JPH04245600A - Radar system collision warning equipment for automatic vehicle - Google Patents

Abstract

PURPOSE:To prevent an unnecessary and troublesome alarm from being raised when it enters into an avoiding operation and it is expected that it is possible to be avoided even when an obstruction is detected in front concerning a radar system collision warning equipment for automatic vehicle. CONSTITUTION:In radar system collision warning equipment for automatic vehicle providing a radar device to detect distance from a certain object in fixed angle range and relative speed, a traveling speed detecting means 2, a danger discriminating means 4 to discriminate whether the danger of collision exists or not based on the above mentioned data and a warming means 5, a steering angle detecting means 3 is provided and a feature is made that the danger discriminating means 4 moreover discriminates whether the object is possible to be avoided from a steering angle.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a radar-type collision warning system for automobiles, which does not generate troublesome warnings, especially after entering collision avoidance operation or when driving normally on a curved road. The present invention relates to a radar-type collision warning system for automobiles.

0002

[Background Art] In order to prevent automobile collisions, it is detected whether there is an object considered to be an obstacle within a predetermined range in front of the vehicle, and if such an object is present, a warning is sent to the driver. Devices that alert people by giving them warning signs are beginning to be used. In such a device, it is necessary to detect the presence or absence of an obstacle in front, and various detection methods have been proposed, but a radar device is generally used.

[0003] Millimeter waves and laser light are used as electromagnetic waves as a medium for radar. Radar devices include pulse radar, CW radar, and FM-CW radar depending on the signal format, but in any case, the radar device is equipped with a distance to an object within the detection angle range corresponding to the angle range of the emitted radar beam. It is possible to detect the relative speed of the object being moved.

FIG. 7 shows the configuration of a conventionally used radar type automobile collision warning system. 1d is a radar device, which is installed toward the front of the vehicle body. 2d is a wheel speed sensor that detects the running speed of the own vehicle. 4d is a danger determination processing unit, and the radar device 1d
The system determines whether there is a risk of collision based on the distance and relative speed to the detected obstacle and the vehicle's traveling speed, according to predetermined conditions. If it is determined that there is a risk of collision,
The alarm 5d issues a warning to the driver.

[0005] The radar device used in such devices detects the distance and relative speed of an object within the radar beam, as described above, and does not detect the size of the object or its position within the radar beam. Generally speaking, this is not possible. If the radiation angle of the radar beam is too large, objects around the driving route, such as structures and street trees on both sides of the road, will be detected as obstacles, resulting in a warning being issued even though there is no risk of collision. . Therefore, the spread angle of the radar beam is 2
° degree is used. With this spread angle,
The radar beam becomes 3.5m wide at 100m ahead.

[0006]

[Problem to be Solved by the Invention] In order to prevent false alarms in which a warning is issued even though there is no danger of collision as described above, the spread angle of the radar beam is made as small as possible. When driving on a curved road or turning at an intersection, an object will come within the range where the radar device determines that there is a risk of collision. Therefore, an alarm will always be issued in such cases. When turning at an intersection, the warning will stop once the vehicle has passed the intersection, but if the road continues to curve as shown in Figure 8, the warning may remain on, which is extremely troublesome.

Therefore, when driving on a curved road, there is a method to prevent false alarms by mechanically or electrically changing the direction of the radar beam depending on the direction of the tires relative to the direction of the vehicle body, that is, the steering angle. Proposed. However, such devices have the problem of being complicated and increasing costs. In addition, when driving on a road that curves with a certain curvature, the distance to the obstacle detected by the radar beam is constant, and the relative speed detected is equal to the vehicle's own speed. A method has also been proposed in which when the relative speed is constant and the relative speed is equal to the own vehicle speed, it is regarded as a curve and no warning is generated. However, although this method is good when there is an object such as a wall, it still has the problem of generating false alarms when there are continuous pillar-shaped objects such as utility poles.

The present invention has been made in view of the above problems, and even if the radar device detects an object in a range where it is determined that there is a risk of collision, the avoidance operation has already been started and the avoidance operation is not completed. It is an object of the present invention to realize a collision warning device that does not generate unnecessary warnings when it is determined that it is possible.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the radar-type automobile collision warning system of the present invention detects the direction of the tires of the automobile, that is, the steering angle, and calculates the predicted direction based on the steering angle. Determine whether the object ahead can be avoided on the driving route. FIG. 1 is a diagram showing the basic configuration of a radar-type automobile collision warning system according to the present invention. In other figures, similar functional parts are represented by the same numbers with lowercase letters.

That is, the radar-type automobile collision warning system of the present invention includes a radar device 1 that is installed facing forward and detects the distance and relative speed of an object within a predetermined angular range;
A traveling speed detection means 2 that detects the traveling speed of the own vehicle; a danger determining means 4 that determines whether there is a risk of collision based on the distance and relative speed of the object detected by the radar device 1 and the traveling speed of the own vehicle. and a warning means 5 that issues a warning to the driver when the danger determination means 4 determines that there is a risk of collision. A steering angle detection means (3) for detecting a certain steering angle is provided, and a danger determination means 4 is provided.
This is a radar-type collision warning system for an automobile, which further determines whether the object can be avoided based on the steering angle, and then determines whether to generate an alarm.

[0011]

[Operation] Conventionally, the danger determination means 4 determines whether there is a risk of collision based on the distance and relative speed to the object detected by the radar device 1 and the own vehicle speed detected by the traveling speed detection means 2. Therefore, even if the driver had already turned the steering wheel to avoid an object in front of him on a curved road or at an intersection, the warning means 5 would issue an alarm. However, in the radar type automobile collision warning system of the present invention, the steering angle detection means 3 detects the steering angle, which is the direction of the tires, and the danger determination means 4 calculates the expected travel trajectory based on this steering angle. After further determining whether it can be avoided, a warning is issued only if it is determined that it cannot be avoided. Therefore, unnecessary warnings are not issued when the driver turns the steering wheel to take an evasive action, or when the vehicle is on a curved road or at an intersection, and the driver can concentrate on driving, which is favorable from a safety standpoint.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the structure of an embodiment of the radar type collision warning system for automobiles according to the present invention. 1a is a radar device, and here an FM-CW type radar device using millimeter waves is used, but other laser radars have a predetermined detection angle range and the distance to objects within that range. A radar device that can detect relative speed is sufficient. 2a is a wheel speed sensor that detects the running speed of the own vehicle. A steering angle detector 3a detects a steering angle corresponding to the direction of the tires. 5a is an alarm sound generator for generating an alarm sound, and the alarm sound is generated from a speaker 51a.

In this embodiment, all processes necessary for reading data from each detector and determining the risk of collision are performed by a microcomputer system. 6a is a microcomputer, 7a is a ROM, and 8a is a RAM. First, the radar device 1a will be explained. Radar device 1a
is an FM-CW type radar that uses millimeter waves, and its basic configuration is shown in Figure 3. 11b is an FM modulator, 12b
is an oscillator, and 13b is a transmitting antenna. Radio waves emitted from the transmitting antenna 13b are reflected by the object 18b and captured by the receiving antenna 14b. A mixer 15b mixes the reflected signal captured by the receiving antenna 14b with the original transmitted signal. 16b is an amplifier, and 17b is an analyzer. The analyzer 17b determines the distance D and relative velocity v to the object 18b.

As shown in FIG. 4, the radio waves output from the transmitting antenna 13b are expressed as fO, with the center frequency being fO.
Suppose that it is modulated and output at a period of 1/fm in the range of +ΔF/2 and fO -ΔF/2. When the reflected wave signal and the transmitted signal are mixed in the mixer 15b, the transmitted frequency is lowered.
In the down period and the increasing fup period, a signal with a frequency as shown in FIG. 4 is obtained. These can be expressed numerically as follows.

[0015]

[Math 1]

If fdown and fup are measured from the above equation, since ΔF, fm and fO are known, the distance D and relative velocity v to the object can be determined. Next, a description will be given of how to determine whether the detected object is avoidable. FIG. 5 is a diagram for explaining this relationship. As described above, in this radar device, the emitted radar beam has a spread angle θB, and when the object 18c is within the radar beam, the distance D and relative velocity vs to the object 18c can be detected. However, the size of the object 18c and its position within the radar beam cannot be detected. Therefore, in this embodiment, the object 18
Assume that the magnitude of c is equal to the width of the radar beam. Then, the width W of the object 18c is expressed by the following equation. W=2Dtan θB /2 Furthermore, the radius of rotation R is determined from the steering angle of the vehicle 19c in which the alarm device of the present invention is mounted. Assuming there is no slippage between the tires and the road surface, the turning radius R is determined by the steering angle. Assuming that the vehicle 19c now draws a trajectory with a radius R centered on point O, the position of the object 18c is shifted by an avoidance amount L from the center of the object 18c, that is, the center of the radar beam. L is expressed by D and R as shown in the following formula. L=R-RCOS (sin -1D/R) From the above formula, L
If it is larger than W/2, it is considered that the collision can be avoided. Naturally, the width of the vehicle and other factors are also taken into consideration at this time, but their explanation will be omitted here.

Next, the processing performed by the microcomputer 6a for making the above determination will be explained based on the flowchart shown in FIG. In FIG. 6, step 104
108 are newly added parts according to the present invention, and other than that, the processing is the same as in the conventional alarm device. In step 101, the presence or absence of an obstacle is read from the radar device 1a, and if an obstacle exists, the distance and relative speed to the obstacle are read. In step 102, these read data are processed, and in step 103, it is determined whether there is a risk of collision and it is necessary to output a warning. The processing up to this point is similar to that of conventional devices.

[0018] If it is determined that there is a risk of collision,
In step 104, the angle θB of the radar beam and the distance L
The width W of the object is calculated from the above formula. In step 105, the steering angle is detected, and in step 106
The expected travel route, that is, the turning radius R is calculated. In step 107, the avoidance amount L is calculated from the distance D to the object and the radius of rotation R. Then, in step 108, it is determined whether the collision can be avoided, and only when it is predicted that the collision cannot be avoided, a warning for the collision is generated in step 109.

In this embodiment, it is assumed that the width of the object that is an obstacle is equal to the width of the radar beam, but it may be assumed that it is twice or half the beam width depending on the spread angle of the radar beam. It's okay. Further, although the turning radius R was calculated only from the steering angle, the accuracy of the determination can be improved by calculating the turning radius by taking into account the vehicle running speed, tire slippage, and the like.

Alternatively, it may be determined whether the object is stationary based on the relative speed with the object and the traveling speed of the own vehicle, and the present invention may be applied only when the object is stationary.

[0021]

[Effects of the Invention] According to the present invention, even if there is an obstacle in front of the vehicle, the vehicle is in the process of avoiding the obstacle, and when it is expected that the obstacle can be avoided, a collision warning is not generated. An alarm device can be realized. This eliminates unnecessary and intrusive warnings when driving on curved roads or at intersections, allowing you to concentrate on driving.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a radar-type automobile collision warning system according to the present invention.

FIG. 2 is a diagram showing the configuration of an embodiment using a microcomputer for control.

FIG. 3 is a diagram showing the configuration of an FM-CW type radar used in the embodiment of FIG. 2;

FIG. 4 is a diagram illustrating the measurement principle and analysis method in the radar device of FIG. 3;

FIG. 5 is a diagram illustrating how to determine whether an obstacle can be avoided based on the relationship between the distance to the obstacle and the turning radius of the vehicle.

FIG. 6 is a flowchart showing processing by a microcomputer in the apparatus of FIG. 2;

FIG. 7 is a diagram showing the configuration of a conventional example of a radar-type automobile collision warning system.

FIG. 8 is a diagram illustrating driving in a place where there are obstacles along a curved road and detection of the obstacles by the radar device.

[Explanation of symbols]

1...Radar device 2... Traveling speed detection means 3...Steering angle detection means 4...Risk determination means 5...Alarm means 6a...Microcomputer

Claims (1)

[Claims] [Claim 1] A radar device (1) that is installed facing forward and detects the distance and relative speed to an object within a predetermined angular range, and a traveling speed detection means (2) that detects the traveling speed of the own vehicle. , a risk determining means (4) for determining whether there is a risk of collision based on the distance and relative speed to the object detected by the radar device (1) and the traveling speed of the own vehicle; and the risk determining means (4). In a radar-type collision warning system for automobiles, which is equipped with a warning means (5) that issues a warning to the driver when it is determined that there is a risk of a collision, the steering angle, which is the direction of the own vehicle's tires; The steering angle detecting means (3) is characterized in that the danger determining means (4) further determines whether the object can be avoided from the steering angle and then determines whether to generate an alarm. Radar-based collision warning system for automobiles.