Distance measuring device

Abstract

A distance measuring device (1) is provided with a sweeping unit (20) having a mirror (21) that reflects a transmission wave and an actuator (30) that swings and drives the mirror (21) so that the transmission wave scans a scanning range, an encoder (40) that outputs an angle signal corresponding to the rotation of the mirror (21), and a control unit (50) having a position calculation unit (51), a drive control unit (53), and an abnormality diagnosis unit (55), a position calculation unit (51) calculates the position of an object reflecting a transmitted wave of a scan, a drive control unit (53) controls the driving of an actuator (30), and an abnormality diagnosis unit (55) performs an abnormality diagnosis relating to the operating state of a sweeping unit (20) on the basis of a signal output from an encoder (40).

Description

[0001] Cross-references of related applications

[0002] This application is based on Japanese Patent Application No. 2022-187502 filed on November 24, 2022, and the contents described therein are cited herein. Technical Field

[0003] The present disclosure relates to a distance measuring device. Background Art

[0004] In the past, there is a known distance measuring device that irradiates a transmission wave and detects a reflected wave from an object to detect the distance of the object. The distance measuring device is equipped with a sweeping unit that changes the irradiation direction of the transmission wave. For example, in Patent Document 1, a swing-driven reflector is used in the sweeping unit.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-81419 Summary of the invention

[0008] In Patent Document 1, the rotation position of the reflector is controlled by using an incremental encoder for position detection. However, Patent Document 1 does not mention details of abnormality detection of the sweeping unit. The purpose of the present disclosure is to provide a distance measuring device that can appropriately detect abnormalities in the operating state of the sweeping unit.

[0009] The distance measuring device disclosed in the present invention includes a sweep unit, an encoder, and a control unit. The sweep unit includes a reflector for reflecting a transmission wave and an actuator for swinging and driving the reflector so that the transmission wave scans a scanning range. The encoder outputs an angle signal corresponding to the rotation position of the reflector.

[0010] The control unit includes a position calculation unit, a drive control unit, and an abnormality diagnosis unit. The position calculation unit calculates the position of the object that reflects the scanning transmission wave. The drive control unit controls the drive of the actuator. The abnormality diagnosis unit performs abnormality diagnosis related to the action state of the sweeping unit based on the signal output from the encoder. Thus, the abnormality of the action state of the sweeping unit can be appropriately detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above-mentioned object and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.

[0012] Figure 1 This is a block diagram showing the structure of a distance measuring device according to one embodiment.

[0013] Figure 2 This is a schematic diagram showing a distance measuring device according to an embodiment as viewed from above.

[0014] Figure 3 It is a perspective view showing a measuring unit according to one embodiment.

[0015] Figure 4 This is a schematic diagram corresponding to a cross section obtained by cutting the swing motor according to one embodiment along a plane perpendicular to the swing axis.

[0016] Figure 5 It is an exploded perspective view showing an encoder according to one embodiment.

[0017] Figure 6 It is a schematic diagram showing the operation of the reflecting mirror according to one embodiment.

[0018] Figure 7 It is a diagram showing an A-phase signal, a B-phase signal, and a Z-phase signal according to one embodiment.

[0019] Figure 8 This is a flowchart illustrating scan control according to one embodiment.

[0020] Fig. 9 This is a timing chart for explaining the scanning control according to one embodiment.

[0021] Fig.10 It is a time chart explaining the amplitude abnormality according to one embodiment.

[0022] Fig.11 This is a flowchart illustrating the amplitude abnormality diagnosis process according to one embodiment.

[0023] Fig.12 It is a time chart explaining angular velocity abnormality according to one embodiment.

[0024] Fig.13 This is a flowchart illustrating an angular velocity abnormality diagnosis process according to one embodiment.

[0025] Fig.14 1 is a timing chart illustrating an abnormality in an angle signal according to one embodiment.

[0026] Fig.15 This is a flowchart illustrating the angle signal abnormality diagnosis process according to one embodiment.

[0027] Fig.16 1 is a timing chart illustrating a reference signal abnormality according to an embodiment.

[0028] Fig.17 This is a flowchart illustrating a reference signal abnormality diagnosis process according to one embodiment.

[0029] Fig.18AIt is a time diagram showing the angle and angular velocity of the reflector when the ranging cycle is relatively long.

[0030] Fig.18B It is a time diagram showing the angle and angular velocity of the reflector when the ranging cycle is relatively short.

[0031] Fig.19A This is a timing diagram showing the angle signal when the ranging period is relatively long.

[0032] Fig.19B This is a timing diagram showing the angle signal when the ranging period is relatively short.

[0033] Fig. 20A This is a time chart showing the angle of the reflector when the ranging range is relatively wide.

[0034] Fig. 20B It is a time chart showing the angle of the reflector when the ranging range is relatively narrow.

[0035] Fig.21A This is a time chart showing the angular velocity when the ranging range is relatively wide.

[0036] Fig.21B It is a time chart showing the angular velocity when the ranging range is relatively narrow.

[0037] Fig.22A This is a time chart showing the angle signal when the ranging range is relatively wide.

[0038] Fig. 22B This is a timing diagram showing an angle signal when the ranging range is relatively narrow.

[0039] Fig.23A This is a time chart showing the angle and angular velocity of the reflector when distance measurement is performed during forward rotation.

[0040] Fig. 23B This is a time chart showing the angle and angular velocity of the reflector when distance measurement is performed during reversal. DETAILED DESCRIPTION

[0041] (One embodiment)

[0042] Hereinafter, the distance measuring device disclosed in the present invention will be described based on the accompanying drawings. Figure 1 to Figure 23B One implementation method is shown in FIG. Figure 1 and Figure 2As shown, the distance measuring device 1 is a laser radar (LiDAR) device that measures the distance to an object by irradiating light and detecting reflected light from the irradiated object. The distance measuring device 1 is mounted on a vehicle, for example, and is used to detect an object in front of the vehicle.

[0043] The distance measuring device 1 includes a measuring unit 5 and a control unit 50. The measuring unit 5 includes a light emitting unit 10, a light receiving unit 15, a scanning unit 20, and an encoder 40. Figure 2 As shown, the measuring unit 5 is housed in a housing 6. The housing 6 is, for example, a rectangular parallelepiped formed of resin, and one side thereof is open. A transparent optical window 7 for transmitting light is provided at the opening so as to cover the entire opening.

[0044] The light emitting unit 10 is accommodated on the upper side and the light receiving unit 15 is accommodated on the lower side in the housing 6. The light emitting unit 10 intermittently outputs a light beam B. The light receiving unit 15 receives reflected light R from an object irradiated with the light beam B and converts it into an electrical signal.

[0045] The sweep unit 20 includes a reflective mirror 21 that is driven to swing, and a swing motor 30 that drives the reflective mirror 21 to swing (see FIG. Figure 3 The scanning unit 20 reflects the light beam B output from the light emitting unit 10 by the reflector 21 and emits the light beam B to the outside from the optical window 7 in a direction corresponding to the rotation position of the reflector 21, thereby scanning the light beam B within a preset scanning range.

[0046] like Figure 3 As shown, the reflector 21 is a flat plate-shaped member having a reflecting surface for reflecting light, and is mounted on the swing shaft 22 so as to move integrally with the swing shaft 22. The swing shaft 22 is formed to extend in the vertical direction, and the reflector 21 is fixed to the swing shaft 22 in a manner that the swing shaft 22 is along the center line of the vertical direction of the surface on the surface opposite to the reflecting surface.

[0047] The swing motor 30 is disposed below the reflector 21 in the vertical direction, and drives the swing shaft 22 to swing the reflector 21 around the swing shaft 22. Thus, the light beam B output from the light emitting unit 10 is scanned within a predetermined scanning range.

[0048] like Figure 4As shown, the swing motor 30 includes a rotating magnet 31, a pair of fixed magnets 32, an electromagnetic coil 33 and a rotating shaft 35, and is housed in a box 38. The rotating magnet 31 is a disk-shaped magnet with an axial hole at the center. The rotating shaft 35 is fixed to the axial hole of the rotating magnet 31 by pressing in or the like. The rotating shaft 35 is supported by the box 38 in a rotatable manner. The rotating magnet 31 is arranged in a manner such that the direction in which the two poles are arranged is perpendicular to the axial direction.

[0049] A pair of fixed magnets 32 are arranged with their two poles in a direction perpendicular to the axial direction of the rotating shaft 35 (i.e. Figure 4 The box 38 is fixed in the manner of (upper and lower directions of the paper). Figure 4 In the example of FIG. 1 , the fixed magnet 32 ​​is arranged so that the upper side on the paper is the S pole and the lower side is the N pole.

[0050] The magnetic field of the rotating magnet 31 interacts with the magnetic field of the pair of fixed magnets 32 , so that the rotating magnet 31 stops at a stationary position where its magnetic poles are in opposite directions to the magnetic poles of the fixed magnets 32 . Figure 4 represents the state where the rotating magnet 31 is stationary at the stationary position. Figure 4 In the example of FIG. 1 , the upper side of the paper is the N pole and the lower side is the S pole for the rotating magnet 31. In other words, it can also be understood that the rotating magnet 31 is urged by the magnetic force of the fixed magnet 32 ​​to return to the stationary position.

[0051] The electromagnetic coil 33 is Figure 4 The electromagnetic coil 33 is wound around the outer periphery of the box 38 in the vertical direction of the paper, and generates magnetic lines of force having a perpendicular component to the magnetic lines of force generated between the rotating magnet 31 and the fixed magnet 32 ​​by energizing. The electromagnetic coil 33 is connected to an AC power source or a pulse oscillation power source.

[0052] The rotating magnet 31 is stationary when no power is supplied. Figure 4 When the electromagnetic coil 33 is energized, magnetic lines of force having a perpendicular component to the magnetic lines of force generated between the rotating magnet 31 and the fixed magnet 32 ​​are generated, and the rotating magnet 31 swings around the static position.

[0053] Swinging refers to a movement in which the rotational motion is repeated periodically between forward rotation and reverse rotation within a specified angular range of less than 360°. After the rotating magnet 31 rotates forward from the static position to a specified angle, it switches to reverse rotation, returns to the static position, and then rotates reversely from the static position to a specified angle. Then, it switches to forward rotation again, and after returning to the static position, the above-mentioned action is repeated. In the present embodiment, the angular range of forward rotation from the static position is equal to the angular range of reverse rotation, but the angular range in the forward rotation direction and the angular range in the reverse rotation direction may also be different. If the power to the electromagnetic coil 33 is cut off, the rotating magnet 31 returns to the static position and becomes stationary.

[0054] The further away from the static position, the greater the repulsive force between the rotating magnet 31 and the fixed magnet 32. Therefore, in order to maintain a certain position, the greater the rotation angle from the static position, the greater the torque required to overcome the reaction force.

[0055] In this embodiment, Figure 4 The clockwise rotation is regarded as the forward rotation, and the counterclockwise rotation is regarded as the reverse rotation. In addition, when the distance measuring device 1 is mounted on the vehicle, Figure 4 The rotation direction in the image is consistent with the rotation direction observed from the upper side in the vertical direction.

[0056] The swing shaft 22 is provided so as to move integrally with the rotating magnet 31. That is, the swing shaft 22 stops at a static position when the swing motor 30 is not energized, and swings around the static position when energized.

[0057] The reflector 21 is mounted on the swing shaft 22 in such a manner that the reflector 21 is in a reference position capable of reflecting the light beam B in the approximate center direction of the scanning range when the swing shaft 22 is in the static position. The reflector 21 swings within a predetermined angle range including the reference position as the swing shaft 22 rotates. If the power to the swing motor 30 is cut off, the swing shaft returns to the static position, so the reflector 21 returns to the reference position and remains static. That is, the reflector 21 is urged in the direction of returning to the reference position by the magnetic force of the fixed magnet 32.

[0058] like Figure 5 As shown, the encoder 40 detects the rotation angle of the reflector 21 and is a three-phase output type incremental encoder in this embodiment. The encoder 40 includes a rotating disk 41, a fixed slit 42, a light emitting element 43, a light receiving element 44, and the like.

[0059] The rotating disk 41 is formed in a disk shape. The rotating disk 41 is formed with a plurality of peripheral slits 411 formed on the outer periphery of the rotating disk 41 and an origin slit 413, wherein the plurality of peripheral slits 411 are formed on the outer periphery of the rotating disk 41, and the origin slit 413 is formed on the inner periphery side compared with the peripheral slits 411, indicating the origin position. The rotating shaft 415 of the rotating disk 41 is fixed to the swing shaft 22. Thus, the rotating disk 41 rotates integrally with the swing shaft 22 as shown by arrow E.

[0060] In order to make the output signal multi-phase, three types of slits, namely, A-phase slit 421, B-phase slit 422, and Z-phase slit 423, are formed in the fixed slit 42. The A-phase slit 421 and the B-phase slit 422 are formed at positions opposite to the outer peripheral slit 411 of the rotating disk 41 so that the phase difference between the output signal of the A phase and the output signal of the B phase becomes 90°. The Z-phase slit 423 is formed at a position opposite to the origin slit 413.

[0061] The light emitting element 43 is, for example, a light emitting diode, and irradiates light toward the rotating disk 41. The light emitting element 43 and the light receiving element 44 are arranged in a manner opposite to each other across the rotating disk 41 and the fixed slit 42. The light receiving element 44 is, for example, a phototransistor, and receives light that has passed through the slits of the rotating disk 41 and the fixed slit 42, and outputs pulse signals of the A phase, the B phase, and the Z phase. The encoder 40 detects the edges of the A phase signal and the B phase signal, and accumulates the count value. In addition, when the rising edge of the Z phase is detected, the count value is reset.

[0062] Figure 6 2 is a schematic diagram showing a cross section of the reflector 21 cut along a plane perpendicular to the swing axis 22. Figure 6 In the figure, the state of the reflection mirror 21 being in the reference position is shown in the center of the paper, the state of moving from the left to the right of the paper corresponds to the forward rotation, and the state of moving from the right to the left of the paper corresponds to the reverse rotation.

[0063] The encoder 40 is provided on the swing motor 30 in such a manner that the Z-phase signal is output when the reflector 21 is in the reference position. That is, the rotating shaft 415 of the rotating disk 41 is fixed to the swing shaft 22 in such a manner that the Z-phase signal is output when the swing shaft 22 is in the static position. In the reference position, if the angle between the reflector 21 and the light beam B output from the light emitting unit 10 is set to X° (45° in this embodiment), the Z-phase signal is output at X°.

[0064] like Figure 7As shown, when the reflector 21 rotates forward, the B-phase signal is outputted with a delay of 90° relative to the A-phase signal. When the reflector 21 rotates reversely, the A-phase signal is outputted with a delay of 90° relative to the B-phase signal. Thus, the encoder 40 can detect the rotation angle of the reflector 21 relative to the reference position, that is, the reflector angle θ, based on the waveforms of the A-phase signal and the B-phase signal after the Z-phase signal is detected.

[0065] like Figure 1 As shown, the control unit 50 is mainly composed of a microcomputer, etc., and has a CPU, ROM, RAM, I / O, and a bus connecting these structures, all of which are not shown. Each process in the control unit 50 can be a software process performed by the CPU executing a program pre-stored in a physical memory device such as a ROM (i.e., a readable non-temporary tangible recording medium), or a hardware process performed by a dedicated electronic circuit.

[0066] As functional blocks, the control unit 50 has a position calculation unit 51, a drive control unit 53, an abnormality diagnosis unit 55, etc. The position calculation unit 51 calculates the distance to the object that has reflected the light beam B. Specifically, the position calculation unit 51 determines the timing (time point) of receiving the reflected light based on the waveform of the electrical signal output from the light receiving unit 15, and calculates the distance to the object based on the difference from the timing (time point) of outputting the light beam. In addition, the position calculation unit 51 can calculate position information such as the direction at which the object that has reflected the light beam is located. The drive control unit 53 controls the drive of the swing motor 30 that drives the reflector 21. The abnormality diagnosis unit 55 performs abnormality judgment on the sweeping unit 20. When an abnormality in the sweeping unit 20 is detected, for example, the distance measurement is terminated.

[0067] The drive control unit 53 performs alignment control before scanning control. In the alignment control, the swing motor 30 is driven at a specified voltage value through open-loop control without using the detection value of the encoder 40. The origin is searched through the alignment control, and the position where the Z-phase signal is detected is set to the reflector angle θ=0°. In addition, the angle difference from the reflector position when no power is applied is stored as a correction value. In addition, since the swing motor 30 is forced in the direction of returning to the reference position, the swing range during the alignment control does not need to swing with the same swing amplitude as during the scanning control, and can be a relatively narrow range.

[0068] After the positioning control, the drive control unit 53 performs scanning control in which the swing motor 30 is driven to swing the reflection mirror 21 from the reference position within a predetermined angle range to scan the light beam. The scanning control is feedback control based on the detection value of the encoder 40 .

[0069] based on Figure 8The scanning control of this embodiment is described with reference to the flowchart of FIG. This process is executed by the control unit 50 at a predetermined cycle after the positioning control. Hereinafter, the "steps" such as step S101 are omitted and simply written as the symbol "S".

[0070] In S101, the control unit 50 obtains the current mirror angle θ and angular velocity ω based on the detection values ​​of the encoder 40. In S102, the drive control unit 53 calculates the target mirror angle θ based on the elapsed time from the start of the scanning control. * In this embodiment, the target reflector angle θ is set according to time. * , so that the reflecting mirror 21 swings at a certain period.

[0071] In S103, the drive control unit 53 sets the target mirror angle θ according to the target mirror angle θ. * The difference Δθ from the current reflector angle θ is used to calculate the target angular velocity ω * In S104, the drive control unit 53 adjusts the angular velocity ω according to the target angular velocity ω. * The difference Δω from the current angular velocity ω is used to calculate the target duty ratio D in PWM control. * In S105, the drive control unit 53 sets the target duty ratio D * The swing motor 30 is energized.

[0072] based on Fig. 9 The scanning control of this embodiment is explained with reference to the timing chart of FIG. Fig. 9 , with the common time axis as the horizontal axis, the mirror angle θ, angular velocity ω, motor current, A-phase signal, B-phase signal, and Z-phase signal are shown from the upper stage.

[0073] The reflector angle θ is 0° when the reflector 21 is in the reference position, and is calculated by detecting the edges of the A-phase signal and the B-phase signal and accumulating the count value. In addition, the count value is reset by detecting the edge of the Z-phase signal, so that the detection deviation and the like can be reset. The angular velocity ω is calculated based on the time differential of the reflector angle θ. In addition, the period from the detection of the Z-phase pulse during reversal to the detection of the Z-phase pulse during the next reversal is set as one cycle of the scanning control. In addition, one cycle of the scanning control is appropriately set as a "distance measurement period".

[0074] In the scanning control, the reflector 21 is swung by alternately performing a forward rotation period, in which the reflector 21 is driven from one side of the reference position to the other side at a constant speed, and a reverse rotation period, in which the reflector 21 returns from the other side to one side, and the reverse rotation period is relatively shorter than the forward rotation period. In addition, when the reflector 21 rotates at a constant speed during the forward rotation period, distance measurement based on LiDAR is performed.

[0075] If the angular velocity ω or the detection value of the encoder 40 is abnormal, the accuracy of distance measurement to the object decreases or normal distance measurement cannot be performed. Therefore, in this embodiment, the abnormality diagnosis unit 55 performs abnormality determination based on the signal output from the encoder 40 .

[0076] based on Fig.10 and Fig.11 The amplitude abnormality diagnosis according to the present embodiment will be described. Fig.10 This is a simplified time chart, and the baseline and other information are omitted as appropriate. In addition, the dynamics during abnormal conditions are indicated by a circle with a single dot-dashed line. Fig.12 The same applies to the time charts of various abnormality diagnoses described later.

[0077] like Fig.10 As shown in the figure, when there is no amplitude abnormality, the direction of rotation is reversed when the mirror angle θ is within the normal range. On the other hand, when an amplitude abnormality occurs, as indicated by the circular mark with a single dotted line, the direction of rotation is reversed before reaching the normal range, and the amplitude of the mirror angle θ becomes narrower than normal. The amplitude of the mirror angle θ corresponds to the field of view of the LiDAR. When the amplitude of the mirror angle θ is small, it can be said that the field of view in the scanning control is narrowed. If the LiDAR field of view is missing, obstacles may be missed, so it is judged as abnormal.

[0078] based on Fig.11 The amplitude abnormality diagnosis process is explained with reference to the flowchart of. In S201, the abnormality diagnosis unit 55 determines whether the ranging control is stable. For example, at the start of the action, when the origin position and the correction value are reset, since the target angle cannot be controlled, it is set not to perform abnormality diagnosis. Here, after the origin is explored and the correction process based on the correction value can be implemented, a positive judgment is made. When it is determined that the ranging control is unstable (S201: No), the processing after S202 is skipped.

[0079] In S202, the abnormality diagnosis unit 55 determines whether one cycle of the scanning control has been completed. If it is determined that one cycle has not been completed (S202: No), the determination process is repeated. If it is determined that one cycle has been completed (S202: Yes), the process proceeds to S203 to obtain the maximum value θmax and the minimum value θmin of the mirror angle θ in one cycle.

[0080] In S204, the abnormality diagnosis unit 55 determines whether at least one of the maximum value θmax and the minimum value θmin is outside the normal range. If it is determined that the maximum value θmax and the minimum value θmin are within the normal range (S204: No), the processing after S205 is skipped. If it is determined that at least one of the maximum value θmax and the minimum value θmin is outside the normal range (S204: Yes), the process moves to S205.

[0081] In S205, the abnormality diagnosis unit 55 determines whether the state that at least one of the maximum value θmax and the minimum value θmin is outside the normal range is continuous for n cycles. n can be set to any natural number (for example, n=2). The same is true in the embodiments described below. In the case where it is determined that at least one of the maximum value θmax and the minimum value θmin is outside the normal range for less than n consecutive cycles (S205: No), the processing of S206 is skipped. In the case where it is determined that at least one of the maximum value θmax and the minimum value θmin is outside the normal range for n consecutive cycles (S205: Yes), the process is transferred to S206 and detected as an amplitude abnormality.

[0082] based on Fig.12 and Fig.13 The angular velocity abnormality diagnosis according to the present embodiment will be described. Fig.12 In the figure, the common time axis is used as the horizontal axis, and the mirror angle θ, the angular velocity ω, and the angular velocity abnormality count value Cω are shown from the upper stage.

[0083] like Fig.12 As shown in the figure, during forward rotation, in order to perform LiDAR measurement, feedback control is performed to make the angular velocity ω constant. In the event of an angular velocity abnormality in which the angular velocity ω during forward rotation is outside the normal range, the angle accuracy of the LiDAR decreases. The upper limit of the normal range is determined by the CPU's computing power, and the lower limit is determined by the LiDAR measurement cycle. If the angular velocity ω is outside the normal range, a lack of field of view and a cycle delay due to exceeding the processing power will occur, and correct position detection will no longer be possible, so it is judged as an abnormality.

[0084] based on Fig.13 The angular velocity abnormality diagnosis process is explained with reference to the flowchart of. In S301, the abnormality diagnosis unit 55 determines whether the distance measurement control is stable and is moving in the forward direction. In the case where it is determined that the distance measurement control is unstable or is moving in the reverse direction (S301: No), the processing after S302 is skipped. In the case where it is determined that the distance measurement control is stable and is moving in the forward direction (S301: Yes), angular velocity abnormality diagnosis is performed. A positive judgment is made in S301 and the process is transferred to S302 to obtain the current angular velocity ω.

[0085] In S303, the abnormality diagnosis unit 55 determines whether the angular velocity ω is outside the normal range. If it is determined that the angular velocity ω is within the normal range (S303: No), the processing after S304 is skipped. If it is determined that the angular velocity ω is outside the normal range (S303: Yes), the process proceeds to S304 and the angular velocity abnormality count value Cω is incremented. In addition, the angular velocity abnormality count value Cω is reset at the end of one cycle.

[0086] In S305, the abnormality diagnosis unit 55 determines whether the angular velocity abnormality count value Cω is greater than the abnormality determination threshold value THω. If it is determined that the angular velocity abnormality count value Cω is less than the abnormality determination threshold value THω (S305: No), the processing after S306 is skipped. If it is determined that the angular velocity abnormality count value Cω is greater than the abnormality determination threshold value THω (S305: Yes), the process proceeds to S306.

[0087] In S306, the abnormality diagnosis unit 55 determines whether the state in which the angular velocity abnormality count value Cω is greater than the abnormality determination threshold value THω is continuous for n cycles. In the case where it is determined that the state in which the angular velocity abnormality count value Cω is greater than the abnormality determination threshold value THω is less than n cycles (S306: No), the processing of S307 is skipped. In the case in which it is determined that the state in which the angular velocity abnormality count value Cω is greater than the abnormality determination threshold value THω is continuous for n cycles (S306: Yes), the process proceeds to S307 and detects an angular velocity abnormality. In addition, the number of cycles for abnormality detection may be the same value or different values ​​depending on the abnormality detected.

[0088] based on Fig.14 and Fig.15 To illustrate the angle signal abnormality diagnosis. Fig.14 The horizontal axis is the common time axis, and the reflector angle, A-phase signal, B-phase signal, and pulse interval are shown from the top. Fig.14 In the above, the A-phase signal and the B-phase signal are collectively referred to as "AB phase". Fig.19A , Fig.19B , Fig.22A and Fig. 22B The same is true for the pulse interval. The pulse interval is the interval between edges, which is the time from when an edge is detected to when the next edge is detected. If an edge is detected, the time is reset and counting starts again.

[0089] like Fig.14As shown in the figure, as described above, in the forward rotation, in order to perform LiDAR measurement, control is performed so that the angular velocity ω becomes constant. Therefore, in the forward rotation, if it is normal, the pulse detection interval of the A phase signal and the B phase signal as the angle signal is approximately constant. On the other hand, in the case where the pulse increases due to pulse deficiency, noise, etc., the pulse detection interval is destroyed. If the pulse interval is destroyed, since the calculated angle is different from the actual reflector position, it is no longer possible to perform correct position detection, so it is judged as abnormal.

[0090] based on Fig.15 The flowchart of step S401 is used to illustrate the angle signal abnormality diagnosis process. Fig.13 The processing of S301 in is the same. If a positive determination is made in S401, the angle signal abnormality diagnosis is performed. In S402, the abnormality diagnosis unit 55 detects the rising edge and the falling edge of the A-phase signal and the B-phase signal, and obtains the pulse interval based on the time interval between the edges.

[0091] In S403, the abnormality diagnosis unit 55 determines whether the pulse interval is outside the normal range. If it is determined that the pulse interval is within the normal range (S403: No), the process of S404 is skipped. If it is determined that the pulse interval is outside the normal range (S403: Yes), the process proceeds to S404 and detects that the angle signal is abnormal.

[0092] based on Fig.16 and Fig.17 To illustrate the reference signal abnormality diagnosis. Fig.16 The horizontal axis is the common time axis, and the mirror angle θ, Z phase signal, and edge detection times are shown from the top. Fig.16 As shown in the figure, when the distance measurement control is performed, since the origin is crossed twice in one cycle, the rising edge and falling edge of the Z phase signal are detected 4 times in total in normal state. On the other hand, if the pulse increases due to pulse deficiency, noise, etc., the number of edge detections becomes more than 4. In the case where the Z phase signal is abnormal, the correct position detection is no longer possible due to the reference position deviation, so it is judged as abnormal.

[0093] based on Fig.17 The flowchart of the reference signal abnormality diagnosis process is used to illustrate the process of the reference signal abnormality diagnosis process. Fig.11 The processing of S201 and S202 in is the same. In addition, in order to facilitate the edge detection of the Z phase signal during one cycle, for example, Fig.16 As shown in the figure, the period from the start of reverse rotation to the end of forward rotation is set as 1 cycle. Fig. 9 Different.

[0094] In S503, the abnormality diagnosis unit 55 obtains the number of pulse edges of the Z-phase signal in one cycle. In S504, the abnormality diagnosis unit 55 determines whether the number of pulse edges of the Z-phase signal is outside the normal range. When it is determined that the number of pulse edges of the Z-phase signal is within the normal range (S504: No), that is, when the number of pulse edges of the Z-phase signal is 4, the processing after S505 is skipped. When it is determined that the number of pulse edges of the Z-phase signal is outside the normal range (S504: Yes), that is, when the number of pulse edges of the Z-phase signal is other than 4, the process is transferred to S505.

[0095] In S505, the abnormality diagnosis unit 55 determines whether the state where the number of pulse edges of the Z-phase signal is outside the normal range is continuous for n cycles. If it is determined that the state where the number of pulse edges of the Z-phase signal is outside the normal range is less than n consecutive cycles (S505: No), the processing of S506 is skipped. If it is determined that the state where the number of pulse edges of the Z-phase signal is outside the normal range is continuous for n cycles (S506: Yes), the process moves to S506 and detects that the reference signal is abnormal.

[0096] Here, the operation method of the distance measuring device 1 may be changed according to the adapted mobility. In the present embodiment, by changing the normal range, it is possible to perform abnormality determination according to the adapted mobility.

[0097] Fig.18A Indicates that the ranging cycle is relatively long. Fig.18B This indicates a case where the ranging cycle is relatively short. When the ranging cycle is short, the angular velocity ω becomes larger than when the ranging cycle is long. In such a case, abnormality determination can be performed by changing the normal range.

[0098] Fig.19A Indicates that the ranging cycle is relatively long. Fig.19B Indicates the case where the ranging cycle is relatively short. When the ranging cycle is short, the pulse intervals of the A-phase signal and the B-phase signal become smaller than when the ranging cycle is long. In such a case, abnormality determination can be performed by changing the normal range.

[0099] Fig. 20A Indicates that the ranging range is relatively wide. Fig. 20B This indicates a case where the distance measurement range is relatively narrow. When the distance measurement range is narrow, the amplitude of the reflector angle θ becomes smaller than when the distance measurement range is wide. In such a case, abnormality determination can be performed by changing the normal range.

[0100] Fig.21A This is the case where the ranging range is relatively wide. Fig.21BThis is the case where the distance measurement range is relatively narrow, and the distance measurement cycles are equal. When the distance measurement cycles are equal and the distance measurement range is narrow, the angular velocity ω becomes smaller. In such a case, abnormality determination can be performed by changing the normal range.

[0101] Fig.22A This is the case where the ranging range is relatively wide. Fig. 22B This is the case where the ranging range is relatively narrow, and the ranging cycles are assumed to be equal. Fig.21A and Fig.21B As described in , when the ranging period is equal and the ranging range is narrow, the angular velocity ω becomes smaller, so the pulse interval of the A-phase signal and the B-phase signal becomes larger. In such a case, abnormality determination can be performed by changing the normal range.

[0102] Fig.23A Indicates the distance measurement during forward rotation. Fig. 23B Indicates the case where the distance measurement is performed during the reversal. In the case where the distance measurement is performed during the reversal, it is assumed that the abnormality diagnosis is performed during the reversal, and the angular velocity ω during the diagnosis is a negative value. In this case, the abnormality determination can be performed by changing the normal range. In addition, if the period and amplitude are the same, just change Fig.23A The sign should be within the normal range.

[0103] As described above, the distance measuring device 1 of this embodiment includes a sweeping unit 20, an encoder 40, and a control unit 50. The sweeping unit 20 includes a reflector 21 and a swing motor 30. The reflector 21 reflects the light beam as the transmission wave output from the light emitting unit 10. The swing motor 30 swings the reflector 21 so that the light beam scans the scanning range. The encoder 40 outputs an angle signal corresponding to the rotation of the reflector 21.

[0104] The control unit 50 includes a position calculation unit 51, a drive control unit 53, and an abnormality diagnosis unit 55. The position calculation unit 51 calculates the position of the object reflecting the scanning light beam. The drive control unit 53 controls the drive of the swing motor 30. The abnormality diagnosis unit 55 performs abnormality diagnosis related to the operation state of the sweep unit 20 based on the signal output from the encoder 40. Thus, the operation abnormality of the sweep unit 20 can be appropriately detected based on the signal from the encoder 40.

[0105] The abnormality diagnosis unit 55 determines that the swing amplitude is abnormal when at least one of the maximum value and the minimum value of the mirror angle θ calculated based on the angle signal is outside the normal range during one cycle of the scanning control. Thus, the amplitude abnormality can be appropriately detected, for example, the lack of the distance measurement range can be detected based on the insufficient amplitude caused by the failure of the swing motor 30, the increase of the load, etc.

[0106] The abnormality diagnosis unit 55 determines that the angular velocity ω of the reflector 21 calculated based on the angle signal is outside the normal range within the range where the distance measurement can be implemented. In this embodiment, the abnormality diagnosis related to the angular velocity ω is mainly implemented in the forward rotation corresponding to the "range where the distance measurement can be implemented", but for example, the range of the rotation direction other than the specified range before and after the reversal can be set as the "range where the distance measurement can be implemented", and the abnormality diagnosis can be implemented in this range. In addition, regarding Fig. 23B , when reversing, it corresponds to the "distance measurement feasible range". Similarly, for example, the range of the rotation direction other than the specified range before and after the reversal can be set as the "distance measurement feasible range". The same is true for abnormal diagnosis of angle signals. In this way, it is possible to detect the decrease in distance measurement accuracy caused by abnormal angular velocity.

[0107] The encoder 40 outputs a plurality of pulse signals, namely, an A-phase signal and a B-phase signal as an angle signal. When the edge interval of the A-phase signal and the B-phase signal within the range where the distance measurement can be implemented is outside the normal range, the abnormality diagnosis unit 55 determines that the output of the angle signal is abnormal. Thus, according to the output abnormality of the encoder 40, it is possible to detect that the calculated reflector angle θ is different from the actual one.

[0108] The encoder 40 outputs a Z-phase signal as a pulse signal as a reference signal in addition to the angle signal. The abnormality diagnosis unit 55 determines that the reference signal is abnormal when the number of edge detections of the reference signal is outside the normal range during one cycle of the scanning control. Thus, it is possible to detect a situation where the reference position of the reflector 21 cannot be identified.

[0109] In addition, if the A-phase signal and the B-phase signal as the angle signal of the encoder 40 and the Z-phase signal as the reference signal are abnormal, the swing of the reflector 21 can no longer be properly controlled, so the diagnosis of the abnormality of the A-phase signal, the B-phase signal and the Z-phase signal is included in the concept of "abnormality diagnosis related to the operation state". In addition, in the embodiment, the swing motor 30 corresponds to the "actuator".

[0110] (Other embodiments)

[0111] In the above embodiment, the reflector is urged to return to the reference position by magnetic force. In other embodiments, the reflector may also be urged to return to the reference position by elastic components such as springs. In addition, the structure of the sweeping unit and the details of the distance measurement control may also be different from the above embodiment.

[0112] In the above embodiment, the encoder outputs two phase signals, namely, the A phase signal and the B phase signal, as the angle signal. In other embodiments, the encoder may output signals of three or more phases as the angle signal. In addition, the reference signal may be omitted.

[0113] The control unit and method described in the present disclosure may also be implemented by a special-purpose computer as follows: the special-purpose computer is provided by constituting a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and method described in the present disclosure may also be implemented by a special-purpose computer as follows: the special-purpose computer is provided by constituting a processor with one or more special-purpose hardware logic circuits. Alternatively, the control unit and method described in the present disclosure may also be implemented by one or more special-purpose computers as follows: the one or more special-purpose computers are constituted by combining a processor and a memory programmed to execute one or more functions and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored in a computer-readable non-transient tangible recording medium as an instruction executed by a computer. As described above, the present disclosure is not limited to the above-mentioned embodiments at all, but can be implemented in various forms without departing from its main purpose.

[0114] The present disclosure is described based on the embodiments. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms that only include one element, include the elements above or the elements below them, also fall within the scope and thought of the present disclosure.

Claims

1. A distance measuring device, have: The sweeping unit (20) comprises a reflector (21) and an actuator (30), wherein the reflector reflects the transmission wave, and the actuator drives the reflector to swing so that the transmission wave scans the scanning range; An encoder (40) outputs an angle signal corresponding to the rotation of the reflector; as well as The control unit (50) comprises a position calculation unit (51), a drive control unit (53) and an abnormality diagnosis unit (55), wherein the position calculation unit calculates the position of an object that reflects the scanning transmission wave, the drive control unit controls the drive of the actuator, and the abnormality diagnosis unit performs abnormality diagnosis related to the operation state of the sweeping unit based on the signal output from the encoder.

2. The distance measuring device according to claim 1, The abnormality diagnosis unit determines that the oscillation amplitude is abnormal when at least one of the maximum value and the minimum value of the mirror angle calculated based on the angle signal in one cycle of scanning control is outside a normal range.

3. The distance measuring device according to claim 1, The abnormality diagnosis unit determines that the angular velocity is abnormal when the angular velocity of the reflector calculated based on the angle signal is outside a normal range in the distance measurement executable range.

4. The distance measuring device according to claim 1, The encoder outputs a plurality of pulse signals as the angle signal, The abnormality diagnosis unit determines that the output of the angle signal is abnormal when the edge interval of the pulse signal in the distance measurement practicable range is outside a normal range.

5. The distance measuring device according to claim 1, In addition to outputting the angle signal, the encoder also outputs a pulse signal as a reference signal. The abnormality diagnosis unit determines that the reference signal is abnormal when the number of edge detections of the reference signal in one cycle of scanning control is outside a normal range.

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