Distance measurement device and distance measurement method

Abstract

A distance measurement device is provided with: a light-emitting element that projects pulse-wave projection light; a light-receiving element that receives reflected light; and a controller that measures the distance to an object on the basis of the time between the light-emitting timing of the light-emitting element and the light-receiving timing of the light-receiving element. The controller uses the first distance or the third distance to complement the second distance when the first distance and the third distance among the measured first distance, at least one second distance measured after the first distance, and the third distance measured after the second distance are estimated to be not abnormal and the second distance is estimated to be abnormal.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a distance measuring apparatus and a distance measuring method. BACKGROUND

[0002] A distance measuring apparatus that transmits a pulse wave and measures a required time until a reflected wave returns to calculate a distance to an object is known. A distance measuring apparatus disclosed in Patent Literature 1 has a transmission unit that transmits a pulse wave, a reception unit that receives a reflected wave reflected by an object, a time measuring unit that measures a required time from the transmission of the pulse wave to the detection of the reflected wave, a pulse width measuring unit that takes in a reception waveform of the reflected wave based on the reception unit and measures a pulse width of the reception waveform, a correction value calculating unit that calculates a correction value of the required time corresponding to the pulse width of the reception waveform based on an input-output characteristic of an active region and a saturation region in the reception unit, and a distance calculating unit that corrects the required time measured by the time measuring unit using the correction value and multiplies a propagation speed of the pulse wave to calculate a distance to the object.

[0003] PRIOR ART LITERATURE

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 8-179032 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Since the level of the reception waveform of the actual reflected wave is various, the comparator cannot normally binarize the reception waveform of the level near the threshold value, and an abnormal signal can be output. The reliability of the distance to the object calculated using such an abnormal signal is low, and it can be erroneous. That is, an erroneous distance can be output.

[0008] An object of the present disclosure is to provide a technique that suppresses a distance measuring apparatus from outputting an erroneous distance.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] One embodiment of the distance measuring device includes: a light-emitting element that projects pulsed light; a light-receiving element that receives reflected light from an object; and a controller that measures the distance to the object based on the time between the light-emitting element's light-emitting timing and the light-receiving element's light-receiving timing, wherein if the first distance and the third distance are presumed to be normal among a first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, and the second distance is presumed to be abnormal, the controller uses the first distance or the third distance to compensate for the second distance.

[0011] One embodiment of the distance measurement method involves measuring the distance to the object based on the time between the emission timing of the projected light of the pulse wave projected by the light-emitting element and the reception timing of the reflected light of the projected light received by the light-receiving element. In the case where the first distance and the third distance are presumed to be normal among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, and the second distance is presumed to be abnormal, the second distance is supplemented by the first distance or the third distance.

[0012] -Invention Effects-

[0013] According to this disclosure, it is possible to suppress erroneous distance outputs from the distance measuring device. Attached Figure Description

[0014] Figure 1 This is a perspective view of the distance measuring device according to Embodiment 1.

[0015] Figure 2 This is a longitudinal sectional view of the distance measuring device according to Embodiment 1.

[0016] Figure 3 This is a block diagram illustrating a functional structure example of the distance measuring device according to Embodiment 1.

[0017] Figure 4 This is a diagram illustrating the signals input to the comparator and the signals output from the comparator according to Embodiment 1.

[0018] Figure 5 This is a block diagram illustrating an example of the functional structure of the TDC according to Embodiment 1.

[0019] Figure 6 This is a diagram used to illustrate the TDC-based TOF and the measurement method of the light pulse width involved in Embodiment 1.

[0020] Figure 7This is a diagram illustrating the operating conditions under which the TDC involved in Embodiment 1 can normally measure TOF and the width of the light-receiving pulse.

[0021] Figure 8 This is a diagram used to illustrate the smallest object capable of measuring distance involved in Embodiment 1.

[0022] Figure 9 This is a flowchart illustrating a processing example of the controller involved in Embodiment 1.

[0023] Figure 10 This diagram illustrates the compensation method used to explain the situation where the distance between the abnormality flag and the second object is established according to Implementation 1.

[0024] Figure 11 This is a diagram showing a storage example in the storage unit for the first object distance, the second object distance, and the third object distance according to Embodiment 1.

[0025] Figure 12 This is a diagram illustrating an example of actions taken when two or more consecutive points have established corresponding exception flags, as described in Implementation 1. Detailed Implementation

[0026] Hereinafter, embodiments of the present disclosure will be described in detail with appropriate reference to the accompanying drawings. However, sometimes unnecessary details are omitted. For example, detailed descriptions of known matters and repetitive descriptions of substantially the same structures are sometimes omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the patent application.

[0027] (Implementation Method 1)

[0028] <Physical Structure of Distance Measuring Device>

[0029] Figure 1 This is a perspective view of the distance measuring device 1 according to Embodiment 1. Figure 2 This is a longitudinal sectional view of the distance measuring device according to Embodiment 1. Figure 2 Equivalent to Figure 1 A cross-sectional view of the distance measuring device 1 shown.

[0030] like Figure 1 as well as Figure 2 As shown, the distance measuring device 1 includes: a fixed part 100, a rotating part 300, and an outer cover part 10.

[0031] The fixing part 100 is generally rectangular in shape. The rotating part 300 is connected to the upper surface of the fixing part 100 and is cylindrical in shape, rotating about an axis perpendicular to the upper surface as the axis of rotation C. The outer cover part 10 is generally cylindrical and covers the rotating part 300 from above. At least a portion of the outer cover part 10 has a wavelength window 11 constructed using a wavelength selective member. The wavelength selective member is a material that transmits light of a given wavelength (frequency) component used in distance measurement and blocks light of the wavelength (frequency) component in the visible area. The wavelength selective member, for example, has the function of blocking interfering light such as natural light and electric lamps.

[0032] In addition, for ease of explanation, such as Figure 1 As shown, the axis perpendicular to the upper surface (or bottom surface) of the fixing part 100 is designated as the Z-axis. The axis perpendicular to the Z-axis is designated as the X-axis. The axis perpendicular to both the Z-axis and the X-axis is designated as the Y-axis. Furthermore, for ease of explanation, the positive direction of the Z-axis is sometimes referred to as "up," the negative direction as "down," and the direction departing from the Z-axis in the X-axis or Y-axis direction is referred to as "horizontal." Moreover, these descriptions of directions are used for ease of explanation and are not intended to limit the actual posture of the structure during use. For example, Figure 1 The distance measuring device 1 shown can also be used by reversing its orientation. Additionally, Figure 2 The AA section view shown is equivalent to the section view on the YZ plane.

[0033] The bottom surface of the fixing part 100 can also be fixedly disposed on a given plane (such as the ground or the outer shell surface of a given device).

[0034] The rotating part 300 rotates around the central axis (Z-axis) of the cylinder as the rotation axis C. As the rotating part 300 rotates, the optical axis of the projected light (hereinafter referred to as projected light 3A) projected laterally from a portion of the side of the rotating part 300 rotates around the rotation axis C. Simultaneously, the projected light 3A and the area that can be measured by the projected light 3A (hereinafter referred to as the measuring area) also rotate. As described later, the distance measuring device 1 measures the distance to the object present in the measuring area based on the time difference (TOF) between the timing of projecting the projected light 3A and the timing of receiving the light reflected from the object in the measuring area (hereinafter referred to as reflected light 3B). By rotating the part 300 once around the rotation axis C, the distance measuring device 1 can measure the distance to the object present in the measuring area spanning 360 degrees laterally.

[0035] The fixing part 100 includes: a substrate 101, a light-emitting element 102, a light-receiving element 103, a condensing lens 104, a collimating lens 105, a coil 106, and a photoelectric circuit breaker 107. The rotating part 300 includes: a rotating member 301, a magnet 302, and a reflector 303.

[0036] A hollow motor 402 is formed by the coil 106 of the fixed part 100 and the magnet 302 of the rotating part 300 (see reference). Figure 3 Driven by the motor 402, the rotating part 300 rotates around the rotating shaft C.

[0037] Substrate 101 is, for example, a printed circuit board (PCB) and includes comparator 401, TDC 500, and controller 600 (described later). Figure 3 In addition, TDC is an abbreviation for Time to Digital Converter.

[0038] The light-emitting element 102 is configured along the rotation axis C to project the projected light 3A upwards.

[0039] The collimating lens 105 corrects the projected light 3A from the light-emitting element 102 into approximately parallel light and outputs it upwards.

[0040] A reflector 303 is disposed on the rotating member 301, such that parallel light projected upward from the light-emitting element 102 and corrected by the collimating lens 105 is reflected laterally (along the XY plane). Since the reflector 303 rotates together with the rotating member 301, the projected light, over time, is projected (scanned) in a 360-degree radius around the rotation axis C in a direction orthogonal to the rotation axis C (lateral). The projected light 3A reflected by the reflector 303 passes through the wavelength window 11 of the outer cover 10 and is projected onto the ranging area.

[0041] The reflected light 3B of the projected light 3A, which is reflected by the object, passes through the wavelength window 11 of the outer cover 10 and is reflected downward by the reflector 303.

[0042] The focusing lens 104 focuses the reflected light 3B reflected downwards by the reflecting mirror 303 and outputs it downwards.

[0043] The light-receiving element 103 receives the reflected light 3B that is focused by the condenser lens 104.

[0044] The rotating member 301 has a plurality of ribs 311 at constant intervals. The photoelectric circuit breaker 107 is configured to detect the passage of one rib 311. By detecting and counting the passage of one rib 311 using the photoelectric circuit breaker 107, the controller 600 (described later) can detect the rotational position (rotation angle) of the rotating member 301 (i.e., the rotating part 300). Therefore, the photoelectric circuit breaker 107 and the ribs 311 can form the rotational position detector 403 (see reference 107). Figure 3 ).

[0045] <Functional Structure of Distance Measuring Device>

[0046] Figure 3 This is a block diagram illustrating a functional structure example of the distance measuring device 1 according to Embodiment 1.

[0047] The distance measuring device 1 includes: a light-emitting element 102, a light-receiving element 103, a comparator 401, a TDC 500, a motor 402, a rotational position detector 403, and a controller 600. Furthermore, Figure 3 The structure shown is an example, but it could also be a structure in which at least one of the comparator 401 and TDC500 is included in the controller 600.

[0048] The light-emitting element 102 projects projected light 3A, which is a pulse wave corresponding to the input pulse signal (hereinafter referred to as the input pulse signal). Furthermore, in Figure 3 In this context, the input of the input pulse signal is referred to as START. The projected light 3A can also be referred to as a laser or a beam. As described above, the light-receiving element 103 receives the reflected light 3B and outputs a light-receiving signal corresponding to the light-receiving level.

[0049] Figure 4 This is a diagram illustrating the signals input to comparator 401 and the signals output from comparator 401 according to Embodiment 1. Next, refer to... Figure 4 The comparator 401 will be described.

[0050] like Figure 4 As shown in (a), comparator 401 receives a light-receiving signal from light-receiving element 103 and outputs a pulse signal (hereinafter referred to as the light-receiving pulse signal) that sets a given high level for a period when the level of the light-receiving signal is above a given comparator threshold and a given GND level for a period when the level of the light-receiving signal is below the comparator threshold. Furthermore, the high level is greater than the GND level. Additionally, in Figure 3 In this context, the output of the received light pulse signal is described as "STOP".

[0051] When the level of the input light-receiving signal is less than the comparator threshold throughout the entire period, comparator 401, such as Figure 4As shown in (c), the output is a light-receiving pulse signal at the GND level.

[0052] However, when the maximum level of the input light-receiving signal is near the comparator threshold, comparator 401, such as... Figure 4 As shown in (b), sometimes the output light pulse signal has an abnormal waveform that is ambiguous as to whether it is a high level or a GND level. In this embodiment, it is explained that even when the comparator 401 outputs such an abnormal waveform light pulse signal, it is still possible to output a distance measurement result with high reliability.

[0053] Figure 5 This is a block diagram illustrating a functional structure example of the TDC500 according to Embodiment 1. Figure 6 This is a diagram used to illustrate the method for measuring the TOF based on TDC500 and the width of the received pulse, as described in Embodiment 1. Figure 7 This is a diagram illustrating the operating conditions under which the TDC500 according to Embodiment 1 can normally measure TOF and the width of the received light pulse. Next, refer to... Figure 5 , Figure 6 as well as Figure 7 The TDC500 will be explained.

[0054] The TDC500 includes: a measurement unit 501, a data register 502, a status register 503, and an input / output (I / F) 504. Furthermore, "I / F" is an abbreviation for Interface.

[0055] The measurement unit 501 inputs the pulse signal to the light-emitting element 102 at the timing of the input pulse signal. Figure 6 The same input pulse signal (START) as shown in (a) is input to comparator 401 from photodetector 103. Figure 6 As shown in (b), receive the light signal and output it. Figure 6 The light-receiving pulse signal is as shown in (c). The measurement unit 501, at the timing of the comparator 401 outputting the light-receiving pulse signal, inputs a light-receiving pulse signal as shown in (c). Figure 6The light-receiving pulse signal is as shown in (c) (STOP). The measurement unit 501 measures the time from the timing of the input pulse signal to the timing of the light-receiving pulse signal (i.e., TOF) and the pulse width of the light-receiving pulse signal (hereinafter referred to as the light-receiving pulse width). The measurement unit 501 writes the measured TOF and light-receiving pulse width to the data register 502. In addition, the measurement unit 501 writes operation information indicating the operation status at the time of measurement to the status register 503. The operation information may include the number of rising edges and falling edges of the input pulse signal, and the number of rising edges and falling edges of the light-receiving pulse signal. In addition, the operation information may include information indicating whether a light-receiving pulse signal has been input within a given time from the timing of the input pulse signal (i.e., whether a timeout has occurred).

[0056] The input / output I / F 504 outputs the TOF and the measured light pulse width results written to the data register 502. Based on external requests, or together with the individual TOF and light pulse width measurement results, the input / output I / F 504 outputs action information written to the status register 503.

[0057] like Figure 7 As shown, the operating conditions for normal TOF measurement exist in the measurement unit 501. Furthermore, in Figure 7 In the diagram, the horizontal axis represents time, and the vertical axis represents the level of the light pulse signal.

[0058] like Figure 7 As shown in region A, when the level of the light-receiving pulse signal is less than a given threshold, the measurement unit 501 makes the light-receiving pulse signal non-detectable.

[0059] like Figure 7 As shown in region B, the measurement unit 501 performs abnormal measurement if, even if the level of the light-receiving pulse signal is above a given threshold, the time from the input pulse signal to the input light-receiving pulse signal or the pulse width of the light-receiving pulse signal is shorter than a given minimum value (min).

[0060] like Figure 7 As shown in region C, the measurement unit 501 times out if, even if the level of the light-receiving pulse signal is above a given threshold, the time from the input pulse signal to the input light-receiving pulse signal or the pulse width of the light-receiving pulse signal is longer than a given maximum value (max).

[0061] like Figure 7As shown in region D, the measurement unit 501 can normally measure TOF when the level of the light-receiving pulse signal is above a given threshold and when the time from the input pulse signal to the input light-receiving pulse signal or the pulse width of the light-receiving pulse signal is between a given minimum (min) and maximum (max).

[0062] like Figure 7 As shown in region E, when the level of the received light pulse signal is near a given threshold (refer to...), the measurement unit 501... Figure 4 (b) becomes an abnormal measurement. In this embodiment, the output of distance measurement results with low reliability due to such abnormal measurement is suppressed.

[0063] Return to Figure 3 Explanation.

[0064] As described above, the motor 402 consists of a coil 106 and a magnet 302, and rotates the rotating component 301 around the central axis C.

[0065] As described above, the rotation position detector 403 is composed of the rib 311 of the rotating member 301 and the photoelectric circuit breaker 107, and outputs a start signal with a given rotation angle resolution of the rotating part 300. This start signal is used as a signal indicating the timing of light emission.

[0066] The controller 600 performs processing such as calculating the distance to the object existing in the ranging area (hereinafter referred to as the object distance) and controlling the motor 402. The controller 600 includes: a ranging control unit 601, a distance calculation unit 602, a storage unit 603, a compensation unit 604, and a motor control unit 605.

[0067] The ranging control unit 601 receives a start signal from the rotation position detector 403. At the timing of the input start signal, the ranging control unit 601 outputs a light-emitting pulse signal (START) to the light-emitting element 102 and TDC500.

[0068] The ranging control unit 601 inputs the measurement results of TOF and light pulse width from the TDC500. The ranging control unit 601 acquires the action information corresponding to the input measurement results of TOF and light pulse width from the TDC500.

[0069] The ranging control unit 601 includes a TDC anomaly determination unit 611. The TDC anomaly determination unit 611 determines (presumes) whether the measurement result is abnormal based on the TOF or the measured pulse width itself, or on the corresponding motion information. For example, if the TOF measurement result or the measured pulse width is outside a given range, the TDC anomaly determination unit 611 determines (presumes) that the TOF and measured pulse width are abnormal. For example, if the number of rising edges and falling edges of the measured pulse signal in the motion information are inconsistent, the TDC anomaly determination unit 611 determines (presumes) that the TOF and measured pulse width are abnormal. When the TDC anomaly determination unit 611 determines (presumes) that the TOF or measured pulse width is abnormal, it outputs an anomaly flag indicating that the TOF and measured pulse width are abnormal to the distance calculation unit 602.

[0070] The distance calculation unit 602 inputs the measurement results of TOF and light pulse width from the TDC500. In addition, if the measurement results of TOF and light pulse width are abnormal, the distance calculation unit 602 inputs an abnormality flag from the distance control unit 601.

[0071] The distance calculation unit 602 calculates the object distance based on the time-of-flight (TOF) and the measured pulse width. TOF represents the time from the projection of the projected light 3A to the receipt of the reflected light 3B (round-trip time), which is approximately twice the time it takes for the projected light 3A to reach the object. Therefore, firstly, the distance calculation unit 602 calculates a basic distance (referred to as the edge distance) by (the propagation speed of the projected light 3A × TOF / 2). Next, the distance calculation unit 602 corrects this edge distance based on the measured pulse width at that time to calculate the object distance.

[0072] The distance calculation unit 602 stores the calculated object distance in the storage unit 603. At this time, if the distance calculation unit 602 establishes a correspondence between the anomaly flag and the object distance using the TOF and the measurement results of the light pulse width, it establishes a correspondence between the anomaly flag and the object distance and stores it in the storage unit 603.

[0073] The storage unit 603 stores the object distance at three consecutive times (i.e., at three consecutive rotation angles). Additionally, the storage unit 603 also stores information indicating whether an anomaly flag has been associated with the object distance. Furthermore, the storage unit 603 may be composed of volatile storage media and / or non-volatile storage media.

[0074] The supplement unit 604 outputs the second object distance from the three object distances stored in the storage unit 603. Specifically, when an error flag corresponds to the second object distance from the three object distances stored in the storage unit 603, the supplement unit 604 uses the first and / or third object distances to supplement the second object distance and outputs the supplemented second object distance. Details of this process will be described later, but this method outputs a highly reliable object distance.

[0075] The motor control unit 605 controls the rotational speed of the motor 402. For example, the motor control unit 605 controls the motor 402 to keep the rotational speed constant.

[0076] <The smallest object capable of distance measurement>

[0077] Figure 8 This is a diagram used to illustrate the smallest object capable of measuring distance involved in Embodiment 1.

[0078] The distance calculation unit 602 uses the object distance if the difference in distance between two adjacent objects is less than a given threshold. That is, if... Figure 8 As shown, the smallest object size that can be measured is the size that can reflect two adjacent projected lights 3A. In other words, objects that can only reflect one projected light 3A are not detected as objects to be measured. This prevents the distance measuring device 1 from detecting tiny dust particles or other small particles in the air as objects to be measured.

[0079] <Flowchart>

[0080] Figure 9 This is a flowchart illustrating a processing example of the controller 600 according to Embodiment 1. Next, refer to... Figure 9 The processing performed by controller 600 is explained.

[0081] The ranging control unit 601 enters standby mode (S101: No) until a start signal is input from the rotation position detector 403. At the timing of detecting the input of the start signal (S101: Yes), the process proceeds to the next step S102.

[0082] The ranging control unit 601 performs a given start setting (e.g., initialization) on the TDC500 (S102).

[0083] The ranging control unit 601 outputs light-emitting pulse signals to the light-emitting element 102 and TDC500 (S103).

[0084] TDC500 enters standby mode (S104: No) until a light pulse signal is input from comparator 401. When a light pulse signal is input (S104: Yes), it outputs the measurement results of TOF and light pulse width, and the process proceeds to step S105.

[0085] The distance calculation unit 602 acquires the edge distance and / or pulse width based on the TOF and the measurement results of the light pulse width input from the TDC 500 (S105). Furthermore, the distance control unit 601 acquires motion information from the TDC 500 and, based on this motion information, determines whether to establish a correspondence between an anomaly flag and the object distance calculated subsequently (S106). For example, if the TDC anomaly determination unit 611 of the distance control unit 601 determines to establish a correspondence between the anomaly flag and the calculated object distance if the number of rising and falling edges of the light pulse signal in the motion information is inconsistent, or if the edge distance or the light pulse width is outside a given range.

[0086] If the ranging control unit 601 determines that the abnormal flag has not been established (S106: Yes), the process proceeds to step S108.

[0087] If the ranging control unit 601 determines that an abnormality flag should be established (S106: No), it sets the abnormality flag to be established in correspondence with the object distance to be calculated thereafter (S107), and the process proceeds to step S108.

[0088] The distance calculation unit 602 calculates the object distance based on the edge distance and the width of the light pulse (S108).

[0089] The distance calculation unit 602 stores the calculated object distance in the storage unit 603. At this time, if the distance calculation unit establishes a correspondence between the abnormal flag and the object distance when calculating the object distance, it establishes a correspondence between the abnormal flag and the object distance and stores it in the storage unit 603 (S109).

[0090] In the storage unit 603, in addition to the object distance calculated this time (hereinafter referred to as the third object distance), at least the object distance calculated last time (hereinafter referred to as the second object distance) and the object distance calculated the time before last (hereinafter referred to as the first object distance) are also stored.

[0091] The supplementary part 604 determines whether the abnormal flag corresponds to the distance of the second object stored in the storage part 603 (S110).

[0092] When the anomaly flag corresponds to the distance of the second object (S110: Yes), the supplementary unit 604 supplements the distance of the second object using either the distance of the first object or the distance of the third object (S111). In this case, the distance of the second object becomes the supplemented object distance. Further details regarding the supplementation method will be described later. Then, the process proceeds to step S112.

[0093] If the error flag does not correspond to the distance of the second object (S110: No), the supplementary part 604 causes the processing to proceed to step S112.

[0094] The supplementary part 604 outputs the distance to the second object (S112). Then, the processing returns to step S101.

[0095] Through the above processing, when an anomaly flag and the distance to the second object are established, that is, when the reliability of the distance to the second object is low, the distance to the second object is supplemented to the distance to the object with higher reliability and then output.

[0096] <Methods for Compensating for the Distance of the Second Object>

[0097] Figure 10 This diagram illustrates the compensation method used to explain the situation where the distance between the abnormality flag and the second object is established according to Implementation 1. Figure 11 This is a diagram illustrating a storage example in the storage unit 603 for the first object distance, the second object distance, and the third object distance according to Embodiment 1. Next, referring to... Figure 10 as well as Figure 11 , for Figure 9 The method for supplementing the distance to the second object in step S113 will be explained in detail.

[0098] like Figure 10 as well as Figure 11 As shown, assume that at time t=1, the object distance d1 with rotation angle θ1 is measured; at time t=2, the object distance d2 with rotation angle θ2 is measured; at time t=3, the object distance d3 with rotation angle θ3 is measured; at time t=4, the object distance d4 with rotation angle θ4 is measured; and at time t=5, the object distance d5 with rotation angle θ5 is measured. Furthermore, assume that anomaly flags are associated with object distances d3 and d5. Additionally, the rotation angle θ represents the angle from a given reference angle (0 degrees).

[0099] First, at t=3, the object distance d1 at t=1, the object distance d2 at t=2, and the object distance d3 at t=3 are stored in the storage unit 603. In this case, since the exception flag does not correspond to the second object distance d2, the supplementation unit 604 outputs the object distance d2 as is.

[0100] Next, at t = 4, the object distances d2 at t = 2, d3 at t = 3, and d4 at t = 4 are stored in the storage unit 603. In this case, since the anomaly flag corresponds to the second object distance d3, the complementing unit 604 uses the adjacent first object distance d2 or the third object distance d4 that does not correspond to the anomaly flag to complement the second object distance d3. For example, when d2 < d4, the complementing unit 604 replaces the second object distance d3 with the smaller object distance d2. That is, the complementing unit 604 outputs d2 as the object distance at t = 4. Thereby, it is possible to prevent the object distance d3 with low reliability from being output as it is. In addition, the reason for replacing the second object distance with the smaller of the adjacent object distances is to prioritize safety when using the distance measurement device 1 in a monitoring area or the like. Therefore, depending on the usage mode of the distance measurement device 1, the second object distance may also be replaced with the larger of the adjacent object distances.

[0101] Next, at t = 5, the object distances d3 at t = 3, d4 at t = 4, and d5 at t = 5 are stored in the storage unit 603. In this case, since the anomaly flag does not correspond to the second object distance d4, the complementing unit 604 outputs the object distance d4 as it is.

[0102] Next, at t = 6, the object distances d4 at t = 4, d5 at t = 5, and d6 at t = 6 are stored in the storage unit 603. In this case, since the anomaly flag corresponds to the second object distance d5, the complementing unit 604 uses the adjacent first object distance d4 or the third object distance d6 that does not correspond to the anomaly flag to complement the second object distance d5. For example, when d4 < d6, the complementing unit 604 replaces the second object distance d5 with the smaller object distance d4. That is, d4 is output as the object distance at t = 4. Thereby, it is possible to prevent the distance measurement device 1 from outputting the object distance d4 with low reliability as it is.

[0103] <Case where the anomaly flag is associated with two or more consecutive points>

[0104] Figure 12 [[ID=IS15]]It is a diagram for explaining an operation example in the case where the anomaly flag is associated with two or more consecutive points according to Embodiment 1.

[0105] For example, as Figure 12 shown, it is assumed that the anomaly flag corresponds to the object distance d2 at t = 2, and the anomaly flag also corresponds to the consecutive object distance d3 at t = 3.

[0106] In this case, the supplementary unit 604 can output the object distance d3 unchanged without performing the object distance supplementation described above. For example... Figure 12 As shown, the distance from the object to d3 may not be the distance up to the object itself, but rather the distance up to dust or other contaminants located in front of the object. However, since the object to be detected might not be observed within the monitoring area due to dust or other contaminants, safety is prioritized, and it is treated as an object being detected. However, referring to this... Figure 12 The explanatory processing is not a necessary function in the distance measuring device 1.

[0107] <Variation Example>

[0108] In the above implementation, the second object distance corresponding to the anomaly flag is supplemented by replacing it with the first object distance or the third object distance, but the supplementation method is not limited to this. For example, the average of the first object distance and the third object distance can also be calculated as the second object distance.

[0109] In the above embodiment, the storage unit 603 stores the object distance for three consecutive times (e.g., t=1 to 3) (that is, three consecutive rotation angles), but it can also store four times (e.g., t=1 to 4) or more.

[0110] In the above embodiment, object distances at three consecutive time intervals (e.g., t=1 to 3, i.e., at three consecutive rotation angles) are stored in the storage unit 603 to supplement the second object distances corresponding to the anomaly flag. However, multiple object distances corresponding to the anomaly flag can also be supplemented at once. That is, if, among the measured first object distance, multiple second object distances measured after the first distance, and a third object distance measured after the second object distance, the first object distance and the third object distance are presumed to be non-abnormal, while the multiple second object distances are presumed to be abnormal, the first object distance or the third object distance can be used to supplement the multiple second object distances. For example, the object distance at t=1 or the object distance at t=4 can be used to supplement the object distances at t=2 and t=3 corresponding to the anomaly flag at four consecutive time intervals (e.g., t=1 to 4) at once.

[0111] (Summary of Implementation Method 1)

[0112] Based on the description of Embodiment 1 above, the following technology is disclosed.

[0113] <Technology 1>

[0114] The distance measuring device (1) comprises: a light-emitting element (102) that projects pulsed light (3A); a light-receiving element (103) that receives reflected light (3B) from the object; and a controller (600) that measures the distance to the object based on the time between the light-emitting element's light-emitting timing and the light-receiving element's light-receiving timing, wherein the controller uses the first distance or the third distance to supplement the second distance if the first distance and the third distance are presumed to be normal and the second distance is presumed to be abnormal among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance.

[0115] Therefore, since the second distance, which is presumed to be abnormal, is supplemented by the first or third distance, which is presumed to be non-abnormal, the erroneous distance output by the distance measuring device can be suppressed.

[0116] <Technology 2>

[0117] In the distance measuring device described in Technique 1, the projection directions of the projected light used in the measurement of the first distance, the projected light used in the measurement of the second distance, and the projected light used in the measurement of the third distance are different from each other.

[0118] Therefore, since the distance to the object that is presumed to be non-abnormal is measured by using temporally and spatially adjacent projected light, the distance that is presumed to be abnormal can be supplemented with high accuracy.

[0119] <Technology 3>

[0120] In the distance measuring device described in technique 1 or 2, the controller detects the object when it is able to measure at least two temporally adjacent distances.

[0121] This prevents the distance measuring device from detecting tiny objects such as dust and dirt.

[0122] <Technology 4>

[0123] In any of the distance measuring devices described in techniques 1 to 3, the time between the light emission timing and the light reception timing is measured by a TDC (Time to Digital Converter), and the controller, based on the measurement result of the TDC, estimates whether the measured distance is abnormal.

[0124] Therefore, the controller can infer whether the measured distance is abnormal based on the TDC measurement results.

[0125] <Technology 5>

[0126] In any of the distance measuring devices described in techniques 1 to 4, the controller, when supplementing the second distance, uses the smaller of the first distance and the third distance to supplement the second distance.

[0127] Therefore, the object distance device can perform a relatively safe compensation when compensating for distances that are presumed to be abnormal.

[0128] <Technology 6>

[0129] In any of the distance measuring devices described in techniques 1 to 5, the projected light is projected about a given axis as the axis of rotation (C) in a direction orthogonal to that axis. The term "different projection directions" means that the rotation angles at which the projected light is projected are different from each other.

[0130] Thus, the distance measuring device is able to scan a 360-degree space in a direction orthogonal to the rotation axis.

[0131] <Technology 7>

[0132] In a distance measurement method that measures the distance to an object by measuring the time between the emission timing of the projected light (3A) based on the pulse wave projected by the light-emitting element (102) and the light-receiving timing of the light-receiving element (103) receiving the reflected light (3B) reflected by the object, the first distance and the third distance are presumed to be normal, and the second distance is presumed to be abnormal, in the case that the first distance or the third distance is used to supplement the second distance when the first distance is measured, at least one second distance is measured after the first distance, and a third distance is measured after the second distance.

[0133] Therefore, since the second distance, which is presumed to be abnormal, is supplemented by the first or third distance, which is presumed to be non-abnormal, the erroneous distance output by the distance measuring device can be suppressed.

[0134] The embodiments have been described above with reference to the accompanying drawings, but this disclosure is not limited to this example. Those skilled in the art will obviously be able to conceive of various modifications, alterations, substitutions, additions, deletions, and equivalents within the scope of the technical solution described, and should understand that these also fall within the technical scope of this disclosure. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0135] Furthermore, this application is based on Japanese Patent Application No. 2023-202864, filed on November 30, 2023, the contents of which are incorporated herein by reference.

[0136] Industrial availability

[0137] The technology disclosed herein is useful in devices for measuring the distance to an object.

[0138] -Symbol Explanation-

[0139] 1 Distance measuring device

[0140] 3A projected light

[0141] 3B Reflected light

[0142] 10. Outer Cover

[0143] 11 Wavelength window

[0144] 100 Fixed part

[0145] 101 substrate

[0146] 102 Light-emitting element

[0147] 103 Light receiving element

[0148] 104 Condensing Lens

[0149] 105 Collimating Lens

[0150] 106 coil

[0151] 107 Photoelectric Circuit Breaker

[0152] 300 Rotating Part

[0153] 301 Rotating Component

[0154] 302 Magnet

[0155] 303 reflector

[0156] 311 Ribs

[0157] 401 comparator

[0158] 402 motor

[0159] 403 Rotary Position Detector

[0160] 500 TDC

[0161] 501 Measurement Department

[0162] 502 Data Register

[0163] 503 Status Register

[0164] 504 Input / Output I / F

[0165] 600 controller

[0166] 601 Distance Measurement and Control Unit

[0167] 602 Distance Calculation Unit

[0168] 603 Storage Unit

[0169] 604 Supplementary Section

[0170] 605 Motor Control Unit

[0171] 611 TDC Anomaly Detection Unit.

Claims

1. A distance measuring device, comprising: Light-emitting element, projecting pulsed light; A light-receiving element receives the reflected light from the object after the projected light is reflected; and The controller measures the distance to the object based on the time between the light-emitting timing of the light-emitting element and the light-receiving timing of the light-receiving element. If the controller is presumed to be non-abnormal among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, and the second distance is presumed to be anomalous, then the controller uses the first distance or the third distance to supplement the second distance.

2. The distance measuring device according to claim 1, wherein, The projection directions of the projected light used in the measurement of the first distance, the measurement of the second distance, and the measurement of the third distance are different from each other.

3. The distance measuring device according to claim 1, wherein, The controller detects the object when it can determine at least two temporally adjacent distances.

4. The distance measuring device according to claim 1, wherein, The time between the light emission timing and the light reception timing is measured by a time-to-digital converter (TDC). Based on the measurement results of the TDC, the controller estimates whether the measured distance is abnormal.

5. The distance measuring device according to claim 1, wherein, When the controller supplements the second distance, it uses the smaller of the first distance and the third distance to supplement the second distance.

6. The distance measuring device according to any one of claims 1 to 5, wherein, The projected light is projected about a given axis as its rotation axis in a direction orthogonal to that axis. The different projection directions refer to the different rotation angles at which the projected light is projected.

7. A distance measurement method, comprising measuring the distance to the object based on the time between the emission timing of the projected light of a pulse wave projected by a light-emitting element and the reception timing of the reflected light of the projected light reflected by an object by a light-receiving element. In the case where the first distance and the third distance are presumed to be non-abnormal among the first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, and the second distance is presumed to be anomalous, the first distance or the third distance is used to supplement the second distance.

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