JPH0614400B2 - Inter-vehicle distance warning device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inter-vehicle distance warning device that warns of a degree of danger with respect to a distance to a vehicle traveling ahead.

2. Description of the Related Art Recently, as a safety measure for automobiles that mainly protects occupants, a radar is mounted on the automobile to constantly monitor the inter-vehicle distance and the relative speed with respect to the forward traveling vehicle, while preventing the collision of the vehicle with the forward traveling vehicle. Devices have been developed that alert the driver when entering a hazardous area.

Conventionally, as a device of this type, a radar device detects an inter-vehicle distance and a relative speed with respect to a vehicle traveling in front, and a traveling speed of the own vehicle is obtained by a velocity detector, and an appropriate inter-vehicle distance at that time is obtained from each obtained value A device has been developed that calculates a distance and issues a stepwise alarm according to the difference between the calculated appropriate inter-vehicle distance and the actual inter-vehicle distance (see Japanese Patent Application No. 54-94106). .

However, in such a case, since the warning is issued only according to the distance to the vehicle traveling in front, the degree of danger can only be indirectly notified to the driver. .

Aim The present invention has been made in consideration of the above points, and takes into consideration the traveling distance until the preceding vehicle depresses the brake and stops and the traveling distance until the host vehicle depresses the brake and stops. We provide an inter-vehicle distance warning device that can directly inform the driver of the degree of danger by determining the required inter-vehicle distance, and then issuing an alarm by determining the risk index of the collision with the vehicle in front. To do.

Further, the present invention provides an inter-vehicle distance warning device that maintains an appropriate inter-vehicle distance from a vehicle traveling in front by controlling acceleration / deceleration of the own vehicle in accordance with the degree of danger.

Configuration Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The inter-vehicle distance warning device according to the present invention, as shown in FIG. 1, includes an FM-CW radar device 1 that emits radio waves from an antenna ANT to detect an inter-vehicle distance and a relative speed with respect to a vehicle traveling ahead. The speed sensor 2 that generates a pulse signal corresponding to the traveling speed of the vehicle and the mode switching of the radar device 1 are controlled, and the number of pulse signals from the speed sensor 2 is counted to obtain the traveling speed of the vehicle. A signal processing device 3 which derives a risk index by a predetermined calculation based on each detection signal, and under the control of the signal processing device 3, an alarm display of a stepwise risk is performed according to the calculated risk index. And a display device 4 for display.

In such a configuration, the high-frequency signal sent from the radar device 1 to the antenna ANT becomes an electromagnetic wave and is emitted into the air, and the reflected wave from the vehicle traveling in front is received by the antenna ANT. . At that time, the radar device 1 sequentially executes each measurement in the FM-CW mode and the Doppler mode in a time division manner according to the mode switching command SW from the signal processing device 3. In the FM-CW mode,
It becomes possible to measure the inter-vehicle distance from the forward traveling vehicle by emitting a continuous wave that is frequency-modulated with a triangular wave of a constant period and then measuring the frequency difference from the reflected wave from the forward traveling vehicle at that time. Further, in the Doppler mode, it is possible to emit a non-modulated continuous wave and measure the relative speed with respect to the forward traveling vehicle based on the frequency difference from the reflected wave from the forward traveling vehicle at that time. Then, the signal processing device 3 reads the inter-vehicle distance detection signal S1 and the relative speed detection signal S2 sequentially sent from the radar device 1 and counts the pulse signal P sent from the speed sensor 2 for a certain period of time. After detecting the running speed of the own vehicle and calculating the risk index based on each of the detected values by the calculation process described below, the current risk class is selected from the classified levels according to the risk index. Then, an alarm display signal corresponding to the class is given to the display device 4 to display an alarm of the degree of danger. FIG. 2 shows a warning display screen of the degree of danger on the display device 4. Here, a bar graph type in which the risk class is divided into 5 levels is adopted. When the risk level is the smallest, the lowermost display section L1 is turned on, and the display sections L1 and L increase as the risk level increases.
2, L3, L4 are sequentially turned on, and when the degree of danger is highest, all the display parts L1 to L5 are turned on.

In order to perform the calculation process for obtaining the risk index, first, when the target vehicle is traveling in front of the own vehicle, the target vehicle may decelerate and then collide with the target vehicle when the target vehicle is stopped. Find the appropriate inter-vehicle distance required to be able to stop without stopping.

First, consider the mileage of the target vehicle. The initial speed of the target vehicle is Vx, the time when the target vehicle starts deceleration is 0,
Then, the negative acceleration (deceleration) is increased until time Tx at which sufficient deceleration is achieved, and thereafter, the acceleration αm (αm <αm <
It is assumed that the vehicle reaches 0 speed by performing the uniform acceleration operation of 0). T from the time the target vehicle starts decelerating until it reaches a sufficient deceleration
Assuming that the acceleration decreases from 0 to αm in proportion to time during x, the acceleration αt at time T (0 <T <Tx) is given by the following equation.

The velocity Vt at time T is given by the following equation.

Therefore, the distance Rx1 traveled by the time Tx is given by the following equation.

The velocity Vtx at time Tx is given by the following equation.

Next, since the vehicle travels at constant acceleration from time Tx to zero speed, the distance Rx2 traveled during that time is given by the following equation.

Therefore, the total travel distance Rx of the target vehicle is given by the following equation.

The third term on the right side of the equation (6) can be omitted because it takes a sufficiently small value as a whole.

Next, consider the mileage of your vehicle. The initial speed of the host vehicle is Vo, the time when the driver of the target vehicle confirms the deceleration of the target vehicle is time 0, the time when the driver depresses the brake to start deceleration is time Tf, and the acceleration of the vehicle is 0 to αn. It is assumed that the time when (αn <0) is reached is Td, and thereafter, the vehicle travels at a uniform acceleration of the acceleration αn and reaches the speed of 0. While assuming that the vehicle is traveling at a constant speed of Vo at the time T from 0 to Tf and the acceleration is decreased from 0 to αn in proportion to the time from the time Tf to Td, The traveling distance of the vehicle is calculated in the same manner as described above.

The traveling distance Ry1 up to 0 <T <Tf is given by the following equation.

Ry1 = Vo · Tf (8) The traveling distance Ry2 up to Tf <T <Td is given by the following equation.

The traveling distance Ry3 from T> Td to zero speed is given by the following equation.

Therefore, the total traveling distance Ry of the own vehicle is given by the following equation.

The third to fifth terms on the right side of the equation (11) can be omitted because they take a sufficiently small value as a whole.

Thus, when the target vehicle decelerates and then stops, the proper inter-vehicle distance Rs required for the own vehicle to stop without a rear-end collision is given by the following equation.

Rs = Ry−Rx (13) If the relative speed between the target vehicle and the host vehicle is Vs, the speed Vx of the target vehicle is given by the following equation.

Vx = Vo-Vs (14) Therefore, substituting the 14th equation into the 7th equation gives the following equation.

From the 12th and 15th equations, the proper inter-vehicle distance Rs is as follows.

Here, Tx = 0.25 seconds, Td = 1 second, αm = αn =
If it is -4.9 m / s ² , then Rs = 0.125Vs (2V ₀ -Vs) + 0.375V ₀ + 0.125Vs (17).

Here, the risk index indicates the current state of the running vehicle, is a guide for the driver to drive safely, and gives a warning to the driver when it is dangerous. However, there is no official regulation.

Generally, an appropriate inter-vehicle distance is an index for driving a car safely. The driver reads the speed of the vehicle with a speedometer, visually measures the distance to the vehicle traveling ahead, and visually senses the relative speed from the change speed of the distance to see if the current distance is appropriate. The decision is made. Therefore, if the danger index expresses in an easy-to-understand manner what the actual inter-vehicle distance is in relation to the inter-vehicle distance currently required by the running vehicle, it is suitable for the purpose.

In addition, it is considered that the easy-to-understand expression may be any expression as long as it is easy for the driver to easily understand, that is, it matches the actual feeling of a human. Considering human sensation, it has been proved by experiments that there are many absolute human sensations to various stimuli, but they are often proportional to the logarithmic conversion value obtained by comparison with the reference value (for example, loudness of sound). Etc.). Given that the same theory holds in this case as well, the risk index D can be defined as follows.

Therefore, when the own vehicle speed Vo and the relative speed Vs in the above equation are used and the actual vehicle separation is Ro, the risk index D is given by the following equation.

D = log [Ro / {0.102Vs (2Vo-Vs) + 0.375Vo + 0.125Vs}] ... (19) Thus, in the inter-vehicle distance warning device according to the present invention,
In order to display the degree of risk, which is the result of comprehensive judgment of various data for the vehicle traveling ahead and the vehicle,
The driver can immediately understand the content of the alarm, which helps to take appropriate measures promptly.

FIG. 3 shows another embodiment of the present invention. In this case, actuators 5 and 6 for controlling the driving of the brake 7 and the accelerator 8 of the vehicle under the control of the signal processing device 3 are provided. As described above, by appropriately controlling the brake 7 and the accelerator 8 according to the current degree of danger based on the risk index obtained by the signal processing device 3, it is possible to always maintain an appropriate inter-vehicle distance. I have to. That is, the signal processing device 3 determines acceleration / deceleration of the own vehicle from the risk index, calculates control amounts of the actuators 5 and 6, and issues drive commands to the actuators 5 and 6, and the actuators 5 and 6 Receiving each command, the brake 7 and the accelerator 8 are controlled to accelerate and decelerate the vehicle.

With such a configuration, the optimum acceleration (deceleration) is set in order to control the brake and the accelerator based on the risk index which is a comprehensive judgment of various data of the vehicle traveling ahead and the own vehicle. This makes it possible to perform control and is excellent in maintaining an appropriate inter-vehicle distance from the vehicle traveling ahead.

It should be noted that the inter-vehicle distance warning device according to the present invention is not limited to the above-mentioned embodiment at all, and it is also possible to use the danger level warning display means and the acceleration / deceleration control means of the own vehicle together. It is also possible to easily give a driver's attention by issuing a voice alarm at the same time as displaying the danger level warning.

As described above, in the inter-vehicle distance warning device according to the present invention, the traveling distance until the preceding vehicle depresses the brake and stops and the traveling distance until the host vehicle depresses the brake are taken into consideration. Directly determine the danger level to the driver by determining the appropriate inter-vehicle distance, and by issuing an alarm for a risk index that can express the risk of collision with a vehicle traveling in front according to the actual sense of the driver. It has an excellent advantage that the braking control of the own vehicle can be appropriately performed according to the driver's actual feeling according to the degree of danger.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an inter-vehicle distance warning device according to the present invention, FIG. 2 is a view showing an example of a display screen of a display device in the embodiment, and FIG. 3 is another embodiment of the present invention. It is a block block diagram which shows an example. 1 ... Radar device, 2 ... Speed sensor, 3 ... Signal processing device, 4 ... Display device, 5, 6 ... Actuator, 7
…… Brake, 8 …… Accelerator

Claims (2)

[Claims] 1. A means for detecting an inter-vehicle distance and a relative speed with respect to a preceding vehicle, a speed detecting means for detecting a traveling speed of the own vehicle, a relative speed with respect to each of the detected preceding vehicles and a traveling speed of the own vehicle. A signal processing means for obtaining a risk index by logarithmically converting a value obtained by calculating a proper inter-vehicle distance by a predetermined calculation on the basis of the vehicle-interval distance with the detected front-vehicle distance, based on An inter-vehicle distance warning device constituted by an alarm means for issuing a stepwise alarm in accordance with the obtained risk index. 2. A means for detecting an inter-vehicle distance and a relative speed with respect to a preceding vehicle, a speed detecting means for detecting a traveling speed of the own vehicle, a relative speed with respect to each of the detected preceding vehicles and a traveling speed of the own vehicle. A signal processing means for obtaining a risk index by logarithmically converting a value obtained by calculating the appropriate inter-vehicle distance by a predetermined calculation based on the above, and detecting the inter-vehicle distance with the preceding vehicle by the obtained appropriate inter-vehicle distance, An inter-vehicle distance warning device constituted by means for controlling the drive of the brake so as to decelerate the own vehicle in accordance with the obtained risk index.