阅读说明：本技术 测距装置以及测距装置中的异常判定方法 (Distance measuring device and abnormality determination method in distance measuring device ) 是由 尾崎宪幸 林内政人 秦武广 于 2020-02-05 设计创作，主要内容包括：测距装置100具备：受光部30,具有用于接受入射光的多个受光区域,以各受光区域为单位来执行入射光的受光；以及发光部20,与各受光区域对应地排他地执行检测光的照射。测距装置100还具备异常判定部10,在根据检测光的照射而由受光部接受入射光时,该异常判定部10根据多个受光区域中的、与排他性的检测光的照射对应的受光对象区域中的入射光强度的特性和与排他性的检测光的照射不对应的受光非对象区域中的入射光强度的特性之间的不同,进行测距装置中的异常判定。(The distance measuring device 100 includes: a light receiving unit 30 having a plurality of light receiving regions for receiving incident light, and receiving the incident light in units of each light receiving region; and a light emitting unit 20 that exclusively irradiates the detection light in correspondence with each light receiving region. The distance measuring device 100 further includes an abnormality determination unit 10, and when the light receiving unit receives the incident light based on the irradiation of the detection light, the abnormality determination unit 10 performs abnormality determination in the distance measuring device based on a difference between a characteristic of an incident light intensity in a light receiving target region corresponding to the irradiation of the exclusive detection light and a characteristic of an incident light intensity in a light receiving non-target region not corresponding to the irradiation of the exclusive detection light among the plurality of light receiving regions.)

1. A distance measuring device (100) is provided with:

a light receiving unit (30) that has a plurality of light receiving regions for receiving incident light, and that receives the incident light on a per light receiving region basis;

a light emitting unit (20) that exclusively irradiates the detection light in correspondence with each of the light receiving regions; and

and an abnormality determination unit (10) that, when the incident light is received by the light receiving unit in response to the irradiation of the detection light, performs abnormality determination regarding at least one of the light receiving unit and the light emitting unit of the distance measuring device, based on a difference between a characteristic of the intensity of the incident light in a light receiving target region corresponding to the irradiation of the exclusive detection light and a characteristic of the intensity of the incident light in a light receiving non-target region not corresponding to the irradiation of the exclusive detection light, among the plurality of light receiving regions.

2. The ranging apparatus as claimed in claim 1, wherein,

when light reception of the incident light is simultaneously performed in a plurality of the light receiving regions, the abnormality determination section performs abnormality determination in accordance with a difference between a characteristic of the intensity of the incident light in the light receiving target region and a characteristic of the intensity of the incident light in the light receiving non-target region.

3. A ranging apparatus as claimed in claim 1 or 2 wherein,

the abnormality determination unit determines that an abnormality has occurred in the distance measuring device when a characteristic of the intensity of the incident light in the light-receiving target region and a characteristic of the intensity of the incident light in the light-receiving non-target region have a correlation relationship.

4. A ranging apparatus as claimed in claim 3 wherein,

the correlation is a similarity of the waveform of the incident light intensity with respect to time,

the abnormality determination unit determines that an abnormality has occurred in the distance measuring device when the similarity is greater than a predetermined determination similarity.

5. A ranging apparatus as claimed in claim 3 wherein,

the correlation is an approximation of a period of peak generation in a waveform of the incident light intensity with respect to time,

the abnormality determination unit determines that an abnormality has occurred in the distance measuring device when the degree of approximation is greater than a predetermined determination degree of approximation.

6. A ranging apparatus as claimed in any of claims 1 to 5 wherein,

the abnormality determination unit performs the abnormality determination when the reflected light of the detection light enters the light receiving target region.

7. A ranging apparatus as claimed in any of claims 3 to 5 wherein,

the abnormality determination unit determines that an abnormality has occurred in the distance measuring device when the reflected light of the detection light does not enter the light receiving target region and the number of light receiving non-target regions having no correlation is larger than a predetermined second abnormality determination value.

8. A ranging apparatus as claimed in any of claims 3 to 5 wherein,

the abnormality determination unit determines an abnormality of the light receiving unit when the reflected light of the detection light enters the light receiving target region and the number of light receiving non-target regions having the correlation is larger than a predetermined abnormality determination value,

the abnormality determination unit determines an abnormality of the light emitting unit when the reflected light of the detection light does not enter the light receiving target region and the number of light receiving non-target regions having no correlation is larger than a predetermined second abnormality determination value.

9. An abnormality determination method in a distance measuring device (100), comprising:

the irradiation of the detection light is exclusively performed for each light receiving region in a light receiving unit (30) having a plurality of light receiving regions,

when the light receiving unit receives the incident light in response to the irradiation of the detection light, abnormality determination regarding at least one of the light receiving unit and the light emitting unit of the distance measuring device is performed based on a difference between a characteristic of an intensity of the incident light in a light receiving target region corresponding to the exclusive irradiation of the detection light and a characteristic of an intensity of the incident light in a light receiving non-target region not corresponding to the exclusive irradiation of the detection light among the plurality of light receiving regions.

Technical Field

The present invention relates to an abnormality determination technique in a distance measuring device using a laser beam.

Background

An optical distance measuring device for detecting an object using laser light is proposed (for example, japanese patent laid-open nos. 2012 and 60012 and 2016 and 176750).

However, in the conventional distance measuring device, sufficient studies have not been made on the self-determination of an abnormality and the improvement of the accuracy of the determination of an abnormality of the distance measuring device, such as the displacement of the light receiving unit or the light emitting unit in the distance measuring device or the reduction of the S/N due to the adhesion of dirt on the optical system.

Therefore, the distance measuring device is required to perform self-determination of an abnormality in at least one of the light receiving unit and the light emitting unit.

Disclosure of Invention

The present invention can be realized in the following manner.

A first aspect provides a ranging device. A distance measuring device according to a first aspect includes: a light receiving unit having a plurality of light receiving regions for receiving incident light, the light receiving unit receiving the incident light in units of the light receiving regions; a light emitting unit that exclusively irradiates detection light in correspondence with each of the light receiving regions; and an abnormality determination unit that, when the incident light is received by the light receiving unit in response to the irradiation of the detection light, performs abnormality determination regarding at least one of the light receiving unit and the light emitting unit of the distance measuring device, based on a difference between a characteristic of an intensity of the incident light in a light receiving target region corresponding to the irradiation of the exclusive detection light and a characteristic of an intensity of the incident light in a light receiving non-target region not corresponding to the irradiation of the exclusive detection light, among the plurality of light receiving regions.

According to the distance measuring device of the first aspect, it is possible to perform self-determination of an abnormality relating to at least one of the light receiving unit and the light emitting unit in the distance measuring device.

The second mode provides an abnormality determination method in a distance measuring device. A method for determining an abnormality in a distance measuring device according to a second aspect includes: the method includes the steps of exclusively performing irradiation of detection light for each of light receiving regions in a light receiving portion having a plurality of light receiving regions, and performing abnormality determination regarding at least one of the light receiving portion and the light emitting portion of the distance measuring device based on a difference between a characteristic of an intensity of incident light in a light receiving target region corresponding to the exclusive irradiation of the detection light and a characteristic of an intensity of incident light in a light receiving non-target region not corresponding to the exclusive irradiation of the detection light when the light receiving portion performs the light receiving of the incident light based on the irradiation of the detection light.

According to the abnormality determination method in the distance measuring device of the second aspect, it is possible to perform self-determination of an abnormality regarding at least one of the light receiving unit and the light emitting unit in the distance measuring device. The present invention can also be realized as an abnormality determination program in a distance measuring device or a computer-readable recording medium that records the program.

Drawings

Fig. 1 is an explanatory view showing a schematic configuration of a distance measuring device according to a first embodiment.

Fig. 2 is a block diagram showing a functional configuration of a control unit of the distance measuring device according to the first embodiment.

Fig. 3 is an explanatory view schematically showing a light receiving element array provided in the distance measuring device of the first embodiment and illustrating a histogram in each light receiving area.

Fig. 4 is an explanatory view schematically showing a light emitting element provided in the distance measuring device of the first embodiment.

Fig. 5 is an explanatory diagram illustrating an example of the timing of the light receiving process and the light emitting process in the distance measuring device of the first embodiment.

Fig. 6 is a flowchart showing a flow of an abnormality determination process executed by the distance measuring device of the first embodiment.

Fig. 7 is an explanatory diagram illustrating a light receiving form of the light receiving element array.

Fig. 8 is a flowchart showing a flow of an abnormality determination process executed by the distance measuring device of the second embodiment.

Fig. 9 is a flowchart showing a flow of an abnormality determination process executed by the distance measuring device of the third embodiment.

Fig. 10 is an explanatory diagram schematically showing a light receiving element array according to another embodiment.

Detailed Description

The distance measuring device and the abnormality determination method in the distance measuring device according to the present invention will be described below based on embodiments.

The first embodiment:

as shown in fig. 1, the distance measuring device 100 of the first embodiment includes a control unit 10, a light emitting unit 20, a light receiving unit 30, and an electric drive unit 40. Distance measuring device 100 is mounted on a vehicle, for example, and detects an object around the vehicle. The distance measuring device 100 has a predetermined scanning angle range, and performs irradiation of the detection light by the light emitting unit 20 and reception of the reflected light by the light receiving unit 30 in units of a unit scanning angle obtained by dividing the scanning angle range into a plurality of angles, thereby measuring the distance of the entire scanning angle range. The unit scan angle defines the resolution of the distance measuring device 100 or the resolution of the distance measurement result obtained by the distance measuring device 100, and as the unit scan angle decreases, the resolution and resolution increase. In the following, the unit scanning angle is also referred to as a scanning column, and for the sake of distinction, reference numerals such as N scanning columns and N +1 scanning columns are sometimes given. The detection result of the object is used as a determination parameter of driving assistance such as driving force control, brake assistance, and steering assistance. The distance measuring device 100 may include at least the control unit 10, the light emitting unit 20, and the light receiving unit 30. The distance measuring device 100 is, for example, a Lidar (Light Detection and Ranging) device, and includes a scanning mechanism 35 rotationally driven by an electric drive unit 40, and a half-mirror 36 that transmits laser Light emitted from the Light emitting unit 20 and reflects incident Light. In the present embodiment, the light emitting unit 20 or the light receiving unit 30 may include at least a scanning mechanism 35 forming an optical path for emitting or receiving light, and a half-mirror 36, and may further include a cover glass 37 and a lens not shown provided in the distance measuring device 100. In this case, the light emitting system or the light receiving system may be referred to.

The control unit 10 includes: a Central Processing Unit (CPU)11 as an arithmetic section, a memory 12 as a storage section, an input/output interface 13 as an input/output section, and a clock generator not shown. The CPU11, the memory 12, the input-output interface 13, and the clock generator are connected via the internal bus 14 so as to be capable of bidirectional communication. The memory 12 includes: a memory, such as a ROM, in which an abnormality determination processing program P1 for determining an abnormality related to at least one of the light receiving unit and the light emitting unit of the distance measuring device 100 based on a difference between a characteristic of the intensity of incident light in the light receiving target region and a characteristic of the intensity of incident light in the light receiving non-target region is stored in a nonvolatile and read-only manner; and a memory, such as a RAM, that can be read by and written to by the CPU 11. The memory or area of the memory 12, which is readable and writable, includes a histogram-by-area storage area 12a, and the histogram-by-area storage area 12a stores histograms generated for each of the plurality of light-receiving areas included in the light-receiving unit 30. The CPU11, that is, the control unit 10, functions as an abnormality determination unit by expanding and executing the abnormality determination processing program P1 stored in the memory 12 into a readable and writable memory. The CPU11 may be a single CPU, may be a plurality of CPUs that execute respective programs, or may be a multitasking type CPU that can execute a plurality of programs at the same time. In the case where the abnormality determination processing program P1 is executed only for abnormality determination, the CPU11 may execute a ranging program for executing a ranging process stored in the memory 12, whereby the CPU11 functions as a ranging control unit and the ranging apparatus 100 calculates the distance between the target object and the ranging apparatus 100.

The light emission control unit 21, the light reception control unit 31, and the motor driver 41 are connected to the input/output interface 13 via control signal lines, respectively. The light emission control unit 21 is sent a light emission control signal, the light reception control unit 31 receives an incident light intensity signal, and the motor driver 41 is sent a rotation speed instruction signal.

The light receiving unit 30 includes a light receiving control unit 31 and a light receiving element array 32 in a narrow sense. The light receiving element array 32 is a flat plate-like photosensor in which a plurality of light receiving elements are arranged in the vertical and horizontal directions, and each light receiving element is configured by, for example, an SPAD (Single Photon Avalanche Diode) or another photodiode. In addition, as the minimum unit of the light receiving process, the term of the light receiving pixel is sometimes used, and in this case, each light receiving pixel can be constituted by a single light receiving element or a plurality of light receiving elements, and the light receiving element array 32 can have a plurality of light receiving pixels. The light receiving element array 32 is divided into a plurality of light receiving regions. The light receiving region is a unit of the light receiving region in which the light receiving control unit 31 executes the light receiving process in the distance measuring process of receiving the reflected light of the detection light irradiated from the light emitting unit 20, that is, a unit of the light receiving element group or the light receiving pixel group, and in the present embodiment, the light receiving element array 32 is divided into 4 light receiving regions Ra1 to Ra4 identified by numbers, for example, as shown in fig. 3, and each of the light receiving regions Ra1 to Ra4 is configured by 8 light receiving pixels 321. As shown in fig. 5, the light reception control unit 31 executes light reception processing for outputting an incident light intensity signal corresponding to the amount of incident light or the intensity of incident light to each light receiving region for each unit scanning angle, that is, for each scanning column. In fig. 5, reference numeral f denotes the execution of the light receiving process in the case where the light emitting section 20 emits light 1 time for each scanning column, and reference numeral f + p denotes the execution of the light receiving process in the case where the light emitting section 20 emits light a plurality of times for each scanning column, 4 times in the example of fig. 5. In general, when the pixels of the light receiving element array 32 are configured by a plurality of light receiving elements, the incident light intensity signal is generated by 1-time light emission and light receiving processing for adding detection values of the respective light receiving elements, and when the pixels of the light receiving element array 32 are configured by a single light receiving element or a small number of light receiving elements, the incident light intensity signal is generated by a plurality of times of light emission and a plurality of times of light receiving processing without addition, thereby improving S/N. In the light reception process, specifically, the light reception control unit 31 adds the current generated by each light reception pixel constituting each light reception region in accordance with the amount of incident light or the voltage converted from the current for each scanning line in units of each light reception region, and outputs the resultant signal to the control unit 10 as an incident light intensity signal. Alternatively, an incident light intensity signal corresponding to the total number of photons received by the light receiving elements constituting each light receiving pixel may be output to the control unit 10.

The light emitting unit 20 includes a light emission control unit 21 and a light emitting element 22 in a narrow sense, and irradiates detection light for each unit scanning angle. The light emitting element 22 is, for example, an infrared laser diode, and emits infrared laser light as detection light. As shown in fig. 4, the light emitting unit 20 includes light emitting elements LD1 to LD4, and the light emitting elements LD1 to LD4 correspond to the light receiving regions Ra1 to Ra 4. As shown in fig. 5, the light emission control unit 21 exclusively drives the light emitting elements LD1 to LD4 based on a drive signal of a pulse drive waveform in accordance with a light emission control signal for instructing exclusive light emission of the 4 light emitting elements LD1 to LD4, which is input from the control unit 10 via the input/output interface 13 for each unit scanning angle, and performs light emission of the infrared laser light corresponding to each light receiving region Ra1 to Ra 4. That is, the light emitting unit 20 and the light receiving unit 30 are optically configured such that, in units of unit scanning angles, an irradiation region or a scanning region of the detection light that is exclusively irradiated by one light emitting element corresponds to one light receiving region, and reflected light from a target object existing in one irradiation region enters the corresponding one light receiving region. The light reception process performed by the light reception control unit 31 in units of each light reception region is performed at a timing when the corresponding one of the light emitting elements exclusively emits the detection light. Note that, in fig. 4, for the sake of simplicity of explanation, the light emitting unit 20 including 4 LDs 1 to LD4 corresponding to the light receiving regions Ra1 to Ra4 is illustrated, but there may be one light emitting element 22, and in this case, reference numerals of the LDs 1 to LD4 in fig. 4 conceptually indicate exclusive light emission timings of the individual light emitting elements 22. In the case where a plurality of light emitting elements 22 are provided, for example, the scanning mechanism 35 may omit scanning in the vertical direction and realize scanning in the horizontal direction, and in the case where a single light emitting element 22 is provided, the scanning mechanism 35 may realize scanning in the vertical direction in addition to the horizontal direction.

The electric drive unit 40 includes a motor driver 41 and a motor 42. The motor driver 41 receives the rotation speed instruction signal from the control unit 10, changes the voltage applied to the motor 42, and controls the rotation speed of the motor 42. The electric motor 42 is, for example, a brushless motor or a brush motor. The scanning mechanism 35 is attached to a distal end portion of an output shaft of the motor 42. The scanning mechanism 35 is a mirror that is a reflector for horizontally scanning the detection light emitted from the light emitting element 22, and is driven by the motor 42 to rotate, thereby realizing horizontal scanning. The scanning mechanism 35 scans the detection light and receives the reflected light in a scanning angle range of, for example, 120 degrees or 180 degrees. The scanning mechanism 35 may also realize scanning in the vertical direction in addition to the horizontal direction instead of the horizontal direction. In order to realize scanning in the horizontal direction and the vertical direction, the scanning mechanism 35 may be a polygon mirror, for example, a polygon mirror, or may be a single-sided mirror having a mechanism for swinging in the vertical direction or another single-sided mirror for swinging in the vertical direction.

The detection light emitted from the light emitting unit 20 passes through the half mirror 36 and is scanned by the scanning mechanism 35 within a predetermined scanning range in the horizontal direction, that is, a rotation angle range, in units of a unit scanning angle. The reflected light of the detection light reflected by the target object passes through the same optical path as the detection light, is reflected by the semi-transparent and semi-reflective mirror 36, and enters the light receiving unit 30 at each unit scanning angle. The unit operation angle for performing the distance measurement process, that is, the scanning lines sequentially add 1 as in N, N +1, and as a result, the light reception results of all the scanning lines are combined, whereby the distance measurement process of a desired scanning range, that is, the scanning for detecting an object can be performed. In the present embodiment, the reflected light enters the light receiving regions Ra1 to Ra4 corresponding to the irradiation of exclusive detection light from the light emitting elements LD1 to LD 4. Therefore, the light receiving regions Ra1 to Ra4 are distinguished as light receiving target regions corresponding to the irradiation of the exclusive detection light and light receiving non-target regions not corresponding to the irradiation of the exclusive detection light. The light receiving target region may be a light receiving region into which reflected light of the detection light should enter, and the light receiving non-target region may be a light receiving region into which reflected light of the detection light should not enter. The light emitting unit 20 and the light receiving unit 30 may be rotated by the motor 42 together with the scanning mechanism 35, or may be rotated independently of the scanning mechanism 35 without the motor 42. Instead of the scanning mechanism 35, the laser scanner may be configured to include a plurality of light emitting elements 22 and a light receiving element array 32 arranged in an array, and to directly irradiate the outside with laser light and directly receive reflected light.

The abnormality determination process executed by the distance measuring device 100, more specifically, the control unit 10 will be described with reference to fig. 6. For example, after the distance measuring device 100 is started, the processing flow shown in fig. 6 is repeatedly executed at predetermined intervals, for example, in units of several msec. When the distance measuring device 100 is mounted on the vehicle, the operation may be repeatedly performed at predetermined intervals, for example, several msec units, during a period from the start of the system of the vehicle to the end of the system or during a period when the operation switch of the distance measuring device 100 is turned on, or may be performed a predetermined number of times at an arbitrary timing such as at the start or the end of the system of the vehicle.

The CPU11 initializes the counter n, that is, sets n to 1 (step S100). The CPU11 outputs a light emission control signal for causing the light emitting element LDn to emit light to the light emitting unit 20 (step S102). The CPU11 outputs a light reception control signal for simultaneously performing light reception processing of incident light in each of the light reception regions Ra1 to Ra4 to the light receiving section 30 (step S104). The CPU11 generates a histogram showing the characteristics of the intensity of incident light for each of the light receiving regions Ra1 to Ra4 as shown in fig. 3, using the incident light intensity signal, which is the detection signal input from the light receiving unit 30, and stores the histogram in the region-by-region histogram storage region 12a of the memory 12. The generated histogram has an incident light intensity on the vertical axis and an incident time t [ μ s ] from the irradiation of the detection light until the incident light enters on the horizontal axis, and represents the incident light intensity with respect to the incident time in the unit scanning angle. Therefore, the peak value of the waveform W of the incident light intensity indicates the possibility of existence of the target object, and the distance [ m ] between the distance measuring device 100 and the target object can be calculated using the time t. Fig. 3 illustrates histograms of the light-receiving regions Ra1 to Ra4 in the case where N is 1 in the N columns, and each histogram shows signal waveforms Wa1 to Wa4 of incident light intensity in the light-receiving regions Ra1 to Ra 4. When n is 1, the light emitting element LD1 emits light, the light receiving region Ra1 is a light receiving target region, and Ra2 to Ra4 are light receiving non-target regions. In the present embodiment, since the light receiving element array 32 includes the plurality of light receiving regions Ra1 to Ra4, the light receiving process can be simultaneously performed in the light receiving target region and the light receiving non-target region. Also, as shown in FIG. 3, histograms are generated for the N-1 scan column and the N +1 scan column in the same manner.

The CPU11 executes a target object detection process for the light receiving target region Ran (step S106). Specifically, the CPU11 executes the following ranging process: the generated histogram is used to acquire the peak value ILp of the incident light intensity in the light receiving target region Ran, and the distance to the target object is calculated using the time t at which the peak value ILp occurs. The CPU11 determines whether or not the peak value ILp of the intensity of incident light in the light receiving target region Ran is larger than a target determination value ILr predetermined to determine the presence or absence of a target, that is, whether or not ILp > ILr (step S108). The incident light entering the light receiving element array 32 includes not only reflected light of the light reflected by the target object but also disturbance light due to ambient light such as sunlight or a street lamp. Therefore, in order to determine whether the incident light is caused by disturbance light or reflected light, the correlation between the light receiving target region including the target and the light receiving non-target region is determined using the target determination value ILr, thereby improving the accuracy of abnormality determination. In addition, when the amount of disturbance light is large, the peak value ILp of the incident light intensity is also small, and the reliability of the light reception result is low, so that the abnormality determination is not performed. In the example of fig. 3, the peak value ILp of the signal waveform Wa1 of the incident light intensity in the light receiving target region Ra1 is larger than the target criterion value ILr, and it is determined that the target is included in the light receiving target region Ra 1.

When the CPU11 determines that ILp > ILr (step S108: yes), it uses the light-receiving regions Ra1 to Ra4 stored in the area-by-area histogram storage region 12a of the memory 12 to perform abnormality determination regarding at least one of the light-receiving section and the light-emitting section, based on the difference between the characteristics of the incident light intensity in the light-receiving target region and the characteristics of the incident light intensity in the light-receiving non-target region. The CPU11 determines whether or not the characteristics of the incident light intensity of the light receiving target region and the light receiving non-target region have a correlation. The correlation is a similarity of the waveform of the incident light intensity with respect to time or an approximation of the peak generation period in the waveform of the incident light intensity with respect to time. In the present processing flow, the CPU11 calculates the degree of similarity S as an index indicating the correlation (step S110). The similarity S takes a value of 0 to 1, and the larger the value is, the more the characteristics of the incident light intensity of the light receiving object region and the light receiving non-object region can have a correlation. When n is 1, the light receiving region is the light receiving region Ra1, and the light receiving non-target regions are the light receiving regions Ra2 to Ra 4. The characteristic of the intensity of the incident light is, for example, a peak value, a histogram, or a luminance value that is an average value of the histogram, and in the case of using the histogram, discrete values of the intensity of the incident light at a plurality of time sampling points of the waveform W or a generation timing of a peak value are used. The luminance value may be a statistical value such as a median, an average, or a variance. For example, when discrete values of incident light intensity at a plurality of time sampling points of the waveform W are used, the similarity is obtained by a known cosine similarity or packet analysis method. Instead of the similarity S, the time of occurrence of the peak, i.e., the approximation of the time t may be used, and whether or not the similarity is greater than a predetermined determination approximation may be determined, as in the case of the similarity S. When the latter statistical value is used, for example, it is determined that the difference between the values is included in a predetermined range, and it is determined that the values are not similar when the difference exceeds the predetermined range.

The CPU11 counts the light receiving non-target regions having the calculated similarity S greater than the judgment similarity Sr, that is, the light receiving non-target regions having S > Sr, and obtains a total value T (step S112). The determination similarity Sr is a determination value for determining a light-receiving non-target region that should not be similar to the histogram of the light-receiving target region if the light-receiving system has no abnormality, and is, for example, 0.5 to 1. In the example of fig. 3, for example, the light receiving non-target region Ra2 is counted as a light receiving non-target region of S > Sr, and the light receiving non-target regions Ra3 and Ra4 are not counted as a light receiving non-target region of S > Sr. The CPU11 may store the maximum number nmax and the minimum number nmin of the light-receiving non-target region of S > Sr1 in the memory 12. The CPU11 determines whether the total value T is larger than the abnormality determination value Tr, that is, whether T > Tr (step S114). In the present embodiment, the accuracy of abnormality determination is improved by using the total value of the light-receiving non-object regions having a higher similarity S than the determination similarity Sr, in consideration of the decrease in the accuracy or reliability of the calculated similarity S due to the influence of disturbance light. Since the reflected light from the target object does not enter the light-receiving non-target region when no abnormality occurs in at least one of the light-receiving unit and the light-emitting unit of the distance measuring device 100, the abnormality determination value Tr may be 1 or 2 or 3 in consideration of the disturbance light element in the present embodiment.

If the CPU11 determines that T > Tr (step S114: yes), it determines that an abnormality has occurred in at least one of the light-receiving unit and the light-emitting unit of the distance measuring device 100, for example, the light-emitting element 22, the light-receiving element array 32, the cover glass 37, and the scanning mechanism 35 (step S116), and the process proceeds to step S118. If the CPU11 determines that T > Tr is not satisfied (no in step S114), the CPU proceeds to step S118 without performing abnormality determination regarding at least one of the light-receiving unit and the light-emitting unit of the distance measuring device 100. Further, the CPU11 may report the abnormality of the distance measuring device to the driver when it is determined that the abnormality occurs. The CPU11 may record the abnormality occurrence log in the memory 12, and record the total value T as an index indicating the degree of abnormality, or may record, of the light receiving non-target regions having S > Sr, the light receiving non-target region farthest from the light receiving target region as an index indicating the degree of abnormality, using the maximum number nmax and the minimum number nmin of the light receiving non-target regions with respect to the light receiving target region stored in the memory 12. In this case, the larger the total value T, the farther the light-receiving non-target region is, the greater the degree of abnormality.

If the CPU11 determines in step S108 that ILp > ILr, that is, ILp ≦ ILr (no in step S108), it proceeds to step S118. That is, when there is no target in the light receiving target region Ran, the CPU11 proceeds to step S118 without performing the similarity determination because it does not mean that the abnormality determination regarding at least one of the light receiving unit and the light emitting unit is performed with respect to the detection of the target.

In step S118, the CPU11 determines whether the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, that is, whether N is equal to N. Here, N is the number of light receiving regions of the light receiving element array 32, and in the present embodiment, N is 4. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine. When the CPU11 determines that N is not N (no in step S118), it increments N by 1 to change the light-receiving area to be changed (step S120), and proceeds to step S102.

When n is increased to 2, 3, and 4, steps S102 to S108 are executed with the light-emitting elements LD2, LD3, and LD4 and the light-receiving regions Ra2, Ra3, and Ra4 as light-receiving target regions, as in the case where n is 1. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine.

According to the distance measuring device 100 of the first embodiment described above, an abnormality regarding at least one of the light receiving unit and the light emitting unit of the distance measuring device 100 is determined based on the difference between the characteristic of the intensity of incident light in the light receiving target region and the characteristic of the intensity of incident light in the light receiving non-target region. Therefore, it is possible to perform self-determination of an abnormality regarding at least one of the light-receiving portion and the light-emitting portion in the distance measuring device 100, and to improve the accuracy of determination of an abnormality regarding at least one of the light-receiving portion and the light-emitting portion in the distance measuring device 100. More specifically, according to the distance measuring device 100 of the first embodiment, it is possible to determine an abnormality such as dirt on the cover glass 37 or a shift in at least one of the light receiving unit and the light emitting unit in the distance measuring device 100, based on the degree of similarity of the histograms of the light receiving target regions and the light receiving non-target regions of the plurality of light receiving regions Ra1 to Ra4 included in the light receiving element array 32. In addition, according to the distance measuring device 100 of the first embodiment, it is possible to determine an abnormality related to at least one of the light receiving unit and the light emitting unit using the light receiving element array 32 provided in the distance measuring device 100.

In the first embodiment, the light receiving non-target regions related to the light receiving target region are counted regardless of whether the light receiving target region is the end light receiving regions Ra1, Ra4 or the non-end light receiving regions Ra2, Ra3 of the light receiving element array 32. As shown in fig. 7, an abnormality, for example, a light receiving position shift, associated with the light receiving region Ra3 at the non-end portion of the light receiving element array 32 can be detected as Ed2 in the light receiving regions Ra2 and Ra4, respectively. On the other hand, an abnormality related to the light-receiving region Ra1 at the end of the light-receiving element array 32 is detected as Ed2 in the light-receiving region Ra2, while an abnormality Ed1 cannot be detected. That is, the light receiving regions having correlation with the light receiving region Ra1 at the end portion may not be accurately counted. Therefore, the light receiving regions Ra1 and Ra4 at the end portions may be counted by multiplying the number of light receiving non-target regions related to the light receiving target region by 2 times or by adding 1. In this case, the accuracy of determining the abnormality of the light receiving system can be further improved.

In the first embodiment, the light emitting unit 20 including 4 light emitting elements LD1 to LD4 and the light receiving element array 32 including 4 light receiving regions Ra1 to Ra4 have been described as an example, but the number of light emitting elements LD or light emitting regions and light receiving regions may not be the same, may be less than 4, and may be 5 or more. The number of light receiving regions may be equal to or less than the number of light receiving pixels, and the number of irradiation regions or light emitting regions may be equal to or less than the number of light emitting elements.

Second embodiment:

in the abnormality determination process of the first embodiment, an abnormality is determined with respect to at least one of the light receiving unit and the light emitting unit of the distance measuring device 100. In contrast, in the abnormality determination process according to the second embodiment, it is determined which of the light-receiving section and the light-emitting section is the abnormality. The configuration of the distance measuring device of the second embodiment is the same as that of the distance measuring device 100 of the first embodiment, and therefore the same reference numerals are given thereto and the description thereof is omitted.

The abnormality determination process according to the second embodiment, which is executed by the distance measuring device 100, more specifically, the control unit 10, will be described with reference to fig. 8. The processing flow shown in fig. 8 is executed in the same manner as the processing flow shown in fig. 6. Note that the same process steps as those in the process flow shown in fig. 6 are assigned the same step numbers, and the description thereof is omitted.

The CPU11 initializes the counter n, that is, sets n to 1 (step S100). The CPU11 outputs a light emission control signal for causing the light emitting element LDn to emit light to the light emitting unit 20 (S102). The CPU11 executes the light receiving process of the incident light in each of the light receiving regions Ra1 to Ra4 of the light receiving unit 30, generates a histogram for each of the light receiving regions Ra1 to Ra4 using the incident light intensity signal, and stores the histogram in the region-by-region histogram storage region 12a of the memory 12 (step S104).

The CPU11 executes a target object detection process for the light receiving target region Ran (step S106). Specifically, the CPU11 acquires the peak value ILp of the incident light intensity in the light receiving target region Ran using the generated histogram. The CPU11 calculates the similarity S of the characteristics of the incident light intensity in the light receiving object region and the light receiving non-object region using the light receiving regions Ra1 to Ra4 of the region-by-region histogram storage region 12a stored in the memory 12 (step S110).

The CPU11 determines whether or not the peak value ILp of the intensity of incident light in the light receiving target region Ran is larger than a predetermined target determination value ILr for determining the presence or absence of a target, that is, whether or not ILp > ILr (step S111).

When the CPU11 determines that ILp > ILr (step S111: yes), it counts the light-receiving non-target regions having a calculated similarity S greater than the first determined similarity Sr1, that is, the light-receiving non-target regions of S > Sr1, and obtains the total value T (step S112). The CPU11 determines whether the total value T is larger than the first abnormality determination value Tr1, i.e., whether T > Tr1 (step S114). If the CPU11 determines that T > Tr1 (step S114: yes), it determines that an abnormality has occurred in the light receiving unit of the distance measuring device 100, specifically, in the light receiving system such as the light receiving element array 32, the scanning mechanism 35, the half-mirror 36, and the cover glass 37 (step S117), and the process proceeds to step S118. If the CPU11 determines that it is not T > Tr1 (no in step S114), the CPU proceeds to step S118 without performing the abnormality determination of the distance measuring device 100.

In step S111, if ILp > ILr is not present (no in step S111), the CPU11 determines that no target is present in the light receiving target region Ran, counts the light receiving non-target regions with the calculated similarity S having an absolute value smaller than the second determination similarity Sr2, that is, the light receiving non-target regions with | S | < Sr2, and obtains the total value T (step S122). When there is no target in the light receiving target region Ran, the target should not be detected even in the light receiving non-target region, and the similarity S of the characteristics of the incident light intensity in the light receiving target region and the light receiving non-target region must be approximated. Therefore, the second determination similarity Sr2 is used to determine a light receiving non-target region whose similarity to the light receiving target region is not approximate, that is, a light receiving non-target region having a peak of the intensity of incident light corresponding to the target. The similarity Sr2 for the second determination is, for example, a value of 0 to 0.4. The CPU11 determines whether the total value T is larger than the second abnormality determination value Tr2, i.e., whether T > Tr2 (step S124). In the case where no target object is present in the light receiving target region, that is, in the case where no target object is detected, the target object should not be detected in the light receiving non-target region not corresponding to the detection light, and therefore the second abnormality determination value Tr2 is, for example, 0. If the CPU11 determines that T > Tr2 (step S124: yes), it determines that an abnormality has occurred in the light-emitting section of the distance measuring device 100, specifically, the light-emitting element 22, the scanning mechanism 35, the half mirror 36, and the cover glass 37 (step S126), and the process proceeds to step S118. If the CPU11 determines that it is not T > Tr2 (no in step S124), the CPU proceeds to step S118 without performing the abnormality determination of the distance measuring device 100.

In step S118, the CPU11 determines whether the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, that is, whether N is equal to N. Here, N is the number of light receiving regions of the light receiving element array 32, and in the present embodiment, N is 4. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine. When the CPU11 determines that N is not N (no in step S118), it increments N by 1 to change the light-receiving area to be changed (step S120), and proceeds to step S102.

When n is increased to 2, 3, or 4, step S102 and the subsequent steps are executed for the light-emitting elements LD2, LD3, LD4 and the light-receiving object regions Ra2, Ra3, and Ra3, as in the case where n is 1. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine.

According to the distance measuring device 100 of the second embodiment described above, in addition to the advantages obtained by the distance measuring device 100 of the first embodiment, it is possible to determine whether the abnormality in the distance measuring device 100 is an abnormality in the light receiving portion or an abnormality in the light emitting portion. Therefore, the accuracy of determining an abnormality in at least one of the light-receiving unit and the light-emitting unit in the distance measuring device 100 can be further improved.

The abnormality determination process according to the third embodiment, which is executed by the distance measuring device 100, more specifically, the control unit 10, will be described with reference to fig. 9. The processing flow shown in fig. 9 is executed in the same manner as the processing flow shown in fig. 6. Note that the same process steps as those in the process flow shown in fig. 6 or 8 are assigned the same step numbers, and description thereof is omitted.

The CPU11 initializes the counter n, that is, sets n to 1 (step S100). The CPU11 outputs a light emission control signal for causing the light emitting element LDn to emit light to the light emitting unit 20 (S102). The CPU11 executes the light receiving process of the incident light in each of the light receiving regions Ra1 to Ra4 of the light receiving unit 30, generates a histogram for each of the light receiving regions Ra1 to Ra4 using the incident light intensity signal, and stores the histogram in the region-by-region histogram storage region 12a of the memory 12 (step S104).

The CPU11 executes a target object detection process for the light receiving target region Ran (step S106). Specifically, the CPU11 acquires the peak value ILp of the incident light intensity in the light receiving target region Ran using the generated histogram.

The CPU11 determines whether or not the peak value ILp of the intensity of incident light in the light receiving target region Ran is larger than a target determination value ILr predetermined to determine the presence or absence of a target, that is, whether or not ILp > ILr (step S108). If the CPU11 determines that ILp > ILr (yes in step S108), the process proceeds to step S118.

If ILp > ILr is not present (no in step S108), the CPU11 determines that no object is present in the light receiving target region Ran, and calculates the similarity S of the characteristics of the incident light intensity between the light receiving target region and the light receiving non-target region using the light receiving regions Ra1 to Ra4 of the region-by-region histogram storage region 12a stored in the memory 12 (step S110). The CPU101 counts the light-receiving non-object regions having the calculated similarity S smaller in absolute value than the second determination similarity Sr2, that is, light-receiving non-object regions having | S | < Sr2, and obtains the total value T (step S122). When there is no target in the light receiving target region Ran, the target should not be detected even in the light receiving non-target region, and the similarity S of the characteristics of the incident light intensity in the light receiving target region and the light receiving non-target region must be approximated. The CPU11 determines whether the total value T is larger than the second abnormality determination value Tr2, i.e., whether T > Tr2 (step S124). In the case where no target object is present in the light receiving target region, that is, in the case where no target object is detected, the target object should not be detected in the light receiving non-target region not corresponding to the detection light, and therefore the second abnormality determination value Tr2 is, for example, 0. If the CPU11 determines that T > Tr2 (step S124: yes), it determines that an abnormality has occurred in at least one of the light-receiving unit and the light-emitting unit of the distance measuring device 100 (step S125), and the process proceeds to step S118. If the CPU11 determines that it is not T > Tr2 (no in step S124), the CPU proceeds to step S118 without performing the abnormality determination of the distance measuring device 100.

In step S118, the CPU11 determines whether the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, that is, whether N is equal to N. Here, N is the number of light receiving regions of the light receiving element array 32, and in the present embodiment, N is 4. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine. When the CPU11 determines that N is not N (no in step S118), it increments N by 1 to change the light-receiving area to be changed (step S120), and proceeds to step S102.

When n is increased to 2, 3, or 4, step S102 and the subsequent steps are executed for the light-emitting elements LD2, LD3, LD4 and the light-receiving object regions Ra2, Ra3, and Ra3, as in the case where n is 1. When the CPU11 determines that N is equal to N (yes in step S118), it determines that the processing for setting all the light receiving regions Ra1 to Ra4 as light receiving target regions is completed, and ends the present processing routine.

According to the distance measuring device 100 of the third embodiment described above, as with the distance measuring device 100 of the first embodiment, it is possible to perform self-determination of an abnormality relating to at least one of the light receiving unit and the light emitting unit of the distance measuring device 100, and to improve the accuracy of determination of an abnormality relating to at least one of the light receiving unit and the light emitting unit of the distance measuring device 100.

Other embodiments:

(1) in each of the above embodiments, as shown in fig. 3, the light receiving unit 30 including the light receiving element array 32 corresponding to the scanning line is used. In contrast, as shown in fig. 10, for example, a light receiving unit 30 including a light receiving element array 32 corresponding to N-2 scan lines to N +2 scan lines may be used. In this case, the light reception processing time can be made to have a margin. In the above embodiments, the horizontal direction is taken as an example of the scanning direction of the scanning mechanism 35, and the light receiving element array 32 includes a plurality of light receiving regions in the vertical direction. On the other hand, when the scanning direction of the scanning mechanism 35 is the vertical direction, the light receiving element array 32 may include a plurality of light receiving regions in the horizontal direction.

(2) In each of the above embodiments, when the similarity S between the light receiving target region and all the light receiving non-target regions is higher than the determination similarities Sr and Sr1, that is, when the correlation between all the light receiving regions is established, the light emission intensity of the detection light by the light emitting unit 20 may be reduced, and the abnormality determination process may be executed again. When the characteristics of the intensity of incident light in all the light receiving areas have a correlation, there is a possibility that reflected light from a strongly reflecting object, for example, a reflector, enters the light receiving unit 30 as interference light. Therefore, the intensity of the reflected light from the reflector may be reduced by reducing the emission intensity of the detection light, thereby increasing the S/N of the reflected light from the target object with respect to the reflected light from the reflector.

(3) In each of the above embodiments, when determining the similarity S between the light receiving target region and all the light receiving non-target regions, the similarity S may be determined using a histogram from which the clutter portion is removed. Here, the clutter is a phenomenon in which the detection light is reflected by the cover glass 37 and a peak is generated at a start portion or a leading end portion including a time t equal to 0, that is, a distance of 0m in the distance measurement in the histogram. In this case, the influence of the peak as noise can be eliminated or reduced, and the accuracy of the similarity S determination can be improved.

(4) In each of the above embodiments, the abnormality determination process is performed with respect to the detection process of the target object in the light receiving target region, that is, the distance measurement process, but the detection process of the target object may not be performed. That is, the target object detection process and the abnormality determination process may be executed separately. In this case, the frequency of execution of the abnormality determination process may be lower than the target object detection process. The light receiving process of the incident light in the light receiving regions Ra1 to Ra4 of the light receiving unit 30 may not be performed simultaneously as long as the light emitting timing of the light emitting unit 20 is not crossed. In the abnormality determination process, it is sufficient to acquire or generate characteristics of the incident light intensity in each light receiving region Ra and determine an abnormality based on a difference between the characteristics of the incident light intensity in the light receiving target region and the characteristics of the incident light intensity in the light receiving non-target region. The determination as to whether or not the peak value ILp of the intensity of incident light in the light receiving target region is larger than the target determination value ILr and the determination as to whether or not the total value of the light receiving non-target regions having a correlation with the light receiving target region is larger than the abnormality determination value Tr may be performed in order to improve the accuracy of abnormality determination.

(5) In each of the above embodiments, the control unit 10 executes a program to implement a control unit that executes various processes including the abnormality determination process in a software manner, but may be implemented in a hardware manner by a pre-programmed integrated circuit or a discrete circuit. That is, the control unit and the method thereof according to the above embodiments may be implemented by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and the method thereof according to the present invention may be realized by a dedicated computer provided with a processor constituted by one or more dedicated hardware logic circuits. Alternatively, the control unit and the method thereof according to the present invention may be realized by one or more special purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. The computer program may be stored as instructions to be executed by a computer on a non-transitory tangible recording medium that can be read by the computer.

The present invention has been described above based on the embodiments and the modified examples, but the embodiments of the present invention described above are for easy understanding of the present invention and do not limit the present invention. The present invention can be modified and improved without departing from the spirit and claims thereof, and equivalents thereof are included in the present invention. For example, the technical features of the embodiments and the modifications corresponding to the technical features of the respective embodiments described in the section of the summary of the invention may be appropriately replaced or combined in order to solve a part or all of the above-described problems or to achieve a part or all of the above-described effects. Note that, if this technical feature is not described as an essential feature in the present specification, it can be appropriately deleted.