corrected azimuth .theta.c to the correcting means 4 when it determines that the correction azimuth is valid from the above parameters, and at the same time switches the switches 6-1 and 6-2 to calculate the measured vehicle traveling azimuth. The measuring vehicle traveling direction θm is inputted from the means 2 to the correcting means 4. If the corrected azimuth θc cannot be determined to be valid from the above parameters, the measured vehicle advancing azimuth θm from the measured vehicle advancing azimuth calculating means 2 is output as it is.

In the correction means 4, a predetermined weighting factor k is substituted into the above equation (1) from the corrected azimuth θc and the measured vehicle advancing azimuth θm to obtain the final corrected azimuth θm1,
If the corrected azimuth θc is valid in the vehicle traveling corrected azimuth validity determination means 5, the final corrected azimuth θm1 is output. Therefore, the accuracy of the azimuth is improved. Further, at the same time, it is fed back to the measurement vehicle traveling azimuth calculation means 2, and θ in the above equation (2) is calculated.
i-1 is initialized to the final corrected azimuth θm1. Therefore, the direction in which the error is small for a certain period can be provided by the rate sensor thereafter, not only when the corrected heading such as GSP is valid from the vehicle traveling corrected heading output means 3 but also when the corrected heading is not valid. That is, in the past, the rate sensor was initialized only by the azimuth mainly including the geomagnetic sensor, but according to the present embodiment, the rate sensor can be initialized by the corrected azimuth from the outside. The error of can be reduced.

FIG. 2 is a diagram showing a vehicle heading correction device according to a second embodiment of the present invention. In this figure, FIG.
In the first embodiment, the switches 6-1 and 6-2 are removed so that the correction is always performed by the correction means 4. The correction effectiveness is obtained from the parameter from the output means 3, the weighting factor k of the above equation (1) is determined, and the weighting coefficient k is output to the correction means 4. The function and effect are similar to those of the first embodiment.

FIG. 3 is a diagram showing one specific example of the second embodiment. The various azimuth sensors 1 of the traveling azimuth detecting device shown in the figure include a geomagnetic sensor 11 and a gyro sensor 12,
A / D converter 14 for converting analog input signals of the geomagnetic sensor 11 and the gyro sensor 12 into digital signals
And 15 (Analog to Digital Converter), a vehicle speed pulse sensor 13 that generates a pulse according to the traveling distance, and a counter 16 that counts the pulses from the vehicle speed pulse sensor 13.

The measured vehicle traveling azimuth calculating means 2, the vehicle traveling azimuth correction azimuth output means 3, the correcting means 4, the vehicle traveling azimuth effectiveness detecting means 7 and the like are constituted by a CPU (central processing unit),
For example, the vehicle traveling correction direction output unit 3 is formed by a map matching processing unit. The map matching processing unit 3 stores a road map information in a CD-ROM (Compact Disk-Read).
Only Memory) 8 and the CD in the map matching processing unit 3
-CD-RO that controls the output of information from ROM 8
An M control device 9 and an operation unit 10 for issuing various commands to the map matching processing unit 3 are provided.

In the map matching processing section 3, the correction means 4 is used.
Based on the final corrected azimuth .theta.m1, the current position is obtained from the traveling distance of the vehicle together with the corrected azimuth .theta.c, and the matching is evaluated by automatically finding the error while comparing with the map information from the CD-ROM 8. This evaluation stage is, for example, h
It is performed in stages (0 to 255 stages). The vehicle traveling azimuth effectiveness detecting means 7 obtains the weighting coefficient k as k = h / 255, and the correcting means 4 receives the weighting coefficient k.
Is set.

This evaluation is performed based on the certainty of identifying the road in the map matching. For example, first, whether or not a vehicle is present on a specific road is determined by the magnitude of the difference between the orientation on the map obtained by map matching of the current position and the orientation obtained by the present device. The smaller the difference, the higher the effectiveness of the correction. Second, the effectiveness of the correction is high if the past road and the road to be evaluated are connected. If the road is broken, its effectiveness is low. Thirdly, the smaller the distance between the current position using the azimuth data and the road, the higher the effectiveness of the correction. This distance is large The effectiveness is low. Fourth, the effectiveness of the correction is high when the road to be evaluated is long. This is because the shorter the error, the larger the error. When the effectiveness of the correction is the highest in the above comprehensive evaluation, h = 255, and the lowest is h =
It becomes 0.

[0025]

As described above, according to the present invention, the azimuth output by the geomagnetic sensor and the azimuth output by the rate sensor are weighted and averaged to output the measured vehicle advancing azimuth. A final correction azimuth obtained by weighted averaging vehicle travel correction azimuths is derived, it is determined whether the vehicle travel correction azimuth from the outside is valid, and the measured vehicle travel azimuth or the final correction azimuth is alternatively output. As a result, it becomes possible to reduce the bearing error.

[Brief description of drawings]

FIG. 1 is a diagram showing a vehicle signal bearing correction device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a vehicle traveling direction correction device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing one specific example of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Various azimuth sensors 2 ... Measuring vehicle advancing azimuth calculation means 3 ... Vehicle advancing correction azimuth output means 4 ... Correction means 5 ... Vehicle advancing correction azimuth validity determining means 6-1, 6-2 ... Switch 7 ... Vehicle advancing azimuth effectiveness Detecting means 8 ... CD-ROM 11 ... Geomagnetic sensor 12 ... Gyro sensor

Claims (3)

[Claims] 1. A geomagnetic sensor (1) for detecting geomagnetism and outputting an azimuth calculated from the direction of the detected geomagnetism.
In the vehicle traveling direction correction device having 1), the rotation speed is detected and the rotation angle from the reference direction is calculated,
A rate sensor (12) that outputs an azimuth obtained by adding a rotation angle to a reference azimuth, a azimuth output by the geomagnetic sensor (11), and a weighted average of the azimuths output by the rate sensor (12) to measure a vehicle traveling azimuth Measuring vehicle traveling azimuth calculating means for outputting (2)
A vehicle traveling correction azimuth output means (3) for outputting a vehicle traveling corrected azimuth from the outside; a measured vehicle traveling azimuth and the vehicle traveling corrected azimuth output means (3) from the measured vehicle traveling azimuth calculating means (2); A correction means (4) for deriving a final correction azimuth from the correction azimuth by means of a weighted average and a vehicle traveling correction azimuth from the outside of the vehicle traveling correction azimuth output means (3) are judged to determine whether the measured vehicle traveling is effective. A traveling azimuth detecting device, comprising: a vehicle traveling correction azimuth valid determining means (5) for selectively outputting the azimuth or the final corrected azimuth. 2. A vehicle advancing direction from outside the vehicle advancing correction orientation output means (3) instead of the vehicle advancing correction orientation valid determining means (5), the weighted average weighting coefficient in the correcting means (4) is used. The traveling azimuth detecting device according to claim 1, further comprising a corrected azimuth effectiveness detecting means (7) for setting the effectiveness of the azimuth as a function. 3. The final correction azimuth of the correction means (4),
The traveling direction detection device according to claim 1, wherein the reference direction of the rate sensor (12) is updated.