Light control device

Abstract

To provide a light control device capable of acquiring 3 dimensional information by using a single transceiver.SOLUTION: A light control device is installed on a moving body and includes a light emission / reception unit that has an emission unit and a light-receiving unit. The emission unit emits light, and the light-receiving unit receives light that is reflected by a target object in the vicinity of the moving body. By continuously shifting the light emitted by the emission unit in a first direction and a second direction that intersects with the first direction, a control unit controls the emission unit such that a shifting path of the light emitted by the emission unit becomes helical.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a light control device that controls the transition of emitted light. [Background technology]

[0002] LIDAR is known, which detects a point cloud on an object surface by scanning horizontally while intermittently emitting laser light and receiving the reflected light. Patent Document 1 describes a method in which a LIDAR mounted on an automobile scans the surroundings one-dimensionally or two-dimensionally to detect information about the situation around the automobile. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-89691 Summary of the Invention [Problem to be solved by the invention]

[0004] To obtain information about the surrounding environment in three dimensions, a multi-layered lidar must be used, but this requires the same number of optical transceivers as the layers, which makes it very expensive.

[0005] The above is an example of a problem to be solved by the present invention. An object of the present invention is to provide a light control device that makes it possible to acquire three-dimensional information using a single transmitter / receiver. [Means for solving the problem]

[0006] The invention described in the claims is a light control device comprising: a light transmitting / receiving unit installed on a moving body and having an emitting unit that emits light and a light receiving unit that receives light reflected by an object around the moving body; and a control unit that controls the emitting unit so that the transition trajectory of the light emitted by the emitting unit is spiral by continuously transitioning the light emitted by the emitting unit between a first direction and a second direction intersecting the first direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a block diagram showing the configuration of a rider unit according to the embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of an optical transmitting and receiving unit. [Figure 3] 3 shows waveforms of a trigger signal and a segment extraction signal. [Figure 4] 3A and 3B show schematic diagrams of the operation of the omnidirectional scanning unit. [Figure 5] 3 shows the trajectory of spiral scanning according to the first embodiment. [Figure 6] 1 shows a scanning field of view by spiral scanning in the first embodiment. [Figure 7] 10 shows the trajectory of partial multilayer scanning according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] In a preferred embodiment of the present invention, the light control device comprises: a light transmitting / receiving unit that is installed on a moving body and has an emitting unit that emits light and a light receiving unit that receives light reflected by objects around the moving body; and a control unit that controls the emitting unit so that the transition trajectory of the light emitted by the emitting unit is spiral by continuously transitioning the light emitted by the emitting unit between a first direction and a second direction intersecting the first direction.

[0009] The light control device is installed on a moving object and includes a light transmitting / receiving unit having an emitting unit and a light receiving unit. The emitting unit emits light, and the light receiving unit receives light reflected by objects around the moving object. The control unit controls the emitting unit so that the light emitted by the emitting unit transitions continuously between a first direction and a second direction intersecting the first direction, thereby causing the transition locus of the light emitted by the emitting unit to be spiral. In this way, by continuously transitioning the light emitted from the emitting unit between the first direction and the second direction, it becomes possible to detect objects around the moving object in three dimensions.

[0010] One aspect of the above light control device further includes a first acquirer that acquires first angle information indicating an emission angle of the light emitted by the emitter in the first direction, and a second acquirer that acquires second angle information indicating an emission angle of the light emitted by the emitter in the second direction, and the control unit performs the control based on the first angle information and the second angle information. In this aspect, the control unit controls the transition locus of the emitted light to be spiral based on the first angle information and the second angle information.

[0011] In another aspect of the light control device, when the second angle becomes a predetermined angle, the control unit controls the emission unit so that the first angle and the second angle become reference angles within a predetermined time, thereby making it possible to repeat the same control from the reference angle.

[0012] According to another aspect of the light control device, the light receiving unit further includes a detector that detects at least one of a distance and an angle to the object based on the light receiving result of the light receiving unit, thereby obtaining peripheral circular information of the moving object.

[0013] In a preferred example, the first direction is horizontal, the control unit controls the emitting unit so that light is emitted in all directions in the first direction, and the light receiving unit receives light reflected by objects present in all directions in the first direction.

[0014] In another preferred embodiment of the present invention, a light control method executed by a light control device installed on a mobile body and including a light transmitting and receiving unit having an emitter for emitting light and a light receiving unit for receiving light reflected by objects around the mobile body includes a control step of controlling the emitter so that the transition locus of the light emitted by the emitter becomes spiral by continuously transitioning the light emitted from the emitter in a first direction and a second direction intersecting the first direction. This method also makes it possible to detect objects around the mobile body in three dimensions by continuously transitioning the light emitted from the emitter in the first direction and the second direction.

[0015] In another preferred embodiment of the present invention, a light control device includes a light transmitting / receiving unit installed on a mobile body and having an emitter for emitting light and a light receiving unit for receiving light reflected by objects around the mobile body, and a computer, the program executed by the light control device causes the computer to function as a control unit that controls the emitter so that the transition locus of the light emitted by the emitter becomes spiral by continuously transitioning the light emitted by the emitter in a first direction and a second direction intersecting the first direction. By executing this program and continuously transitioning the light emitted from the emitter in the first direction and the second direction, it becomes possible to detect objects around the mobile body in three dimensions.

[0016] In another preferred embodiment of the present invention, the light control device comprises: a light transmitting / receiving unit that is installed on a moving body and has an emitting unit that emits light and a light receiving unit that receives light reflected by objects around the moving body; and a control unit that controls the emitting unit so that the light emitted by the emitting unit traces a spiral trajectory on a predetermined plane in space by continuously transitioning the light between a first direction and a second direction intersecting the first direction.

[0017] The light control device is installed on a mobile object and includes a light transmitting / receiving unit having an emitter and a receiver. The emitter emits light, and the receiver receives light reflected by objects around the mobile object. The controller controls the emitter so that the light emitted by the emitter traces a spiral trajectory on a predetermined plane in space by continuously shifting the light emitted from the emitter between a first direction and a second direction intersecting the first direction. In this way, by continuously shifting the light emitted from the emitter between the first direction and the second direction, it becomes possible to detect objects around the mobile object in three dimensions.

[0018] In another preferred embodiment of the present invention, a light control device comprises: a light transmitting / receiving unit that is installed on a moving body and has an emitting unit that emits light and a receiving unit that receives the light; and a control unit that performs a first control to continuously transition the light in a first direction and a second control to continuously transition the light in a second direction intersecting the first direction, wherein when the emission angle of the light from the emitting unit in the first direction becomes a predetermined angle, the control unit continuously transitions the light in the first direction while transitioning the emission angle of the light from the emitting unit in the second direction by the predetermined angle.

[0019] The light control device is installed on a mobile object and includes a light transmitting / receiving unit having an emitter and a receiver. The emitter emits light, and the receiver receives light reflected by objects around the mobile object. The controller performs a first control to continuously transition the light emitted by the emitter in a first direction and a second control to continuously transition the light in a second direction intersecting the first direction. When the emission angle of the light from the emitter in the first direction reaches a predetermined angle, the controller continuously transitions the light in the first direction while transitioning the emission angle of the light from the emitter in the second direction by a predetermined angle. In this way, by continuously transitioning the light emitted from the emitter in the first direction and the second direction, it is possible to detect objects around the mobile object in three dimensions. [Example]

[0020] Preferred embodiments of the present invention will now be described with reference to the drawings. [composition] 1 is a block diagram showing the configuration of a LIDAR unit 100 according to an embodiment. The LIDAR unit 100 of the embodiment is a TOF (Time Of Flight) LIDAR (Light Detection and Ranging, or Laser Illuminated Detection and Ranging) that measures the distance to an object (target) in all directions in the horizontal direction. As shown in the figure, the LIDAR unit 100 includes an optical transmitter / receiver 1, a signal processor 2, an omnidirectional scanner 3, a scan angle controller 4, and a scan angle detector 5.

[0021] The optical transmitter / receiver 1 includes a laser diode or the like, generates laser pulses PL, and supplies them to the omnidirectional scanner 3. The omnidirectional scanner 3 emits laser pulses (hereinafter also referred to as "transmitted optical pulses Pt") in all 360° horizontal directions while changing the emission direction vertically. At this time, the omnidirectional scanner 3 emits the transmitted optical pulses Pt for each segment (900 segments in this embodiment) obtained by dividing the 360° horizontal directions at equal angles. Furthermore, the omnidirectional scanner 3 receives reflected light of the transmitted optical pulses Pt (hereinafter also referred to as "received optical pulses Pr") within a predetermined period after emitting the transmitted optical pulses Pt, and supplies the reflected light to the optical transmitter / receiver 1. The optical transmitter / receiver 1 generates a signal (hereinafter also referred to as "segment signal Sseg") related to the received light intensity for each segment based on the received optical pulses Pr, and outputs the signal to the signal processor 2.

[0022] The signal processing unit 2 outputs surrounding environment information including at least one of the distance to the object and the angle of the object based on the segment signal Sseg for each segment received from the optical transceiver 1. The surrounding environment information is information that indicates the surrounding environment of the vehicle on which the LIDAR unit 100 is mounted, and specifically, information that indicates the distance and angle of objects that exist in all directions from the vehicle.

[0023] The scan angle detection unit 5 detects the horizontal angle θ and vertical angle φ that indicate the emission direction of the transmission light pulse Pt emitted by the omnidirectional scan unit 3, and supplies them to the signal processing unit 2. The signal processing unit 2 generates a target horizontal angle θt and a target vertical angle φt as control targets based on the horizontal angle θ and vertical angle φ detected by the scan angle detection unit 5, and supplies them to the scan angle control unit 4. The scan angle control unit 4 controls the scan angle of the transmission light pulse Pt by the omnidirectional scan unit 3 based on the target horizontal angle θt and target vertical angle φt supplied from the signal processing unit 2. As a result, the omnidirectional scan unit 3 is controlled to emit the transmission light pulse Pt at the target horizontal angle θt and target vertical angle φ.

[0024] Next, the optical transmitter / receiver 1 will be described in detail. The configuration of the optical transmitter / receiver 1 is shown in Fig. 2. The optical transmitter / receiver 1 mainly includes a crystal oscillator 10, a synchronization control unit 11, an LD driver 12, a laser diode (LD) 13, a light receiving element 16, a current-voltage conversion circuit (transimpedance amplifier) ​​17, an A / D converter 18, and a segmentator 19. The optical transmitter / receiver 1 is an example of the "light transmitting / receiving unit" in the present invention.

[0025] The crystal oscillator 10 outputs a pulsed clock signal S1 to the synchronization control unit 11 and the A / D converter 18. In this embodiment, the clock frequency is set to 1.8 GHz, for example. Hereinafter, the clock indicated by the clock signal S1 will also be referred to as the "sample clock."

[0026] The synchronization control unit 11 outputs a pulse-like signal (hereinafter referred to as "trigger signal S2") to the LD driver 12. In this embodiment, the trigger signal S2 is 131072 (=2 17) sample clock. Hereinafter, the period from when trigger signal S2 is asserted until the next time it is asserted will also be referred to as the "segment period." Furthermore, synchronization control unit 11 outputs a signal (hereinafter referred to as the "segment extraction signal S3") to segmentator 19, which determines the timing at which segmentator 19, described later, extracts the output of A / D converter 18. The trigger signal S2 and segment extraction signal S3 are logical signals, and are synchronized as shown in FIG. 3, described later. In this embodiment, synchronization control unit 11 asserts segment extraction signal S3 for a time width (also referred to as the "gate width Wg") equivalent to 2048 sample clocks.

[0027] The LD driver 12 supplies a pulse current to the laser diode 13 in synchronization with a trigger signal S2 input from the synchronization control unit 11. The laser diode 13 is, for example, an infrared (905 nm) pulse laser, and emits an optical pulse based on the pulse current supplied from the LD driver 12. In this embodiment, the laser diode 13 emits an optical pulse of about 5 nsec.

[0028] The light pulse emitted from the laser diode 13 is sent to the omnidirectional scanning unit 3 via an optical system. The omnidirectional scanning unit 3 emits a transmission light pulse Pt, and receives a light pulse reflected by an object as a reception light pulse Pr, which is sent to the light receiving element 16. The laser diode 13 is an example of the "emitting unit" in the present invention.

[0029] The light receiving element 16 is, for example, an avalanche photodiode, and generates a weak current corresponding to the light intensity of the received light pulse Pr guided by the omnidirectional scanning unit 3. The light receiving element 16 supplies the generated weak current to a current-voltage conversion circuit 17. The current-voltage conversion circuit 17 amplifies the weak current supplied from the light receiving element 16, converts it into a voltage signal, and inputs the converted voltage signal to an A / D converter 18.

[0030] The A / D converter 18 converts the voltage signal supplied from the current-voltage conversion circuit 17 into a digital signal based on the clock signal S1 supplied from the crystal oscillator 10, and supplies the converted digital signal to the segmentator 19. Hereinafter, the digital signal generated by the A / D converter 18 for each clock will also be referred to as a "sample." The light-receiving element 16, the current-voltage conversion circuit 17, and the A / D converter 18 are an example of a "light-receiving unit" in the present invention.

[0031] The segmentator 19 generates a digital signal, which is the output of the A / D converter 18 for 2048 sample clocks during the period of the gate width Wg during which the segment extraction signal S3 is asserted, as a segment signal Sseg. The segmentator 19 supplies the generated segment signal Sseg to the signal processing unit 2.

[0032] 3 shows the waveforms of the trigger signal S2 and the segment extraction signal S3 in time series. As shown in Fig. 3, in this embodiment, the segment period, which is the period of one cycle during which the trigger signal S2 is asserted, is set to a length of 131072 sample clocks (denoted as "smpclk" in the drawing), the pulse width of the trigger signal S2 is set to a length of 64 sample clocks, and the gate width Wg is set to a length of 2048 sample clocks.

[0033] In this case, the segment extraction signal S3 is asserted for only the period of the gate width Wg after the trigger signal S2 is asserted, so the segmentator 19 extracts 2048 samples output by the A / D converter 18 while the trigger signal S2 is asserted. The longer the gate width Wg, the longer the maximum measurement distance (measurement limit distance) from the lidar unit 100.

[0034] Next, the omnidirectional scanning unit 3 will be described in detail. The omnidirectional scanning unit 3 is composed of, for example, a rotatable mirror and an optical system for scanning the transmitted light pulse Pt over 360°. The direction in which the omnidirectional scanning unit 3 transmits and receives light pulses to and from the surrounding environment (hereinafter also referred to as the "emission direction") is determined by a horizontal angle θ and a vertical angle φ. FIG. 4 shows an example of a scanning state by the omnidirectional scanning unit 3. FIG. 4(A) is a perspective view showing the state in which the omnidirectional scanning unit 3 is performing horizontal scanning. FIG. 4(B) is a plan view showing the scanning state of the omnidirectional scanning unit 3 as viewed from above. The light pulse is scanned at a horizontal angle θ with respect to a predetermined horizontal reference axis. The horizontal angle θ changes 360° ([deg]) with respect to the horizontal reference axis. In other words, the light pulse can scan in all directions (0° to 360°). FIG. 4(C) shows the state in which the omnidirectional scanning unit 3 is scanning upward from the horizontal scanning state shown in FIG. 3(A). Specifically, the omnidirectional scanning unit 3 scans the light pulse at a vertical angle φ with respect to a vertical reference axis. In this way, the omnidirectional scanning unit 3 is capable of three-dimensional scanning by continuously changing the horizontal and vertical angles. The omnidirectional scanning unit 3 is an example of the "control unit" in the present invention.

[0035] [Scanning Control] (First Example) Next, we will explain an example of scan control by the omnidirectional scanning unit 3. The omnidirectional scanning unit 3 performs scanning of multiple layers in the vertical direction. Specifically, in the first example described below, the omnidirectional scanning unit 3 performs spiral scanning of seven layers (number of layers n=7) in the vertical direction.

[0036] FIG. 5 shows a trajectory of spiral scanning in the first embodiment. FIG. 5(A) is a perspective view of the trajectory by spiral scanning, FIG. 5(B) is a plan view of the trajectory by spiral scanning, and FIG. 5(C) is a side view of the trajectory by spiral scanning. Note that FIG. 5 shows a trajectory formed by a certain point in the emission direction of the transmission light pulse Pt by scanning with the omnidirectional scanning unit 3. In other words, FIG. 5 shows a trajectory drawn on a predetermined plane in space by the transmission light pulse Pt emitted by the omnidirectional scanning unit 3.

[0037] As shown in the figure, one spiral scan (one frame) by the omnidirectional scanning unit 3 begins at a start point S, spirals through seven layers (seven turns), reaches an end point E, and then returns to the start point S. The omnidirectional scanning unit 3 repeats this spiral scan. Specifically, during one frame of spiral scan, the horizontal angle θ changes from 0° to 360° seven times. During this time, the vertical angle φ changes at a constant rate from a vertical angle −φ0 at the start point S to a vertical angle φ0 at the end point E. The period during which the emission direction of the transmission light pulse Pt returns from the end point E to the start point S is called the “vertical angle transition range.” The vertical angle transition range is the range for returning the emission direction of the transmission light pulse Pt to a predetermined direction in order to repeat the spiral scan.

[0038] Next, the scanning field of view will be explained. Figure 6(A) shows the horizontal field of view of spiral scanning. In this embodiment, of the 360° omnidirectional range, the vertical angle transition range is set to 90°, and the remaining 270° is set to the "effective horizontal field of view angle range θ1." In other words, θ1 = 270°. The effective horizontal field of view angle range is the range obtained by excluding the vertical angle transition range from the 360° omnidirectional range, and is the range in which effective segment data can be obtained from the received optical pulse Pr. Now, assuming that the 360° scan by the omnidirectional scanning unit 3 corresponds to 900 segments, Number of segments per turn = 900 / number of layers In addition, the horizontal angular resolution Δθ is Δθ=360 / 900=0.4° / seg This becomes:

[0039] Figure 6(B) shows the horizontal field of view of the spiral scan. If the number of layers (number of turns) of the spiral scan is n (=7) and the vertical angular resolution of one layer is Δφ = 5°, then: Vertical viewing angle range = (n-1) × Δφ = 30° The vertical angle φ changes in the range of −15°≦φ≦15°.

[0040] In the spiral scan, if the vertical angle φ is changed from the negative side to the positive side, the vertical angle φ becomes −φ0=−15° at time t=0. In addition, if it is desired to acquire segment data for seven layers at a frame rate of 15.26 Hz, for example, the omnidirectional scanning unit 3 transmits the transmitted light pulse Pt at an angular velocity ω: ω=2π×15.26×7=3846deg / s Scan with.

[0041] If the elapsed time after the start of the spiral scan is "t", the horizontal angle can be calculated as follows:

number

[0042] Furthermore, if the number of layers in the spiral scan is n, the vertical angle at the starting point is φ0 = -15°, the coefficient K = 0.1389, and the effective horizontal field of view angle range is θ1 = 270°, the vertical angle can be calculated as follows: Equation (3) shows the vertical angle within the effective horizontal field of view angle range, and Equation (4) shows the vertical angle within the vertical angle transition range.

number

[0043] (Second Example) In the spiral scanning of the first embodiment, the vertical angle φ of the emission direction of the transmission light pulse Pt is changed spirally at a constant rate of change. However, in the spiral scanning of the first embodiment, the data obtained within one layer is data obtained while the vertical angle φ is gradually changed, and therefore, it may be difficult to use the data for subsequent signal processing in the signal processing unit 2.

[0044] In contrast, in the scanning of the second embodiment, the vertical angle φ is changed for each layer. That is, the omnidirectional scanning unit 3 increases the vertical angle φ for each layer within the vertical angle transition range and moves the scanning direction to the next layer. Such scanning according to the second embodiment is also called "partial multilayer scanning."

[0045] Fig. 7 shows a trajectory of partial multi-layer scanning according to the second embodiment. Fig. 7(A) is a perspective view of the trajectory of partial multi-layer scanning, Fig. 7(B) is a plan view of the trajectory of partial multi-layer scanning, and Fig. 7(C) is a side view of the trajectory of partial multi-layer scanning. Fig. 7 shows a trajectory formed by a certain point in the emission direction of the transmitted optical pulse Pt due to scanning by the omnidirectional scanning unit 3.

[0046] As shown in the figure, in the partial multi-layer scanning of the second embodiment, the omnidirectional scanning unit 3 performs scanning without changing the vertical angle φ in the range up to the effective horizontal field of view angle (θ = θ1 = 270°) of each layer. Then, in the subsequent vertical angle transition range, the omnidirectional scanning unit 3 increases the vertical angle φ and moves the emission direction to the next higher layer. The omnidirectional scanning unit 3 performs such scanning in each layer.

[0047] Specifically, as shown in Figures 7(A) and (C), first, the omnidirectional scanning unit 3 scans the lowest layer (first layer) from the start point S1 to the end point E1 without changing the vertical angle φ, and then, in the vertical angle transition range of the subsequent lowest layer, increases the vertical angle φ by one layer and moves the emission direction to the start point S2 of the second layer.

[0048] Next, the omnidirectional scanning unit 3 scans from start point S2 to end point E2 of the second layer without changing the vertical angle φ. Then, in the vertical angle transition range of the subsequent second layer, the vertical angle φ is increased by one layer, and the emission direction is moved to start point S3 of the third layer. The omnidirectional scanning unit 3 sequentially scans each layer in this manner, and when the emission direction reaches end point E7 of the top layer (seventh layer), the vertical angle φ is moved from end point E7 of the top layer to start point E1 of the bottom layer in the vertical angle transition range, just as in the spiral scanning of the first embodiment. Then, scanning of the next frame continues in the same manner, starting from start point S1 of the bottom layer.

[0049] As in the first embodiment, if the number of layers n=7 and the range of the vertical angle φ is -15°≦φ≦15°, the omnidirectional scanning unit 3 will move the emission direction to the next higher layer by increasing the vertical angle φ by 5° within the vertical angle transition range of each layer.

[0050] In the second embodiment, if the time elapsed after the start of partial multilayer scanning is "t", the horizontal angle can be calculated as follows.

number

[0051] Furthermore, if the number of layers in partial multi-layer scanning is n, the vertical angle φ0 at the start point is −15°, and the effective horizontal viewing angle range θ1 is 270°, then the vertical angle φ can be calculated as follows:

number

[0052] In the second embodiment, the omnidirectional scanning unit 3 can acquire three-dimensional segment data by performing partial multilayer scanning with the transmitted light pulses Pt. Also, in the second embodiment, multilayer scanning with a constant vertical angle φ can be realized within the effective horizontal field of view angle range outside the vertical angle transition range, and segment data can be acquired with the vertical angle φ fixed.

[0053] [Variations] In the above embodiment, the number of layers in the spiral scan or partial multilayer scan is seven, but this is merely an example, and scanning can be performed with any number of layers. Also, in the above embodiment, the emission direction is shifted by increasing the perpendicular angle φ from the bottom layer to the top layer, but instead, the emission direction may be shifted by decreasing the perpendicular angle φ from the top layer to the bottom layer. [Industrial Applicability]

[0054] The present invention can be used in a technology for acquiring ambient environment information by emitting laser light. [Explanation of symbols]

[0055] 1 Optical transmitter / receiver 2. Signal Processing Section 3 Omnidirectional scanning unit 4 Scanning angle control section 5. Scanning angle detection unit 13 Laser diode 16 Photodetector

Claims

[Claim 1] a light transmitting / receiving unit that is installed on the moving body and has an emitting unit that emits light and a light receiving unit that receives light reflected by an object around the moving body; a control unit that controls the emitting unit by continuously transitioning the light emitted by the emitting unit in a first direction and a second direction intersecting the first direction so that the transition locus of the light emitted by the emitting unit is spiral; A light control device comprising:

Images