JPH06308237A - Obstacle detecting device - Google Patents

Abstract

PURPOSE:To correctly warn the driver of the danger of a collision by invariably detecting the inter-vehicle distances between multiple front vehicles and one's own vehicle, paying attention to the front vehicle having the highest danger, and issuing an alarm. CONSTITUTION:Pulses P, Q corresponding to reflected signals B, C from a front vehicle and a further front vehicle contained in the amplified 17 light reception signals are generated by a comparator 19. The counting action of a counter 20 is stopped by the pulse P generated first, and the output of a FF circuit 23 is kept at the L-level. When the second pulse Q is generated from the comparator 19, the output of the circuit 23 is inverted to the H-level, and the counting action of a counter 24 is stopped. An arithmetic circuit 43 makes a calculation based on the counted results (distance signals) of the counters 20, 24, and it outputs the alarm signal to a warning unit 52 when either one of them becomes the collision danger distance. An alarm is surely issued even when a collision is made imminent by the abrupt change of the travel state of the nearest front vehicle.

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 used for detecting a front target such as an obstacle in front of a vehicle to prevent a collision accident from occurring.

[0002]

2. Description of the Related Art Conventionally, as this type of obstacle detection device, there is a vehicle collision warning device, which will be described below with reference to, for example, FIG. In the figure, 1 is a distance detection unit that detects a distance between a vehicle and an obstacle using a laser beam (light beam) emitted from a laser diode (hereinafter, LD), and 2 is a vehicle speed. Is a traveling state detection unit that detects the traveling state of the host vehicle.

Reference numeral 3 designates the own 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 a 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 10 Km / h or more, the arithmetic circuit 41 sends a distance detection command signal to the distance detection unit 1. Is sent.

In the distance detecting section 1, a signal corresponding to the distance detection command signal is sent from the arithmetic circuit 41 to the drive signal generating circuit 11
The drive signal generation circuit 11 receives the LD shown in FIG.
The light emission signal is sent to the LD switching driver 12. The LD switching driver 12 sends out the signals shown in FIGS. 5B, 5C, and 5D based on the received LD light emission signal (a).
LD-L, LD- of the LD array 13 as a light emitting means
C and LD-R are made to always 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, and the amplifier circuit 17 amplifies it and outputs the signal of FIG. 5 (e) (the portion shown by the solid line). 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 is 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 this threshold value signal (f) to extract only the reflected signal from the obstacle, and the obstacle shown in FIG. The object detection pulse signal (the portion indicated by the solid line) is output. The counter 20 starts counting the clock pulse signal supplied from the reference pulse generation circuit 21 at the rise of the LD light emission signal (a) as shown in FIG. 5 (h), and the obstacle based on the reflection signal from the obstacle is detected. Counting is stopped at the rise of the detection pulse signal (g), distance information to the obstacle is obtained from the count-up time and the light speed, and the information 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 the START step, and the CPU, RAM, etc. constituting the arithmetic circuit 41 are initialized. Next, in step ST11, a pulse having a predetermined pulse width is output to the drive signal generating circuit 11 in a predetermined cycle, and in the next step ST12, the distance from the counter 20 of the distance detecting unit 1 to the obstacle is determined every predetermined cycle. R
The distance signal indicating the information on the vehicle speed and the vehicle speed signal indicating the information on the own vehicle speed V _f from the vehicle speed sensor 31 of the traveling state detection unit 2 are taken into the arithmetic circuit 41.

Then, in step ST13, the distance signal R is converted into a display signal and sent to the distance display 51 for display.
Next, in step ST14, 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 ST15, the relative speed (d / dt) R and the vehicle speed V _f 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 ST16, and since V _a = 0 in Formula 1, the collision law is calculated by 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 ST19 to generate an alarm signal and send it to the alarm notifying unit 4, and the alarm device 52 causes the danger. A warning for avoidance is issued.

On the other hand, as a result of the judgment in step ST15,
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 error 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 ST17.
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 considered to be infinitely close to the stopped object, and the process proceeds to step ST16, 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 ST17 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 ST18, the risk of collision is determined by the equation 3, and if the equation 3 is satisfied similarly, step ST19 Gives an alarm at.

[0022]

[Equation 3]

[0023]

However, since such a conventional obstacle detection device has a configuration in which only the vehicle immediately before the own vehicle is detected, as shown in FIG. 7, for example, the own vehicle. Considering the case where X and the immediately preceding vehicle Y are following at the same speed, the preceding vehicle Y
Until the vehicle reaches the position indicated by the symbol a, the host vehicle X is the forward vehicle Y.
Is the closest forward vehicle, and the distance L to the forward vehicle Y is
1 is calculated, and if the distance L1 is a safe inter-vehicle distance, no alarm is issued, but because the preceding vehicle Y has moved from the position of code a to the position of code b (further to the position of code c), A new low speed vehicle (own vehicle X
A front vehicle Z such as a vehicle traveling slower) travels,
If the relative speed between the front vehicle Z and the host vehicle X is not a safe inter-vehicle distance with respect to the inter-vehicle distance L2, the host vehicle X is highly likely to collide with the new front vehicle Z. However, if the driver is not paying sufficient attention to the front direction, the warning will only be issued at a very dangerous inter-vehicle distance that requires an instant judgment. The vehicle X may be too close to the vehicle Z and an alarm may be issued, which is already late and there is a risk that the risk avoidance operation may be too late.

The present invention has been made by paying attention to such a problem. Even if there are a plurality of vehicles in front, it is detected and an alarm is appropriately generated when the possibility of a collision increases. The purpose is to improve the reliability of the device.

[0025]

An obstacle detecting apparatus according to the present invention includes a light emitting element which emits a light beam in a pulse shape toward a plurality of front targets through a light projecting lens, and the light emitting element. And a light-receiving element that receives a light beam reflected by each of the front targets, and only the reflected light from each of the front targets is extracted from the signal received by the light-receiving element, and extracted in the order in which the front targets are close. Extraction means for outputting a signal, which is connected in parallel, starts the operation of the timing function in synchronization with the generation of the light beam output from the light emitting element,
Also, a plurality of counters that sequentially stop the operation of the timekeeping function when an extraction signal is supplied from the extraction means, and distances to the respective front targets are calculated based on the outputs of the counters, and the front targets are calculated. And a signal processing means for outputting a warning signal when the possibility of collision with any of the front target objects is increased by judging the risk of collision with.

[0026]

In the device according to the present invention, when a plurality of front vehicles are detected, the inter-vehicle distance between each of the detected front vehicles and the host vehicle is always detected, and the most dangerous front vehicle is detected. Since the warning is generated focusing on, the collision prevention function can be improved.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
1 to 3 are views showing an embodiment of the present invention. First, the configuration will be described with reference to FIG.
4 and 11 to 21, 31, 41, 42, 51, 52 are
Components shown in FIG. 4 that are the same as or equivalent to those of the conventional example are shown, and the same reference numerals are given to those parts and their description is omitted.

That is, FIG. 1 is different from the conventional configuration shown in FIG. 4 in that the second counter 24 and the flip-flop circuit 23 are provided.
Is added and the function of the arithmetic circuit 43 is added, so that point will be described.

The flip-flop circuit 23 has an input terminal connected to each output terminal of the drive signal generation circuit 11 and the comparator 19, and an output terminal of the second counter 2
4 and is output (i) at the rising edge of the LD light emission signal (a) supplied from the drive signal generating circuit 11.
Is set to the low level, and the output (i) is switched to the high level at the rising edge of the second pulse Q of the signal (g) output from the comparator 19.

The second counter 24 is reset at the rising edge of the LD light emission signal (a) output from the drive signal generation circuit 11, starts counting the reference clock pulse from the reference pulse generation circuit 21, and flip-flops. The counting operation is stopped at the rise of the output from the circuit 23, and the distance signal as the counting result is supplied to the arithmetic circuit 43.

The arithmetic circuit 43 performs the same signal processing as the conventional one on the distance signal supplied from the first counter 20, while adding the following signal processing.

That is, although the same signal processing as the distance signal supplied from the first counter 20 is performed based on the distance signal supplied from the second counter 24, any one of the calculation results is expressed by the formula (3). When is not established, an alarm signal is output.

Next, the operation of FIG. 1 will be described with reference to FIGS.

It is assumed that the preceding vehicle Y immediately ahead of the host vehicle X and the preceding vehicle Z ahead thereof are traveling in a state as shown in FIG. 3, and the apparatus is powered on to drive the LD array. It is assumed that the laser beam is emitted from 13 and the reflected light of the laser beam is received by the PD 16. It is also assumed that each of the first and second counters 20 and 24 is in the counting start state due to the rise of the LD generation signal (a) from the drive signal generation circuit 11.

As a result, the output signal (e) of the amplifier circuit 17
In addition to the signal A based on the reflected wave from the short distance road surface and the signal B based on the reflected wave from the preceding vehicle Y immediately before, a signal C based on the reflected wave from the preceding vehicle Z is detected. The detected signals A, B and C are passed through a comparator 19 to obtain pulses P and Q corresponding to the signals B and C, respectively.

Then, the counting operation of the first counter 20 is stopped by the first generated pulse P, but the output of the flip-flop circuit 23 is maintained at the low level. On the other hand, the second pulse Q from the comparator 19
Is generated, the output of the flip-flop circuit 23 is inverted to the high level, and the counting operation of the second counter 24 is stopped. After that, the counting results of the first and second counters 20 and 24 (see FIGS. 2h and 2j) are supplied to the arithmetic circuit 43.

The arithmetic circuit 43 includes the first and second counters 2
The arithmetic operation of Expression 3 is performed based on each of the distance signals supplied from 0 and 24, and when either one of the inequalities is not satisfied, the alarm signal is output to the alarm device 52.

[0038]

As described above, according to the present invention, even if a collision is imminent due to a sudden change in the running condition of the preceding vehicle in front of the vehicle, an alarm can be surely issued. It is possible to improve traffic safety and traffic safety.

[Brief description of drawings]

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

2A and 2B are waveform charts and timing charts showing a time relationship of signals of respective parts in the distance detection unit of FIG.

FIG. 3 is an explanatory diagram for explaining the present invention.

FIG. 4 is a circuit block diagram showing a conventional obstacle detection device.

5A and 5B are waveforms and timing charts showing a time relationship of signals of respective parts in the conventional distance detecting part.

FIG. 6 is a flowchart showing a flow of processing in the arithmetic circuit of FIG.

FIG. 7 is an explanatory diagram for explaining a problem of the conventional obstacle detection device.

[Explanation of symbols]

 11 Drive Signal Generating Circuit 13 Laser Diode (LD) 14 Light Emitting Lens 15 Light Receiving Lens 16 Photodiode (PD) 18 Threshold Generating Circuit 19 Comparator 20, 24 Counter 21 Reference Pulse Generating Circuit 23 Flip-Flop Circuit

Claims (1)

[Claims] 1. A projection lens (1) directed toward a plurality of front targets.
4) A light emitting element (1
3), and a light-receiving element (16) for receiving the light beams emitted from the light-emitting element and reflected by each of the front targets.
And an extraction means (18, 19, 2) for extracting only the reflected light from each of the front targets from the signal received by the light receiving element and outputting the extraction signals in the order of closer front targets.
3) is connected in parallel with the light emitting element (13) to start the operation of the timing function in synchronism with the generation of the light beam output from the light emitting element (13) and is extracted from the extracting means (18, 19, 23). A plurality of counters (20, 24) that sequentially stop the operation of the time counting function when a signal is supplied, and distances to the respective front targets are calculated based on the output of the counters, and the front targets are An obstacle, which is provided with signal processing means (3) for outputting an alarm signal when the possibility of collision with any of the front targets is increased by judging the risk of collision. Detection device.