JPH0858505A - Collision alarm device - Google Patents

Abstract

PURPOSE: To make vehicle collision fully avoidable when an alarm signal is broken out on the basis of a distance signal from an obstruction ahead, relative speed and a reference value by detecting the vehicle slippage run and changing the size of the reference value for the alarm based on the detected signal. CONSTITUTION: Vehicle speed is enumerated by an arithmetic circuit 41 based on the vehicle speed detected by a vehicle sensor 31 and a command signal is output to a drive signal generation circuit 11 when the enumerated value has exceeded the set value of a distance set switch 42. An accident warning flash signal is output from the drive signal generation circuit 11 to an LD changeover driver 12 and causes an LD array to emit. Reflection light from an obstruction ahead is received by a photodiode 16. An alarm signal is generated on the basis of the distance signal to the obstruction ahead, the relative speed and the reference value by the light receiving signal and a counter 20 and an alarm 52 is actuated. In this case, the vehicle slippage run is detected by an anti-skid detection unit 32 and the reference value size for the alarm is changed on the basis of the detected signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision warning device for detecting an obstacle in front of a vehicle to prevent a collision accident from occurring.

[0002]

2. Description of the Related Art As a conventional collision warning device, there is one shown in FIG. 2, for example. In the figure, reference numeral 1 is a distance detection unit that detects a distance between a vehicle and a front obstacle using a laser beam (light beam) emitted from a laser diode (hereinafter referred to as LD). Contamination determination circuit 7, alarm device 8, drive signal generation circuit 11, LD switching driver 12, LD array 13, light transmitting lens 1
4, light receiving lens 15, photodiode (also referred to as PD) 16, amplifier circuit 17, threshold value generating circuit 18, comparator 19, counter 20, reference pulse generating circuit 21
It consists of Reference numeral 2 denotes a running state detection unit that detects the running state of the vehicle such as the vehicle speed.

Reference numeral 3 designates the own vehicle based on the distance information returned to the distance detection unit 1 in response to the distance detection command and the own vehicle speed information detected by the running state detection unit 2. By calculating the relative speed with the front obstacle, it is judged whether the front obstacle is a stationary object or a moving object, and the own vehicle speed, the relative speed,
A signal processing unit (signal processing means) that determines the possibility of collision between the host vehicle and a front obstacle according to the distance setting or the like set according to individual differences in free running time until the driver brakes, It is composed of an arithmetic circuit 41 composed of a microcomputer and the like, and a distance setting switch 42.

Reference numeral 4 indicates the distance between the vehicle and the front obstacle based on the information from the signal processing unit 3, and the signal processing unit 3 judges that there is a possibility of collision with the front obstacle. In the case where the signal is given, it is an alarm detection unit that receives the signal and issues an alarm, and is composed of a distance indicator 51 and an alarm device 52.

Next, the operation of the above configuration will be described. The vehicle speed signal of the own vehicle detected by the vehicle speed sensor 31 is sent to the arithmetic circuit 41, and the arithmetic circuit 41 calculates the vehicle speed based on the vehicle speed signal to 35 Km / h, which is a value artificially set by the distance setting switch 42. If it is above, a distance detection command signal will be sent to the distance signal generation circuit 11 of the distance detection unit 1.

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 receives the signal.
Sends the LD light emission signal shown in FIG. 3A to the LD switching driver 12. The LD switching driver 12 is based on the received LD light emission signal (a), as shown in FIG.
The signals shown in (c) and (d) are transmitted, and L is used as a light emitting means.
The LD-L, LD-C, and LD-R of the D array 13 are sequentially made to emit light.

The laser beam (light beam) from the LD-L of the LD array 13 is projected to the front left of the vehicle, the laser beam from the LD-C is projected to the front, and the laser beam from the LD-R is projected to the front right. The laser beam emitted from the LD-C is emitted through the optical lens 14, and the laser beam emitted from the laser diode LD
The laser beam of L is the vehicle that interrupts from the left lane, LD
The -R laser beam is used to detect an oncoming vehicle from the right lane.

The light reflected from the front obstacle is received by the light receiving lens 15
The light is collected by and is received by the photodiode 16. This received light signal is sent to the amplifier circuit 17, which amplifies it and outputs the signal of FIG. In this signal, a reflection signal B from a front obstacle and a reflection signal A from a short distance road surface are mixed.

The threshold value generation circuit 18 is based on the LD light emission signal (a) output from the drive signal generation circuit 11 and shown in FIG.
The threshold signal shown in FIG.
Output to. The comparator 19 compares only the output signal (e) of the amplifier circuit 17 with the threshold signal (f) to extract only the reflected signal from the obstacle,
The obstacle detection pulse signal shown in FIG.

The counter 20 starts counting the clock pulse signal supplied from the reference pulse generation circuit 21 at the rising edge of the LD light emission signal (a) as shown in FIG. The count is stopped at the rising edge of the obstacle detection pulse signal (g) based on the above, the distance information to the obstacle is obtained from the count-up time and the speed of light, and it is sent to the arithmetic circuit 41 of the signal processing unit 3.

Next, a method of judging 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,
Proceeding to the START step, C constituting the arithmetic circuit 41
Initialization of PU, RAM, etc. is performed. Next, in step ST11, the counter 20 of the distance detection unit 1 is set at predetermined intervals.
A distance signal indicating the information on the distance R from the obstacle and a vehicle speed signal indicating the information on the own vehicle speed Vf from the vehicle speed sensor 31 of the traveling state detection unit 2 are fetched into the arithmetic circuit 41.

Then, in step ST12, the distance signal R is converted into a display signal and sent to the distance display 51 for display. Next, in step ST13, the inter-vehicle distance R is differentiated to differentiate the relative speed (d / dt) between an obstacle such as a preceding vehicle and the host vehicle.
R is calculated using a calculation method such as the least squares method, and the vehicle speed Va of the preceding vehicle is calculated from the own vehicle speed Vf and the relative speed (d / d).
t) Calculated by the sum of R.

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

In determining the possibility of collision with an obstacle, the initial speed of the host vehicle is Vf (m / s), the initial speed of the obstacle (preceding vehicle) is Va (m / s), and both deceleration performances Is α (m / s
² ), the idling time by the time Td before the own vehicle sets the brake on the difference between the stop distance Vf ² / 2α of the own vehicle and the stop distance Va ² / 2α of the preceding vehicle is set. The distance R shown in the equation 1 which is the sum of the distances Vf and Td serves as a criterion.

[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≈Vf, that is, when the obstacle is regarded as a road stop, the process proceeds to step ST15, and since Va = 0 in the formula 1, there is a risk of collision according to the driving law of the following formula 2. To judge.

[0017]

[Equation 2]

When the equation 2 is satisfied, there is a risk that the obstacle collides with the obstacle, and the process proceeds to the switch ST18 to generate an alarm signal to the alarm notification unit 4. The alarm 52 is sent to issue an alarm for avoiding danger.

On the other hand, as a result of the judgment in step ST14,
If-(d / dt) R≈Vf is not satisfied, the obstacle is a preceding vehicle traveling on the road ahead, and the danger judgment should be made according to the equation 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) R <C, the relative speed is slow and it is considered that the vehicle is normally following the vehicle at a constant inter-vehicle distance.
Since the preceding vehicle speed Va is almost equal, the number 1 becomes the number 3 shown below, and in step ST17, the risk of collision is determined by the number 3, and similarly when this number 3 is satisfied, an alarm is issued. .

[0022]

(Equation 3)

[0023]

However, in such a collision warning system, the free running distances Vf and Td, which are set by the distance setting switch 42 and are the time Td before the subject vehicle brakes, are added. Since the distance R shown in Formula 1 is a constant value, even if safety design is performed with a margin, in a complicated road environment, when the vehicle travels on a road surface where wheels are easily slipped, There was a risk that the collision could not be prevented.

The present invention has been made by paying attention to such a problem. When it is determined that the vehicle is a slippery road surface, the criterion is changed to a large value accordingly, The purpose is to be able to avoid collisions sufficiently.

[0025]

A collision warning device according to the present invention comprises a light emitting means for emitting a light beam toward the front, and a light receiving means for receiving reflected light of the light beam from the light emitting means due to an obstacle in front. A signal processing means for generating an alarm signal based on a distance between a light reception signal from the light receiving means and a front obstacle calculated from the vehicle speed of the vehicle detected by the vehicle speed sensor, a relative speed, and a reference value; In a collision warning device having a warning processing means for issuing a warning based on the detection output from the signal processing means and the function deterioration detecting means, a slip detecting means for detecting slip traveling of the vehicle is provided, and a signal from the slip detecting means is provided. The road surface condition is determined based on this, and the magnitude of the reference value is switched.

[0026]

In the collision warning device according to the present invention, the distance R shown in the equation 1 which is the sum of the free running distances Vf and Td due to the time Td before the vehicle is set by the distance setting switch 42 is equal to that of the vehicle. Since it is set so as to change according to the slip state, it is possible to easily avoid a collision in any traveling environment.

[0027]

EXAMPLE Next, the configuration will be described with reference to FIG.
Since the anti-skid detector 32 is added and the other parts are the same as those shown in FIG. 2, only the different parts will be described. That is, the anti-skid detection unit 32
When a wheel slips, the signal is detected because the difference between the pair of wheel speeds of the anti-skid control device becomes a predetermined value or more, and the detection signal is detected.
2 is supplied to the arithmetic circuit 41 from the distance setting switch 42.
Time T before the vehicle brakes
The distance R shown by the equation 1 including the free running distance Vf and Td due to d
Change to increase. As a result, when the vehicle slips, the warning is issued in a state where the inter-vehicle distance is larger than in the case where the vehicle does not slip, so that the danger can be easily avoided.

[0028]

As described above, according to the present invention, when it is determined that the vehicle is traveling on a slippery road surface, an alarm can be issued on the safe side even if the inter-vehicle distance is large. The effect that the danger can be easily avoided is exhibited.

[Brief description of drawings]

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

FIG. 2 is a circuit block explanatory diagram for explaining a conventional example.

FIG. 3 is a timing diagram showing a time relationship of signals of respective parts in the distance detection unit of FIG.

FIG. 4 is a timing chart showing the flow of processing in the arithmetic circuit in FIG.

[Explanation of symbols]

 1 Signal Detection Section 2 Running State Detection Section 3 Signal Processing Section 4 Alarm Notification Section 32 Anti-Skid Detection Section

Claims (1)

[Claims] 1. A light emitting means for emitting a light beam forward, a light receiving means for receiving reflected light of the light beam from the light emitting means due to an obstacle in front, a light receiving signal from the light receiving means and a vehicle speed sensor. Signal processing means for generating an alarm signal based on the distance to the front obstacle, the relative speed, and the reference value calculated from the detected vehicle speed of the own vehicle, and the detection output from the signal processing means and the function deterioration detecting means In a collision warning device having a warning means for issuing a warning based on the above, a slip detection means for detecting slip traveling of the vehicle is provided, the road surface condition is judged based on a signal from the slip detection means, and the reference value A collision warning device characterized by switching the size.