JP3311072B2 - Distance / speed measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance / velocity measuring device, for example, a distance / velocity measuring device suitable for a vehicle collision prediction sensor, and particularly to measuring a distance to an object immediately before a collision and a relative speed with the object. And a distance / speed measuring device.

[0002]

2. Description of the Related Art Conventionally, sensor technology (October 1992, Vol. 12, No. 1) has been used as a distance / speed measuring device.
1, p. 24), there is a triangulation method as shown in Transistor Technology (August, 1990, p. 468). The principle is as shown in FIG. The light is collimated by the optical system 25 and emitted, the target object 26 is irradiated, and the spot image of the measurement light beam is one-dimensional or two-dimensional by the light-receiving optical system 27 arranged at a distance of the base line L from the optical system 25. An image is formed on the light receiving element 28, and the distance to the target object is measured by measuring the position. This apparatus normally performs measurement on a stationary object. In this case, in order to perform measurement with good S / N, measurement is performed a plurality of times, and the average value is taken as a measured value. Using this device, the target object 26
Is detected by measuring the distance to the target object and its time a plurality of times to determine the temporal change in the distance.

[0003]

In the conventional distance / velocity measurement by the triangular distance measuring method, the distance L between the light emitting unit and the light receiving unit is mainly shorter than the distance y to the target object 26, and the distance L in front of the device is measured. A narrow range of angles was targeted for measurement. However, as can be seen in the distance / velocity measurement immediately before the collision, the distance / the distance to the target object 26 and the base length L are substantially the same.
When measuring the speed, there is a disadvantage that the measuring beam does not reach the measuring range in the conventional method. In addition, it is necessary to measure the temporal change of a specific point of the measurement object in order to determine the true speed of the measurement object, but when the measurement object crosses the measurement light beam, the measurement on the measurement object is performed. Since the measured position changes every moment, accurate measurement cannot be performed. The present invention has been made to solve the above-described problem, and can measure a wide area in a direction parallel to a base line.
It is an object of the present invention to provide a distance / speed measuring device capable of reducing errors and performing high-accuracy measurement even under a condition where / N is poor.

[0004]

According to the present invention, (1) a target object is irradiated with a measuring light beam, and
To the target object by detecting and processing the reflected light from
In a device that measures the distance and speed of
A light emitting unit for irradiating a plurality of measurement light beams in different directions ,
The same as the depth of the distance measurement area for measuring the distance of the target object
At a baseline distance of at least
Is emitted when the measurement light beam hits the target object.
A plurality of light receiving sections for detecting and outputting the position of the spot to be generated,
Based on the output signal of the light receiving unit and the principle of triangulation,
While calculating the distance or speed to the target object,
The target object is obtained by performing statistical processing on the result of the calculation.
Distance / speed calculation to calculate average distance or average speed to
Means, and at least one of the measuring light beams
The measurement light beam has an irradiation direction in the base length direction component.
And divides the distance measurement area in the depth direction.
Irradiating from the light-emitting portion to the distance and speed
A degree measuring device is provided. Further, according to the present invention, (2 ) the measurement light beam based on an output signal of the light receiving unit.
Determines whether or not the object has hit the target object, and is effective for measurement.
Is obtained when the output signal is equal to or more than a predetermined threshold value.
Trigger signal generating means for generating a trigger signal is further provided.
And the output of the light receiving section when the trigger signal is output
Signals are used to calculate distance or speed
(1) A distance / speed measuring device according to (1) is provided. Ma
According to the present invention, (3 ) the distance / speed calculating means is an i-th (i: natural number)
Or velocity information obtained by the measuring beam
And the detection output of the light receiving unit and the i-th measurement light beam.
Distance or speed obtained by successive measuring beams
And performing statistical processing by combining
Calculate the average distance or average speed to the measurement object.
The distance / velocity measuring device according to (1) is provided.
Provided.

[0005]

[Action] distance and speed measuring apparatus according to the present invention, when the object on the measuring light beam passes through, which makes it possible to measure the exact speed of the object, a base line length longer, measured
The base line direction is divided so that the distance area is divided in the depth direction.
Because it emits a plurality of measurement rays in the direction having the
It is possible to measure a long wide area in a direction parallel to the base line. Since the distance and time measurements in the same measurement area in one measurement beam are averaged, S /
The error can be reduced even under the condition where N is bad. In addition, since the speed and the distance are calculated using the average values of the distance and the time measured for each measurement area in different measurement light beams, the data can be obtained as more accurate data.
This averages each measurement data in the area i measured by the i-th measurement light beam as shown in FIG.
Find accurate distance and time as the average value in
At the time of entering the next area (i + 1), the speed is obtained based on the data of the area i.

As a principle of measuring the distance, as shown in FIG.
-A, 4-b, PSD (position sen
An image is formed on the passive detectors 5-a and 5-b, the spot positions are measured, and the distance y to the target is calculated. Assuming that the spot positions generated on the left and right PSDs are l _l and l _r , the focal length of the imaging lens is f, and the distance between the left and right lenses, that is, the base line length is L, the distance y to the object is y.
Is calculated by y = f · L / (l ₁ + l _r ).

As shown in FIG. 5, as the target object approaches the plane on which the apparatus is arranged, for example, as indicated by arrows 19-a, 19-b, and 19-c in the direction of arrow 18, ie, as the base line approaches, the target object The positions of the measurement spots are 20-a, 20-b,
20-c, but the trigger signal is actually O
Since the measurement is performed only for a short time after determining the appropriate number of measurements n ₁ after N, the error of the distance measurement caused by the influence of this shift becomes small, and the position of almost the same part of the target object is measured. It is possible to determine an accurate speed of the target object with respect to the measuring device.

[0008] emission of the N number of light rays to sequentially substitute
And monitor the trigger signal together with the light emission.
If so, the light emitter at that time is specified, and measurement is started. The distance value yI _{, J} (I is the number of the measurement light beam, J is the number of the measurement value) calculated based on the measurement value, and the time at that time is tI _{, J.} The number of samples in each light beam for averaging is determined to be n ₁ after the trigger signal indicating that it has been turned ON. The speed calculated from the distance measured at this time is (y _{I, J} −
y _{I, J-1} ) / (t _{I, J} -t _{I, J-1} ). In this formula, the error becomes large when the S / N in the distance measurement in each measurement is not good. It is necessary to perform an appropriate averaging process. Therefore, several points appropriately determined first from the start of measurement with the I-th light beam are first averaged, and when the measurement with this light beam is completed, one average is obtained from a set of distance data obtained with this light beam. Data, for example, y
_{m, I} = Σy _{I, J} / n _I , and the average time is t _{m, I} = Σt
_I, calculated as _J / n _I, then if y _m as a reference value of speed _{calculation, I,} t _m, to the use of _I, accurate values of the region measured in this ray is determined Will be.

When the measurement is performed on a plurality of light beams, as shown in FIG.
a, 22-b, and 22-c, portions 23-a, 23-b, and 23-c at which each measurement light beam starts to come into contact with the object.
That is, since the portions are almost the same, an accurate speed can be obtained by calculating the change in the measured distance even if the difference in the measurement with each light beam is obtained. The measurement in this case uses a speed as an average value obtained by the measurement with one light beam as described above in a certain measurement light beam, and when the measurement with the next measurement light beam is started, Since the speed is calculated using the measurement result of the measurement beam before that, more accurate measurement can be performed.

[0010]

FIG. 1 shows the arrangement of an optical system according to the present invention. A plurality of light emitting elements 1-a to 1-
f, which are sequentially exchanged by the light emitting element drive circuit 2.
Intensity modulated by the light emitting to cash, converts the light from each element into parallel beams by these optical systems is arranged in front of the elements 3-a, 3-b, a plurality of intensity-modulated measuring light When the light is emitted and the target object passes over the measurement light beam, a spot of the measurement light beam is generated on the target object, and the spot is imaged on the PSDs 5-a and 5-b by the light receiving optical systems 4-a and 4-b. The position of the object is measured from the straight line connecting the light receiving optical systems of the two devices by measuring the position by the detection light processing circuit 6.

The detection light processing circuit 6 is constituted by a microprocessor or the like, has a function of determining whether or not an object to be measured has come into contact with a measurement light beam and generating a trigger signal, and validating a received signal measured by the trigger signal. , The ability to determine invalidity,
By calculating the distance from the received signal, calculating the speed from the sequentially measured distance and time interval, and performing statistical processing of the distance measured for each area measured by each ray, the distance and the speed are calculated. It has a function of obtaining an average value and also obtaining a speed from distance and time information between different areas.

The light-emitting element driving circuit 2 sequentially changes
The intensity-modulated measurement light beams are emitted from the light emitting elements 1-a to 1-f.
When a target beam crosses the measurement light beam, the spot image generated at that time is detected by the light receiving optical systems 4-a and 4-b.
Images are formed on D5-a and 5-b. The signal corresponding to the position on the PSD is captured by the detection light processing circuit 6, sampled at appropriate time intervals, and A / D converted. At this time, the detection light processing circuit 6 always monitors the intensity and the like of the detection signal, and when the monitoring signal becomes equal to or more than a certain threshold value, the target object starts to come into contact with a certain measurement light beam. The trigger signal is generated upon determination, and the distance is calculated using the A / D converted value at this time. Note that a detection signal less than the threshold value is determined to be invalid and is not treated as a signal.
By such processing, it is possible to avoid performing a measurement with a large error due to a signal having a poor S / N.

Next, the flow of measurement will be described based on the processing flow of FIG. In the figure, I indicates the I-th measurement light beam, and J indicates the number of measurements. In the figure, the light emitting elements emit light sequentially (step 7), and distance data and time data to the corresponding object are obtained (step 8). Next, ON / OFF of the trigger signal is recognized based on the level of the received signal from the light receiving element, and it is determined whether or not the distance data is usable (step 9).

If the trigger is OFF, the process returns to step 7 to wait for the LED to emit light. Trigger signal is ON
, The distance data y measured at this time
(I, J) and time data t (I, J) at the time of measurement are stored (step 10) and used as data for averaging. Next, the number of measurements in the measurement of the I-th measurement light beam is compared with an appropriately determined number of times n _I (step 11). If there is a value larger than n _I , the measurement with this light beam is terminated, It waits for the measurement with the next light beam to start (step 12). If the number of measurements J is equal to or less than n _I , the speed is calculated (step 13). In the calculation of the velocity, v (I, J) is given by: v (I, J) = {y (I, J-1) -y (I, J)} / {t (I, J) -t (I, J-1)｝ is the velocity calculated from the distance difference and the time difference for each measurement, and v _m (I, J) is obtained as follows: v _m (I, J) = ｛y _m (I ) -y (I, J)} / {t (I, J) -t m (I)} first calculation while taking several averages a predetermined suitably measured in the measurement beam I as a velocity, further _{v O (I, J, I} ') _{is, v O (I, J,} I') = {y m (I') -y (I, J)} / {t (I , J) is a -t _m (I') measurement beam I and the calculated speed in relation to its pre-measurement light I'involved in the measurement as}.

[0015] Then, the number n _O for averaging which is appropriately determined number of measurements J in I-th measurement _beam, as compared to _I (step 14), the number of measurements J is n _O, is greater than _I Does not further perform the averaging process, and the number of measurements J is n
If it is less than _{O, I} , a process of averaging the distance and time is performed (step 15). Here averaging process _{is, y m (I, J)} = {(J-1) * y m (I) + y (I, J)} / J t m (I, J) = {(J-1 ) * T _m (I) + t (I, J)｝ / J, multiplying the average value obtained last time by (J−1), further adding the J-th data, and dividing by the number of times J Ask by Next, the determined distance and speed are determined (step 16), and signals such as approach information are generated.
Returning to the light emission of the LED (step 7), a series of operations is repeated in the same manner.

In another embodiment, one of the left and right measurement beams may be emitted at first outside each of the left and right measurement beams for measuring a relatively distant place. The measurement is started when the target object approaches and hits one of the outer light emission measurement light beams and the monitored trigger signal is turned ON. Thereafter, when the number of measurement samples reaches a certain number, the measurement light beam is switched to a light beam inside the measurement light beam. When the object is further approached, it hits the switched light beam again, so the same operation as above is performed to switch to the light beam inside. Since the average value of the distance has been obtained in the measurement with the previous measurement light beam, the speed can be calculated with high accuracy by calculating the speed using the average value. This can be implemented by performing the LED switching operation in step 12 of FIG.

[0017]

As described above, the distance and measurement device according to the present invention is
According to the apparatus , since a plurality of measurement light beams are used, a wide range of measurement can be performed, and the distance to the target and the relative speed to the target immediately before the collision can be detected. In addition, the measurement values of each measurement beam are averaged in each region, and the speed is calculated based on the averaged distance between the regions, so that more accurate measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement of an optical system according to the present invention.

FIG. 2 is a diagram illustrating a distance / speed calculation algorithm.

FIG. 3 is a conceptual diagram of measurement in the present invention.

FIG. 4 is a diagram illustrating the principle of triangulation.

FIG. 5 is a diagram showing a process of measurement using one measurement light beam.

FIG. 6 is a diagram showing a process of measurement using a plurality of measurement light beams.

FIG. 7 is a diagram illustrating conventional triangulation.

[Explanation of symbols]

 1-a to 1-f Light-emitting element 2 Light-emitting element drive circuit 3-a, 3-b Optical system 4-a, 4-b Light-receiving optical system 5-a, 5-b PSD 6 Detection light Processing circuit

Continuation of the front page (56) References JP-A-5-80154 (JP, A) JP-A-2-19708 (JP, A) JP-A-59-114409 (JP, A) JP-A-57-197414 (JP) , A) Japanese Patent Publication No. 5-18069 (JP, B2) Japanese Utility Model Publication No. 1-28407 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 3/06 G02B 7/30

Claims (3)

(57) [Claims] An object is irradiated with a measuring light beam.
By detecting and processing the reflected light from the target object,
In a device that measures the distance and speed to an object, irradiates a plurality of measurement light beams that alternately emit light sequentially in different directions.
And the depth of a distance measurement area for measuring the distance of the target object.
At a baseline distance of at least
Is emitted when the measurement light beam hits the target object.
A plurality of light receiving units for detecting and outputting the position of the spot to be generated, based on the output signal of the light receiving unit and the principle of triangulation,
While calculating the distance or speed to the target object,
The target object is obtained by performing statistical processing on the result of the calculation.
Distance / speed calculation to calculate average distance or average speed to
Means, and at least one of the measuring light beams
The measurement light beam has an irradiation direction in the base length direction component.
And divides the distance measurement area in the depth direction.
A distance / velocity measuring device, which is radiated from the light emitting section . 2. The method according to claim 2, further comprising:
It is determined whether or not the measurement light beam has hit the target object, and the measurement is performed.
The output signal above a predetermined threshold value that is
Trigger signal generation means that generates a trigger signal when
The light receiving when the trigger signal is output
Using the output signal of the unit to calculate the distance or speed
The distance / velocity measuring device according to claim 1, wherein: 3. The method according to claim 2, wherein the distance / speed calculating means is i (i: natural
Number) the distance or velocity obtained by the th measuring beam
Information, the detection output of the light receiving section and the i-th measurement
The distance obtained by the measuring light beam
Is a combination of speed information and statistical processing.
Calculate the average distance or average speed to the object to be measured
2. The distance / speed measuring device according to claim 1, wherein
Place.