Detection apparatus, control method, and storage medium

Abstract

To provide a detection device capable of suitably detecting an object around a moving body.SOLUTION: The LIDAR 1 includes a scanning unit 55 that emits the projection light Lo according to the pulse trigger signal PT, an APD41 that receives the return light Lr of the projection light Lo, and a DSP16. The DSP16 acquires current position information IP and the like indicating the position of the car from the on-board device 2. Then, the DSP16 controls the intensity and emission frequency of the emission light Lo emitted by the scanner 55 based on the current position information IP and the like.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a technique for controlling the emission of light pulses for measurement. [Background technology]

[0002] There are known techniques for measuring the distance to surrounding objects. For example, Patent Document 1 discloses an in-vehicle system equipped with a lidar that detects a point cloud on the surface of an object by scanning the horizontal direction while intermittently emitting laser light and receiving the reflected light. [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] When using a lidar to capture landmarks in the surrounding environment, if the landmarks are far away or if the landmarks included in the scanning plane are relatively small compared to the scanning angle resolution, the number of measurement points corresponding to the landmarks may be excessively small, making it impossible to correctly recognize the shape of the landmark, etc. As such, conventional lidars emit light at a constant light intensity and a constant scanning angle resolution, which sometimes makes it impossible to accurately detect surrounding objects.

[0005] The present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to provide a detection device that can suitably detect objects around a moving body. [Means for solving the problem]

[0006] The claimed invention is a detection device that can be placed on a moving body, and is equipped with an emission unit that emits light and a light receiving unit that receives the light reflected by an object, and the emission interval of the light emitted into a certain angular range in front of the moving body is closer than in other angular ranges different from the certain angular range, or the intensity of the light emitted into the certain angular range in front of the moving body is higher than in other angular ranges different from the certain angular range.

[0007] The invention described in the claims is a detection device that can be placed on a moving body, and comprises an emission unit that emits light, a light receiving unit that receives the light reflected by an object, and a control unit that controls at least one of the emission interval and intensity of the light emitted by the emission unit, wherein the control unit controls the emission interval of the light that the emission unit emits into a certain angular range in front of the moving body to be closer than in other angular ranges that are different from the certain angular range, or controls the intensity of the light that the emission unit emits into a certain angular range in front of the moving body to be higher than in other angular ranges that are different from the certain angular range.

[0008] The claimed invention is a control method executed by a detection device that can be placed on a moving body and that has an emission unit that emits light, a light receiving unit that receives the light reflected by an object, and a first acquisition unit that acquires position information indicating the position of the moving body, and includes a control step of controlling at least one of the emission interval and intensity of the light emitted by the emission unit, wherein the control step is a step of controlling, based on the position information, the emission interval of the light that the emission unit emits into a certain angular range in front of the moving body so that it is closer than in other angular ranges that are different from the certain angular range, or a step of controlling the intensity of the light that the emission unit emits into a certain angular range in front of the moving body so that it is higher than in other angular ranges that are different from the certain angular range.

[0009] The invention described in the claims is a program executed by a computer of a detection device that can be placed on a moving body, the detection device having an emission unit that emits light, a light receiving unit that receives the light reflected by an object, and a first acquisition unit that acquires position information indicating the position of the moving body, wherein the emission unit controls at least one of the intensity and emission frequency of the emitted light, and controls the emission interval of the light that the emission unit emits into a certain angular range in front of the moving body to be closer than other angular ranges that are different from the certain angular range, or controls the intensity of the light that the emission unit emits into a certain angular range in front of the moving body to be higher than other angular ranges that are different from the certain angular range. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows a schematic configuration of an object detection system according to an embodiment. [Figure 2] 1 shows the overall configuration of a lidar according to an embodiment. [Figure 3] The transmitter and receiver configurations are shown. [Figure 4] 1 shows the configuration of a scanning optical unit. [Figure 5] 10 shows an example of register settings for control signals generated by the synchronization control unit. [Figure 6] 1 shows the time relationship of control signals generated by the synchronization control unit. [Figure 7] 10 is a graph showing the relationship between an ADC output signal and a gate. [Figure 8] 1 shows the time relationship of the pulse train of a rotary encoder. [Figure 9] The time relationship between the encoder pulse and the segment slot in the steady state is shown. [Figure 10] FIG. 1 is a block diagram of signal processing by a DSP. [Figure 11] 1 is a plan view of the vicinity of a vehicle, in which the emission power of emitted light and the scanning angular resolution during 360-degree scanning in a first control mode are roughly indicated by dashed arrows. FIG. [Figure 12]10 is a plan view of the vicinity of a vehicle, in which the emission power of emitted light and the scanning angular resolution during 360-degree scanning in the second control mode are roughly indicated by dashed arrows. FIG. [Figure 13] FIG. 10 is a plan view of the vicinity of a vehicle, in which the emission power of emitted light and the scanning angular resolution during 360-degree scanning in the third control mode are roughly indicated by dashed arrows. [Figure 14] FIG. 10 is a plan view of the vicinity of a vehicle, in which the emission power of emitted light and the scanning angular resolution during 360-degree scanning in the fourth control mode are roughly indicated by dashed arrows. DETAILED DESCRIPTION OF THE INVENTION

[0011] In one preferred embodiment of the present invention, a detection device that can be placed on a moving body includes an emission unit that emits light, a light receiving unit that receives the light reflected by an object, a first acquisition unit that acquires position information that indicates the position of the moving body, and a control unit that controls at least one of the intensity and emission frequency of the light emitted by the emission unit based on the position information.

[0012] The detection device includes an emitter that emits light, a light receiver that receives light reflected by an object, a first acquirer, and a controller. The first acquirer acquires position information indicating the position of the moving object. The controller controls at least one of the intensity and emission frequency of the light emitted by the emitter based on the position information acquired by the first acquirer. According to this aspect, the detection device can preferably detect an object that should be preferentially detected depending on the position of the moving object.

[0013] In one aspect of the above detection device, the detection device further includes a second acquisition unit that acquires route information regarding the moving route of the moving object, and the control unit controls at least one of the intensity and frequency of emission of light emitted by the emission unit based on the position information and the route information. Generally, the direction in which an object to be detected with priority exists differs depending on the moving route (e.g., a route that turns right or a route that turns left, etc.). Therefore, according to this aspect, the detection device can take the moving route of the moving object into consideration and preferably detect an object existing in a direction with high detection priority.

[0014] In another aspect of the detection device, the control unit controls the emission unit so that the intensity and emission frequency of the light differ between the front and the sides of the moving object. This aspect makes it possible to preferably detect an object present in a direction that has a high priority for detection.

[0015] In another aspect of the detection device, the control unit controls the light so that the intensity of the light is higher and the frequency of emission is lower in the front of the moving body than in the sides of the moving body, thereby enabling the detection device to detect obstacles, etc. in front of the moving body early while satisfying eye-safety standards.

[0016] In another aspect of the detection device, when a sidewalk is present on the side of the moving object, the control unit controls the light intensity on the side where the sidewalk is present to be higher than on the opposite side. This aspect allows the detection device to preferably detect objects (e.g., pedestrians) present on the side of the sidewalk that require particular attention when driving.

[0017] In another aspect of the detection device, when a sidewalk is present on the side of the moving object, the control unit controls the frequency of the light emission on the side where the sidewalk is present to be higher than on the opposite side. This aspect allows the detection device to preferably detect objects (e.g., pedestrians) on the side of the sidewalk that require special attention when driving. This aspect also allows the detection device to preferably detect narrow features such as kilometer posts and signs.

[0018] In another aspect of the detection device, when the moving object makes a right turn, the control unit controls the light intensity to be higher on the front right side of the moving object than on the other side, and the frequency of the light emission to be lower. With this aspect, when the moving object makes a right turn, the detection device can quickly detect, for example, an oncoming vehicle traveling at high speed toward the right turn point.

[0019] In another aspect of the detection device, when the moving body makes a left turn, the control unit controls the left side of the moving body so that the intensity of the light is weaker and the frequency of the light emission is higher than that of the other side. This aspect allows the detection device to accurately detect pedestrians, motorcycles, etc. that may be hit when the moving body makes a left turn.

[0020] In another preferred embodiment of the present invention, a detection device that can be installed on a moving body includes an emitter that emits light, a light-receiving unit that receives the light reflected by an object, and a control unit that controls the emitter so that the intensity of the light emitted by the emitter in front of the moving body is higher than the intensity of the light emitted by the emitter to the sides of the moving body and the emission frequency of the emitter in the front is lower than the emission frequency to the sides. According to this aspect, the detection device can detect an obstacle, etc. in front of the moving body early while satisfying eye-safety standards.

[0021] In another preferred embodiment of the present invention, a control method is performed by a detection device that can be installed on a moving body and has an emitter that emits light and a light receiver that receives the light reflected by an object, the control method comprising: a first acquisition step of acquiring position information indicating the position of the moving body; and a control step of controlling at least one of the intensity and emission frequency of the light emitted by the emitter based on the position information. By executing this control method, the detection device can preferably detect an object that should be preferentially detected depending on the position of the moving body.

[0022] In another preferred embodiment of the present invention, a computer-executable program for a detection device that can be installed on a moving object includes an emitter that emits light and a light-receiving unit that receives the light reflected by an object, and the program causes the computer to function as a first acquirer that acquires position information indicating the position of the moving object and a controller that controls at least one of the intensity and frequency of light emitted by the emitter based on the position information. The detection device can be realized by executing this program on a computer. The program can be stored in a storage medium and used. [Example]

[0023] Preferred embodiments of the present invention will now be described with reference to the drawings.

[0024] [Object detection system overview] 1 is a schematic diagram of an object detection system according to this embodiment. The object detection system includes a Lidar (Light Detection and Ranging, or Laser Illuminated Detection and Ranging) 1 that moves with a vehicle, and an in-vehicle device 2 that can communicate with the Lidar 1.

[0025] The lidar 1 emits a pulsed laser within a predetermined angular range in the horizontal and vertical directions to discretely measure the distance to an object in the external world, generates three-dimensional point cloud information indicating the position of the object, and supplies this to the vehicle-mounted device 2. In this embodiment, the lidar 1 receives current position information, map information, and route information from the vehicle-mounted device 2, and changes the emission power and emission interval (i.e., emission frequency or scanning angular resolution) of the pulsed laser for each direction. The lidar 1 is an example of a "detection device" in the present invention.

[0026] The vehicle-mounted device 2 detects objects around the vehicle based on the point cloud information output by the LIDAR 1, controls the vehicle for driving assistance (including autonomous driving), and performs predetermined display and audio output. In this embodiment, the vehicle-mounted device 2 supplies current position information "IP", map information "IM", and route information "IR" to the LIDAR 1. Here, the vehicle-mounted device 2 may transmit position information output by a GPS receiver or the like to the LIDAR 1 as the current position information IP, or may transmit position information estimated by a known self-position estimation process using the output of the LIDAR 1 or another external sensor to the LIDAR 1 as the current position information IP. In addition, the vehicle-mounted device 2 transmits map information around the current position extracted from a map database to the LIDAR 1 as map information IM. In addition, the vehicle-mounted device 2 transmits information regarding the route to the set destination to the LIDAR 1 as route information IR.

[0027] 1 is an example, and the configuration to which the present invention can be applied is not limited to this. For example, instead of receiving the map information IM from the vehicle-mounted device 1, the LIDAR 1 may receive the map information IM via a network from a server device (not shown) that stores a map database. In another example, instead of receiving the current position information IP from the vehicle-mounted device 1, the LIDAR 1 may generate the current position information IP itself by including a GPS receiver or the like, or may generate the current position information IP by estimating its own position based on point cloud information or the like generated by the LIDAR 1.

[0028] The route information IR here is typically information about a route to a destination set by the vehicle-mounted device 2, but is not limited to this. For example, in addition to the route set by the user of the vehicle-mounted device 2, it may also be information indicating a predicted course (travel trajectory) along which the vehicle will travel in the future.

[0029] [Basic Rider Configuration] First, the basic configuration of the lidar according to the embodiment will be described.

[0030] (1) Overall structure 2 shows the overall configuration of a LIDAR according to an embodiment. The LIDAR 1 scans the surrounding space by appropriately controlling the emission direction (hereinafter referred to as the "scanning direction") of repeatedly emitted light pulses, and by observing the returned light, obtains information about objects present in the vicinity (e.g., distance, probability of existence, reflectivity, etc.). Specifically, the LIDAR 1 emits light pulses (hereinafter referred to as "emitted light Lo") and receives light pulses (hereinafter referred to as "returned light Lr") reflected by an external object (target), thereby generating information about the object.

[0031] 2, the lidar 1 is broadly composed of a system CPU 5, an ASIC 10, a transmitter 30, a receiver 40, and a scanning optical unit 50. The transmitter 30 repeatedly outputs laser light pulses with a width of approximately 5 nsec in response to a pulse trigger signal PT supplied from the ASIC 10. The light pulses output from the transmitter 30 are guided to the scanning optical unit 50.

[0032] The scanning optical unit 50 emits the optical pulses output by the transmitter 30 in an appropriate direction, and also collects the return light Lr that returns when the emitted light encounters an object in space and is reflected or scattered, and guides the collected light to the receiver 40. The scanning optical unit 50 is an example of an "emitting unit" in the present invention. The receiver 40 outputs a signal proportional to the intensity of the return light Lr to the ASIC 10. The receiver 40 is an example of a "light receiving unit" in the present invention.

[0033] The ASIC 10 analyzes the output signal of the receiver 40 to estimate and output parameters related to an object in the scanning space, such as its distance. The ASIC 10 also controls the scanning optical unit 50 so that an appropriate scan is performed. The ASIC 10 also supplies the high voltages required by the transmitter 30 and the receiver 40. The system CPU 5 performs at least the initial setting, monitoring, and control of the ASIC 10 through a communication interface. Other functions vary depending on the application. In the simplest case of a lidar, the system CPU 5 simply converts the target information TI output by the ASIC 10 into an appropriate format and outputs it. For example, the system CPU 5 converts the target information TI into a versatile point cloud format and then outputs it through a USB interface.

[0034] (2) Transmitter Transmitter 30 outputs an optical pulse with a width of approximately 5 nsec in response to a pulse trigger signal PT supplied from ASIC 10. The configuration of transmitter 30 is shown in Figure 3(A). Transmitter 30 includes a charging resistor 31, a driver circuit 32, a capacitor 33, a charging diode 34, a laser diode (LD) 35, and a CMOS switch 36.

[0035] The pulse trigger signal PT input from the ASIC 10 drives a switch 36 such as a CMOS transistor via a driver circuit 32. The driver circuit 32 is inserted to drive the switch 36 at high speed. During the non-assertion period of the pulse trigger signal PT, the switch 36 is open, and a capacitor 33 in the transmitter 30 is connected to the high voltage "V TX On the other hand, during the assertion period of the pulse trigger signal PT, the switch 36 closes and the charge stored in the capacitor 33 is discharged through the LD 35. As a result, an optical pulse is output from the LD 35.

[0036] (3) Receiver The receiver 40 outputs a voltage signal proportional to the intensity of the return light Lr from the object. Generally, photodetection elements such as PDs and APDs output a current, so the receiver 40 converts this current into a voltage (I / V conversion) and outputs it. The configuration of the receiver 40 is shown in FIG. 3(B). The receiver 40 includes an APD (Avalanche Photodiode) 41, an I / V conversion unit 42, a resistor 45, a capacitor 46, and a low-pass filter (LPF) 47. The I / V conversion unit 42 includes a feedback resistor 43 and an operational amplifier 44.

[0037] In this embodiment, an APD 41 is used as the photodetector element. The APD 41 receives a high voltage "V RX " is applied as a reverse bias, and a detection current proportional to the return light Lr from the object flows. Applying a reverse bias close to the breakdown voltage of the APD 41 achieves a high avalanche gain, making it possible to detect even weak return light. The final-stage LPF 47 is installed to limit the signal bandwidth before sampling by the ADC 20 in the ASIC 10. In this embodiment, the sampling frequency of the ADC 20 is 512 MHz, and the cutoff frequency of the LPF 47 is approximately 250 MHz.

[0038] (4) Scanning optical unit The scanning optical unit 50 emits the light pulse input from the transmitter 30 as emitted light Lo in an appropriate direction, and also guides the returned light Lr, which is returned when the emitted light Lo encounters an object in space and is reflected or scattered, to the receiver 40. An example configuration of the scanning optical unit 50 is shown in FIG. 4. The scanning optical unit 50 includes a rotating mirror 61, a collimator lens 62, a condenser lens 64, an optical filter 65, a coaxial mirror 66, and a rotary encoder 67.

[0039] The optical pulse output from the LD 35 of the transmitter 30 is incident on the collimator lens 62. The collimator lens 62 collimates the laser light to an appropriate divergence angle (generally about 0 to 1°). The light emitted from the collimator lens 62 is reflected vertically downward by a small coaxial mirror 66 and enters the rotation axis (center) of the rotating mirror 61. The rotating mirror 61 reflects the laser light incident from vertically above horizontally and emits it into the scanning space. The rotating mirror 61 is attached to the rotating part of the motor 54, and the laser light reflected by the rotating mirror 61 scans a horizontal plane as emitted light Lo as the motor 54 rotates.

[0040] The return light Lr, which returns to the lidar 1 after being reflected or scattered by an object in the scanning space, is reflected vertically upward by the rotating mirror 61 and enters the optical filter 65. In addition to the return light Lr, background light generated by the sun or other sources illuminating the object also enters the optical filter 65. The optical filter 65 is installed to selectively reject this background light. Specifically, the optical filter 65 selectively passes only components within a wavelength range of approximately ±10 nm around the wavelength of the emitted light Lo (905 nm in this embodiment). If the passband of the optical filter 65 is wide, much of the background light will enter the receiver 40 in the subsequent stage. As a result, a large DC current component will appear in the output of the APD 41 in the receiver 40. This DC component will undesirably degrade the signal-to-noise ratio (SN ratio) due to the impact of shot noise (background light shot noise) caused by the DC component. However, if the passband is too narrow, the emitted light itself will also be suppressed, which is undesirable. The condenser lens 64 condenses the light that has passed through the optical filter 65 and guides it to the APD 41 of the receiver 40 .

[0041] A rotary encoder 67 is attached to the motor 54 to detect the scanning direction. The rotary encoder 67 includes a rotating disk 68 attached to the motor rotating section and a code detector 69 attached to the motor base. Slits representing the rotation angle of the motor 54 are engraved on the outer periphery of the rotating disk 68, which are read and output by the code detector 69. The specific specifications of the rotary encoder 67 and motor control based on its output will be described later.

[0042] In the above configuration, the collimator lens 62 constitutes the transmitting optical system 51 shown in FIG. 2, the rotating mirror 61 and the motor 54 constitute the scanning unit 55 shown in FIG. 2, the optical filter 65 and the condenser lens 64 constitute the receiving optical system 52 shown in FIG. 2, and the rotary encoder 67 constitutes the scanning direction detection unit 53 in FIG. 2.

[0043] (5) ASIC The ASIC 10 controls the timing of emitted optical pulses and performs AD conversion of the APD output signal. The ASIC 10 also performs appropriate signal processing on the AD-converted output to estimate parameters related to the object (distance, return light intensity, etc.) and outputs the estimation results to the outside. As shown in Fig. 2, the ASIC 10 includes a register unit 11, a clock generation unit 12, a synchronization control unit 13, a gate extraction unit 14, a received segment memory 15, a DSP 16, a transmitter high voltage generation unit (TXHV) 17, a receiver high voltage generation unit (RXHV) 18, a preamplifier 19, an AD converter (ADC) 20, and a scan control unit 21.

[0044] The register unit 11 includes registers for communication with the system CPU 5, an external processor. The registers provided in the register unit 11 are broadly divided into R registers, which can only be referenced externally, and W registers, which can be set externally. The R registers mainly hold status values ​​within the ASIC, and the system CPU 5 can monitor the internal status of the ASIC 10 by reading these values ​​through the communication interface. On the other hand, the W registers hold various parameter values ​​referenced within the ASIC 10. These various parameter values ​​can be set by the system CPU 5 through the communication interface. The communication registers may be implemented using flip-flops or RAM.

[0045] The clock generation unit 12 generates a system clock "SCK" and supplies it to each block within the ASIC 10. Many blocks within the ASIC 10 operate in synchronization with the system clock SCK. In this embodiment, the frequency of the system clock SCK is 512 MHz. The system clock SCK is generated by a PLL so that it is synchronized with an externally input reference clock "RCK." Typically, a crystal oscillator is used as the source of the reference clock RCK.

[0046] The TXHV17 supplies the high voltage V required by the transmitter 30. TX This high voltage is generated by boosting the low voltage using a DC-DC converter circuit. As will be described later, the TXHV17 generates the high voltage V based on the control signal "Ct" supplied from the DSP16. TX is changed to adjust the voltage applied to the LD 35 in the transmitter 30.

[0047] The RXHV 18 generates a high DC voltage (about 100 V) required by the receiver 40. This high voltage is generated by boosting a low voltage (about 5 V to 15 V) using a DC-DC converter circuit.

[0048] The synchronization control unit 13 generates and outputs various control signals. In this embodiment, the synchronization control unit 13 outputs two control signals: a pulse trigger signal PT and an AD gate signal GT. An example of how these control signals are set is shown in FIG. 5, and their temporal relationships are shown in FIG. 6. As shown in FIG. 6, these control signals are generated in synchronization with time intervals (segment slots) divided at predetermined intervals. The time interval width (segment period) of the segment slots can be set using "nSeg." Here, the longer the segment period nSeg, the fewer the number of segment slots in a 360-degree scan of the emitted light Lo, and the coarser the emission interval of the emitted light Lo. On the other hand, the shorter the segment period nSeg, the more the number of segment slots in a 360-degree scan of the emitted light Lo, and the denser the emission interval of the emitted light Lo.

[0049] The pulse trigger signal PT is supplied to a transmitter 30 provided outside the ASIC 10. The transmitter 30 outputs an optical pulse in response to the pulse trigger signal PT. For the pulse trigger signal PT, a delay "dTrg" relative to the start of the segment slot and a pulse width "wTrg" can be set. Note that if the pulse width wTrg is too narrow, the transmitter 30 will not respond, so the pulse width wTrg is determined in consideration of the trigger response specifications of the transmitter 30.

[0050] The AD gate signal GT is supplied to a gate extraction unit 14. As will be described later, the gate extraction unit 14 extracts only the assertion period of the AD gate signal GT from the ADC output signal input from the ADC 20 and stores it in a received segment memory 15. For the AD gate signal GT, a delay time "dGate" relative to the start point of the segment slot and a gate width "wGate" can be set. Here, the longer the gate width wGate, the longer the maximum ranging distance (ranging limit distance) of the LIDAR 1.

[0051] Furthermore, in this embodiment, the synchronization control unit 13 changes the segment period nSeg based on the control signal "Cs" supplied from the DSP 16. Specifically, based on the control signal Cs, the synchronization control unit 13 sets the segment period nSeg shorter than the normal period (e.g., nSeg = 8192) in the scanning direction in which the emitted light Lo is densely emitted, and sets the segment period nSeg longer than the normal period in the scanning direction in which the emitted light Lo is sparsely emitted. In addition to this, the synchronization control unit 13 may set the gate width wGate longer than the normal width (e.g., wGate = 1024) in the scanning direction in which the emission power of the emitted light Lo is increased, thereby increasing the maximum ranging distance of the LIDAR 1, and may set the gate width wGate shorter than the normal width in the scanning direction in which the emission power of the emitted light Lo is decreased, thereby shortening the maximum ranging distance of the LIDAR 1.

[0052] The preamplifier 19 amplifies the analog voltage signal input from the receiver 40 installed outside the ASIC 10, and supplies the amplified signal to the subsequent ADC 20. The voltage gain of the preamplifier 19 can be set by the W register.

[0053] The ADC 20 converts the output signal of the preamplifier 19 into a digital series by AD conversion. In this embodiment, the system clock SCK is used as the sampling clock of the ADC 20, and the input signal to the ADC 20 is sampled at 512 MHz.

[0054] The gate extraction unit 14 extracts only the assertion interval of the AD gate signal GT from the ADC output signal input from the ADC 20 and stores it in the received segment memory 15. The interval signal extracted by the gate extraction unit 14 is hereinafter referred to as the "received segment signal RS." That is, the received segment signal RS is a real vector whose vector length is equal to the gate width wGate.

[0055] Here, we will explain the relationship between the ADC output signal and the received segment, and the setting of the gate position. Figure 7(A) shows a segment slot. As shown in Figure 7(B), the pulse trigger signal PT is asserted with a delay of dTrg from the start of the segment slot. In the example of Figure 7, since "dTrg=0", the pulse trigger signal PT is asserted at the start of the segment slot. Figure 7(C) shows the ADC output signal (received segment signal RS) when an object is placed at the scanning origin of the lidar. That is, Figure 7(C) illustrates the received segment signal RS when the target distance (radius R) is 0 m. As shown in the figure, even when R=0 m, the rising edge of the received pulse occurs with a system delay D from the rising edge of the pulse trigger signal. SYS The observation is delayed by the system delay D SYS Possible causes of this include an electrical delay in the LD driver circuit in the transmitter 30, an optical delay in the transmission optical system 51, an optical delay in the reception optical system 52, an electrical delay in the receiver 40, and a conversion delay in the ADC 20.

[0056] Figure 7(D) shows an example of the received segment signal RS when the object is placed at radius R. In this case, compared to Figure 7(C), the delay increases by the round-trip time of light from the scanning origin to the object. This increased delay is the so-called "TOF (Time Of Flight) delay." If this TOF delay is D samples, the radius R can be calculated using the following formula.

[0057]

number

[0058]

number

[0059] Note that instead of the example in Fig. 7, the gate delay dGate may be set equal to the system delay time, which enables valid parameter estimation even for objects at greater distances.

[0060] The scanning control unit 21 monitors the output of a rotary encoder 67 installed outside the ASIC 10 and controls the rotation of the motor 54 based on this output. Specifically, the scanning control unit 21 supplies a torque control signal "TC" to the motor 54 based on the scanning direction information "SDI" output from the rotary encoder 67 (scanning direction detection unit 53) of the scanning optical unit 50. In this embodiment, the rotary encoder 67 outputs two pulse trains (hereinafter referred to as "encoder pulses"), one for the A phase and one for the Z phase. The time relationship between these two pulse trains is shown in FIG. 8A. As shown in the figure, for the A phase, one pulse is generated and output for every 1° of rotation of the motor 54. Therefore, 360 A-phase encoder pulses are generated and output for every rotation of the motor 54. On the other hand, for the Z phase, one pulse is generated and output for every rotation of the motor 54, corresponding to a predetermined rotation angle.

[0061] The scanning control unit 21 measures the rising time of the encoder pulse as a counter value of the system clock SCK and controls the torque of the motor 54 so that this becomes the desired value. In other words, the scanning control unit 21 PLL controls the motor 54 so that the encoder pulse and the segment slot have the desired time relationship.

[0062] The time relationship between the encoder pulse and the segment slot can be set using the W register shown in Figure 8(B). "nPpr" is set to the number of A-phase encoder pulses per motor revolution. This value is determined by the specifications of the rotary encoder 67, and in this embodiment, it is set to the aforementioned 360. "nRpf" specifies the number of rotations per frame, and "nSpf" specifies the number of segments per frame. "dSmpA" and "dSmpZ" are provided to adjust the time relationship between the rising edge of the encoder pulse and the segment slot in sample clock units, and can specify the delay of the encoder pulse relative to the start of the segment slot. Meanwhile, "dSegZ" is provided to adjust the time relationship between the rising edge of the Z-phase pulse and the frame in segment units.

[0063] The time relationship between the encoder pulses and segment slots in the steady state is shown in Figure 9. As shown in the figure, in the default settings, one frame consists of 1800 segments, and one frame means that the motor 54 makes one rotation.

[0064] (6) DSP First, the DSP 16 reads the received segment "y" from the received segment memory 15. frm,seg Here, "frm" is the frame index and "seg" is the segment index. Below, we will omit the notation of these indexes to avoid any misunderstanding.

[0065] 10(A) shows a block diagram of the signal processing performed by the DSP 16. As shown in the figure, the DSP 16 comprises a receiving filter 71, a peak detector 72, a decision unit 73, and a formatter 74. The DSP 16 sequentially reads out the received segment y from the received segment memory 15 and processes it. The received segment y is a real vector with a vector length wGate and is expressed by the following equation:

[0066]

number

[0067] The receiving filter unit 71 convolves (circular convolution) a predetermined impulse response h with the received segment y to calculate a filtered segment z. The impulse response of the receiving filter unit 71 can be set by the W register, and is set in advance by the system CPU 5 so that the SNR at the filter output is large.

[0068] For example, the filter impulse response h is set to satisfy the following equation: By setting it in this way, optimal performance (high SNR) can be achieved when the noise is white and the system overall impulse response is significantly shorter than wGate.

[0069]

number

[0070] The peak detector 72 detects the point where the amplitude is maximum within the filtered segment, i.e., the peak point, with sub-sample accuracy and outputs the delay D and amplitude A of the peak point. The decision unit 73 determines whether an object is present at the detected point based on the peak point information D and A (delay D, amplitude A) output from the peak detector 72. This determination is made by comparing the peak point amplitude A with a determination threshold tDec. Specifically, if A > tDec, the decision unit 73 determines that an object is present and outputs the peak point information. On the other hand, if A ≦ tDec, the decision unit 73 determines that an object is not present and does not output the peak point information. The formatter 74 converts the peak point information D and A output from the decision unit 73 and the scanning information (frame index frm, segment index seg) corresponding to the peak point into a format that is easy for the user (host system) to use.

[0071] The cyclic convolution operation of the receive filter 71 may be realized in the frequency domain using DFT. This allows for a significant reduction in the amount of calculation. In this case, instead of making the impulse response h settable using the W register, it is preferable to perform a DFT operation on the impulse response h in advance to obtain the frequency response H, thereby making the frequency response H settable. Figure 10(B) shows a block diagram of the signal processing performed by the DSP 16 when the cyclic convolution operation of the receive filter 71 is realized in the frequency domain using DFT.

[0072] Furthermore, the DSP 16 performs control (also simply referred to as "emission control") to adjust the emission power and emission interval (i.e., scanning angle resolution) of the emitted light Lo according to the scanning direction of the emitted light Lo. In this case, the DSP 16 performs the emission control using control signals Ct and Cs.

[0073] Specifically, first, the DSP 16 detects the scanning direction based on the scanning direction information SDI received from the scanning direction detection unit 53. Then, the DSP 16 controls the high voltage V generated by the TXHV 17 in accordance with the detected scanning direction. TXThe DSP 16 adjusts the emission power of the LD 35 by supplying a control signal Ct to the TXHV 17 for adjusting the segment period nSeg. Furthermore, the DSP 16 adjusts the emission interval by supplying a control signal Cs to the synchronization control unit 13 for adjusting the segment period nSeg according to the detected scanning direction. In this case, for example, the DSP 16 adjusts the high voltage V to be set for each scanning direction. TX A table showing combinations of the segment period nSeg and the control signals Ct and Cs are stored in advance in a W register or the like, and the control signals Ct and Cs are generated according to the detected scanning direction by referring to the table. Note that specific settings of the emission power and emission interval of the emitted light Lo for each scanning direction will be explained in the next section. Note that the DSP 16 is an example of the "first acquisition unit," "second acquisition unit," and "control unit" of the present invention, and a computer that executes the program of the present invention.

[0074] [Setting the injection power and injection interval according to the scanning direction] Next, an example of setting the emission power and emission interval according to the scanning direction will be described. During normal vehicle driving, the DS16 executes a control mode (also called "normal mode") in which light is emitted uniformly (with the same intensity and frequency) in all directions. In this embodiment, the DSP16 may execute the following first to fourth control modes instead of the normal mode. Below, examples of setting the emission power and the emission interval will be described.

[0075] (1) Settings in the first control mode Fig. 11 is a plan view of the vicinity of a vehicle, which schematically shows the emission power and emission interval of the emitted light Lo during 360-degree scanning in the first control mode using dashed arrows. In Fig. 11, the length of the dashed arrows indicates the emission power, and the interval between the dashed arrows indicates the emission interval (emission frequency) of the emitted light Lo. Note that the length of the dashed arrows shown in Fig. 11 does not indicate the range that the emitted light Lo actually reaches, and the number of dashed arrows does not match the number of emitted light beams Lo actually emitted during 360-degree scanning.

[0076] As shown in FIG. 11, in the first control mode, the DSP 16 increases the emission power of the emitted light Lo in the forward direction of the vehicle (in a range of approximately 30 degrees to the left and right of the traveling direction in FIG. 11) and decreases the interval between the emitted light Lo (i.e., decreases the scanning angle resolution). In this way, the DSP 16 increases the emission power of the emitted light Lo emitted in the forward direction of the vehicle from the viewpoint of detecting obstacles at a greater distance than usual. Also, in this case, the DSP 16 decreases the emission power of the emitted light Lo emitted in the forward direction of the vehicle from the viewpoint of eye-safety and the like. This allows the DSP 16 to preferentially detect relatively large objects located ahead within a distance range equal to or greater than the braking distance, while favorably satisfying the eye-safety standard. In other words, it becomes possible to detect objects in front of the vehicle that are farther away than those to the side or rear, while favorably satisfying the eye-safety standard.

[0077] 11, in the first control mode, the DSP 16 weakens the emission power of the emitted light Lo and emits the emitted light Lo coarsely in the rearward direction of the vehicle (in FIG. 11, directions of about 30 degrees to the left and right of the backward movement direction). In this way, the DSP 16 prevents unnecessary detection of distant objects present behind the vehicle in the rearward direction, where obstacle detection is relatively less necessary.

[0078] Furthermore, as shown in FIG. 11 , in the first control mode, the DSP 16 weakens the emission power of the emitted light Lo in the lateral directions (right and left lateral directions) of the vehicle and narrows the intervals between the emitted light Lo (i.e., increases the scanning angle resolution). Generally, objects that exist far away in the lateral directions are far from the road and therefore do not need to be detected. On the other hand, kilometer posts, other signs, billboards, etc. that exist relatively close in the lateral directions need to be detected as landmarks for self-localization, for example, and may have a relatively thin shape. In addition, moving objects that exist in the lateral directions (e.g., vehicles in other lanes, pedestrians on the sidewalk, etc.) also need to be detected from the perspective of obstacle detection. Furthermore, simply increasing the emission frequency alone may result in failure to meet the eye-safety standards. Taking the above into consideration, DSP16 detects relatively close objects to the side of the vehicle with high accuracy while preferably satisfying the eye-safety standards by making the emission power of the emitted light Lo weaker than usual and emitting the emitted light Lo densely in the side direction of the vehicle.

[0079] (2) Settings in 2nd to 4th control modes Next, an example of setting the emission power and emission interval for each scanning direction when a predetermined condition is satisfied will be described. Below, three modes (second to fourth control modes) will be described in order as specific examples.

[0080] (2-1) When driving on a road adjacent to a sidewalk When the DSP16 detects, based on the current position information IP and the map information IM, that the vehicle is traveling on a road adjacent to a sidewalk (in the case of a road with multiple lanes, the lane closest to the sidewalk), it controls the emission power and scanning angle resolution of the emitted light Lo in the second control mode described below. In this case, for example, the DSP16 recognizes the road on which the vehicle is currently traveling based on the current position information IP and the map information IM, and determines whether or not there is a sidewalk adjacent to the road by referring to the map information IM.

[0081] 12 is a plan view of the vicinity of the vehicle, in which the emission power and emission interval of the emitted light Lo during 360-degree scanning in the second control mode are schematically shown by dashed arrows. In the example of FIG. 12, the DSP 16 recognizes, based on the current position information IP and the map information IM, that the vehicle is traveling in a lane 81 adjacent to a sidewalk 80 registered in the map information IM, and executes the second control mode.

[0082] 12, the DSP16 makes the emission power of the emission light Lo slightly stronger in the left side direction, which is the lateral direction where the sidewalk 80 exists, than in the right side direction, and also emits the emission light Lo densely (i.e., with a high scanning angle resolution). In other words, the DSP16 emits the emission light Lo densely in the left side direction, while increasing the emission power of the emission light Lo within a range that satisfies the eye-safety criteria.

[0083] In this way, in the second control mode, the DSP 16 makes the emission power of the emitted light Lo in the left side direction where the sidewalk 80 exists stronger than the emission power of the emitted light Lo in the opposite right side direction, and makes the scanning angle resolution of the emitted light Lo in the left side direction higher than the scanning angle resolution of the emitted light Lo in the opposite right side direction. In this way, the DSP 16 can suitably improve the accuracy of detecting objects on the sidewalk where pedestrians and the like who need to be accurately captured for safety purposes exist.

[0084] In the second control mode, the DSP16 may increase the emission power of the emitted light Lo and increase the interval between the emitted light Lo (i.e., decrease the scanning angle resolution) in the forward direction of the vehicle, similar to the first control mode described above. As a result, the DSP16 preferentially detects relatively large obstacles located ahead within a distance range equal to or greater than the braking distance while satisfying the eye-safety criteria, similar to the first control mode. In the second control mode, the DSP16 may decrease the emission power of the emitted light Lo and increase the interval between the emitted light Lo in the backward direction of the vehicle, where the need for obstacle detection is relatively low, similar to the first control mode.

[0085] (2-2) Turning right at an intersection When DSP16 detects, based on current position information IP, map information IM, and route information IR, that the vehicle is approaching within a predetermined distance an intersection where the vehicle should turn right, it performs ejection control in a third control mode, which will be described below. In this case, for example, DSP16 recognizes the road on which the vehicle is currently traveling based on the current position information IP and map information IM, and determines, based on the route information IR, whether or not there is a right-turn point on the recognized road. If DSP16 determines that there is a right-turn point, it then determines whether or not the distance from the current position to the right-turn point is within a predetermined distance, and if the distance is within the predetermined distance, it executes the third control mode.

[0086] 13 is a plan view of the vicinity of the vehicle, in which the emission power and emission interval of the emitted light Lo during 360-degree scanning in the third control mode are schematically shown by dashed arrows. In the example of FIG. 13, the DSP 16 recognizes that the vehicle has approached within a predetermined distance an intersection 82 corresponding to the next right turn point based on the current position information IP, map information IM, and route information IR, and executes the third control mode.

[0087] In the example of FIG. 13, the DSP 16 increases the emission power of the emitted light Lo more than usual in the right forward direction (a direction within approximately 45 degrees to the right of the straight-ahead direction in FIG. 13), which is the direction in which an oncoming vehicle is estimated to be present. Also, in consideration of satisfying the eye-safe standard, the emitted light Lo is emitted coarsely (i.e., the scanning angle resolution is low). In this way, in the third control mode, when turning right, when oncoming vehicles should be detected with priority, the emission power is increased more than usual, taking into consideration cases in which oncoming vehicles are moving at high speed, so that oncoming vehicles that are located at a certain distance can also be detected. This enables the DSP 16 to preferably detect oncoming vehicles while preferably complying with the eye-safe standard.

[0088] In the example of Figure 13, DSP16 sets the emission power and scanning angle resolution of the emitted light Lo to normal settings or settings lower than normal in directions other than the right front direction, which is a direction in which an oncoming vehicle is estimated to be present.

[0089] (2-3) Turning left at an intersection When the DSP 16 detects, based on the current position information IP, map information IM, and route information IR, that the vehicle is approaching within a predetermined distance an intersection where the vehicle should turn left, it controls the emission power and scanning angle resolution of the emitted light Lo in a fourth control mode described below. In this case, for example, the DSP 16 recognizes the road the vehicle is currently traveling on based on the current position information IP and map information IM, and determines, based on the route information IR, whether or not there is a left-turn point on the recognized road. Then, when the DSP 16 determines that there is a left-turn point, it determines whether or not the distance from the current position to the left-turn point is within a predetermined distance, and if the distance is within the predetermined distance, it executes the fourth control mode.

[0090] 14 is a plan view of the vicinity of the vehicle, in which the emission power and scanning angle resolution of the emitted light Lo during 360-degree scanning in the fourth control mode are schematically shown by dashed arrows. In the example of FIG. 14, the DSP 16 recognizes that the vehicle is approaching within a predetermined distance an intersection 83 corresponding to the next left turn point based on the current position information IP, map information IM, and route information IR, and executes the fourth control mode.

[0091] In the example of Figure 14, DSP16 weakens the emission power in the left side direction (a range of approximately 120 degrees centered on the left direction of the vehicle in Figure 14), which is the direction in which it is estimated that there are pedestrians crossing the crosswalk going straight through the intersection 83, motorcycles going straight through the intersection 83, etc., and emits the emitted light Lo densely.

[0092] Generally, when turning left, it is necessary to give priority to detecting relatively close objects on the left side of the vehicle in order to prevent pedestrians and motorcycles, particularly those crossing the road, from being hit. Taking this into consideration, in the fourth control mode, the emission power is weakened compared to normal in the left side direction, while the scanning angle resolution is increased so that pedestrians and motorcycles crossing the road can be reliably detected. This allows the DSP16 to accurately detect pedestrians, motorcycles, and other objects requiring caution when turning left, while satisfies the eye-safety standards.

[0093] In the example of FIG. 14, the DSP 16 sets the emission power and scanning angle resolution of the emitted light Lo to normal settings or settings lower than normal in directions other than the left side direction.

[0094] As described above, the LIDAR 1 according to the embodiment includes the scanning unit 55 that emits emitted light Lo in response to the pulse trigger signal PT, the APD 41 that receives return light Lr of the emitted light Lo, and the DSP 16. The DSP 16 acquires current position information IP indicating the position of the vehicle from the onboard device 2. Then, the DSP 16 controls the intensity and emission frequency of the emitted light Lo emitted by the scanning unit 55 based on the current position information IP, etc. This allows the LIDAR 1 to suitably improve the object detection performance required for autonomous driving, etc.

[0095] [Variations] Next, preferred modifications of the embodiment will be described. The following modifications may be applied in combination to the above-described embodiment.

[0096] (Variation 1) Instead of receiving route information IR and the like from the in-vehicle device 2, the DSP 16 may receive turn signal information from the vehicle using a predetermined communication protocol such as CAN to determine whether or not to execute the third or fourth control mode.

[0097] In this case, the DSP 16 determines that the third control mode should be executed when turn signal information indicating a right turn is received, and determines that the fourth control mode should be executed when turn signal information indicating a left turn is received. This configuration also allows the rider 1 to appropriately detect that the vehicle is approaching a right turn point or a left turn point, and executes ejection control appropriate for the situation. In this case, the turn signal information is an example of "route information" in the present invention.

[0098] (Variation 2) The DSP 16 may control only either the emission power or the emission interval of the emitted light Lo as the emission control.

[0099] For example, when adjusting only the emission power of the emitted light Lo, the DSP16 makes the emission power in the forward direction stronger than the emission power in other directions in the first control mode, and makes the emission power in the right-forward direction stronger than the emission power in other directions in the third control mode. Furthermore, when adjusting only the emission interval of the emitted light Lo, the DSP16 emits the emitted light Lo more densely in the side direction than in other directions in the first control mode, and emits the emitted light Lo more densely in the left side direction than in other directions in the second and fourth control modes. Thus, even with this modification, the DSP16 can preferably improve the detection accuracy of an object that should be detected with priority. [Explanation of symbols]

[0100] 1 Rider 2 On-vehicle device 10 ASIC 16 DSP 17 Transmitter high voltage generator (TXHV) 18 Receiver high voltage generator (RXHV) 30 Transmitters 35LD 40 Receiver 50 Scanning optical unit

Claims

1. A detection device that can be placed on a moving body, an emission unit that emits light; a light receiving unit that receives the light reflected by an object, A detection device in which the emission interval of the light emitted into a certain angular range in front of the moving body is closer than that of other angular ranges different from the certain angular range, or the intensity of the light emitted into a certain angular range in front of the moving body is higher than that of other angular ranges different from the certain angular range.

2. A detection device that can be placed on a moving body, an emission unit that emits light; a light receiving unit that receives the light reflected by an object; a control unit that controls at least one of the emission interval and intensity of the light emitted by the emission unit, The control unit controls the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is closer than in other angular ranges different from the certain angular range, or controls the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is higher than in other angular ranges different from the certain angular range.

3. a first acquisition unit that acquires location information indicating a location of the moving object; 2. The detection device according to claim 1, wherein the emitter emits the light at a closer emission interval in a partial angular range in front of the moving body than in other angular ranges different from the partial angular range, based on the position information, or emits the light at a higher intensity in a partial angular range in front of the moving body than in other angular ranges different from the partial angular range.

4. The detection device according to claim 1, wherein the emission unit emits the light in a partial angular range ahead of the moving body at a closer emission interval than in other angular ranges different from the partial angular range, based on the presence or absence of a specific point on the road, or emits the light in a partial angular range ahead of the moving body at a higher intensity than in other angular ranges different from the partial angular range.

5. a first acquisition unit that acquires location information indicating a location of the moving object; The detection device described in claim 2, wherein the control unit controls, based on the position information, the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is closer than in other angular ranges different from the certain angular range, or controls the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is higher than in other angular ranges different from the certain angular range.

6. The detection device described in claim 2, wherein the control unit controls the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is closer than other angular ranges different from the certain angular range, based on the presence or absence of a specific point on the road, or controls the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is higher than other angular ranges different from the certain angular range.

7. a second acquisition unit that acquires route information relating to a travel route of the moving object; The detection device described in claim 3, wherein the emission unit emits the light at a closer emission interval in a partial angular range in front of the moving body than in other angular ranges different from the partial angular range, based on the position information and the path information, or emits the light at a higher intensity in a partial angular range in front of the moving body than in other angular ranges different from the partial angular range.

8. a second acquisition unit that acquires route information relating to a travel route of the moving object; The detection device described in claim 5, wherein the control unit controls, based on the position information and the path information, the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is closer than in other angular ranges different from the certain angular range, or controls the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is higher than in other angular ranges different from the certain angular range.

9. The detection device according to claim 1 , wherein the partial angle range is adjacent to another angle range different from the partial angle range.

10. The detection device according to claim 3 or 7, wherein the emission section varies the interval at which the light is emitted and the intensity of the light in front of the moving body and to the sides of the moving body.

11. The detection device according to claim 10 , wherein the emission section emits the light to the sides of the moving body so that the intensity of the light is high in front of the moving body and the emission intervals are sparse.

12. The detection device according to claim 7, wherein the emission unit emits light so that, when the moving body turns right, the intensity of the light is higher on the front right side of the moving body than on the other side, and the emission interval of the light is wider.

13. 13. The detection device according to claim 7, wherein the emission unit emits the light so that, when the moving body turns left, the intensity of the light is higher on the left side of the moving body than on the other side, and the emission intervals of the light are wider.

14. A control method executed by a detection device that can be placed on a moving body, the detection device having an emission unit that emits light, a light receiving unit that receives the light reflected by an object, and a first acquisition unit that acquires position information that indicates a position of the moving body, the method comprising: a control step of controlling at least one of an emission interval and an intensity of the light emitted by the emission unit, The control process is a control method in which, based on the position information, the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body is controlled so that it is closer than in other angular ranges different from the certain angular range, or the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body is controlled so that it is higher than in other angular ranges different from the certain angular range.

15. A program executed by a computer of a detection device that can be placed on a moving body, the detection device having an emission unit that emits light, a light receiving unit that receives the light reflected by an object, and a first acquisition unit that acquires position information that indicates a position of the moving body, the emission unit controls at least one of the intensity and emission frequency of the emitted light, A program that controls the emission interval of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is closer than other angular ranges different from the certain angular range, or controls the intensity of the light emitted by the emission unit into a certain angular range in front of the moving body so that it is higher than other angular ranges different from the certain angular range.

16. A storage medium storing the program according to claim 15.

Images