JPH09150689A - Collision prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid unconscious collision at the super low speed running by preparing a warning signal when it is judged that the speed signal from a car speed sensor is nearly 0Km/h and the car to car distance between a front target and an own vehicle is getting to shorten and outputting it to a warning device. SOLUTION: A car speed sensor 31 is provided in a running state detection part 2 and a calculation circuit 41A and a distance set switch 42 are provided in a signal process part 3. The car speed signal of an own vehicle detected by the car speed sensor 31 is sent to the calculation circuit 41A, which judges the possibility of a collision to an obstacle based on the car speed signal. In a distance detection part, an order signal is received by a drive signal generation circuit 11 and a LD flash signal with a constant frequency is sent out to a driver 12 and a LD alley 13 is emitted in order. In this state, a relative acceleration is found out based on the difference between the car speed of a front vehicle and the car speed of the own vehicle and it is judged whether the car to car distance is changed by 0.2m or not in a approaching direction and a single warning is issued from an alarm 52 at every time to shorten by 0.2m.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to, for example, emitting a laser beam in front of a vehicle to measure an inter-vehicle distance to a vehicle ahead (a target object) and issuing an alarm when the vehicle approaches the vehicle ahead. , A collision prevention device for preventing a collision with a vehicle ahead of the collision prevention device.

[0002]

2. Description of the Related Art A conventional collision prevention device will be described by taking the collision prevention device shown in FIG. 7 as an example. In the figure, reference numeral 1 is a distance detection unit that detects a distance between a vehicle and an obstacle by using a laser beam emitted from a laser diode (hereinafter referred to as LD), and 2 is a vehicle speed such as a vehicle speed. It is a running state detection unit that detects a running state of the vehicle.

A reference numeral 3 designates a distance detection unit 1 to detect a distance, and based on the distance information returned in response thereto and the own vehicle speed information detected by the traveling state detection unit 2, the own vehicle, It calculates the relative speed with the obstacle such as the vehicle in front and judges whether the obstacle is a stationary object or a moving object, and also the individual vehicle speed, relative speed, and the free running time until the driver brakes. It is a signal processing unit that determines the possibility of collision between the host vehicle and an obstacle according to the distance setting or the like set according to the difference.

4 is based on the information from the signal processing unit 3,
This is an alarm notification unit that displays the distance between the host vehicle and the obstacle and issues an alarm when the signal processing unit 3 determines that there is a possibility of collision with the obstacle.

Next, the operation of the above configuration will be described. The traveling state detection unit 2 includes a vehicle speed sensor 31, and the signal processing unit 3 includes an arithmetic circuit 41 and a distance setting switch 42. The vehicle speed signal of the host vehicle detected by the vehicle speed sensor 31 is sent to the arithmetic circuit 41, and the arithmetic circuit 41 determines the possibility of collision with an obstacle based on the vehicle speed signal.

In the distance detecting section 1, the drive signal generating circuit 11 receives the distance detection command signal, and the drive signal generating circuit 11 sends an LD light emission signal having a constant frequency shown in FIG. Based on the received LD light emission signal (a), the LD switching driver 12 is shown in FIG.
The signals shown in (c) and (d) are transmitted, and the LD-L, LD-C, and LD-R of the LD array 13 as the light emitting means are made to sequentially emit light with the same intensity at all times.

The laser beam from the LD-L of the LD array 13 is directed to the front left of the vehicle, the laser beam from the LD-C is directed to the front, and the laser beam from the LD-R is directed to the front right by the light projecting lens 14. Is emitted through LD-
The laser beam of C is used to detect an obstacle ahead, the laser beam of LD-L is used to detect an interrupting vehicle from the left lane, and the laser beam of LD-R is used to detect an interrupting vehicle from the right lane.

The reflected light from the obstacle is condensed by the light receiving lens 15 and is received by the photodiode (hereinafter referred to as PD) 16. This received light signal is sent to the amplifier circuit 17, which amplifies it and outputs the signal B of FIG. 8 (e).

The threshold generation circuit 18 outputs the reference voltage V ₀ shown in FIG. 8 (f) to the comparison circuit (comparator) 19. The comparison circuit 19 outputs the output signal (e) of the amplification circuit 17.
And a level comparison with the reference voltage waveform shown in FIG. 8 (f) are performed to extract the reflection signal from the obstacle.
The obstacle detection pulse signal shown in (g) is output.

The counter 20 has an L level as shown in FIG.
At the rise of the D light emission signal (a), the reference pulse generation circuit 21
Starts counting the clock pulse signal supplied from, stops counting at the rising edge of the obstacle detection pulse signal (g) based on the reflection signal from the obstacle, and counts from the count-up time and the speed of light to the obstacle. Seeking distance information,
It is sent to the arithmetic circuit 41 of the signal processing unit 3.

Next, a method of determining the possibility of collision in the arithmetic circuit 41 of the signal processing unit 3 will be described with reference to the flowchart shown in FIG. First, when the power is turned on, the process proceeds to a start step ST10, and the CPU, the RAM, etc. constituting the arithmetic circuit 41 are initialized. Next, in step ST11, the distance signal indicating the information on the distance R to the obstacle from the counter 20 of the distance detecting unit 1 and the information on the own vehicle speed V _f from the vehicle speed sensor 31 of the traveling state detecting unit 2 at predetermined intervals. The vehicle speed signal indicating is taken into the arithmetic circuit 41.

Then, in step ST12, the distance signal R is converted into a display signal, which is sent to the distance display 51 and displayed.
Next, in step ST13, the inter-vehicle distance R is differentiated to determine the relative speed (d / dt) R between the obstacle such as the preceding vehicle and the host vehicle.
Is calculated using a calculation method such as a least squares method, and the vehicle speed V _{a of the} preceding vehicle is relative to the own vehicle speed V _f and the relative speed (d / dt).
It is calculated by the sum with R.

In this calculation, (d / dt) R <0
In the case of (d / dt) R> 0, the distance is decreasing, and the distance is decreasing, and (d / dt) R = 0. In the case of, it shows that there is no change in the distance.

In determining the possibility of collision with an obstacle, the initial speed of the vehicle is V _f (m / s) and the initial speed of the obstacle (preceding vehicle) is V _a (m / s). Deceleration performance is α (m /
When s ²⁾ that, to the difference between the preceding vehicle stopping distance V _a ² / 2α and vehicle stopping distance V _f ² / 2α, time to distance setting set vehicle switch 42 depresses the brake T _The distance R shown in the equation 1, which is the _sum of the free running distance V _f · T _{d due} to _d , becomes the reference for collision judgment.

[0015]

(Equation 1)

Therefore, first, in step ST14, the relative speed (d / dt) R and the vehicle speed _Vf are compared, and-(d /
dt) In the case of R≈V _f , that is, when the obstacle is regarded as a road stop, the process proceeds to step ST15, and since V _a = 0 in Formula 1, the collision law is calculated according to the following formula 2 Determine the risk.

[0017]

(Equation 2)

When the equation 2 is satisfied, there is a risk of collision with an obstacle, and the process proceeds to step ST18 to generate an alarm signal and send it to the alarm notifying unit 4, and the alarm device 52 causes a danger. A warning for avoidance is issued.

On the other hand, as a result of the judgment in step ST14,
- (d / dt) obstacles if not R ≒ V _f is a preceding vehicle running ahead of the road, it should perform risk judgment according to the original number 1. However, the relative velocity (d / d
t) Since the calculation accuracy of R cannot be strictly obtained, the calculation error may give an erroneous alarm. Therefore, in the case of a preceding vehicle in which an obstacle moves, the relative speed (d / dt) in step ST16.
First, it is determined whether R is equal to or higher than a predetermined speed C (m / sec).

As a result, when (d / dt) R ≧ C, the relative speed is fast and the vehicle is approaching rapidly. Therefore, the preceding vehicle is regarded as infinitely close to the stopped object, and the process proceeds to step ST15. With the same logic as that of the stop obstacle, the warning output judgment is performed by the discriminant equation of Formula 2.

Further, the determination result of step ST16 is (d
/ Dt) In the case of R <C, it is assumed that the relative speed is low and the vehicle is running normally following the vehicle at a constant inter-vehicle distance, and the own vehicle speed V
_{Since f} and the preceding vehicle speed V _a are almost equal to each other, Formula 1 becomes Formula 3 shown below. In Step ST17, the risk of collision is determined by this Formula 3, and if this Formula 3 is satisfied similarly, Step 3 Create an alarm signal in ST18,
An alarm is issued from the alarm device 52 and step ST11
Return to

[0022]

(Equation 3)

[0023]

However, in such a collision preventing device, when the vehicle speed Vf is close to 0 m / h or approximately 0 m / h, an alarm is issued when the inter-vehicle distance does not become 0 m or approximately 0 m. There was a problem that was not generated.

The present invention has been made to solve the above problems, and when the vehicle is stopped waiting for a signal at an intersection or the like, and runs at a very low speed of 2 to 3 km / h while following a vehicle ahead. While driving, the driver's pressure on the brake pedal weakens due to tiredness caused by long-time driving, etc. The purpose of this is to prevent the vehicle from colliding with the host vehicle and the vehicle in front of the vehicle without knowing the creeping of the automatic vehicle.

[0025]

According to another aspect of the present invention, there is provided a collision prevention device, wherein the front target is based on a vehicle speed detected by a vehicle speed sensor and an inter-vehicle distance between the front target and the own vehicle. In the collision prevention device including an information processing circuit that outputs a warning signal to the notification device when determining the risk of a collision of the host vehicle with respect to the collision risk, the information processing circuit is If it is determined that the speed signal from the vehicle speed sensor is approximately 0 Km / h and that the inter-vehicle distance between the front target and the host vehicle is becoming shorter, the warning signal for collision prevention is generated. , And outputs the alarm signal to the notification device.

According to a second aspect of the present invention, there is provided a collision prevention device, based on a vehicle speed detected by a vehicle speed sensor and an inter-vehicle distance between the front target and the own vehicle, the collision of the own vehicle against the front target is detected. In a collision prevention device including an information processing circuit that determines a risk and outputs an alarm signal to a notification device when it is determined that there is a risk of collision, the information processing circuit, when the brake is operated. When the determination is made and it is determined that the inter-vehicle distance between the front target and the own vehicle is becoming shorter, the warning signal for collision prevention is generated and the warning signal is output to the notification device.

With this configuration, an alarm is issued when the vehicle-to-vehicle distance is gradually reduced after the vehicle comes close to the vehicle in front and the vehicle is stopped. A rear-end collision can be prevented.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same components as those described with reference to FIG. 7 or equivalent components are designated by the same reference numerals, and the description thereof will be omitted. Only different components will be described below. Also in the flowchart of FIG. 2, the same functions as those described in FIG. 9 or those having equivalent functions are denoted by the same reference numerals, and the description thereof will be omitted. Only different configurations will be described below.

That is, only the arithmetic circuit 41A in FIG. 1 is different from the arithmetic circuit 41 in FIG. 7, and the first point is different from the flowchart of the conventional arithmetic circuit 41 in FIG. Compared with the conventional function, in this embodiment, in step ST23, the difference between the vehicle speed Vf of the front vehicle, which is the front target, and the vehicle speed Va of the host vehicle, that is, the time derivative of the relative speed is differentiated.

[0030]

(Equation 4)

## EQU1 ## Equation (1) has been determined as a relational expression as a point for obtaining the relative acceleration a on the basis of the above, and conventionally as a criterion for determining a collision, but in this embodiment, in step ST24, For this number 1

[0032]

(Equation 5)

The point is that the relational expression shown in is used.

Next, the second difference will be described below.
That is, in step ST19, the vehicle speed Vf is 0 km /
It is determined whether the vehicle speed is h (including low vehicle speed such as 3 Km / h or less), and if it is 0 Km / h, the process proceeds to step ST20. In step ST20, it is determined whether the inter-vehicle distance R is less than 2 m, for example. If it is determined that it is less than 2 m, the process proceeds to step ST21.

In step ST21, it is determined whether or not the inter-vehicle distance R has changed by 0.2 m in the approaching direction, and if it is determined that it has changed by 0.2 m, the process proceeds to step ST22. In step ST22, a single alarm signal (for example, pulse width 0.
A single pulse of 2 seconds) is output and the alarm device 52 issues an alarm. If the conditions are not satisfied in steps ST19 to ST21, that is, if NO is determined, the process proceeds to step ST12.

Further, the above operation will be described below with reference to FIG. The figure shows that when the vehicle-to-vehicle distance R between the front vehicle, which is the front target, is kept at a distance of less than 2 m and the vehicle is stopped due to waiting for a signal, etc. As a result, the pressing force of the brake pedal is weakened due to the looseness of the air, and the host vehicle starts to move forward and the inter-vehicle distance R gradually decreases. That is, at this time, in step ST19, although the host vehicle gradually approaches the vehicle in front, the host vehicle speed V
Since it is determined that f is 0 km / h, step ST
Go to 20.

In step ST20, the inter-vehicle distance R is 2 m.
It is determined whether or not it is less than, and the process proceeds to step ST21. In step ST21, it is determined whether or not the inter-vehicle distance R has been reduced by 0.2 m.
A single alarm is generated at 22. That is, as shown in the figure, the warning sound is emitted every time the inter-vehicle distance R falls below 1.8 m, 1.6 m, 1.4 m ...

In addition, when the pressing force of the brake pedal is further weakened or the idling speed of the engine is faster than in the above situation, the distance R between vehicles shortens faster than in the above case, It becomes like FIG. In this case, the operation is exactly the same as that in FIG. 3, but the frequency of alarm generation is increased and the degree of danger is emphasized.

Embodiment 2 In this embodiment, as shown in FIG. 5, a stop lamp switch 32 is added to the configuration shown in FIG.
The operation is described below with reference to the flowchart shown in FIG. In this flowchart, step ST19 is replaced with step ST19 shown in FIG.
25 is inserted. That is, in step ST25, it is determined whether the brake is operating or 3 seconds have elapsed since the brake was inactivated. In other words, during the period from the start of the operation of the brake to the end of the operation and the lapse of 3 seconds, the brake is operated to stop, and the own vehicle speed Vf during that time is judged to be 0 km / h, and the next In step ST20, signal processing is performed.

Incidentally, the above-mentioned steps ST19 and S
T25 may be used alone as in the above embodiment, or both step ST19 and step ST25 may be arranged in series and used in combination, and both step ST19 may be used. Needless to say, the step ST25 may be omitted and the case where the inter-vehicle distance R is simply detected and determined may be determined. Next, the effects in those cases will be described. That is, (1) When step ST19 and step ST25 are not present, the only determination is that the inter-vehicle distance R is shortened every 2 m. Thereby, it is possible to warn the side-view driving during normal driving, the side-view driving at the tollgate, the back of the vehicle ahead, the creep of the automatic vehicle, and the like. (2) When step ST19 is present and step ST25 is not present, the determination is made only at the point where the vehicle speed Vf is 0 km / h and the point where the inter-vehicle distance R is reduced by 2 m. With this, it is possible to warn the driver at the tollgate, the back of the vehicle ahead, the creep of the automatic vehicle, and the like. (3) When there is no step ST19 and there is a determination only during brake operation in step ST25, the determination is that the brake operation is in progress and the inter-vehicle distance R shortens every 2 m. Thereby, it is possible to warn the creep of the automatic vehicle. (4) When there is no step ST19 but step ST25, the determination is only to reduce the inter-vehicle distance R every 2 m. Thereby, it is possible to warn the driver at the tollgate, the creep of the automatic vehicle, etc.

[0041]

As described above, according to the invention of claim 1 or 2, the own vehicle speed is approximately 0 km / m.
Even if it is close to h or 0 km / h, when the inter-vehicle distance is gradually shortened, an alarm is issued according to the approaching degree, so you may collide with a vehicle ahead of you such as waiting for a signal, or while stopped. The braking force is weakened, and the effect of preventing rear-end collision accidents such as creeping of automatic vehicles and downhill of manual vehicles can be exhibited.

Further, even when the host vehicle is completely stopped, the braking operation force of the preceding vehicle is weakened on an uphill or the like, and when the host vehicle approaches the host vehicle, a horn or the like causes the host vehicle to approach. The effect that the warning to the vehicle ahead can be promptly displayed is exhibited.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of FIG.

FIG. 3 is a diagram for explaining the operation of the embodiment according to the present invention.

FIG. 4 is a diagram illustrating a situation in which an alarm is issued when the inter-vehicle distance is reduced at a faster speed than in the case of FIG.

FIG. 5 is a circuit block diagram showing another embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of FIG.

FIG. 7 is a circuit block diagram of a conventional device.

FIG. 8 is a timing chart for explaining FIG. 7.

FIG. 9 is a flowchart for explaining the operation of FIG.

[Explanation of symbols]

 11 Drive Signal Generation Circuit 13 LD Array (Light Emitting Means) 16 Photodiode 20 Counter 32 Stop Lamp Switch (Brake) 41, 41A Operation Circuit

Claims (2)

[Claims] 1. The risk of collision of the host vehicle with the front target is determined based on the speed of the host vehicle detected by a vehicle speed sensor and the inter-vehicle distance between the front target and the target vehicle. In the collision prevention device including an information processing circuit that outputs an alarm signal to the notification device when it is determined that the speed signal from the vehicle speed sensor is 0 Km / h or approximately 0 Km / h. If it is determined that the inter-vehicle distance between the front target and the host vehicle is becoming shorter, the warning signal for collision prevention is created, and the warning signal is output to the notification device. Characteristic collision prevention device. 2. The risk of collision of the host vehicle with the front target is determined based on the speed of the host vehicle detected by the vehicle speed sensor and the inter-vehicle distance between the front target and the target vehicle, and the risk of collision occurs. In the collision prevention device including an information processing circuit that outputs an alarm signal to the notification device when it is determined that the brake is operated, the information processing circuit determines that the front target and the host vehicle. A collision prevention device, which generates the alarm signal for collision prevention when it is determined that the inter-vehicle distance between the vehicle and the vehicle is becoming shorter, and outputs the alarm signal to the notification device.