JP2958020B2 - Travel control device for mobile vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a travel control for a mobile vehicle provided with attitude angle determining means such as a gyrocompass for determining an attitude angle of the own vehicle with respect to a reference direction. The present invention relates to an apparatus, and more particularly to an improvement in calibration of an output signal of the attitude angle determination means using stored map information.

(Prior Art) In order to perform autonomous traveling control or navigation traveling, it is indispensable to know the traveling direction (ie, attitude angle) of the own vehicle. Conventionally used methods for knowing the attitude angle include a method of receiving a specific radio wave from a ground station located at a predetermined position (Loran method) and a method of receiving a radio wave from artificial hygiene (GPS method) And there is a method using a gyro compass.

The method of using a gyrocompass has been widely spread, with the simplicity of the device. However, the gyro compass has an error. For example, in a gyrocompass using the principle of the coma, although the influence of a temperature change is small, an error generated due to drift due to the rotation of the earth becomes very large. In addition, a gas rate gyro or the like has a large temperature error.

As a conventional technique for correcting the error of the gyro compass, there is, for example, JP-A-62-14212. This Japanese Patent Application Laid-Open Publication No. Sho-A-59-210 relates to the calibration of a rate gyro having an offset or drift such as a gas rate gyro. This rate gyroscope detects the rotation angle by measuring the turbulence of the gas flow accompanying the rotation of the vehicle body with two temperature sensors, and the offset correction is performed at the time of stoppage due to the solid-state characteristics of the sensor. This is necessary because an analog output is output from the sensor. Drift correction is necessary because the offset value itself changes with the temperature change of the gyro body.

The calibration in this Japanese Patent Laid-Open Publication is to stop the vehicle completely at fixed time intervals and reset the gyro at that time. That is, if the vehicle is completely stopped, the outputs from the two temperature sensors must be equal, and if the vehicle is out of balance, it is all due to offset and drift, so Is used as an offset correction value or a drift correction value, the rate gyroscope will be calibrated.

However, the calibration in Japanese Patent Application Laid-Open No. Sho 62-14212 is not a calibration based on an absolute reference but a relative calibration. The reason is that errors are accumulated in the trajectory traveled before the reset is performed, and therefore, the position and attitude angle of the vehicle at the point where the reset is performed include the errors. Therefore, even if the amount of reset can be reduced to reduce the amount of error that occurs with future traveling, the error that has occurred in the past cannot be canceled.

Therefore, as a method of correcting not only the error caused by the temperature change and the influence of the rotation of the earth but also the absolute reference, the vehicle is placed in a specific booth whose direction and position are known. There is also proposed a method of performing a reset while stopping.

(Problems to be Solved by the Invention) However, a method of calibrating the attitude angle by resting the vehicle at the specific booth and performing the reset with respect to an absolute reference, for example, in a factory, etc. Can be applied only when the booth can be prepared, and it is practically impossible on a general road or the like. In addition, even if a vehicle equipped with a gyro compass is used in an area where such a special booth is prepared, the vehicle must be moved to the special booth, and it cannot be reset at any time. .

On the other hand, the absolute attitude angle can be determined by the above-mentioned Laurent method or GPS method, but as described above, there are problems in terms of cost and scale.

Therefore, the present invention has been proposed in order to eliminate the disadvantages of the above-described conventional example. The purpose of the present invention is to calibrate the attitude angle of the vehicle with respect to an absolute reference even if it is simple. An object of the present invention is to propose a travel control device for a mobile vehicle, which is enabled by using map information stored in the means.

(Means and Actions for Achieving the Object) The configuration of the present invention for achieving the above object includes: a storage unit that stores map information; A traveling control device for a mobile vehicle, comprising: an attitude angle determination unit that outputs a signal representing an attitude angle; an image input unit that inputs an image for recognizing an external world; and a setting based on map information from the storage unit. Based on the direction information and the image input from the image input means,
Direction recognition means for recognizing a direction of a predetermined image in the input image with respect to a reference direction of the own vehicle; and a posture angle for calculating a posture angle of the own vehicle with respect to the reference direction from the direction recognized with respect to the predetermined image. Calculating means, based on an attitude angle of the own vehicle with respect to the reference direction,
A calibration means for calibrating the signal from the attitude angle determination means, and a travel control means for performing travel control based on the calibrated signal.

The attitude angle determining means is, for example, a gyrocompass as shown in FIG. Further, the predetermined image is, for example,
An image representing a roadside of the road, wherein the direction recognizing means determines the direction of the predetermined image with respect to the reference by using the recognized predetermined image and direction information set from map information from the storage means. Can be recognized based on The azimuth with respect to the reference direction of the predetermined image and the attitude angle of the own vehicle with respect to the reference direction obtained from the recognized azimuth of the predetermined image reflect the error of the attitude angle determination means and calculate the error. be able to.

(Embodiment) With reference to the accompanying drawings, the present invention is applied to a traveling control system that detects a posture angle using a gyro compass using the principle of a top and performs traveling control based on the posture angle. An embodiment will be described.

FIG. 2 is a block diagram of the traveling control system of this embodiment. In the figure, reference numeral 10 denotes a camera, which captures an image of the outside world, and the image is stored in an image memory 11. Reference numeral 12 denotes an image processing unit that performs predetermined image processing on the image stored in the image memory 11. Reference numeral 13 denotes a gyro compass using a frame, which outputs a signal indicating the number of rotations with respect to a reference. This signal is converted to a digital value by the interface 14 and taken into the host computer 15.

Reference numeral 16 denotes a distance sensor attached to wheels or the like, which detects a traveling distance. Reference numeral 17 denotes a map storage device for storing map information and the like. Reference numeral 18 denotes a traveling control unit, which is a host computer
Inputting the attitude angle and the traveling distance calculated in 15, the steering actuator 19 and the accelerator actuator 20
To perform steering control and vehicle speed control.

In the travel control system shown in FIG. 2, the host computer 15 recognizes the position of the host vehicle based on the attitude angle obtained from the gyro compass 13 and the travel distance obtained from the distance sensor 16.

The host computer 15 compares the recognized vehicle position with the map information stored in the map storage device 17 to create a trajectory. Then, the steering angle and the accelerator opening are calculated from the track and the attitude angle of the own vehicle, and these are sent to the travel control unit 18.

: Calibrate the gyroscope 13 at a predetermined timing.

In the present embodiment, the predetermined timing is when the accumulated traveling distance detected by the distance sensor 16 reaches a constant value. It should be noted that this predetermined timing is detected that the host vehicle position recognized by the host computer 15 is inconsistent with the map information stored in the map storage unit 17 (for example, the recognized host vehicle position is not on the road). It may be when.

The calibration of the gyro is as follows. From the image obtained by the camera 10, for example, a road edge of a road is detected. Also,
Estimate the current position of the vehicle. This position is estimated based on the travel distance per unit time in the X direction and the Y direction from the travel distance per unit time and the attitude angle of the own vehicle per unit time.
It is obtained by obtaining X and ΔY and integrating them. Further, the map storage unit 17 is searched to select a road closest to the estimated position. Next, the direction of the road (the direction of the road obtained from this map is absolutely correct unless an erroneous road is searched for) is compared with the direction of the road end of the road obtained by image processing. Thus, the gyro compass 13 is calibrated. This calibration is possible because the direction of the roadside obtained by the above image processing is based on a coordinate system on which the gyro compass depends.

3A and 3B are diagrams for explaining the principle of this calibration. FIG. 3A shows an image of a road obtained when the gyro compass 13 has no error. At this time, it is assumed that the vehicle is at an attitude angle θ with respect to the geomagnetic north pole. That is, the road where the vehicle is located is shifted by θ degrees from the N pole, and the vehicle is positioned parallel to this road. At this time, the read value θ is obtained from the gyro compass 13. If the vehicle is located at the center of this road, the camera 10 is installed at the center of the vehicle, and its optical axis extends in front of the vehicle, the image stored in the image memory 11 Roadside is 3A
It is shown as shown. That is, the roadsides AB and CD are symmetric with respect to the center line XX of the image memory. When reverse perspective transformation is performed on this roadside image, the angle of the roadside camera with respect to the optical axis is 0 because the own vehicle is positioned parallel to the road.
Degrees, and the attitude angle of the host vehicle with respect to the N pole is θ.

FIG. 3B shows a case where the gyro compass 13 has an error.
This shows a case where the vehicle comes to the same position as in FIG. 3A. Using a gyro compass having an error, the vehicle is placed on the road so that the attitude angle with respect to the N pole is θ degrees (actually, it is θ ′ degrees because of the error). It is inclined at a certain angle α to the end. Since the vehicle is inclined α degrees with respect to the road, the image of the roadside is as shown in FIG.
A'B 'and C'D'. By applying the reverse perspective transformation to the roadside images A'B 'and C'D' as in the case of FIG. 3A, the attitude angle α of the own vehicle with respect to the road can be detected. In other words, the reading error コ ン (=
θ′−θ), that is, although the attitude angle with respect to the earth magnetism is actually θ ′, the gyro compass
Since the read value of 13 becomes θ, the attitude of the host vehicle with respect to the road is shifted by α degrees, so Δθ = α. Therefore, this α is used as a subsequent correction value.
If the read value of the gyroscope is θ _i degrees, the formal attitude angle with respect to the N pole is θ _i + △ θ degrees.

FIG. 4 is a flowchart showing a control procedure, which is executed by the host computer 15. Step S2
First, it is determined whether the gyro compass is to be corrected. This is, as described above, when the accumulated traveling distance detected by the distance sensor 16 has reached a fixed value, or when the host vehicle position recognized by the host computer 15 is in the map storage unit 17.
Is inconsistent with the map information stored in the vehicle (for example, the recognized position of the vehicle is not on the road).

When it is determined that the correction is not to be performed, the process proceeds to step S20 and thereafter, and the traveling control based on the gyro read value is performed. That is, at step S20, the designated value θ _i of the gyro compass 13 is read, and at step S22, the θ _i
To the previously calculated correction value し た θ. That is, θ _i + △ θ is obtained as a calibration value in the azimuth direction of the own vehicle. Based on this calibration value, predetermined traveling control is performed in step S24. That is, θ _i + θ and the distance sensor 16
Based on the travel distance obtained from the host computer 15, the host computer 15 recognizes the position of the vehicle, and compares the recognized vehicle position with the map information stored in the map storage device 17 to determine the attitude angle of the vehicle. Then, the steering angle and the accelerator opening are sent to the traveling control unit 18.

If it is determined in step S2 that it is time to make a correction, the process proceeds to step S4 and subsequent steps. First, in step S4, an image is input. In step S6, image processing such as binarization processing and labeling is performed to extract an image of a reference object indicating the direction of a roadside or the like. Then, in step S8, the attitude angle α of the own vehicle with respect to the reference object is calculated. If the attitude of the host vehicle with respect to the road when reading the image in step S2 is set to α ′ degrees based on the measurement result of the gyro compass, α−α ′ is directly used as an error. Component △ θ. In step S10,
A correction value is calculated based on this equation. In FIG. 3B, α ′
= 0 (that is, the vehicle was intended to be placed parallel to the road despite the error). This △ θ is used hereinafter as a correction value of step S22.

In this way, according to the above-described embodiment, the calibration can be performed so that the attitude angle of the own vehicle with respect to the geomagnetic N pole, that is, the attitude angle of the own vehicle with respect to the absolute reference can be obtained.
And, based on this accurate attitude angle, accurate driving control,
For example, it is possible to perform forward vehicle following control, navigation traveling control, and the like.

The present invention can be variously modified without departing from the gist thereof.

For example, in the control procedure shown in FIG. 4, the correction is performed in step S22 every time the indicated value of the gyro compass 13 is read, but the correction value is sent to the gyro compass 13 without doing so. The gyro compass 13 may send the corrected read value to the host computer 15.

In the embodiment shown in FIG. 2, the direction of the road is known from the map information stored in the map storage unit 17. Instead of this, for example, it is also possible to recognize an electric pole in an image and to know the azimuth of the own vehicle with respect to the N pole from the direction of the shadow of the electric pole. This is because the shadow of the telephone pole is a fixed value regardless of the season and longitude if the latitude and time of the vehicle are known.

In the above embodiment, the embodiment for correcting the attitude angle with respect to the geomagnetic north pole, that is, for correcting the attitude angle with respect to the absolute reference direction, has been described.
As in 62-14212, the present invention can be applied to the case where the purpose is calibration for a relative reference. That is, in the above embodiment, as described with reference to FIGS. 3A and 3B, the road on which the own vehicle is placed when capturing the image is assumed to have a known extension direction with respect to the N pole. . Because of this, an error in the gyro compass could be detected by detecting from the image how much the vehicle deviated from the road. Therefore, even if the azimuth angle of the road with respect to the N pole is not known, for example, the vehicle is placed parallel to the road, and the gyro compass reading at that time indicates the gyro compass error as it is. Become. This makes it possible to detect a relative error.

(Effect of the Invention) As described above, the traveling control device for a mobile vehicle according to the present invention uses the map information in which the azimuth of a predetermined image such as a roadside in the image of the outside world is stored in the storage unit. Utilizing the fact that it can be recognized, the output signal from the attitude angle determining means such as a gyro sensor is corrected.

That is, the traveling control device of the present invention recognizes the azimuth relative to the reference direction of a predetermined image such as a roadside, based on the direction information set from the map information from the storage unit and the input image of the outside world, The attitude angle of the own vehicle is calculated from the recognized orientation, and the output signal from the attitude angle determination means is calibrated based on the attitude angle of the own vehicle. Then, travel control is performed based on the calibrated signal.

Therefore, for example, it is possible to easily know the error of the attitude angle determining means such as a gyro compass or the like, so that accurate traveling control is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing the configuration of an embodiment system to which the present invention is applied, and FIGS. 3A and 3B are diagrams showing gyrocompass readings in the embodiment. FIG. 4 is a flowchart for explaining the principle of a method of deriving a correction value. FIG. 4 is a flowchart showing a control procedure of the embodiment. In the figure, 10: camera, 11: image memory, 12: image processing unit,
13 ... Gyro compass, 14 ... Interface, 15
... a host computer, 16 ... a distance sensor, 17 ... a map storage section, 18 ... a traveling control section, 19 ... a steering actuator, 20 ... an accelerator actuator.

────────────────────────────────────────────────── (5) References JP-A-60-84610 (JP, A) JP-A-63-124114 (JP, A) JP-A-64-54215 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G05D 1/02 G08G 1/0969

Claims (1)

(57) [Claims] 1. A mobile vehicle comprising: storage means for storing map information; and attitude angle determination means for outputting a signal representing the attitude angle of the vehicle with respect to a reference direction of the vehicle based on the running state of the vehicle. A travel control device, based on image input means for inputting an image for recognizing the outside world, direction information set from map information from the storage means, and an image input from the image input means. Direction recognition means for recognizing a direction of a predetermined image in the input image with respect to a reference direction of the own vehicle; and a posture angle for calculating a posture angle of the own vehicle with respect to the reference direction from the direction recognized with respect to the predetermined image. Calculating means; calibrating means for calibrating the signal from the attitude angle determining means based on the attitude angle of the own vehicle with respect to the reference direction; and running control for performing running control based on the calibrated signal. Traveling control apparatus for a mobile vehicle, characterized in that a means.