JP6733495B2 - Distance measuring device - Google Patents

Description

The present disclosure relates to a technique of irradiating an object with light and receiving the reflected light to measure the distance to the object.

A technique is known in which light is emitted toward an object and the reflected light is received to measure the distance to the object.
In Patent Document 1, when the intensity of the light received during the emission stop period of the laser light is equal to or more than a predetermined value, it is determined that there is an input of the laser light from another vehicle that causes a decrease in distance measurement accuracy. Technology to do so has been proposed. Hereinafter, the technique proposed in Patent Document 1 will be referred to as a conventional technique.

JP, 2001-255371, A

However, in the above-mentioned conventional technique, all the light received during the emission stop period of the laser light and having the intensity equal to or higher than the predetermined value is determined to be the light that deteriorates the distance measurement accuracy. Therefore, even if the light does not actually reduce the distance measurement accuracy, if the light is received during the emission stop period of the laser light and the intensity is equal to or higher than a predetermined value, the distance measurement accuracy is There is a possibility that it may be judged that the light is a light that lowers.

The present disclosure provides a technique for accurately detecting the presence or absence of light that may reduce the accuracy of distance measurement.

The distance measuring device (11) of the present disclosure is a device that measures the distance to an object by receiving the reflected light of the light emitted from the irradiation unit (21) at the light receiving unit (23). The distance measuring device includes an irradiation processing unit (55), a light reception processing unit (56), and a determination unit (57).

The irradiation processing unit irradiates the irradiation unit with light. The light reception processing unit acquires a light reception result by the light reception unit. The determination unit, based on the intensity of light represented by the light reception result obtained in the immediately preceding period, which is a predetermined period immediately before the irradiation of light by the irradiation unit, interferes with light emitted from other than the irradiation unit. Determine the presence of light.

When the interference light is generated immediately before the irradiation, the distance measurement accuracy is deteriorated due to the influence of the interference light.
According to the present disclosure, it is determined whether or not interference light is generated based on the intensity of light received by the light receiving unit within the immediately preceding period immediately before irradiation. It is possible to exclude the detection of interference light that has no possibility of reducing That is, it is possible to accurately detect the presence or absence of light that may reduce the accuracy of distance measurement.

It should be noted that the reference numerals in parentheses described in this column and the claims indicate the correspondence with the specific means described in the embodiments to be described later as one aspect, and do not indicate the technical scope of the present disclosure. It is not limited.

The block diagram which shows the structure of a distance measuring device. Explanatory drawing which shows the mounting position and search range of the laser radar in a vehicle. Explanatory drawing which shows the structure of an irradiation part. Explanatory drawing which shows the structure of a light-receiving part. The block diagram which shows the functional structure of a control part. The figure which shows the flowchart of a measurement process. The figure explaining the waveform which the interference light was superimposed on the reflected light. The figure explaining the waveform in the immediately preceding period in reflected light when there is no interference light. 3 is a flowchart of interference light processing according to the first embodiment. The figure which shows the example which determines the presence or absence of the interference light in 1st Embodiment. The flowchart of the interference light process of 2nd Embodiment. The figure which shows the example which determines the presence or absence of the interference light in 2nd Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
The distance measuring device 10 shown in FIG. 1 is a device mounted on a vehicle. Hereinafter, a vehicle equipped with the distance measuring device 10 is also referred to as a host vehicle. As shown in FIG. 1, the distance measuring device 10 includes a control unit 11, a laser radar 12, and a driving support unit 13.

The laser radar 12 is attached near the center of the right side surface of the vehicle 1, as shown in FIG. The right side here means the right side with respect to the traveling direction of the host vehicle. As shown in FIG. 1, the laser radar 12 includes an irradiation unit 21, a light receiving unit 23, and a distance measuring unit 25.

The distance measuring device 10 is a device that measures the distance to an object by receiving the reflected light of the light emitted from the irradiation unit 21 at the light receiving unit 23.
As shown in FIG. 3, the irradiation section 21 includes a drive circuit 211, an LD 212, and an irradiation optical section 213. LD is an abbreviation for laser diode and represents a light emitting element.

The drive circuit 211 drives the LD 212 according to the light emission control signal SC. The light emission control signal SC is a signal indicating the timing for instructing the transmission of laser light. The light emission control signal SC is supplied from the control unit 11 at each preset detection cycle. The light emission control signal SC is supplied to the distance measuring unit 25, and the distance measuring unit 25 outputs a drive signal for driving the LD 212 to the drive circuit 211. The LD 212 emits pulsed laser light by being driven by the drive circuit 211.

The irradiation optical unit 213 includes, for example, a collimator lens, and adjusts the search range SF of the pulsed laser light emitted from the LD 212. In the present embodiment, the laser radar 12 is attached to the right side surface of the host vehicle, and the search range SF is predetermined including the direction perpendicular to the traveling direction of the host vehicle, as shown in FIG. The angle range is set.

The search range SF is arbitrarily determined according to the mounting position of the laser radar 12 and the detection target which is an object to be detected. In addition, the object mentioned here represents a tangible object. The tangible objects may include people, vehicles, buildings, white lines on roads, and the like.

In this way, the irradiation unit 21 drives the LD by the light emission control signal SC and irradiates the pulsed laser light toward the search range SF.
As shown in FIG. 4, the light receiving section 23 includes a light receiving optical section 231, a light receiving element section 232, and an amplifying section 233.

The light receiving optical unit 231 includes, for example, a condenser lens, and condenses the light coming from the search range SF.
The light receiving element section 232 includes a plurality of PDs 234. PD is an abbreviation for Photodiode and represents a light receiving element. Each PD 234 generates a light reception signal having a voltage value according to the magnitude of the light received via the light receiving optical unit 231. The amplification section 233 amplifies the received light signal and outputs it. The light receiving result by the light receiving unit 23 is the light receiving signals R1 to RN output from the light receiving unit 23.

The number of PDs 234 is equal to the number of divided ranges A1 to AN. The division range is, as shown in FIG. 2 described above, N areas generated by dividing the search range SF for each predetermined angle. N is a natural number. That is, each of the N PDs 234 outputs one of the light reception signals R1 to RN.

As described above, when the light emission control signal SC is output, the light receiving unit 23 receives light at different timings for each divided range Ai according to the instruction of the control unit 11, and outputs the light reception signal Ri according to the magnitude of the light. Output. The division range Ai represents one of the division ranges A1 to AN. i is an arbitrary natural number from 1 to N. For example, the received light signal generated by the light coming from the divided range A1 is the received light signal R1.

Returning to FIG. 1, the description will be continued. The distance measuring unit 25 measures the magnitude of the light receiving signals R1 to RN supplied from the light receiving unit 23 for each sampling cycle that is a predetermined cycle. The distance measuring unit 25 causes the laser light to reach the laser radar 12 and the distance measuring point based on the irradiation timing of the laser light specified by the light emission control signal SC and the light reception timing of the reflected light specified by the light reception signals R1 to RN. The time required to reciprocate between the two is measured for each of the light receiving signals R1 to RN. The distance measuring point indicates a position on the object that reflects the laser light.

The distance measuring unit 25 determines the distance from the laser radar 12 to the distance measuring point (hereinafter, distance measuring point distance) by using the time required for the laser light to reciprocate between the laser radar 12 and the distance measuring point. calculate.
Further, the distance measuring unit 25 estimates the direction of the distance measuring point with respect to the laser radar 12 (hereinafter referred to as the distance measuring point direction), depending on which one of the light reception signals R1 to RN is used.

When receiving an instruction from the control unit 11, the distance measuring unit 25 outputs data including the distance measuring point distance and the distance measuring point direction (hereinafter, distance measuring data) to the control unit 11.
The control unit 11 is mainly composed of a well-known microcomputer having a CPU 51 and a semiconductor memory (hereinafter, referred to as a memory 52) such as a RAM, a ROM, and a flash memory. Various functions of the control unit 11 are realized by the CPU 51 executing the programs stored in the non-transitional physical recording medium. In this example, the memory 52 corresponds to the non-transitional substantive recording medium storing the program. Further, by executing this program, the method corresponding to the program is executed. It should be noted that the number of microcomputers forming the control unit 11 may be one or more.

The control unit 11 includes an irradiation processing unit 55, a light receiving processing unit 56, a determination unit 57, and a distance calculation unit 58, as shown in FIG. 5, as a configuration of functions realized by the CPU 51 executing a program. Prepare The method of realizing these elements forming the control unit 11 is not limited to software, and some or all of the elements may be realized by using hardware that is a combination of logic circuits and analog circuits.

The control unit 11 is connected to the driving support unit 13 by a communication line 15 and can communicate with the driving support unit 13 by CAN. CAN is an abbreviation for Controller Area Network and is a registered trademark.

The driving support unit 13 is configured to receive distance measurement data from the control unit 11 and perform various driving assistance using the distance measurement data. The driving assistance may include, for example, speed control, acceleration control, deceleration control, etc. for keeping a distance to an object above a certain level.

[1-2. processing]
Next, the measurement process executed by the control unit 11 will be described with reference to the flowchart of FIG. When the subject is omitted in the following description, the control unit 11 is the subject.

The measurement process is a process of determining the presence or absence of interference light that may reduce the accuracy of distance measurement, calculating the distance when there is no interference light, and not calculating the distance when there is interference light. is there. The measurement process is repeatedly executed at every predetermined detection cycle.

The interference light referred to here is the light received by the light receiving unit 23, and is the light emitted from other than the irradiation unit 21. The interference light is a pulsed light such as a laser light emitted from a laser radar 91 mounted on another vehicle 9 traveling in an adjacent lane adjacent to the lane in which the vehicle 1 shown in FIG. 2 travels. Can be included.

If such pulsed interference light is received by the light receiving unit 23 before receiving the reflected light from the object, the waveform of the reflected light is disturbed as shown in FIG. There is a problem that the timing shown is deviated and the accuracy of measuring the distance to the object is reduced.

Therefore, in this measurement process, as shown in FIG. 8, the presence or absence of interference light is determined based on the received light intensity in the immediately preceding period T, which is a predetermined period immediately before irradiation. The irradiation time refers to a time point when the laser light is emitted from the irradiation unit 21. The immediately preceding period T represents a period in which the waveform of the reflected light is affected if there is interference light in that period. The received light intensity is the intensity of light represented by the light receiving result by the light receiving unit 23.

The received light intensity may be represented as a numerical value with the magnitude of any received light intensity being zero. That is, the received light intensity can be expressed as a positive or negative numerical value with zero as an arbitrary magnitude within the range of the received light intensity. Alternatively, the received light intensity can be expressed as a positive numerical value with zero as a magnitude equal to or smaller than the minimum value of the received light intensity.

In the present embodiment, the received light intensity is represented as a positive or negative numerical value that makes the so-called noise level zero. The noise level can be set to any value within the range of noise. In the present embodiment, the noise level is set to a central value within a range that noise can take, for example. That is, the received light signals R1 to RN are represented by received light intensity that is a positive or negative numerical value.

In the present embodiment, the magnitude of the received light signal Ri measured by the distance measuring unit 25 is acquired at each sampling cycle by a process different from the main measurement process executed by the control unit 11, and the received light intensity is obtained by the AD converter. The numerical value represented as is recorded in the memory 52.

In the following, a period including a sampling period that is past the sampling period in which the received light intensity at the time of irradiation is acquired, and a period that includes one sampling period from the previous sampling period to five previous sampling periods is immediately before. The period T will be described. Then, the received light intensity at the time of irradiation is referred to as X(0), and the received light intensities acquired in the past sampling cycle five previous to the previous sampling cycle X(−1) and X( -2)..., X (-5). In accordance with the description, the received light intensities X(-1), X(-2),..., X(-5) are referred to as the received light intensity X.

The immediately preceding period T is not limited to a period including one past sampling period before the irradiation to five past sampling periods before the irradiation. For example, the immediately preceding period T can be set to a period including the previous sampling period to the arbitrary number of past sampling periods. Further, the immediately preceding period T can be set to a period including an arbitrary number of previous sampling periods before the irradiation to a sampling period earlier than this.

Returning to FIG. 6, the description will be continued. The control part 11 makes the irradiation part 21 irradiate a laser beam in S10. Specifically, the light emission control signal SC is output, and the irradiation unit 21 is irradiated with laser light via the distance measuring unit 25.

In S20, the control unit 11 determines whether or not the laser light is emitted from the irradiation unit 21. If the laser beam is emitted, the process proceeds to S30, and if not, the process waits until the laser beam is emitted.

The laser light is not emitted from the irradiation unit 21 at the same time as the emission control signal SC is output, but may be emitted from the emission unit 21 after a predetermined delay time has elapsed since the emission control signal SC was output. The delay time is specified based on the delay in the circuit element, the wiring, and the like from the time when the emission control signal SC is output by the control unit 11 to the time when the laser light is emitted.

The control unit 11 determines whether or not the laser light is emitted from the irradiation unit 21 when the irradiation time is the time when the delay time elapses after the emission control signal SC is output in S10. However, the present invention is not limited to this, and the control unit 11 may use the time point when the light emission control signal SC is output as the irradiation time.

The control unit 11 acquires, from the memory 52, the light reception result by the light receiving unit 23 in the immediately preceding period T in S<b>30 when the laser light is emitted from the irradiation unit 21 and then transitions. Specifically, in the present embodiment, the received light intensity X in the immediately preceding period T is acquired from the memory 52 for each of the received light signals R1 to RN.

The control part 11 performs an interference light process in S40. The interference light processing is processing for determining the presence or absence of interference light based on the received light intensity X acquired within the immediately preceding period T, as described later. When the interference light is generated within the immediately preceding period T, the influence of the interference light may reduce the accuracy of distance measurement. In the interference light processing, the interference flag is set when it is determined that there is interference light, and the interference flag is reset when it is determined that there is no interference light.

In S50, the control unit 11 determines whether or not there is interference light. Specifically, it is determined that there is interference light when the interference flag is set.
Here, when there is no interference light, the control unit 11 shifts the processing to S60, calculates the distance in S60, and then ends the main measurement processing. In this embodiment, in S60, the distance measuring unit 25 is made to calculate the distance measuring data, and the calculated distance measuring data is acquired. However, the present invention is not limited to this, and the control unit 11 may be configured to calculate the distance measurement data in S60.

On the other hand, when there is interference light, the control unit 11 ends the main measurement process without calculating the distance in S60.
In this way, in this measurement process, the presence or absence of interference light is determined based on the received light intensity X within the immediately preceding period T. When the interference light is present, the distance calculation based on the reflected light is not performed.

Next, the interference light processing executed in S40 of the main measurement processing will be described with reference to the flowchart of FIG. In the present embodiment, the processes of S110, S120, and S130-S140 described below are executed for each of the light reception signals R1 to RN.

In S110, the control unit 11 determines whether or not the change mode when the received light intensity X in the immediately preceding period T changes with the passage of time is a monotonous decrease. If it is a monotonic decrease, the process proceeds to S140, and if it is not a monotonic decrease, the process proceeds to S120. That is, when the received light intensities X(−1), X(−2),..., X(−5) in the immediately preceding period T are lined up with the passage of time, and if they show a monotonic decrease, the processing is S140. Shift to.

In S120, the control unit 11 determines whether or not the change mode when the received light intensity X in the immediately preceding period T changes with the passage of time is a monotonous increase. If it is a monotone increase, the process proceeds to S140, and if it is not a monotone decrease, the process proceeds to S130. That is, when the received light intensities X(−1), X(−2),..., X(−5) in the immediately preceding period T are lined up with the passage of time, and if they show a monotonic increase, the processing is performed at S140. Shift to.

In S130, the control unit 11 determines that there is no interference light, resets the interference flag, and ends the interference light processing.
In S140, the control unit 11 determines that there is interference light, sets the interference flag, and ends the interference light processing. The interference flag can be set when it is determined that there is interference light based on at least one received light signal of the received light signals R1 to RN.

For example, as shown in FIG. 10, when the falling edge of the pulsed interference light is superimposed before the reflected light from the object is received, the waveform of the light received by the light receiving unit 23 within the immediately preceding period T. It has been confirmed by experiments that indicates a monotonic decrease. Further, when the overshoot at the trailing edge of the pulsed interference light is superimposed before the reflected light from the object is received, the waveform of the light received by the light receiving unit 23 in the immediately preceding period T monotonically increases. It has been confirmed by experiments that

If such a situation that the pulsed interference light is received by the light receiving unit 23 before receiving the reflected light from the object, there arises a problem that the measurement accuracy of the distance to the object decreases.
In the present interference light processing, it is determined that there is interference light when the waveform of the light received by the light receiving unit 23 shows a monotonous decrease or a monotonous increase within the immediately preceding period T. The presence or absence of interference light that may cause a decrease is accurately detected.

[1-3. effect]
According to the first embodiment described in detail above, the following effects are achieved.
(1a) The distance measuring device 10 measures the distance to the object by receiving the reflected light of the light emitted from the irradiation unit 21 at the light receiving unit 23. In the control unit 11, the irradiation processing unit 55 causes the irradiation unit 21 to emit light. Further, the light reception processing unit 56 acquires the light reception result by the light reception unit 23. Then, the determining unit 57 irradiates from other than the irradiating unit 21 on the basis of the light intensity represented by the light reception result acquired in the immediately preceding period T which is a predetermined period immediately before the irradiation of the light by the irradiating unit 21. The presence or absence of the interference light that is the emitted light is determined.

According to the present disclosure, it is determined whether or not the interference light is generated based on the intensity of the light received by the light receiving unit 23 within the immediately preceding period T immediately before the irradiation, and therefore, unlike the related art, the distance It is possible to exclude the detection of interference light that does not reduce the measurement accuracy. That is, it is possible to accurately detect the presence or absence of light that may reduce the accuracy of distance measurement.

(1b) The control unit 11 determines that there is interference light in the determination unit 57 when the change mode when the intensity of light represented by the light reception result changes with the passage of time is a monotonous decrease.
In general, since the intensity of noise changes randomly, a signal that monotonically decreases within the immediately preceding period T can be distinguished as a signal different from noise.

According to this, based on the light reception result acquired in the immediately preceding period T, there is interference light when the change mode in which the intensity of light represented by the light reception result changes monotonically with time. Since the determination is made, it is possible to detect the occurrence of interference light that may reduce the accuracy of distance measurement, as in (1a).

(1c) The control unit 11 determines that there is interference light when the determination unit 57 has a monotonically increasing change mode when the intensity of light represented by the light reception result changes with the passage of time. A signal that monotonically increases in the immediately preceding period T can be distinguished as a signal different from noise.

According to this, based on the light reception result acquired in the immediately preceding period T, there is interference light when the change mode in which the intensity of the light represented by the light reception result changes with the passage of time is a monotonous increase. Since the judgment is made, the same effect as (1b) can be obtained.

(1d) In the distance calculation unit 58, the control unit 11 calculates the distance to the object when the judgment unit 57 judges that there is no interference light, and when it judges that there is interference light, the distance to the object. Is not calculated.

According to this, since the control unit 11 does not calculate the distance to the object when it is determined that there is the interference light, it is possible to suppress obtaining an incorrect calculation result.
[2. Second Embodiment]
[2-1. Differences from the first embodiment]
The second embodiment has the same basic configuration as that of the first embodiment, and therefore the differences will be described below. The same reference numerals as those in the first embodiment indicate the same configurations, and refer to the preceding description.

In the above-described first embodiment, it is determined based on the waveform of the light received by the light receiving unit 23 within the immediately preceding period T whether or not there is interference light that may reduce the distance measurement accuracy. Was there. On the other hand, in the second embodiment, based on whether or not the intensity of the light received by the light receiving unit 23 within the immediately preceding period T becomes a value outside the detection range, which is a predetermined range, This is different from the first embodiment in that it is determined whether or not there is interference light that may reduce the measurement accuracy.

[2-2. processing]
Next, the interference light processing executed by the control unit 11 of the second embodiment instead of the interference light processing (FIG. 9) of the first embodiment will be described using the flowchart of FIG. 11. Since the processing of S130-S140 in FIG. 11 is the same as the processing of S130-S140 in FIG. 9, a part of the description is simplified.

In S105, the control unit 11 determines whether or not the received light intensity X acquired within the immediately preceding period T is a value outside the predetermined detection range. When the received light intensities X acquired within the immediately preceding period T are numerical values outside the predetermined detection range, all the received light intensities X acquired during the immediately preceding period T are outside the detection range, and A case may be included in which at least one of the received light intensities X acquired within the immediately preceding period T is a numerical value outside the detection range. In the present embodiment, it is assumed that the control unit 11 determines in this step whether or not the received light intensities X acquired within the immediately preceding period T are all values outside the detection range.

The control unit 11 shifts the processing to S140 when the received light intensities X acquired in the immediately preceding period T are all values outside the detection range, and shifts the processing to S115 when all are not outside the detection range. Let The case where all of the received light intensities are not outside the detection range means that one or more received light intensities of the received light intensities X acquired in the immediately preceding period T are within the detection range.

As shown in FIG. 8, the detection range is set in a band-like range from −α, which is the lower limit value of the detection range, to +β, which is the upper limit value of the detection range. The lower limit value and the upper limit value of the detection range can be set to arbitrary values.

The numerical value outside the detection range in the present embodiment means a value smaller than the lower limit value of the detection range and a value larger than the upper limit value of the detection range. That is, it means a numerical value smaller than the lower limit value -α and a numerical value larger than the upper limit value +β.

It should be noted that in the present embodiment, a predetermined detection threshold value is set as the values of α and β. That is, a band-shaped range from − detection threshold value to + detection threshold value sandwiching 0 is set as the detection range.

The detection threshold is a predetermined magnitude of received light intensity. In the present embodiment, for example, the detection threshold value is set to a value that distinguishes the minimum value that can be assumed as the received light intensity of the reflected light from the object from the noise. When there is no interference light that reduces the distance measurement accuracy, the received light intensity in the immediately preceding period T can be detected as a noise level, as shown in FIG. Therefore, when the received light intensities X in the immediately preceding period T are all values outside the detection range, the control unit 11 determines that interference light is present and shifts the processing to S140.

In S115, the control unit 11 does not monotonically increase the change mode when the received light intensities X acquired in the immediately preceding period T are not all values outside the detection range and the received light intensities X change with the passage of time. If it is, it is determined that there is interference light, and the process proceeds to S140. If the received light intensities X acquired within the immediately preceding period T are not all values outside the detection range, and the change mode when the received light intensities X change with the passage of time is not a monotonic increase, the process proceeds to S125. Transfer.

In S125, the control unit 11 monotonically decreases the change mode when the received light intensities X acquired within the immediately preceding period T are not all values outside the detection range and the received light intensities X change with the passage of time. If it is, it is determined that there is interference light, and the process proceeds to S140. If the received light intensities X acquired within the immediately preceding period T are not all values outside the detection range and the change mode when the received light intensities X change with the passage of time is not monotonically decreasing, the process proceeds to S130. Transfer.

In S130 and S140, the control unit 11 executes the same processing as the processing of S130 to S140 in FIG. 9 and ends the interference light processing.
That is, in the present embodiment, the control unit 11 shifts the processing to S130 and resets the interference flag when a negative determination is made in all the determination conditions of S105, S115, and S125. Further, in the present embodiment, the control unit 11 shifts the processing to S140 and sets the interference flag when an affirmative determination is made in at least one of these determination conditions.

For example, as shown in FIG. 12, when the pulsed interference light is superimposed before the reflected light from the object is received, all the received light intensities X in the immediately preceding period T indicate values outside the detection range. Experiments have confirmed that there are cases. It has been confirmed by experiments that the received light intensities X may not monotonically increase or monotonically decrease. If such pulsed interference light is received by the light receiving unit 23 immediately before receiving the reflected light from the object, there arises a problem that the measurement accuracy of the distance to the object is reduced.

In this interference light processing, since it is determined that there is interference light when the received light intensity is all outside the detection range in the waveform of the light received by the light receiving unit 23 in the immediately preceding period T, the distance measurement is performed. The presence or absence of light that may reduce the accuracy is accurately detected. Even when the light waveform shows neither a monotonous increase nor a monotonous decrease, it is determined that there is interference light if all the received light intensities are values outside the detection range, so the distance measurement accuracy is improved. The presence or absence of light that may cause a decrease is accurately detected.

However, when the received light intensities X are not all values outside the detection range within the immediately preceding period T, it does not mean that there is no interfering light that may reduce the distance measurement accuracy before receiving the reflected light from the object. Absent. This is because the interference light has an overshoot at the time of rising or falling. In the overshoot when the interference light rises or falls, unlike the noise that randomly changes, the waveform shows a monotonous increase or monotonic decrease.

By utilizing this, in the interference light processing, in the waveform of the light received by the light receiving unit 23 in the immediately preceding period T, when the received light intensities are not all values outside the detection range, the waveform increases monotonically or If it shows a monotonic decrease, it is determined that there is interference light. As a result, the presence or absence of interference light that may reduce the accuracy of distance measurement is accurately detected.

[2-3. effect]
According to the second embodiment described in detail above, the effect (1a) of the above-described first embodiment is exerted, and further the following effect is exerted.

(2a) In the control unit 11, the determination unit 57 determines that interference light is present when the light intensity represented by the light reception result acquired within the immediately preceding period T is a numerical value outside the predetermined detection range. To do.
According to this, by comparing the received light intensity and the detection range in the immediately preceding period T, it is possible to accurately and easily determine the presence or absence of interference light that may reduce the distance measurement accuracy.

(2b) In the control unit 11, the determination unit 57 determines that the light intensity represented by the light reception result acquired in the last period T is not a numerical value outside the predetermined detection range, and the light intensity represented by the light reception result. When there is a monotonic increase in the change mode when changes with time, it is determined that there is interference light.

According to this, it is possible to detect the start or the end of the generation of the interference light within the immediately preceding period T. As a result, it is possible to accurately determine the presence or absence of interference light that may reduce the distance measurement accuracy.

(2c) In the control unit 11, the determination unit 57 determines that the light intensity represented by the light reception result acquired within the immediately preceding period T is not a numerical value outside the predetermined detection range, and the light intensity represented by the light reception result is It is determined that there is interference light when the change mode when changing over time is a monotonous increase.

According to this, the same effect as (2b) can be obtained.
[3. Other Embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be implemented.

(3a) In the above embodiment, the presence or absence of interference light that may reduce the accuracy of distance measurement is determined based on a plurality of determination criteria, but the present invention is not limited to this. For example, in the interference light processing shown in FIG. 9, the presence/absence of interference light may be determined based on only the determination in S120 without deleting the determination in S110. Alternatively, the determination in S120 may be deleted. Further, for example, in the interference light processing shown in FIG. 11, at least one of the determinations in S105, S115, and S125 may be deleted.

(3b) In the above embodiment, the control unit 11 has been described as determining whether or not the received light intensities X acquired within the immediately preceding period T are all values outside the detection range in S105. It is not limited to. The control unit 11 may be configured to determine in S105 whether or not at least one of the received light intensities X acquired in the immediately preceding period T is a numerical value outside the detection range. However, the present invention is not limited to this, and the control unit 11 may be configured to determine in S105 whether or not at least two received light intensities are values outside the detection range. Alternatively, the control unit 11 may be configured to determine in S105 whether at least three or at least four received light intensities are values outside the detection range.

(3c) In the above-described embodiment, in the distance measuring device 10, the irradiation unit 21 irradiates the entire search range SF with the laser light, and the light receiving unit 23 receives the reflected light in each divided range Ai, that is, so-called collective light emission. It was a divided light receiving system. However, the configuration of the distance measuring device 10 is not limited to this.

The distance measuring device 10 may be, for example, a so-called split emission split light receiving system in which the irradiation unit 21 emits the laser beam in each divided range Ai and the light receiving unit 23 receives the reflected light in each divided range Ai.

In the distance measuring device 10 in this case, the irradiation optical unit 213 includes, although not shown, a polygon mirror that reflects the laser light in an arbitrary direction and a drive rotating machine that drives the polygon mirror, instead of the collimator lens. May be. The control unit 11 may be configured to output a signal for controlling the rotational driving of the polygon mirror to the driving rotating machine to change the irradiation direction of the laser light.

Further, in the distance measuring device 10 in this case, the control unit 11 makes the division range Ai in which the irradiation unit 21 emits the laser light and the division range Ai in which the light reception unit 23 receives the reflected light to be the same. In addition, it may be configured to control the irradiation unit 21 and the light receiving unit 23. Since the configuration of such a distance measuring device 10 is a configuration well known in various documents, detailed description will be omitted here.

Then, in the measurement process, the control unit 11 may be configured to execute the interference light process for each of the light reception signals R1 to RN obtained by sequentially irradiating the divided ranges A1 to AN with the laser light. Even in such an example, the same effect as that of the above-described embodiment can be obtained.

(3d) The control unit 11 causes the driving support unit 13 to perform driving support using the distance measurement data when the interference flag is not set, and causes the driving support unit 13 to perform when the interference flag is set. The driving assistance using the ranging data may not be executed.

(3e) In the above embodiment, the received light intensity is represented as a positive or negative numerical value, but the invention is not limited to this. As described above, the received light intensity may be represented as a positive numerical value whose magnitude is equal to or smaller than the minimum value that the received light intensity can take, and in this case, the received light intensity is represented as a positive value. Then, the above-mentioned detection range may be appropriately set according to the value that is zero when the received light intensity is represented.

(3f) A plurality of functions of one constituent element in the above-described embodiment may be realized by a plurality of constituent elements, or one function of one constituent element may be realized by a plurality of constituent elements. .. Further, a plurality of functions of a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. Moreover, you may omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above-described embodiment may be added or replaced with respect to the configuration of the other above-described embodiment. Note that all aspects included in the technical idea specified by the wording recited in the claims are embodiments of the present disclosure.

(3g) In addition to the distance measuring device 10 and the control unit 11 described above, various programs such as a program for causing the control unit 11 to function, a non-transitional actual recording medium such as a semiconductor memory in which the program is recorded, and a distance measuring method are used. The present disclosure can be realized in a form.

[4. Correspondence between Claims and Embodiments]
S10 corresponds to the processing as the irradiation processing unit 55, S30 corresponds to the processing as the light receiving processing unit 56, S40, S105, S110, S115, S120, and S125 correspond to the processing as the determination unit 57, and S60 corresponds to This corresponds to the processing as the distance calculation unit.

10 distance measuring device, 11 control unit, 21 irradiation unit, 23 light receiving unit.

Claims (3)

A distance measuring device (10) for measuring a distance to an object by receiving reflected light of light emitted from an irradiation unit (21) at a light receiving unit (23),
An irradiation processing section (55) for irradiating the irradiation section with light,
A light receiving processing unit (56) for acquiring a light receiving result by the light receiving unit,
Based on the intensity of light has been the light reception result obtained in immediately preceding period represents a predetermined period immediately before the time of irradiation of light by the irradiation unit, the other a light emitted from other than the irradiation unit A determination unit (57) configured to determine the presence or absence of interference light, which is pulsed light emitted from the vehicle ,
Equipped with
The determination unit (S110, S125) determines that at least one of the light intensities represented by the light reception result acquired in the immediately preceding period has a value outside the detection range, which is a predetermined range. It is determined that there is, all the light intensity represented by the light reception result acquired in the immediately preceding period is a value within the detection range, and the light intensity represented by the light reception result is When the change mode when changing with time is a monotone increase or a monotone decrease, it is determined that there is the interference light.
Distance measuring device. The distance measuring device according to claim 1,
The determination unit determines that there is the interference light when at least one of the light intensities represented by the light reception result acquired in the immediately preceding period has a value outside the detection range, and All the light intensities represented by the light reception result acquired in the immediately preceding period are values within the detection range, and the change mode when the light intensity represented by the light reception result changes with the passage of time. Is not monotonically increasing or monotonically decreasing, it is determined that there is no interference light.
Distance measuring device. The distance measuring device according to claim 1 or 2 , wherein
A distance calculation unit (58) that calculates a distance to the object when the judgment unit judges that there is no interference light and does not calculate a distance to the object when it judges that the interference light exists.
A distance measuring device further comprising: