JPS61191913A - Onboard distance measuring apparatus for vehicle - Google Patents

Abstract

PURPOSE:To enable highly accurate measurement of distance from long to short range, by arranging a laser distance measuring device, a proximity sensor, a running state detector and a control means for switching a selection means over to the laser distance measuring device. CONSTITUTION:A proximity sensor 11 is provided outside a laser distance measuring device 10. A running state detector 13 is provided to detect that an automobile stops or almost stops and the sending of a laser light from the distance measuring device 10 is controlled by a control means 14 into which the detection signal of the detector and an object detection signal of the sensor 11 are inputted. On the other hand, a switch 12 does a changeover between the output of the distance measuring device 10 and the detection distance output of the sensor 11. In other words, the control means 14 halts the sending of a laser light from the distance measuring device 10 only when the automobile stops or almost stops while an object is detected with the sensor 11 while changes the switch 12 over to the sensor 11 position to perform a measurement of the shortest range. To measure long range, the distance measuring device 10 is actuated and the switch 12 is changed over to the position of the measuring device 10. This enables highly accurate distance measuring from long to the shortest range.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an on-vehicle range finder, and more particularly to an on-vehicle range finder that combines a laser range finder and a proximity sensor using means other than laser light.

BACKGROUND OF THE INVENTION In the past, various types of in-vehicle distance measuring devices have been proposed, but 11! Laser range finders that can measure distances with high precision over t (about 1 m) are attracting attention.

Problems to be Solved by the Invention However, with laser range finders, it is not possible to measure distances at close range (within lrn) with high precision. Laser range finders cannot accurately measure distances even though highly accurate distance measurement at close range is required in cases such as when the vehicle is moving slowly, or when another vehicle gradually approaches while the vehicle is stopped. The drawback was that it was not possible to perform long distances.

The present invention solves these conventional problems, and its purpose is to provide an on-vehicle distance measuring device that covers distances from long distances to close ranges with high precision.

Means for Solving the Problems FIG. 1 is an explanatory diagram of the configuration of the present invention. In addition to the laser range finder 10 that uses laser light, the in-vehicle distance measuring device of the present invention uses means other than laser light, such as relatively weak light such as a light emitting diode, or ultrasonic waves to detect objects at a relatively short distance. A proximity sensor 11 is provided to measure the presence or absence of and the distance therebetween. Further, a driving state detector 13 is provided for detecting that the vehicle has stopped or substantially stopped, and a control means 14 that inputs this detection signal and an object detection signal of the proximity sensor 11 controls the laser beam of the laser range finder 10. and a switch 12 that switches between the output of the laser range finder 10 and the detected distance output of the proximity sensor 11.

That is, only when the vehicle is stopped or almost stopped and an object is detected by the proximity sensor 11, the control means 14 stops the laser beam emission of the laser range finder IO and switches the switch 12 to the proximity sensor. In other cases, the laser range finder 10 is activated, and the switch 12 is switched to the laser range finder 1 side.
Switch to 0 side.

Function Vehicle-mounted distance measuring devices are usually mounted on the front of an automobile, for example, near the front grill, and highly accurate distance measurement at close range is required only when the vehicle is stopped or almost stopped. This is because during normal driving, measures such as deceleration must be taken before the vehicle approaches the object to be measured at close range.

In the present invention, when the vehicle is stopped or almost stopped, the proximity sensor 1
1 detects an object, the laser output is turned off, and during that time the proximity sensor 11 measures the distance, making it possible to measure the distance at close range with high accuracy.

Example FIG. 2 is a block diagram of the main parts of the embodiment of the present invention.

In the figure, a transmitting section, a receiving section 22, and a processing section constitute a laser range finder, and the transmitting section 20 includes a pulse oscillator 20a, a laser light generating means, for example, a laser diode 20b,
It consists of a transmission lens 20C. Further, the receiving section n includes a receiving lens 22G, a photodiode 22b that converts light from the receiving lens 22C into an electrical signal, and an amplifier 22a that amplifies the output thereof. Furthermore, the processing circuit receives the output pulse of the pulse oscillator 20a and the output pulse of the amplifier 22a, and includes a time measurement circuit 23a that measures the input time difference td between the two pulses, and a time measurement circuit 23a that measures the input time difference td between the two pulses. and a distance calculation circuit 23b that calculates the distance R to the object 21 using the following equation.

R1-tdxC/2-(1) However, since C is high speed, if the distance R to the object 21 is extremely short, the error in time td becomes large and accurate distance measurement becomes extremely difficult.

Further, in FIG. 2, a vehicle speed sensor 26 generates a pulse with a frequency substantially proportional to the vehicle speed, and is composed of, for example, a permanent magnet rotated by a speed cable and a reed switch placed close to the permanent magnet. The output of the vehicle speed sensor 26 is sent to an integrator 27.
The voltage is then smoothed and a voltage approximately proportional to the vehicle speed is generated. The output voltage of the integrator 27 is added to the manual input of the comparator 4, where it is compared with the reference voltage Vo, and a signal a which becomes l'' when the vehicle speed is zero or almost zero is generated.

The proximity sensor 30 generates a signal indicating the presence or absence of a relatively close object and a signal for determining the distance.The object detection signal is manually input to the comparator 31, and the signal for determining the distance is input to the distance calculation circuit 29. are input respectively. Comparator 3
The reference voltage V is used for 1 person's power.

is input, and the comparator 31 outputs a signal that becomes "■" when an object is detected by the proximity sensor 30.

Further, the distance calculation circuit 29 calculates the distance MR2 to the object based on the output of the proximity sensor 30.

The output R1 of the processing section and the output R2 of the distance calculation circuit 29 are
The signal is input to the switch 24. This switch 24 is connected to the comparator 2
Switching is controlled by the output of the AND circuit 32 which calculates the AND of the outputs of 8.31, and when the output of the AND circuit 32 is "1", the switch 24 is switched to the distance calculation circuit 29 side, and the output of the AND circuit 32 is When it is "0", the processing section is switched to the edict side. The output of the AND circuit 32 is the pulse oscillator 20a of the transmitter 20.
The pulse oscillator 20a is also added to the AND circuit 32.
It operates when the output is "0" and stops operating when it is '1'.

FIG. 3 shows the output a of the comparator and the output of the comparator 31.

5 is a timing chart showing an example of temporal changes in the laser beam sending state of the transmitter 20 and the type of ranging output appearing at the output terminal 5. FIG. When the car is running and no object is detected by the proximity sensor 30, both signals a and b are “O”.
Since the output of the AND circuit 32 is '0', the pulse oscillator 20a is sending out pulses, and the transmitter 20
Laser light is emitted toward the target object 21 from. Further, the switch 24 is switched to the processing section n side.

Therefore, the output of the processing unit, that is, the distance measurement output R9 of the laser range finder appears at the output terminal. If an object is detected by the proximity sensor 30 while driving, the signal S becomes "l", but the output of the AND circuit 32 remains "01", and the laser beam is sent out in the same way as above. The distance measurement output of the range finder appears at the output terminal section.This is because during normal driving, the distance to the object is measured with high precision by the laser range finder even before the object is detected by the proximity sensor 30. Proximity sensor 30
This is because by the time an object is detected, measures such as deceleration have already been taken based on the distance measurement output of the laser range finder. When the speed of the vehicle becomes zero or almost zero and an object is detected by the proximity sensor 3o, the output a of the comparator 28.31,
b both become "l" and the output of the AND circuit 32 becomes 11"
Therefore, the pulse oscillator 20a is inactive and the transmission of laser light is stopped. Further, the switch 24 is switched to the distance calculation circuit 29 side. Therefore, distance measurement can be performed with high precision by the proximity sensor 30 while the vehicle is stopped. When the proximity sensor 3o no longer detects an object while the car is stopped, the output of the AND circuit 32 becomes “O” and the transmitter 20
Sending out of the laser beam is started, and the switch 24 is switched to the processing section n side.

This is because there is no target object at close range, and it is also possible to detect the distance of a distant object.

FIG. 4 is a block diagram of main parts of an embodiment of the proximity sensor 30. As shown in FIG. This example shows the configuration of a proximity sensor using the principle of triangulation.

In the figure, a modulation drive circuit 40 generates a high frequency signal to drive a light emitting diode 41. The light emitted from the light emitting diode 4 is transmitted as a narrow beam by the transmitting lens 42 toward the region where the target object 43, 43' is present. The light reflected by the target object 43, 43' is incident on the photodiode array 45 via the receiving lens 44. The photodiode array 45 has a plurality of photodiodes arranged in columns, and the output of each element is input to a multiplexer 46 and an adder 47. If there is a target object, an output will appear in any element of the photodiode array 45, so this will appear in the output of the adder 47, and by detecting this with the level detection circuit 48, the presence or absence of the object can be detected. The output of the level detection circuit 48 is applied to the comparator 31 shown in FIG. Also,
The position on the photodiode array 45 where the reflected light is incident changes depending on the distance to the target object, and thereby the position to the object can be determined as described later.

The clock of the clock generator 52 is passed through a synchronous detection circuit 50° frequency divider 53. The pulses applied to the counter 54 and divided by the frequency divider are applied to the multiplexer 46 as a switching timing signal. Further, the frequency divider 53 sends a clear signal to the counter 5 every time one scan of the multiplexer 46 is completed.
Clear this in addition to 4. The output of each element of the photodiode array 45 selected by the multiplexer 46 is amplified by an amplifier 49 and input to a synchronous detection circuit 50.

The synchronous detection circuit 50 synchronously detects the output of each element based on the clock of the clock generator 52, and sends the detected output to the comparator 5.
Add to the ten-man power of 1. A reference voltage v2 is applied to the voltage of the comparator 51, and when a voltage higher than a predetermined level appears at the output of the synchronous detection circuit 50, the output is set to "1" and the content of the counter 54 is latched in the launch circuit 55. let

Since the counter 54 counts the clocks applied to the synchronous detection circuit 50 and is cleared every time one scan of the multiplexer 46 is completed, the value of the counter 54 latched in the U-nochi circuit 55 is determined by the reflected light incident on the counter 54. This corresponds to the position of the element of the photodiode array 45 that has been set. The output of the latch circuit 55 is applied to a distance calculating circuit 56, where the distance is determined, and is applied to the switch 24 in FIG.

Now, let us take the distance between the light emitting surface of the light emitting diode 41 and the transmitting lens 42, and the distance between the center line of the transmitting lens 42 and the center line of the receiving lens 44 as D, and the distance between the center line of the receiving lens 44 and the photodiode array from which the output was obtained. The distance to element 45 is Y
Then, the distance R from the transmitting lens 42 to the target object is
2 is determined by the following equation.

R2=LXD/Y ・-(2) Here, Y is uniquely determined from the value of the counter 54.

Therefore, if the above distances @L and D are set with high precision, the distance R2 to the object 43 can be measured with high precision at close range.

In addition, the proximity sensor 30 can also use a method using ultrasonic waves other than the above. That is, any type of proximity sensor other than laser light can be used as the proximity sensor.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, when the proximity sensor detects an object while the vehicle is stopped or almost stopped, the laser beam from the laser range finder is stopped and the proximity sensor starts measuring the object. Since the distance is carried out, the driving of the car as a whole,
Highly accurate distance measurement can be performed for objects ranging from long distances to close ranges regardless of whether the vehicle is stopped.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of the present invention, FIG. 2 is a block diagram of main parts of an embodiment of the present invention, FIG. 3 is an explanatory diagram of the operation of FIG. 2, and FIG. 4 is a block diagram of an embodiment of the proximity sensor 30. It is. 10 is a laser distance finder, 11 is a proximity sensor, 12 is a switch, 13 is a running state detection part number, and 14 is a control means.

Claims (1)

[Scope of Claims] A laser range finder that measures the distance to an object using a laser beam; A proximity sensor that detects an object at a short distance and measures the distance to the detected object by means other than a laser beam; a driving state detector for detecting that the vehicle has stopped or almost stopped; a selection means for selecting the output of the laser range finder and the output of the short distance sensor; When an object is detected, the laser range finder stops transmitting the laser beam and switches the selection means to the proximity sensor side; otherwise, the laser range finder is activated and the selection means is switched to the proximity sensor side. A vehicle-mounted distance measuring device characterized by comprising a control means for switching to the distance measuring device side.