Distance measuring apparatus, and distance measuring method

Abstract

To provide a distance measuring apparatus capable of preventing the output of incorrect distances.SOLUTION: The distance measuring apparatus includes: a light-emitting element that projects pulse wave projected light; a light-receiving element that receives reflected light resulting from the projected light being reflected by an object; and a controller that measures the distance to an object based on the time between the light emission of the light-emitting element and the reception of light by the light-receiving element. The controller is configured so as to, when the first distance and the third distance are estimated to be normal out of the first measured distance, at least one of the second distances measured after the first distance, and a third distance measured after the second distance, and when the first distance and the third distance are estimated to be normal, and the second distance is estimated to be abnormal, complement the second distance using the first distance or the third distance.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] There is known a distance measuring device that transmits a pulse wave, measures the time required until the reflected wave returns, and calculates the distance to an object. Patent Document 1 discloses a distance measuring device including: transmission means for transmitting a pulse wave; reception means for receiving a reflected wave reflected by an object; time measurement means for measuring the time required from the transmission of the pulse wave to the detection of the reflected wave; pulse width measurement means for capturing the reception waveform of the reflected wave by the reception means and measuring the pulse width of the reception waveform; correction value calculation means for calculating a correction value of the time required corresponding to the pulse width of the reception waveform based on the input / output characteristics of the active region and the saturation region in the reception means; and distance calculation means for correcting the time required measured by the time measurement means using the correction value and calculating the distance to the object by multiplying the propagation speed of the pulse wave.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the levels of actual reception waveforms of reflected waves vary, the comparator may not be able to perform a normal binarization operation on reception waveforms at levels near the threshold value, and may output abnormal signals. The distance to the object calculated using such abnormal signals may be unreliable and may be incorrect. That is, there is a possibility that an incorrect distance may be output.

[0005] An object of the present disclosure is to provide a technique for suppressing a distance measuring device from outputting an incorrect distance.

Means for Solving the Problem

[0006] A distance measuring device according to an embodiment includes a light emitting element that projects pulsed-wave projection light, a light receiving element that receives reflected light obtained by reflecting the projection light by an object, and a controller that measures the distance to the object based on the time between the light emission timing of the light emitting element and the light reception timing of the light receiving element. When it is estimated that the first distance and the third distance are not 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 it is estimated that the second distance is abnormal, the controller complements the second distance using the first distance or the third distance.

[0007] A distance measuring method according to an embodiment is a distance measuring method for measuring the distance to an object based on the time between the light emission timing at which a light emitting element projects pulsed-wave projection light and the light reception timing at which a light receiving element receives reflected light obtained by reflecting the projection light by an object. When it is estimated that the first distance and the third distance are not 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 it is estimated that the second distance is abnormal, the second distance is complemented using the first distance or the third distance.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to suppress the distance measuring device from outputting an incorrect distance.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with appropriate reference to the drawings. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art. Note that 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 claims.

[0011] (Embodiment 1) <Physical Configuration of the Distance Measuring Device> FIG. 1 is an external perspective view of the distance measuring device 1 according to Embodiment 1. FIG. 2 is a longitudinal sectional view of the distance measuring device according to Embodiment 1. FIG. 2 corresponds to the A-A sectional view of the distance measuring device 1 shown in FIG. 1.

[0012] As shown in FIGS. 1 and 2, the distance measuring device 1 includes a fixed part 100, a rotating part 300, and an outer cover part 10.

[0013] The fixed part 100 has a substantially rectangular parallelepiped shape. The rotating part 300 is connected to the upper surface of the fixed part 100 and has a cylindrical shape that rotates about an axis perpendicular to the upper surface with the rotation axis C. The outer cover part 10 has a substantially cylindrical shape and covers the rotating part 300 from above. The outer cover part 10 has a wavelength window 11 formed using a wavelength selection member on at least a part of its side surface. The wavelength selection member is a material that transmits light of a predetermined wavelength (frequency) component used for distance measurement and blocks light of a wavelength (frequency) component in the visible region. The wavelength selection member has a role of blocking disturbing light such as natural light and electric lights, for example.

[0014] For convenience of explanation, as shown in FIG. 1, an axis perpendicular to the upper surface (or bottom surface) of the fixed part 100 is defined as the Z-axis. An axis perpendicular to the Z-axis is defined as the X-axis. An axis perpendicular to the Z-axis and the X-axis is defined as the Y-axis. Also, for convenience of explanation, the positive direction of the Z-axis may be referred to as "up", the negative direction of the Z-axis may be referred to as "down", and the direction away from the Z-axis in the X-axis direction or the Y-axis direction may be referred to as "sideways". Note that these expressions regarding directions are used for convenience of explanation and are not intended to limit the posture during actual use of the structure. For example, the distance measuring device 1 shown in FIG. 1 may be used with the top and bottom reversed. Also, the A-A sectional view shown in FIG. 2 corresponds to a sectional view of the YZ plane.

[0015] The bottom surface of the fixed part 100 may be fixedly installed on a predetermined plane (for example, a floor surface or a housing surface of a predetermined device, etc.).

[0016] The rotating part 300 rotates about the central axis in the height direction (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 the projected light 3A) projected laterally from a part of the side surface of the rotating part 300 rotates about the rotation axis C. Accordingly, the projected light 3A and the region where distance measurement is possible with the projected light 3A (hereinafter referred to as the distance measurement region) also rotate. As will be described later, the distance measurement device 1 measures the distance to an object existing in the distance measurement region based on the time difference (Time of Flight (TOF)) between the timing when the projected light 3A is projected and the timing when the light reflected by the object in the distance measurement region (hereinafter referred to as the reflected light 3B) is received. When the rotating part 300 makes one full rotation about the rotation axis C, the distance measurement device 1 can measure the distance to an object existing in the distance measurement region of 360 degrees in the lateral circumferential direction.

[0017] The fixed part 100 includes a substrate 101, a light emitting element 102, a light receiving element 103, a condenser lens 104, a collimator lens 105, a coil 106, and a photo interrupter 107. The rotating part 300 includes a rotating member 301, a magnet 302, and a reflecting mirror 303.

[0018] A hollow motor 402 (see FIG. 3) is formed by the coil 106 of the fixed part 100 and the magnet 302 of the rotating part 300. By driving this motor 402, the rotating part 300 rotates about the rotation axis C.

[0019] The substrate 101 is, for example, a Printed Circuit Board (PCB) and has a comparator 401, a TDC 500, and a controller 600 (see FIG. 3) described later. Note that TDC is an abbreviation for Time to Digital Converter.

[0020] The light emitting element 102 is arranged along the rotation axis C and projects the projected light 3A upward.

[0021] The collimator lens 105 corrects the projected light 3A projected from the light emitting element 102 into substantially parallel light and outputs it upward.

[0022] The reflecting mirror 303 is provided on the rotating member 301 so as to reflect, in the lateral direction (direction along the XY plane), the parallel light projected upward from the light emitting element 102 and corrected by the collimator lens 105. Since the reflecting mirror 303 rotates together with the rotating member 301, the projected light is projected (scanned) 360 degrees around the rotation axis C in the direction orthogonal to the rotation axis C (lateral direction) over time. The projected light 3A reflected by the reflecting mirror 303 passes through the wavelength window 11 of the outer cover portion 10 and is projected onto the distance measurement region.

[0023] The reflected light 3B obtained by reflecting the projected light 3A by the object passes through the wavelength window 11 of the outer cover portion 10 and is reflected downward by the reflecting mirror 303.

[0024] The condenser lens 104 condenses the reflected light 3B reflected downward by the reflecting mirror 303 and outputs it downward.

[0025] The light receiving element 103 receives the reflected light 3B condensed by the condenser lens 104.

[0026] The rotating member 301 includes a plurality of ribs 311 at regular intervals. The photointerrupter 107 is arranged so as to be able to detect the passage of one rib 311. By detecting and counting the passage of one rib 311 using the photointerrupter 107, the controller 600 described later can detect the rotation position (rotation angle) of the rotating member 301 (that is, the rotating portion 300). Therefore, the photointerrupter 107 and the rib 311 can constitute a rotation position detector 403 (see FIG. 3) described later.

[0027] <Functional Configuration of Distance Measuring Device> FIG. 3 is a block diagram showing a functional configuration example of the distance measuring device 1 according to Embodiment 1.

[0028] The distance measurement 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. Note that the configuration shown in FIG. 3 is an example, and a configuration in which at least one of the comparator 401 and the TDC 500 is included in the controller 600 may be used.

[0029] The light emitting element 102 projects pulsed light 3A of a pulse wave corresponding to an input pulse signal (hereinafter referred to as an input pulse signal). In FIG. 3, the input of the input pulse signal is expressed as START. The projected light 3A may be read as laser light or a beam. The light receiving element 103 receives the reflected light 3B as described above and outputs a light reception signal corresponding to the light reception level.

[0030] FIG. 4 is a diagram for explaining a signal input to the comparator 401 and a signal output from the comparator 401 according to the first embodiment. Next, the comparator 401 will be described with reference to FIG. 4.

[0031] As shown in FIG. 4(a), the comparator 401 receives a light reception signal from the light receiving element 103, and sets a period during which the level of the light reception signal is equal to or higher than a predetermined comparator threshold value to a predetermined High level, and sets a time during which the level of the light reception signal is lower than the comparator threshold value to a predetermined GND level, and outputs a pulse signal (hereinafter referred to as a light reception pulse signal). Note that the High level is larger than the GND level. In FIG. 3, the output of the light reception pulse signal is expressed as STOP.

[0032] When the level of the input light reception signal is lower than the comparator threshold value over the entire period, the comparator 401 outputs a light reception pulse signal of the GND level as shown in FIG. 4(c).

[0033] However, when the maximum value of the level of the input received light signal is near the comparator threshold, as shown in FIG. 4(b), the comparator 401 may output a received light pulse signal with an abnormal waveform that is halfway between a High level and a GND level. In the present embodiment, a method for outputting a highly reliable distance measurement result even when the comparator 401 outputs a received light pulse signal with such an abnormal waveform will be described.

[0034] FIG. 5 is a block diagram showing a functional configuration example of the TDC 500 according to Embodiment 1. FIG. 6 is a diagram for explaining a method of measuring the TOF and the received light pulse width by the TDC 500 according to Embodiment 1. FIG. 7 is a diagram for explaining the operating conditions under which the TDC 500 according to Embodiment 1 can normally measure the TOF and the received light pulse width. Next, the TDC 500 will be described with reference to FIGS. 5, 6, and 7.

[0035] The TDC 500 includes a measurement unit 501, a data register 502, a status register 503, and an input / output I / F 504. Note that "I / F" is an abbreviation for Interface.

[0036] When an input pulse signal is input to the light emitting element 102, the measurement unit 501 starts (START) with the same input pulse signal as shown in Fig. 6(a) at the timing when the input pulse signal is input. The comparator 401 receives a light reception signal as shown in Fig. 6(b) from the light receiving element 103 and outputs a light reception pulse signal as shown in Fig. 6(c). When the comparator 401 outputs the light reception pulse signal, the measurement unit 501 stops (STOP) with the light reception pulse signal as shown in Fig. 6(c) at the timing when the light reception pulse signal is input. The measurement unit 501 measures the time (i.e., TOF) from the timing when the input pulse signal is input to the timing when the light reception pulse signal is input, and the pulse width of the light reception pulse signal (hereinafter referred to as the light reception pulse width). The measurement unit 501 writes the measured TOF and light reception pulse width into the data register 502. Further, the measurement unit 501 writes operation information indicating the operation state at the time of the measurement into 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 reception pulse signal. Further, the operation information may include information indicating whether the light reception pulse signal is input within a predetermined time from the timing when the input pulse signal is input (i.e., whether a timeout has occurred).

[0037] The input / output I / F 504 outputs the measurement results of the TOF and the light reception pulse width written in the data register 502. The input / output I / F 504 outputs the operation information written in the status register 503 in response to a request from the outside or together with the output of the measurement results of the TOF and the light reception pulse width respectively.

[0038] As shown in Fig. 7, there are operating conditions under which the measurement unit 501 can normally measure the TOF. In Fig. 7, the horizontal axis represents time and the vertical axis represents the level of the light reception pulse signal.

[0039] As shown in region A of Fig. 7, when the level of the light reception pulse signal is less than a predetermined threshold, the measurement unit 501 determines that the light reception pulse signal is not detected.

[0040] As shown in region B of FIG. 7, even if the level of the received light pulse signal is equal to or higher than a predetermined threshold value, if the time from when the input pulse signal is input until the received light pulse signal is input or the pulse width of the received light pulse signal is shorter than a predetermined minimum value (min), it is an abnormal measurement.

[0041] As shown in region C of FIG. 7, even if the level of the received light pulse signal is equal to or higher than a predetermined threshold value, if the time from when the input pulse signal is input until the received light pulse signal is input or the pulse width of the received light pulse signal is longer than a predetermined maximum value (max), it is a timeout.

[0042] As shown in region D of FIG. 7, when the level of the received light pulse signal is equal to or higher than a predetermined threshold value and the time from when the input pulse signal is input until the received light pulse signal is input or the pulse width of the received light pulse signal is between a predetermined minimum value (min) and a maximum value (max), TOF can be measured normally.

[0043] As shown in region E of FIG. 7, when the level of the received light pulse signal is near a predetermined threshold value (see FIG. 4(b)), it is an abnormal measurement. In the present embodiment, such an abnormal measurement is suppressed from outputting a distance measurement result with low reliability.

[0044] Return to the description of FIG. 3.

[0045] As described above, the motor 402 is composed of the coil 106 and the magnet 302, and rotates the rotating member 301 about the central axis C.

[0046] As described above, the rotation position detector 403 is composed of the rib 311 of the rotating member 301 and the photointerrupter 107, and outputs a start signal with a predetermined rotational angle resolution of the rotating part 300. This start signal is used as a signal indicating the light emission timing.

[0047] The controller 600 performs processes such as calculating the distance to an 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.

[0048] The ranging control unit 601 receives a start signal from the rotation position detector 403. The ranging control unit 601 outputs a light emission pulse signal (START) to the light emitting element 102 and the TDC 500 at the timing when the start signal is input.

[0049] The ranging control unit 601 receives the measurement results of the TOF and the received light pulse width from the TDC 500. The ranging control unit 601 acquires operation information corresponding to the input measurement results of the TOF and the received light pulse width from the TDC 500.

[0050] The ranging control unit 601 includes a TDC abnormality determination unit 611. The TDC abnormality determination unit 611 determines (estimates) whether or not the measurement result is abnormal based on the measurement result itself of the TOF or the received light pulse width, or the operation information corresponding to the measurement result. For example, when the measurement result of the TOF or the received light pulse width is outside a predetermined range, the TDC abnormality determination unit 611 determines (estimates) that the measurement results of the TOF and the received light pulse width are abnormal. For example, when the number of rising edges and the number of falling edges of the received light pulse signal do not match in the operation information, the TDC abnormality determination unit 611 determines (estimates) that the measurement results of the TOF and the received light pulse width are abnormal. When the TDC abnormality determination unit 611 determines (estimates) that the measurement result of the TOF or the received light pulse width is abnormal, the TDC abnormality determination unit 611 outputs an abnormality flag indicating that the measurement results of the TOF and the received light pulse width are abnormal to the distance calculation unit 602.

[0051] The distance calculation unit 602 receives the measurement results of the TOF and the received light pulse width from the TDC 500. Also, when the measurement results of the TOF and the received light pulse width are abnormal, the distance calculation unit 602 receives an abnormality flag from the ranging control unit 601.

[0052] The distance calculation unit 602 calculates the object distance based on the measurement results of TOF and the received light pulse width. The time indicated by TOF is the time (round-trip time) from when the projected light 3A is projected until the reflected light 3B is received, and corresponds to approximately twice the time it takes for the projected light 3A to reach the object. Therefore, the distance calculation unit 602 first calculates a basic distance (referred to as the edge distance) by (propagation speed of the projected light 3A × TOF / 2). Next, the distance calculation unit 602 corrects this edge distance according to the measurement result of the received light pulse width at this time to calculate the object distance.

[0053] The distance calculation unit 602 stores the calculated object distance in the storage unit 603. At this time, if an abnormality flag is associated with the measurement results of TOF and the received light pulse width used for calculating the object distance, the distance calculation unit 602 associates the abnormality flag with the object distance and stores it in the storage unit 603.

[0054] The storage unit 603 stores the object distances for three consecutive times (i.e., at three consecutive rotation angles). In addition, the storage unit 603 also stores information indicating whether an abnormality flag is associated with the object distance. Note that the storage unit 603 may be composed of a volatile storage medium and / or a non-volatile storage medium.

[0055] The complementing unit 604 outputs the second object distance among the three object distances stored in the storage unit 603. However, if an abnormality flag is associated with the second object distance among the three object distances stored in the storage unit 603, the complementing unit 604 uses the first and / or third object distances to complement the second object distance, and outputs the complemented second object distance. Although the details of this process will be described later, this outputs a highly reliable object distance.

[0056] The motor control unit 605 controls the rotation speed of the motor 402. For example, the motor control unit 605 controls the motor 402 so that the rotation speed is constant.

[0057] <The smallest object whose distance can be measured> FIG. 8 is a diagram for explaining the smallest object whose distance can be measured according to Embodiment 1.

[0058] When the difference between two adjacent object distances is less than a predetermined threshold, the distance calculation unit 602 adopts the object distance. That is, as shown in FIG. 8, the size of the smallest object that can be measured is a size that can reflect two adjacent projection lights 3A. In other words, an object with a size that can reflect only one projection light 3A is not detected as an object to be measured. This prevents the distance measuring device 1 from detecting minute dust or dust in the air as an object to be measured.

[0059] <Flowchart> FIG. 9 is a flowchart showing a processing example of the controller 600 according to Embodiment 1. Next, the processing performed by the controller 600 will be described with reference to FIG. 9.

[0060] The distance measurement control unit 601 waits until a start signal is input from the rotation position detector 403 (S101: NO), and when the input of the start signal is detected (S101: YES), the process proceeds to the next step S102.

[0061] The distance measurement control unit 601 performs a predetermined start setting (for example, initialization) on the TDC 500 (S102).

[0062] The distance measurement control unit 601 outputs a light emission pulse signal to the light emitting element 102 and the TDC 500 (S103).

[0063] The TDC 500 waits until a light reception pulse signal is input from the comparator 401 (S104: NO), and when the light reception pulse signal is input (S104: YES), outputs the measurement results of the TOF and the light reception pulse width, and the process proceeds to step S105.

[0064] The distance calculation unit 602 acquires the edge distance and / or the pulse width from the measurement results of the TOF and the received light pulse width input from the TDC500 (S105). Then, the distance measurement control unit 601 acquires the operation information from the TDC500, and determines whether to associate an abnormality flag with the object distance to be calculated later based on the operation information (S106). For example, when the number of rising edges and the number of falling edges of the received light pulse signal do not match in the operation information, or when the edge distance or the received light pulse width is outside a predetermined range, the TDC abnormality determination unit 611 of the distance measurement control unit 601 determines to associate an abnormality flag with the object distance after calculation.

[0065] If the distance measurement control unit 601 determines not to associate an abnormality flag (S106: YES), the process proceeds to step S108.

[0066] If the distance measurement control unit 601 determines to associate an abnormality flag (S106: NO), it sets to associate an abnormality flag with the object distance to be calculated later (S107), and the process proceeds to step S108.

[0067] The distance calculation unit 602 calculates the object distance based on the edge distance and the received light pulse width (S108).

[0068] The distance calculation unit 602 stores the calculated object distance in the storage unit 603. At this time, when an abnormality flag is associated with the calculation of the object distance, the distance calculation unit stores the object distance in the storage unit 603 with the abnormality flag associated (S109).

[0069] The storage unit 603 stores at least the object distance calculated this time (hereinafter referred to as the third object distance), 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).

[0070] The complement unit 604 determines whether an abnormality flag is associated with the second object distance stored in the storage unit 603 (S110).

[0071] When the abnormality flag is associated with the second object distance (S110: YES), the completion unit 604 completes the second object distance using the first object distance or the third object distance (S111). In this case, the second object distance becomes the object distance after completion. The details of the completion method will be described later. Then, the process proceeds to step S112.

[0072] When the abnormality flag is not associated with the second object distance (S110: NO), the completion unit 604 advances the process to step S112.

[0073] The completion unit 604 outputs the second object distance (S112). Then, the process returns to step S101.

[0074] Through the above processing, when the abnormality flag is associated with the second object distance, that is, when the reliability of the second object distance is low, the second object distance is complemented with a highly reliable object distance and output.

[0075] <Complementary method for the second object distance> FIG. 10 is a diagram for explaining a complementary method when the abnormality flag is associated with the second object distance according to Embodiment 1. FIG. 11 is a diagram showing a storage example in the storage unit 603 of the first object distance, the second object distance, and the third object distance according to Embodiment 1. Next, with reference to FIGS. 10 and 11, the complementary method for the second object distance performed in step S113 of FIG. 9 will be described in detail.

[0076] As shown in FIGS. 10 and 11, assume that the object distance d1 at the rotation angle θ1 is measured at the timing t = 1, the object distance d2 at the rotation angle θ2 is measured at the timing t = 2, the object distance d3 at the rotation angle θ3 is measured at the timing t = 3, the object distance d4 at the rotation angle θ4 is measured at the timing t = 4, and the object distance d5 at the rotation angle θ5 is measured at the timing t = 5. And assume that the abnormality flag is associated with the object distance d3 and the object distance d5. Note that the rotation angle θ indicates an angle from a predetermined reference angle (0 degrees).

[0077] First, when t = 3, the storage unit 603 stores the object distance d1 at t = 1, the object distance d2 at t = 2, and the object distance d3 at t = 3. In this case, since no anomaly flag is associated with the second object distance d2, the complement unit 604 outputs the object distance d2 as it is.

[0078] Next, when t = 4, the storage unit 603 stores the object distance d2 at t = 2, the object distance d3 at t = 3, and the object distance d4 at t = 4. In this case, since an anomaly flag is associated with the second object distance d3, the complement unit 604 complements the second object distance d3 using the first object distance d2 or the third object distance d4 that has no adjacent anomaly flag associated with it. For example, when d2 < d4, the complement unit 604 replaces the second object distance d3 with the smaller of the object distances, d2. That is, the complement unit 604 outputs d2 as the object distance at t = 4. This can prevent the unreliable object distance d3 from being output as it is. The reason for replacing the second object distance with the smaller of the adjacent object distances is to prioritize safety when the distance measurement device 1 is used in a monitoring area or the like. Therefore, depending on the usage mode of the distance measurement device 1, the second object distance may be replaced with the larger of the adjacent object distances.

[0079] Next, when t = 5, the storage unit 603 stores the object distance d3 at t = 3, the object distance d4 at t = 4, and the object distance d5 at t = 5. In this case, since no anomaly flag is associated with the second object distance d4, the complement unit 604 outputs the object distance d4 as it is.

[0080] Next, when t = 6, the storage unit 603 stores the object distance d4 at t = 4, the object distance d5 at t = 5, and the object distance d6 at t = 6. In this case, since the abnormal flag is associated with the second object distance d5, the first object distance d4 or the third object distance d6 without the associated abnormal flag adjacent to it is used to complement the second object distance d5. For example, when d4 < d6, the smaller object distance d4 is used by the complementing unit 604 to replace the second object distance d5. That is, d4 is output as the object distance at t = 4. Thereby, it can be prevented that the distance measuring device 1 outputs the object distance d4 with low reliability as it is.

[0081] <When abnormal flags are associated with two or more points continuously> FIG. 12 is a diagram for explaining an operation example when abnormal flags are associated with two or more points continuously according to Embodiment 1.

[0082] For example, as shown in FIG. 12, assume that an abnormal flag is associated with the object distance d2 at t = 2, and an abnormal flag is also associated with the consecutive object distance d3 at t = 3.

[0083] In this case, the complementing unit 604 may output the object distance d3 as it is without performing the complement of the object distance described above. As shown in FIG. 12, although the object distance d3 may be the distance to dust or dirt existing in front of the object rather than the distance to the object, there is also a possibility that the object to be detected in the monitoring area cannot be seen due to dust or dirt. Therefore, giving priority to safety, it is treated as the object detected as an object. However, the process described with reference to FIG. 12 is not an essential function in the distance measuring device 1.

[0084] <Modification example> In the above-described embodiment, the second object distance associated with the abnormal flag is complemented by replacing it with the first object distance or the third object distance. However, the complementing method is not limited to this. For example, the average value of the first object distance and the third object distance may be calculated and used as the second object distance.

[0085] In the above-described embodiment, the storage unit 603 stores the object distances for three consecutive times (for example, t = 1 to 3) (that is, at three consecutive rotation angles), but may store the object distances for four times (for example, t = 1 to 4) or more times.

[0086] In the above-described embodiment, the storage unit 603 stores the object distances for three consecutive times (for example, t = 1 to 3) (that is, at three consecutive rotation angles), and complements the second object distance associated with the abnormality flag. However, a plurality of object distances associated with the abnormality flag may be complemented at once. That is, among the measured first object distance, the plurality of second object distances measured after the first distance, and the third object distance measured after the second object distance, when it is estimated that the first object distance and the third object distance are not abnormal and the plurality of second object distances are abnormal, the plurality of second object distances may be complemented using the first object distance or the third object distance. For example, among the object distances for four consecutive times (for example, t = 1 to 4), the object distances at t = 2 and t = 3 associated with the abnormality flag may be complemented at once with the object distance at t = 1 or the object distance at t = 4.

[0087] (Summary of Embodiment 1) According to the description of the above Embodiment 1, the following technology is disclosed.

[0088] <Technology 1> The distance measurement device (1) includes a light emitting element (102) that projects pulsed projection light (3A), a light receiving element (103) that receives reflected light (3B) reflected by an object from the projection light, and a controller (600) that measures the distance to the object based on the time between the light emission timing of the light emitting element and the light reception timing of the light receiving element. When it is estimated that the first distance measured and the third distance measured after the second distance are not abnormal, and the second distance is abnormal, the controller complements the second distance using the first distance or the third distance. Thereby, since the second distance estimated to be abnormal is complemented by the first distance or the third distance estimated not to be abnormal, it is possible to suppress the distance measurement device from outputting an incorrect distance.

[0089] <Technology 2> In the distance measurement device according to Technology 1, the projection directions of the projection light used for measuring the first distance, the projection light used for measuring the second distance, and the projection light used for measuring the third distance are different from each other. Thereby, since it is complemented by the distance to the object estimated not to be abnormal, measured with projection light that is temporally and spatially adjacent, the distance estimated to be abnormal can be complemented with high accuracy.

[0090] <Technology 3> In the distance measurement device according to Technology 1 or 2, when the controller can measure at least two distances that are temporally adjacent, the controller detects the object. Thereby, it is possible to prevent the distance measurement device from detecting even minute objects such as dust and debris.

[0091] <Technology 4> In the distance measurement device according to any one of Technologies 1 to 3, the time between the light emission timing and the light reception timing is measured by a Time to Digital Converter (TDC), and the controller estimates whether the measured distance is abnormal based on the measurement result of the TDC. Thereby, the controller can estimate whether the measured distance is abnormal based on the measurement result of the TDC.

[0092] <Technology 5> In the distance measurement device according to any one of Technologies 1 to 4, when the controller complements the second distance, the controller complements the second distance using the smaller one of the first distance and the third distance. Thereby, when the object distance device complements the distance estimated to be abnormal, it can perform highly safe complementation.

[0093] <Technology 6> In the distance measurement device according to any one of Technologies 1 to 5, the projected light is projected in a direction orthogonal to the axis with a predetermined axis as the rotation axis (C), and the fact that the projection directions are different from each other means that the rotation angles at which the projected light is projected are different from each other. Thereby, the distance measurement device can scan a 360-degree space in a direction orthogonal to the rotation axis.

[0094] <Technology 7> In a distance measurement method for measuring the distance to an object based on the time between the light emission timing at which the light emitting element (102) projects pulsed projection light (3A) and the light reception timing at which the light receiving element (103) receives reflected light (3B) obtained by reflecting the projection light by the object, among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, when the first distance and the third distance are estimated to be normal and the second distance is estimated to be abnormal, the second distance is complemented using the first distance or the third distance. As a result, the second distance estimated to be abnormal is complemented by the first distance or the third distance estimated not to be abnormal, so that it is possible to suppress the distance measuring device from outputting an incorrect distance.

[0095] As described above, the embodiments have been described with reference to the accompanying drawings, but the present disclosure is not limited to such examples. It is obvious that those skilled in the art can conceive various modification examples, correction examples, replacement examples, addition examples, deletion examples, and equivalent examples within the scope described in the claims, and it is understood that they also belong to the technical scope of the present disclosure. In addition, within the scope not departing from the gist of the invention, the components in the above-described embodiments may be arbitrarily combined.

Industrial Applicability

[0096] The technology of the present disclosure is useful for a device that measures the distance to an object.

Explanation of Signs

[0097] 1 Distance measuring device 3A Projected light 3B Reflected light 10 Outer cover part 11 Wavelength window 100 Fixed part 101 Substrate 102 Light emitting element 103 Light receiving element 104 Condensing lens 105 Collimator lens 106 Coil 107 Photointerrupter 300 Rotating part 301 Rotating member 302 Magnet 303 Mirror 311 Rib 401 Comparator 402 Motor 403 Rotation position detector 500 TDC 501 Measuring part 502 Data register 503 Status Register 504 Input / Output I / F 600 Controller 601 Distance Measurement Control Unit 602 Distance Calculation Unit 603 Memory Unit 604 Completion Unit 605 Motor Control Unit 611 TDC Abnormality Judgment Unit

Claims

1. A light-emitting element that projects pulsed light, A light-receiving element that receives the reflected light reflected by an object from the projected light, A controller that 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, and The controller, Among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, when it is estimated that the first distance and the third distance are not abnormal and the second distance is abnormal, the second distance is complemented using the first distance or the third distance. A distance measurement device.

2. The projected light used for measuring the first distance, the projected light used for measuring the second distance, and the projected light used for measuring the third distance have different projection directions from each other. The distance measurement device according to Claim 1.

3. When the controller can measure at least two distances adjacent in time, the object is detected. The distance measurement device according to Claim 1.

4. The time between the light-emitting timing and the light-receiving timing is measured by a Time to Digital Converter (TDC), The controller estimates whether the measured distance is abnormal based on the measurement result of the TDC. The distance measurement device according to Claim 1.

5. When the controller complements the second distance, the second distance is complemented using the smaller of the first distance and the third distance. The distance measurement device according to Claim 1.

6. The projected light is projected in a direction orthogonal to the axis with a predetermined axis as the rotation axis, The fact that the projection directions are different from each other means that the rotation angles at which the projected light is projected are different from each other. The distance measurement device according to any one of Claims 1 to 5.

7. A distance measurement method for measuring the distance to an object based on the time between the light-emitting timing when a light-emitting element projects pulsed light and the light-receiving timing when a light-receiving element receives the reflected light reflected by the object from the projected light. Among the measured first distance, at least one second distance measured after the first distance, and a third distance measured after the second distance, when it is estimated that the first distance and the third distance are not abnormal and the second distance is estimated to be abnormal, the second distance is complemented using the first distance or the third distance. Distance measurement method.

Images