JPH06174848A - Obstacle detecting device - Google Patents

Abstract

PURPOSE:To appropriately issue an alarm according to the criterion of danger with slopes taken into account by calculating the gradient of a road from the amount of inclination of a vehicle detected by an inclination sensor, and using it in computing the braking distance. CONSTITUTION:The longitudinal inclination theta of a vehicle body is detected by an inclination sensor 32 provided in a running state detecting portion 2 and is fed to an arithmetic circuit 43. The arithmetic circuit 43 calculates the criterion for the danger of collision by using the following relational expression showing the reference of judgment about collision: alpha=alpha+g.sin theta (g is gravitational acceleration), where alpha is the deceleration (m/s<2>) of the vehicle at braking. An alarm is issued when the following conditional expression is met: VrTd+(Vr<2>-Va<2>)/2(alpha+g.sin theta)>=R where Vr is the vehicle velocity, Td is the response delay time of the driver, Va is the initial velocity of an obstacle (vehicle ahead) and R is the distance between the obstacle and the vehicle. Therefore, since the alarm is issued using the criterion with the gradient of the road taken into account, a device which can match road conditions is obtained.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a conventional obstacle detecting device, there is one shown in FIG. 2, for example. In the figure, 1 is a distance detection unit that detects the 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 such as vehicle speed. Is a running state detection unit that detects the running state of the vehicle.

Reference numeral 3 designates a vehicle based on the distance information sent back to the distance detection unit 1 in response to the distance detection command and the own vehicle speed information detected by the traveling state detection unit 2; 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 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. Vehicle speed sensor 3
The vehicle speed signal of the host vehicle detected in 1 is sent to the arithmetic circuit 41. When the vehicle speed calculated based on the vehicle speed signal is 35 Km / h or more, the arithmetic circuit 41 sends the distance detection command signal to the distance detection unit 1. Is sent.

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 LD light emission signal shown in FIG.
Send to. The LD switching driver 12 receives the LD
3 (b), (c), based on the light emission signal (a),
The signal shown in (d) is 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.

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 of FIG. In this signal, a reflection signal B from an 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 the level of the output signal (e) of the amplifier circuit 17 with the threshold signal (f) to extract only the reflected signal from the obstacle, and the obstacle shown in FIG. Outputs the object detection pulse signal.

The counter 20 has an L level as shown in FIG.
At the rising edge of the D 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 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, S
Proceeding to the TART step, the CP forming the arithmetic circuit 41
U, RAM, etc. are initialized. Next, step S
At T11, a distance signal indicating the information of the distance R to the obstacle from the counter 20 of the distance detecting unit 1 and a vehicle speed signal indicating the information of the own vehicle speed V _f from the vehicle speed sensor 31 of the traveling state detecting unit 2 at a predetermined cycle. Are 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 the least squares method, and the vehicle speed V _{a of the} preceding vehicle is relative to the own vehicle speed V _f (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 /
s ² ), the difference between the stop distance V _f ² / 2α of the host vehicle and the stop distance V _a ² / 2α of the preceding vehicle is set to the time T until the host vehicle sets the brake by the distance setting switch 42. _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,
When − (d / dt) R≈V _f is not satisfied, the obstacle is a preceding vehicle traveling on the road ahead, and the danger judgment should be originally made according to Equation 1. However, the relative velocity (d /
Since the calculation accuracy of dt) R may not be strict, the calculation error may give an erroneous alarm. Therefore, in the case of a preceding vehicle with an obstacle moving, the relative speed (d / d) is calculated in step ST16.
t) 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 of the equation 2.

Further, the determination result of step ST16 is (d
/ Dt) R <In the case of C, the slow relative speed, regarded as being the normal follow-up running at a constant inter-vehicle distance, vehicle speed V _f
Since the preceding vehicle speed V _a is almost equal, the equation 1 becomes the equation 3 shown below. In step ST17, the danger of a collision is determined by the equation 3, and if the equation 3 is satisfied similarly, in step ST18. Give an alarm.

[0022]

[Equation 3]

[0023]

However, in such a conventional obstacle detection device, since the criterion of the risk of collision is calculated based on the equation 2 regardless of the road gradient, On slopes, there is a risk of collision unless a distance that is longer than the calculated criterion is set, and on uphill slopes there is a risk that an alarm will be issued even though there is no possibility of collision. There was a problem that was not suitable for

The present invention has been made by paying attention to such a problem, and an object thereof is to obtain a risk judgment standard in consideration of a slope.

[0025]

An obstacle detecting device according to the present invention determines the risk of collision of a host vehicle with a front target, and issues an alarm signal when it is determined that there is a risk of a rear-end collision. In the collision warning device including an information processing circuit, the information processing circuit creates a danger signal for collision prevention based on the amount of leaning of the host vehicle, the speed of the front target, the speed of the host vehicle, and the like.

[0026]

The device according to the invention uses the road slope and the braking distance in the formula to improve the adequacy of the alarm.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the present invention. First, the configuration will be described. Here, reference numerals 1 to 4 and 11 to 17, 1
9 to 21, 31, 42, 51 and 52 are the same as those in the conventional example of FIG.

In FIG. 1, reference numeral 32 denotes an inclination angle sensor, which detects the longitudinal inclination of the vehicle body and supplies the detection result to the arithmetic circuit 43. As a result, the arithmetic circuit 43 operates as shown in
The following points are different from the flowchart showing the conventional function in. That is, in the past, the equation 1 was determined as the relational expression as the criterion for the collision determination, but in this embodiment, the relational expression shown in the following equation 4 is used for the equation 1. . That is, the deceleration due to the brake of the host vehicle in the conventional example is

[0029]

[Equation 4]

And

[0031]

[Equation 5]

Calculate the risk judgment criteria based on

[0033]

[Equation 6]

By executing the judgment in step ST15, if the conditional expression shown in equation 6 is satisfied, the process proceeds to step ST18 to issue an alarm, and if not satisfied, the process returns to step ST11.

[0035]

As described above, according to the present invention, since an alarm is issued according to the judgment criterion in consideration of the road gradient, it is possible to obtain the effect that a device that matches the actual road condition can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an obstacle detection device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional obstacle detection device.

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

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

[Explanation of symbols]

 13 Light emitting means (LD array) 19 Comparator 53 Visibility indicator

Claims (1)

[Claims] 1. A collision warning device provided with an information processing circuit for judging the risk of collision of a vehicle with respect to a front target object and issuing an alarm signal when it is judged that there is a danger of a rear-end collision. The circuit is the amount of leaning of the italic vehicle,
An obstacle detection device, which creates a danger signal for collision prevention based on the speed of a target in front, the speed of the host vehicle, and the like.