Optical distance measuring device

Abstract

An optical distance measuring device (10, 11) includes: a light emitting section (21); a mirror (26) that reflects illumination light (IL) emitted from the light emitting section; a scanner (28) that reciprocally moves the mirror to scan a predetermined scanning range with the illumination light; a light receiving section (30) that detects reflected light (RL) that is reflected by an object existing in the scanning range and returns from the object; a distance calculating section (40) that calculates a distance to the object using a time from when the illumination light is emitted from the light emitting section to when the reflected light from the object is detected by the light receiving section during a forward movement operation of the mirror; a timing signal generating section (60) that generates a timing signal based on a signal from outside; and a control section (50) that controls emission of the light emitting section and operation of the scanner (50, 51), and that synchronizes the operation of the scanner with the timing signal by adjusting a time of one cycle of the scanner while maintaining a distance measuring period of the forward movement operation constant.

Description

[0001] Cross-references to related applications

[0002] This application claims priority based on two Japanese applications filed on November 19, 2020 (Japan Patent Application No. 2020-192593) and October 8, 2021 (Japan Patent Application No. 2021-166131), all of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to optical ranging devices. Background Technology

[0004] Patent document 1 (U.S. Patent Application Publication No. 2019 / 0011544) discloses multiple vehicles equipped with a LiDAR device as an optical ranging device. The LiDAR device includes an actuator that rotates the LiDAR device about its axis to adjust the direction of light projection, a communication interface for receiving timing information from an external system, and a controller that adjusts the direction of light projection by the actuator according to the received timing information, so that the light from each vehicle does not interfere with each other. Summary of the Invention

[0005] The timing adjustment of the LiDAR device described in Patent Document 1 is for the timing adjustment between LiDAR devices in other vehicles, and does not consider the timing adjustment between the LiDAR device and other devices in the same vehicle. Furthermore, in the LiDAR device described in Patent Document 1, timing adjustments during ranging can sometimes affect the ranging results.

[0006] According to one aspect of this disclosure, an optical ranging device is provided. This optical ranging device includes: a light-emitting unit; a reflector that reflects illumination light emitted by the light-emitting unit; a scanner that scans a predetermined scanning range using the illumination light by reciprocating the reflector; a light receiving unit that detects reflected light from the illumination light reflected back to an object present in the scanning range; a distance calculation unit that calculates the distance to the object using the time from when the illumination light is emitted by the light-emitting unit to when the light receiving unit detects the reflected light from the object during the reciprocating motion of the reflector; and a control unit that controls the light emission of the light-emitting unit and the operation of the scanner, synchronizing the operation of the scanner with a timing signal by adjusting the cycle time of one cycle of the scanner while keeping the reciprocating motion of the reflector constant. According to this method, since the control unit synchronizes the operation of the scanner with the timing signal by adjusting the cycle time of one cycle of the scanner while keeping the distance measurement period of the reciprocating motion of the reflector constant, this synchronization process can be prevented from affecting the distance measurement to the object. Attached Figure Description

[0007] The above-mentioned and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings are as follows:

[0008] Figure 1 It is an explanatory diagram showing vehicles traveling on a road;

[0009] Figure 2 This is an explanatory diagram showing an optical rangefinder;

[0010] Figure 3 This is an explanatory diagram showing the process before the pulsed laser emitted from the light-emitting device reaches the light-receiving unit;

[0011] Figure 4 This is an explanatory diagram showing the modular structure of an optical rangefinder;

[0012] Figure 5 It is a graph showing the relationship between time and the angle of the reflector in an optical rangefinder;

[0013] Figure 6 This is an explanatory diagram showing the module configuration of the optical ranging device according to the second embodiment;

[0014] Figure 7 It is a graph showing the relationship between the time in the optical rangefinder and the angle and count value of the reflector;

[0015] Figure 8 This is a flowchart of the timing adjustment control performed by the control unit in the third embodiment;

[0016] Figure 9 This is a timing diagram when the adjustment time is above the threshold;

[0017] Figure 10 This is a timing diagram when the adjustment time is less than the threshold;

[0018] Figure 11 This is a timing diagram showing the relationship between time and angle command values ​​in the optical ranging device of the fourth embodiment;

[0019] Figure 12 This is an explanatory diagram showing the module configuration of the optical ranging device according to the fifth embodiment. Detailed Implementation

[0020] • First implementation method:

[0021] like Figure 1As shown, a vehicle 100 traveling on road 200 is equipped with an optical rangefinder 10 and a millimeter-wave radar 90. The optical rangefinder 10 illuminates a scanning range MR in front of the vehicle 100 with an illumination light IL. If there is an object in the scanning range MR, the reflected light RL from the object is received. The optical rangefinder 10 calculates the distance L to the object based on the time T from emitting the illumination light IL to receiving the reflected light RL. If c is set as the speed of light, the distance L is calculated using ct / 2. Figure 1 In the example shown, vehicle 101 is traveling in the opposite lane of road 200, which is sandwiched between center lines 201. Vehicles 102 and 103 are parked on either side of road 205, which intersects road 200, which is sandwiched between center lines 206. Vehicles 101 and 102 are present in the scanning range MR, and the optical rangefinder 10 receives the reflected light RL from vehicles 101 and 102. The millimeter-wave radar 90 of vehicle 100, like the optical rangefinder 10, uses millimeter waves to scan the front of vehicle 100 and senses the targets within its scanning range. At this time, if the scanning timing of the millimeter-wave radar 90 is synchronized with the scanning timing of the illumination light IL of the optical rangefinder 10, the direction of vehicles 101 and 102 and the distance to vehicles 101 and 102 can be calculated with higher accuracy.

[0022] like Figure 2 As shown, the optical ranging device 10 includes a light-emitting device 20, a light-receiving unit 30, and a distance calculation unit 40. The light-emitting device 20 emits an illumination light IL, which scans the measurement range MR along the scanning direction SD. The illumination light IL is formed into a rectangular shape with its length direction orthogonal to the scanning direction SD. The light-receiving unit 30 receives reflected light RL from the measurement range MR, which includes the area corresponding to the illumination of the illumination light IL, via a light-receiving lens 31, and outputs a signal corresponding to the light receiving state of the reflected light RL. The distance calculation unit 40 uses the signal output from the light-receiving unit 30 to measure the distance to a target existing within the measurement range MR.

[0023] use Figure 3The following description will cover the period before the pulsed laser emitted from the light-emitting device 20 reaches the light-receiving unit 30. The light-emitting device 20 includes a light-emitting unit 21, a collimating lens 22, a reflecting mirror 26, and a scanner 28. The pulsed laser emitted from the light-emitting unit 21 is transformed into an elongated rectangular illumination light IL by the collimating lens 22. Alternatively, a slit can be used instead of the collimating lens 22 to form the elongated rectangular illumination light IL. The rectangular illumination light IL is reflected at the reflecting mirror 26 and illuminates the exterior of the optical rangefinder 10. At this time, the scanner 28 scans the illumination light IL along the SD direction within the measurement range MR by reciprocating the reflecting mirror 26. If a target is present in the scanning range MR, the illumination light IL diffusely reflects off the surface of the target, and a portion of it returns to the optical rangefinder 10. The reflected light RL returning from the target to the optical rangefinder 10 is collected by the light-receiving lens 31 and illuminates the light-receiving unit 30, where it is detected. The distance L to the target is calculated based on the time T from when the pulsed laser emitted from the light-emitting device 20 to when the reflected light RL is detected by the light receiving unit 30.

[0024] Figure 4 This is an explanatory diagram showing the modular configuration of the optical ranging device 10. The optical ranging device 10 includes a light-emitting unit 21, a scanner 28, a light-receiving unit 30, a distance calculation unit 40, a control unit 50, and a timing signal generation unit 60. Externally, the optical ranging device 10 includes a data processing unit 72 and a Global Positioning Satellite System (GNSS) receiver 74. The light-emitting unit 21, scanner 28, light-receiving unit 30, and distance calculation unit 40 have already been described; therefore, the control unit 50, timing signal generation unit 60, data processing unit 72, and GNSS receiver 74 will be described.

[0025] The Global Positioning System (GPS) receiver 74 receives radio waves from multiple satellites and calculates its current position and time t. As a Global Positioning System, it can utilize the United States' GPS, Japan's Quasi-Zenith Satellite System (QZSS), the Russian Federation's GLONASS, and the European Union's Galileo.

[0026] The timing signal generation unit 60 receives time t as a signal from the Global Positioning Satellite System receiver 74 and generates a timing signal ts at a preset period. The timing signal generation unit 60 also receives a synchronization signal ts1 transmitted at time t0 in each period from the control unit 50 (described later). Each period includes two actions: forward motion and return motion, with time t0 being the timing point for switching from return motion to forward motion. The timing signal generation unit 60 generates an adjustment time d that offsets the synchronization signal ts1 in a manner that makes the timing signal ts consistent with the synchronization signal ts1, and sends this d to the adjustment time calculation unit 52 (described later).

[0027] The control unit 50 includes an adjustment time calculation unit 52 and an angle command value calculation unit 53. The adjustment time calculation unit 52 obtains the adjustment time d from the timing signal generation unit 60 as adjustment time information, and adds the adjustment time d to the reference length D of the return motion to generate a new return motion length D+d. The reference length D of the return motion is pre-stored in the adjustment time calculation unit 52. How the timing signal generation unit 60 obtains the adjustment time d will be described later. The angle command value calculation unit 53 instructs the scanner 28 on the angle command a(t) of the reflector 26 corresponding to time t.

[0028] The data processing unit 72 uses the ranging data output from the distance calculation unit 40 and the ranging data from the millimeter-wave radar 90 to perform processing, and calculates the azimuth and distance to the target more accurately.

[0029] Figure 5 This is a graph showing the relationship between time t and angle θ(t) of the reflector 26 in the optical ranging device 10. The control unit 50... Figure 5 During the forward motion from t0 to t1, as shown, the angle command value calculation unit 53 generates an angle command a(t) for the mirror 26 corresponding to time t by increasing the angle θ(t) of the mirror 26 from θs to θe, and sends the angle command a(t) to the scanner 28. The angle command value calculation unit 53 can also obtain the angle θ(t) of the mirror from the scanner 28 and perform feedback control on the angle command a(t) through PID control or the like. During the forward motion from time t0 to t1, the optical ranging device 10 measures the distance to the target. Furthermore, during the return motion from time t1 to t2, the angle command value calculation unit 53 generates an angle command a(t) for the mirror 26 corresponding to time t by decreasing the angle θ(t) of the mirror 26 from θe to θs, and sends the angle command a(t) to the scanner 28. As described above, the reference length of the return motion from time t1 to t2 is D. The angle command value calculation unit 53 can also provide feedback control for the angle command a(t). Furthermore, the optical rangefinder 10 does not measure the distance to the target during its return motion from time t1 to t2. However, the optical rangefinder 10 can measure the distance to the target during its return motion from time t1 to t2. Moreover, the time of one cycle from time t0 to t2 (t0 of the next cycle) is approximately 100 ms.

[0030] If the adjustment time calculation unit 52 receives the adjustment time d from the synchronization timing generation unit, it calculates the new return motion time D+d and sends it to the angle command value calculation unit 53. The angle command value calculation unit 53 sets the duration of the return motion in the next cycle, i.e., the length from time t3 to t5, as time D+d, and calculates the new angle command a(t) of the reflector 26 in such a way that the angle of the reflector 26 decreases to θe at time t3 and to θs at time t5, and instructs it to the scanner 28. Thus, in the next cycle, the synchronization signal ts1 can be made consistent with the timing signal ts.

[0031] According to the first embodiment, instead of changing the period during which the distance between the object and the reflector 26 is measured (i.e., the forward travel time of the reflector 26), the period during which the distance between the object and the reflector 26 is not measured (i.e., the return travel time D of the reflector 26) is adjusted. This adjusts the time of one cycle, synchronizing the operation of the scanner 28 with the timing signal ts. As a result, the timing adjustment processing performed by the control unit 50 does not affect the distance measurement results.

[0032] In the first embodiment, the period of switching from forward motion to return motion or from return motion to forward motion is zero. The time of one cycle is adjusted by adjusting the return motion time D of the reflector 26 during the period when the distance between the object and the target is not measured. However, the time of one cycle can also be adjusted by setting the length of the period of switching from forward motion to return motion or from return motion to forward motion as the adjustment time d.

[0033] • Second implementation method:

[0034] Figure 6 This is an explanatory diagram showing the modular configuration of the optical rangefinder 11 according to the second embodiment. The optical rangefinder 11 differs from the optical rangefinder 10 of the first embodiment in that the control unit 51 includes a counter 56. Furthermore, the adjustment time calculation unit 54 and the angle command value calculation unit 55 of the optical rangefinder 11 differ slightly in operation from the adjustment time calculation unit 52 and the angle command value calculation unit 53 of the optical rangefinder 10 of the first embodiment. In the second embodiment, a pulse signal generation unit 61 is provided outside the optical rangefinder 11, replacing the timing signal generation unit 60. In the first embodiment, the control unit 50 of the optical rangefinder 10 obtains the adjustment time d from the outside to adjust the operation timing of the scanner 28; however, in the second embodiment, the control unit 51 of the optical rangefinder 11 receives a pulse signal P2 from the outside and synchronizes the operation timing of the scanner 28 with the pulse signal P2 inside the optical rangefinder 11. The differences will be explained below.

[0035] The pulse signal generation unit 61 receives time t from the global positioning satellite system receiver 74 and generates a pulse signal P2 at a preset period. Alternatively, the timing signal generation unit 60 of the first embodiment can be used instead of the pulse signal generation unit 61, using the timing signal ts as the pulse signal P2.

[0036] Counter 56 is a counter that increments at regular intervals according to a timer (not shown) within the control unit 51, and sends the count value C(t) to the adjustment time calculation unit 54 and the angle command value calculation unit 55. In this embodiment, the time for each count by counter 56 is t1 / C1. If counter 56 receives a reset signal Rst from the angle command value calculation unit 55, it resets the count value C(t) to zero. The adjustment time calculation unit 54 receives the count value C(t) from counter 56, receives a pulse signal P2 from pulse signal generation unit 61, sets the count value C(t) received when pulse signal P2 is received as the count value C3, and sends the sum of count value C2 and count value C3, C2+C3, to the angle command value calculation unit 55. Here, without adjusting the return travel time, the count value C2 is the count value C(t) of counter 56 when the angle θ of the reflector 26 returns to θs.

[0037] If the angle command value calculation unit 55 receives a count value C(t), it sends the corresponding angle command a(C(t)) to the scanner 28. Specifically, during the forward motion of the count value C(t) from 0 to C1, the angle command value calculation unit 55 increases the angle command a(t) by (θe - θs) / C1 for each increment of the count value C(t). During the return motion of the count value from C1 to (C2 + C3), the angle command value calculation unit 55 decreases the angle command a(t) by (θe - θs) / (C2 + C3) for each increment of the count value C(t). The angle command value calculation unit 55 can also obtain the angle θ(C(t)) of the reflector from the scanner 28 and perform feedback control on the angle command a(C(t)) through PID control or the like. If the count value C(t) reaches C2 + C3, the angle command value calculation unit 55 sends a reset signal Rst to the counter 56.

[0038] Figure 7This is a graph showing the relationship between time t in the optical ranging device 11, the angle θ(t) of the reflector 26, and the count value C(t). At time t0, the count value C(t) of the counter 56 is 0. Afterwards, the count value C(t) of the counter 56 increases at regular intervals according to the timer in the control unit 51, and at time t1, the count value C(t) of the counter 56 becomes C1. During the period from 0 to C1, that is, during the forward motion, for each increment of the count value C(t), the angle command calculation unit 55 increases the angle command a(t) by (θe - θs) / c1, causing the reflector angle θ(t) to increase from θs to θe.

[0039] Suppose that at time ta between time t0 and t1, Figure 6 The pulse signal generation unit 61 generates pulse P2 and sends it to the adjustment time calculation unit 54. Furthermore, the length from this moment t0 to ta corresponds to the adjustment time d in the first embodiment. The adjustment time calculation unit 54 receives the count value C(t) from the counter 56 and obtains the count value C3 when pulse P2 is received. The adjustment time calculation unit 54 calculates C2+C3 and sends it to the angle command value calculation unit 55.

[0040] If the time changes to t1, the count value C(t1) becomes C1, and the mirror angle θ(C1) becomes θe. After time t1, for each increment of the count value C(t), the angle command value calculation unit 55 decreases the angle command a(C(t1)) by (θe - θs) / (C2 + C3). If the count value C3 is 0, at time t2, the count value becomes C2, and the angle command a(C(t2)) becomes θs. If the count value C3 is not 0, at time t2, the angle command a(C(t2)) is a value between θe and θs. If the time changes to t3, the count value C(t3) becomes C2 + C3, and the mirror angle θ(C2 + C3) becomes θs. If the count value C(t3) becomes C2 + C3, the angle command value calculation unit 55 sends a reset signal Rst to the counter 56. If the counter 56 receives the reset signal Rst, it resets the count value C(t) to 0. Furthermore, if the time becomes tb, the pulse signal generation unit 61 generates pulse P2. Here, since time tb and time t3 are the same timing, the count value C(tb) when the adjustment time calculation unit 54 receives pulse P2 becomes 0. Therefore, the new count value C3 becomes 0.

[0041] At time t3 (t0 of the next cycle), the adjustment time calculation unit 54 sends C2+C3 to the control unit 51. However, since the counter value C(t) of the counter 56 when the adjustment time calculation unit 54 receives pulse P2 is 0, C3 becomes 0. The C2+C3 sent from the adjustment time calculation unit 54 to the angle command value calculation unit 55 becomes the same value as C2. During the forward motion of the counter value C(t) from 0 to C1 in the next cycle, the control unit 51 receives the counter value C(t) from the counter 56. For each increment of the counter value C(t), the angle command a(t) is increased by (θe-θs) / c1, causing the reflector angle θ(t) to increase from θs to θe.

[0042] If the time changes to t4, the count value C(t4) becomes C1, and the mirror angle θ(t4) becomes θe. During the return motion from C1 to C2, for each increment of the count value C(t), the angle command calculation unit 55 decreases the angle command a(t) by (θe - θs) / C2.

[0043] If the time changes to t5, the count value C(t5) becomes C2 + C3 (where C3 is 0), and the reflector angle θ(t5) becomes θs. If the count value C(t5) becomes C2 + C3 (where C3 is 0), the angle command value calculation unit 55 sends a reset signal Rst to the counter 56. If the counter 56 receives the reset signal Rst, it resets the count value C(t) to 0. Furthermore, if the time changes to tc, the pulse signal generation unit 61 generates a pulse P2. Here, since time tc and time t5 are the same timing, the count value C(tc) when the adjustment time calculation unit 54 receives the pulse P2 becomes 0. That is, the operation of the reflector 26 and the scanner 28 is synchronized with the pulse signal P2.

[0044] According to the second embodiment, the optical ranging device 11 has a counter 56 that increments based on the passage of time and resets when the scanner 28 performs one cycle of operation. The control unit 51 uses the count value C3 of the counter 56 when the timing signal P2 is received to adjust the time for the reflector 26 to perform its return motion. With this structure, the adjustment time can be generated internally in the control unit 51 to adjust the timing of the operation of the reflector 26 and the scanner 28.

[0045] • Third implementation method:

[0046] Figure 8This is a flowchart of the timing adjustment control performed by the control unit 50 in the third embodiment. The third embodiment has a structure that is roughly the same as the first embodiment, except that the control unit 50 sets the return motion time to D+d when the adjustment time d is greater than or equal to the threshold dth, and sets the return motion time to D+Δd (Δd is a value smaller than the threshold dth) when the adjustment time d is less than the threshold dth.

[0047] In step S100, the adjustment time calculation unit 52 of the control unit 50 substitutes the return travel time D into the reference return travel time Dstd. Thus, in the initial step, the return travel time D is equal to the reference return travel time Dstd.

[0048] In step S110, the adjustment time calculation unit 52 of the control unit 50 obtains the adjustment time d from the timing signal generation unit 60. In step S120, the adjustment time calculation unit 52 determines whether the absolute value of the adjustment time d is less than Δd / 2. Here, Δd is a preset minimum adjustment time, which is the adjustment amount when adjusting the return motion time in the steps described later. In step S120, if the absolute value of the adjustment time d is less than Δd / 2, the control unit 50 causes the adjustment process to proceed to step S180; if the absolute value of the adjustment time d is greater than or equal to Δd / 2, the process proceeds to step S130.

[0049] In step S130, the adjustment time calculation unit 52 determines whether the adjustment time d is greater than or equal to the threshold dth. If the adjustment time d is greater than or equal to the threshold dth, the control unit 50 causes the process to proceed to step S140; if the adjustment time d is less than the threshold dth, the process proceeds to step S150.

[0050] In step S140, the adjustment time calculation unit 52 sets the return travel time of the next cycle to D+d. In step S150, the adjustment time calculation unit 52 determines whether the adjustment time d is greater than 0. If the adjustment time d is greater than 0, the process proceeds to step S160; if the adjustment time d is not greater than 0, the process proceeds to step S170. In step S160, the adjustment time calculation unit 52 sets the return travel time of the next cycle to D+Δd, and in step S170, it sets the return travel time of the next cycle to D-Δd.

[0051] Figure 9 This is the timing diagram when the adjustment time d is above the threshold dth. In the second cycle, the adjustment time calculation unit 52 adjusts the timing in one go by setting the return motion time to D+d. In the third cycle, the return motion time becomes D, and no timing adjustment is required.

[0052] Figure 10This is the timing diagram when the adjustment time d is less than the threshold dth. In the second cycle, the adjustment time calculation unit 52 slightly adjusts the timing by setting the return motion time to D + Δd. In the third cycle, the adjustment time calculation unit 52 adjusts the timing little by little by setting the return motion time to D - Δd. When adjusting the return motion time in a decreasing direction, it may affect the ranging action performed during the forward motion time. Therefore, the adjustment time calculation unit 52 performs timing adjustment by dividing the range (-Δd) into segments that do not affect the ranging action.

[0053] According to the third embodiment, the timing adjustment is switched between being performed all at once and being performed little by little, depending on the magnitude of the adjustment time d. For example, after the vehicle 100 equipped with the optical rangefinder 10 has just started up, such as when the power switch (not shown) is turned on, the generated timing signal ts and synchronization signal ts1 may deviate significantly. In this case, the adjustment time d becomes a threshold dth or higher. When the adjustment time d is a threshold dth or higher, the adjustment time calculation unit 52 adjusts the entire adjustment amount at once by setting the return travel time to D+d. On the other hand, when the adjustment time d is less than the threshold dth, the adjustment time calculation unit 52 can perform timing adjustment by dividing the return travel time into ranges (-Δd) that do not affect the ranging operation by setting the return travel time to D+Δd or D-Δd.

[0054] Fourth implementation method:

[0055] Figure 11 This is a timing diagram showing the relationship between time and angle command values ​​in the fourth embodiment. In the fourth embodiment, the angle command value calculation unit 53 stores the times t of several points, such as times t0, t1, t2, t3, and the angle command values ​​a(t0), a(t1), a(t2), a(t3) at those times t0, t1, t2, t3, in an internal storage unit (not shown). At any time ti between the time t0, which is the first timing, and the time t1, which is the second timing, the angle command value calculation unit 53 uses the angle command values ​​a(t0), a(t1) at times t0, t1, and calculates the angle command value a(ti) by linear interpolation. Specifically, the angle command value a(ti) at time ti is calculated using the following equation (1).

[0056] a(ti)=(ti-t0)·(a(t1)-a(t0) / (t1-t0)

[0057] =(ti-t0)·(a1-a0) / (t1-t0)…(1)

[0058] At time tj between time t1 and t2, and at time tk between time t2 and t3, the angle command values ​​a(tj) and a(tk) are calculated using the following equations (2) and (3), respectively.

[0059] a(tj)=a1+(tj-t1)·(a(t2)-a(t1) / (t2-t1)

[0060] =a1+(tj-t1)·(a2-a1) / (t2-t1)…(2)

[0061] a(tk)=a2+(tk-t2)·(a(t2)-a(t1) / (t3-t2)

[0062] =a2+(tk-t2)·(a0-a2 / (t3-t2)…(3)

[0063] According to the fourth embodiment, the angle command value calculation unit 53 does not need to store angle command values ​​a(t) other than times t0, t1, t2, and t3. Furthermore, during the return motion, even if the time t3 at the end of a cycle changes due to timing adjustments, the angle command value at time t can be calculated using linear interpolation. For example, according to the fourth embodiment, in the return motion of the second cycle, when the adjustment time d is 0, time t6 becomes the second timing; when the adjustment time is not 0, the adjustment time calculation unit 52 adds or subtracts the adjustment amount d to the time of one cycle, i.e., the frame time, changing the time t6, which is the second timing, to time t7, and can calculate the angle command value a(t) between time t5 and time t7 using linear interpolation.

[0064] In the first embodiment described above, the adjustment time calculation unit 52 is configured to be provided inside the control unit 50, but the adjustment time calculation unit 52 may also be provided outside the control unit 50.

[0065] Fifth implementation method:

[0066] Figure 12This is an explanatory diagram showing the modular configuration of the optical ranging device 12 according to the fifth embodiment. The vehicle 101 includes the optical ranging device 12 and an external control unit 71. The external control unit 71 includes a data processing unit 72, a Global Positioning Satellite System (GNSS) receiver 74, and a timing signal generation unit 76. The timing signal generation unit 76 has the same function as the timing signal generation unit 60 of the optical ranging device 10 in the first embodiment, but the timing signal generation unit 76 is located within the external control unit 71, which differs from the structure of the first embodiment. In the optical ranging device 12 of the fifth embodiment, the synchronization signal ts1 is transmitted to the timing signal generation unit 76 of the external control unit 71 via the distance calculation unit 40 and the data processing unit 72. Furthermore, the synchronization signal ts1 can also be directly transmitted from the control unit 57 of the optical ranging device 12 to the timing signal generation unit 76 of the external control unit 71. Additionally, in the optical ranging device 12, the adjustment time calculation unit 52 is located outside the control unit 57, which differs from the optical ranging device 10 of the first embodiment. However, the time adjustment calculation unit 52 can also be provided inside the control unit 57 in the same way as the optical ranging device 10 in the first embodiment.

[0067] The timing information generated by the timing signal generation unit 76 may include, in addition to the information on the target value set for adjustment by the control unit 57 of the optical ranging device 12, the time information of the time when communication occurred. Alternatively, the distance calculation unit 40 may include the time information of each ranging point in the ranging data, and the data processing unit 72 may calculate the timing information based on this time information.

[0068] In the optical ranging device 12 of the fifth embodiment, the external control unit 71 calculates the offset time required for the timing adjustment of the optical ranging device 12 based on the vehicle's driving environment, the operation status of other sensors, the time information of each ranging point using ranging data, and sends it. The optical ranging device 12 can synchronize and perform timing adjustment processing by receiving the offset time information and controlling the scanner 28.

[0069] The fifth embodiment can also be combined with any of the second to fourth embodiments. For example, in the fifth embodiment, as in the third embodiment, when the adjustment time d is above the threshold dth, the control unit 57 adjusts the timing all at once by setting the return motion time to D+d; when the adjustment time d is less than the threshold dth, the adjustment time calculation unit 52 performs timing adjustment by dividing the return motion time into a range (-Δd) that does not affect the ranging action by setting the return motion time to D+Δd or D-Δd. Alternatively, in the fifth embodiment, the external control unit 71 may determine whether to perform timing adjustment in one go or in stages based on the adjustment time d and issue an instruction; the control unit 57 receives the result of this determination and performs timing adjustment by one go or in stages.

[0070] In the above embodiments, the distance calculation unit 40 uses the time from the emission of the illumination light IL from the light-emitting unit 21 to the detection of the reflected light RL from the target by the light receiving unit 30 to calculate the distance to the target. However, the phase difference between the phase of the illumination light IL and the phase of the reflected light RL can also be used to calculate the distance to the target.

[0071] In the above embodiments, the period of forward motion is maintained, but it is sufficient to maintain the distance measurement period of the forward motion, or it is not necessary to maintain the period of the forward motion. This is because as long as the distance measurement period can be maintained, the distance measurement will not be affected.

[0072] This disclosure is not limited to the embodiments described above, and can be implemented in various structures without departing from its spirit. For example, the technical features of the embodiments corresponding to the technical features in the various methods described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. In addition, any technical feature that is not described as an essential feature in this specification can be appropriately deleted.

Claims

1. An optical ranging device, characterized in that, have: Light-emitting part; A reflector that reflects the illumination light emitted by the light-emitting part; A scanner that scans a pre-defined scanning range using the illumination light by reciprocating the mirror; A light receiving unit that detects the reflected light that is reflected and returned by the irradiating light to a target existing within the scanning range; The distance calculation unit calculates the distance to the target using the time from the emission of the illumination light from the light-emitting unit to the detection of the reflected light from the target by the light-receiving unit during the reciprocating motion of the reflector. as well as The control unit controls the light emission of the light-emitting unit and the operation of the scanner. By adjusting the time of one cycle of the scanner while keeping the distance measurement period of the reciprocating motion of the reflector constant, the operation of the scanner is synchronized with a preset timing signal.

2. The optical ranging device according to claim 1, characterized in that, The optical ranging device includes a timing signal generation unit that generates the timing signal based on a signal from outside the optical ranging device.

3. The optical ranging device according to claim 1 or 2, characterized in that, If the adjustment amount for the time during which the reflector performs its return motion is above a threshold, the control unit increases the adjustment amount for the time during which the reflector performs its return motion all at once during the next cycle. If the adjustment amount for the time during which the reflector performs a return motion is less than the threshold, the control unit, in the next cycle, increases or decreases the time during which the reflector performs a return motion by a minimum adjustment time smaller than the threshold.

4. The optical ranging device according to claim 1, characterized in that, The control unit obtains the timing signal from an external control unit located outside the optical ranging device and has a timing signal generation unit.

5. The optical ranging device according to claim 4, characterized in that, Upon receiving a one-time adjustment instruction from the external control unit, the control unit increases the adjustment amount of the time for the reflector to return during the next cycle. When the control unit receives an instruction for phased adjustment from the external control unit, it increases or decreases the time for the reflector to return to its original position by a minimum adjustment time during the time for the reflector to return to its original position in the next cycle.

6. The optical ranging device according to claim 1 or 2, characterized in that, The control unit adjusts the time of one cycle of the scanner by adjusting the time it takes for the reflector to return to its original position.

7. The optical ranging device according to claim 1 or 2, characterized in that, The scanner changes the angle of the reflector according to the angle command value from the control unit.

8. The optical ranging device according to claim 1 or 2, characterized in that, The optical ranging device has a counter that increments over time and resets at the end of each scanner cycle. The timing signal is a pulse signal. The control unit uses the counter value received when the timing signal is received to adjust the time for the reflector to perform its return motion.

9. The optical ranging device according to claim 1 or 2, characterized in that, The timing signal includes adjustment timing information for adjusting the time for the reflector to perform its return motion.

10. The optical ranging device according to claim 1 or 2, characterized in that, The control unit uses a cycle time, multiple timings including a first timing for switching the reflector from return motion to forward motion and a second timing for switching the reflector from forward motion to return motion, and angle command values ​​under the multiple timings. It uses linear interpolation to calculate the angle command value under any timing in a cycle, adds or subtracts the adjustment amount for the time of the reflector's return motion to the cycle time, and changes the second timing.

Images