JPH04273301A - Automatic vehicle driving device - Google Patents

Abstract

PURPOSE:To attain the precise and smooth automatic drive of a vehicle along a white line with an automatic vehicle driving device by controlling the relative displacement value between the vehicle and the white line and the angle of the vehicle formed to the white line-respectively. CONSTITUTION:A white line is photographed by the CCD cameras 10 and 11 at a prescribed front-attention distance and supplied to an arithmetic processing circuit 14. At the same time, a speed sensor 16 detects the speed. The circuit 14 calculates the relative displacement value (e) between the vehicle and the white line and also the time change value de/dt of the value (e). Furthermore the circuit 14 has an access to a memory 30 to calculate the control gain value according to the distance from the white line and the speed and then calculates a steering angle from theta= KP.e+Ke.de/dt. The value de/dt shows an angle formed to the white line, and the vehicle is driven along the white line with control of the angle shown by the de/dt.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an automatic driving system for a vehicle, and in particular, to detecting relative displacement between a white line laid on a road and a vehicle.
The present invention relates to an automatic vehicle driving system that controls the steering of a vehicle based on the detected relative displacement.

0002

2. Description of the Related Art Various automatic driving devices have been developed for the purpose of reducing the burden on drivers. In this context, research is being conducted on autonomous driving in which steering wheel operations are performed automatically, and consideration is being given to equipping ordinary cars with mechanisms that allow for autonomous driving.

[0003] In order to carry out such automatic driving, it is necessary to constantly grasp the position of the vehicle with respect to the running track and to control the vehicle so that it runs along the running track. It has been proposed that a vehicle-mounted television camera take a picture of the white line in front of the vehicle, and control the steering of the vehicle based on the relative positional relationship between the white line and the vehicle.

[0004] In other words, roads usually have center lines and lines separating lanes, and if position detection for autonomous driving is based on white lines, roadside equipment can be made very simple. It is.

For example, Japanese Patent Application Laid-Open No. 60-37011 discloses a device that photographs a white line placed on the road a predetermined distance ahead using a television camera or the like and performs steering control based on the detected position of the white line. has been done.

[0006]

[Problems to be Solved by the Invention] Conventionally, a television camera or the like mounted on a vehicle photographs a white line a predetermined distance ahead, and the vehicle is steered based on the amount of relative displacement between the detected white line and the vehicle. However, the white line detected by the in-vehicle television camera is a white line located a predetermined distance from the vehicle. Therefore, for example, if the vehicle is traveling on an uphill road instead of a flat road, The detection distance will differ depending on the case.

Since the steering control system performs steering control based on the amount of relative displacement between the white line and the vehicle over a predetermined distance, if the detection distance of the white line differs in this way, accurate steering control cannot be performed and There was a problem with automatic driving along the lines.

[0008] Therefore, the applicant of the present application has proposed an automatic driving device that detects the distance to the white line and calculates the amount of steering based on the relative displacement amount and the distance to the white line.

However, the purpose of steering control is not only to eliminate the relative displacement of the vehicle with respect to the white line, but also to align the traveling direction of the vehicle with the direction in which the white line is laid. However, there was a problem in that it was not possible to perform smooth control that matched actual driving.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide an automatic driving system for a vehicle that is capable of performing smooth and accurate steering control along the white line.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the automatic driving device for a vehicle of the present invention includes a CCD sensor that photographs a white line and detects the amount of relative displacement between the vehicle and the white line;
The vehicle is characterized by having a calculation means for calculating the amount of change over time in the amount of relative displacement detected by the CD sensor, and a control means for calculating the amount of steering of the vehicle based on the amount of relative displacement and the amount of change over time in the amount of relative displacement. do.

0012

[Operation] The automatic driving device for a vehicle of the present invention has such a configuration, in which the CCD sensor detects the amount of relative displacement between the vehicle and the white line, and the calculation means calculates the change over time in this relative displacement amount. Calculate the amount. The amount of change in relative displacement over time indicates which direction the vehicle is facing with respect to the white line, and is a physical quantity that indirectly indicates the yaw angle of the vehicle.

Therefore, by determining the steering amount of the vehicle based not only on the relative displacement amount but also on the amount of time change in this relative displacement amount, the relative displacement amount with respect to the white line can be eliminated, and the direction in which the white line is laid and the direction in which the vehicle is traveling can be determined. can be matched.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the automatic vehicle driving system according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of this embodiment. Two CCD cameras 10 and 11 are mounted at predetermined positions on a vehicle and take pictures of the front direction of the vehicle. The CCD cameras 10 and 11 are arranged in parallel in the horizontal direction, and each has a plurality of CCDs (solid-state image pickup devices), and captures a linear image of the road ahead of the vehicle and outputs an image signal. And this CC
The image signals output from the D cameras 10 and 11 are converted into digital data by the A/D converter 12 and then supplied to the arithmetic processing circuit 14.

A schematic diagram of the configuration of the CCD cameras 10 and 11 is shown in FIG. 2, and a condenser lens 112 is provided on the front surface of a sensor case 110. The light L incident on the condenser lens 112 is focused on the one-dimensional CCD 114 and converted into an electrical signal according to the brightness of the incident light. The infrared filter 116 placed between the condenser lens 112 and the CCD 114 is used to eliminate errors caused by temperature in the CCD 114, and the aperture 118 is used to limit the light incident on the CCD 114 within a predetermined range. It is set up to limit.

[0017] As described above, a plurality of CCDs 114 in the CCD cameras 10 and 11 are arranged.
When the CCD cameras 10 and 11 photograph the road ahead, a linear area 120 as shown by the broken line in FIG. 3 will be detected. In addition, in FIG. 3, the white lines laid on the road are designated by reference numerals 122 and 124, respectively.

The arithmetic processing circuit 14 includes CCD cameras 10 and 1.
1 to process the image signal supplied from white line 122, 12.
4, but for this purpose, the input digital data is first compared with a predetermined threshold value, and when the input image signal is larger than the threshold value, it is judged as H, and when it is smaller than the threshold value, it is judged as L, and the binary value for each CCD bit is determined. Obtain conversion data.

[0019] Then, from this binarized data, L→H, H
→By finding the address of the CCD bit that becomes L, the position of the white line can be detected.

After the white line position is detected, the arithmetic processing circuit 1
Step 4 then calculates the amount of lateral displacement between a predetermined reference line of the vehicle (in this embodiment, a center line parallel to the longitudinal direction of the vehicle) and the detected white line. Here, as shown in FIG. 4, the amount of lateral displacement is determined by the intersection b between the detection line and the detected white line at the forward gaze distance L of the CCD cameras 10 and 11 from the vehicle position, and the intersection b between the detection line and the longitudinal center line of the vehicle. The distance e between the intersection a
Defined by In this embodiment, the CCD camera 10
, 11, the forward gaze distance L is set to 20 m.

Furthermore, in this embodiment, the vehicle speed sensor 1
6 is provided at a predetermined position, and supplies a vehicle speed signal SPD from this vehicle speed sensor 16 to the arithmetic processing circuit 14.

Furthermore, an automatic operation switch 20 is provided near the driver's seat of the vehicle, and by turning on this switch, the arithmetic processing circuit 14 supplies a control signal to the steering actuator 22 based on each input detection signal. It is the composition.

The arithmetic processing performed by this arithmetic processing circuit 14 will be explained below. In FIG. 5, CCD cameras 10 and 11 are shown.
The configuration and light amount profile of the CCD 114 inside are shown. Assuming that the images obtained by the left and right CCD cameras 10 and 11 are the standard part and the reference part, respectively, the lateral shift between the standard image projected onto the standard part and the reference image projected onto the reference part depends on the distance to the white line. The distance to the white line can be determined by reading the distance between the left and right images.

That is, if the output of the i-th element of the reference part is Si, and the output of the i-th element of the reference part is Ci, then if the deviation between the left and right images is exactly equal to the distance between the reference part and the reference part, then Si-Ci =0. However, in general, the CCD camera 10, 1
Since a lateral shift occurs due to the defocus of 1, the result is not necessarily 0.

[0025] Therefore, the sum of the absolute values of the differences in the outputs of the corresponding elements is calculated, and this sum is designated as A and used as a measure of the amount of correlation.

A(m)=Σ|(Si+k)−C(j+k+n)|where i is the number of the first element of the reference part and j is the number of the first element of the reference part. Moreover, k represents the k-th element counting from the first element of the standard part and the reference part.

Then, the data number of the reference part is fixed, the data number of the reference part is shifted one by one by m, and the relationship between the shift amount m and the correlation amount A(m) is calculated.

As is clear from the definition, the correlation amount A(
n) is a measure of the degree of mismatch between the left and right images. Therefore, the shift amount m that minimizes this correlation amount A(n) is the optimal shift amount with the highest correlation between the left and right images. Since the amount of image shift depends on the distance to the white line, the distance to the white line is calculated.

Generally, when the amount of deviation between the left and right images is n and the distance to the white line is R, the relationship is approximately R=c/n. However, c is a constant determined by the focal length of the condenser lens 112 and the element length of the CCD 114.

In this manner, the arithmetic processing circuit 14 calculates the distance R to the white line using the parallax between the CCD cameras 10 and 11, and further determines the control gain for steering control based on the distance R to the white line. . That is, as shown in FIG. 6, control gain values KP and Ke corresponding to a plurality of preset vehicle speed values and a plurality of predetermined distances are stored as a map in the memory 30, and the arithmetic processing circuit 1
4 accesses this memory 30 and selects a control gain value corresponding to the detected vehicle speed and distance.

Next, the arithmetic processing circuit 14 calculates the temporal change amount de/dt of the calculated relative displacement amount e. If this temporal change is a large negative value, the relative displacement e
means that it is rapidly decreasing, and therefore the angle between the center line of the vehicle and the tangent to the white line is large, indicating that the vehicle is facing toward the white line. Furthermore, when the temporal change amount is a large positive value, it means that the relative displacement amount e is rapidly increasing, and therefore indicates that the vehicle is heading in the opposite direction to the white line.

In this way, by calculating the temporal change amount de/dt of the relative displacement amount e, and indirectly monitoring the angle formed between the vehicle and the white line, the relative displacement amount and the traveling direction of the vehicle can be determined. It becomes possible to quickly control to a desired value.

That is, using the calculated relative displacement amount e, the temporal change amount de/dt of the relative displacement amount, and the control gains KP and Ke read from the memory 30, θ=K.
The steering angle θ of the front wheels is calculated from P ・e+Ke ・de/dt. However, the neutral position is 0
Right steering is defined as +, and left steering is defined as -. Here, the first term on the right side is a term that controls the amount of relative displacement between the vehicle center line and the white line, and the second term on the right side is a term that controls the angle formed between the vehicle and the white line.

In this way, in this embodiment, as shown in the control flowchart of FIG. 7, the white line is detected and the relative displacement amount is calculated (S101), and the difference with the relative displacement amount one step before is calculated. By doing this, the amount of change over time is calculated (S102), the steering angle is calculated (S103), and an instruction is given to the steering actuator 22 (S104) to perform steering control, and the steering is controlled accurately and smoothly along the white line. can be controlled.

FIG. 8 shows the simulation results when the vehicle is automatically steered along a predetermined white line using the configuration and control of this embodiment. The assumed curve was 90R, the vehicle speed was 100 km/h, and the control time was 100 ms. In the figure, the horizontal axis shows the traveling distance in the X-axis direction, and the vertical axis shows the traveling distance in the Y-axis direction. Further, the traveling course of the vehicle, the current steering angle, the relative displacement amount, the vehicle yaw angle, and the yaw rate are shown on this XY map. For comparison, FIG. 9 shows simulation results when only the amount of relative displacement with respect to the white line is controlled (θ=K·e).

In both figures, if we focus on the changes in the steering angle and yaw rate, we can see that when only the relative displacement amount is controlled, an overshoot occurs and the vehicle is steered in the opposite direction and travels in a meandering manner, but the relative displacement amount and its time are It can be seen that when the amount of change is controlled, this problem does not occur and the vehicle runs smoothly along the white line.

In this embodiment, the control gain is changed according to the vehicle speed, but the time change amount may be calculated by changing the difference calculation time according to the vehicle speed.

Furthermore, the inventor has found that the simulation results of this embodiment give almost the same results as when control is actually performed by detecting the angle formed between the vehicle and the white line, and therefore, a separate angle detection sensor, etc. This has the effect that control can be performed without the need to provide a

[0039]

[Effects of the Invention] As explained above, according to the automatic driving device for a vehicle according to the present invention, steering control is carried out taking into account the amount of change in relative displacement over time, so that the vehicle can be steered accurately and along the white line. This enables smooth automatic driving.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of an embodiment of an automatic driving device for a vehicle according to the present invention.

FIG. 2 is a configuration diagram of a CCD camera of the same embodiment.

FIG. 3 is an explanatory view of the field of view of the CCD camera of the same embodiment.

FIG. 4 is an explanatory diagram of the amount of forward displacement in the same embodiment.

FIG. 5 is an explanatory diagram of the detection output of the CCD of the same embodiment.

FIG. 6 is an explanatory diagram of a control gain value map of the same embodiment.

FIG. 7 is a control flowchart diagram of the same embodiment.

FIG. 8 is an explanatory diagram of simulation results of the same example.

FIG. 9 is an explanatory diagram of simulation results of a comparative example in the same example.

[Explanation of symbols]

10,11 CCD camera 14 Arithmetic processing circuit 22 Steering actuator 122,124 White line

Claims (1)

[Claims] Claim 1: An automatic driving device for a vehicle that detects a white line laid on a road and controls the steering of the vehicle based on the amount of relative displacement between the vehicle and the detected white line, which photographs the white line and detects the distance between the vehicle and the white line. a CCD sensor that detects the relative displacement amount of the CCD sensor;
It is characterized by comprising: a calculation means for calculating the amount of change over time in the amount of relative displacement detected by the sensor; and a control means for calculating the amount of steering of the vehicle based on the amount of relative displacement and the amount of change over time in the amount of relative displacement. Automatic driving equipment for vehicles.