Lidar apparatus and control method thereof

Abstract

The present invention provides a LiDAR device comprising: a light source that emits pulsed light; a light detection unit that detects reflected light that is reflected back from an object after the pulsed light is reflected by the object; a mirror having a plurality of reflective surfaces that reflects the pulsed light to the object and reflects the reflected light to the light detection unit; a motor that rotates the mirror; an encoder that detects the rotational position of the mirror and outputs a detection signal; and a control unit that controls the emission timing of the light source and the detection time of the light detection unit using the detection signal.

Description

Technology Field

[0001] The present invention relates to a lidar device and a method for controlling the same. Background Technology

[0003] Recently, in the fields of autonomous and intelligent vehicles, there is a growing demand for vehicles to proactively respond to unexpected situations. Specifically, it is necessary to identify situations that threaten the safety of drivers and pedestrians in advance, such as recognizing the sudden appearance of pedestrians, detecting obstacles in areas beyond the lighting range during dark nights, detecting obstacles caused by weakened headlight illumination during rain, or detecting road damage beforehand.

[0004] In response to these demands, automotive LiDAR (Light Detection And Ranging) devices have been developed. LiDAR devices are installed on the vehicle's windshield or at the front to acquire images of the area in front of the vehicle based on their own emitted light. When the vehicle is moving, the LiDAR device can identify objects ahead and warn the driver in advance. The LiDAR device transmits images to the vehicle's Electronic Control Unit (ECU), which serve as the basis for the vehicle to stop or avoid obstacles. The ECU then performs various control operations using the images received from the LiDAR device.

[0005] A LiDAR device detects an object by measuring the time difference between the pulsed light emitted from a light source and the reflected light returning from the object, thereby calculating the distance from the LiDAR device to the object.

[0006] Lidar devices are classified into mechanical (rotary) lidar devices with mirrors and flash lidar devices without mirrors, depending on the presence or absence of mirrors. Here, mechanical lidar devices require a motor to rotate the mirror, and the motor must rotate at a constant speed to maintain the horizontal resolution of the lidar device at a certain level.

[0007] Generally, mechanical lidar devices ensure constant rotation of the motor by having the control unit receive feedback on the motor's rotational speed and adjust the motor control signal according to the motor's rotational speed.

[0008] However, this method has the problem of not being able to satisfy the specifications of a LiDAR device that requires jitter performance of 0.5% or less. The problem to be solved

[0010] The present invention aims to provide a lidar device and a control method thereof that can not only improve the horizontal resolution of the lidar device but also reduce the manufacturing cost of the lidar device by enabling the use of a relatively low-spec motor in the lidar device.

[0011] In addition, according to the present invention, the purpose is to provide a LiDAR device and a control method thereof that can block the detection of noise signals unnecessary for object detection and reduce the data capacity for detection signal processing.

[0012] The technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0014] To achieve the aforementioned objective, the present invention provides a LiDAR device comprising: a light source that emits pulsed light; a light detection unit that detects reflected light that is reflected back from an object after the pulsed light is reflected by the object; a mirror having a plurality of reflective surfaces that reflects the pulsed light to the object and reflects the reflected light to the light detection unit; a motor that rotates the mirror; an encoder that detects the rotational position of the mirror and outputs a detection signal; and a control unit that controls the emission timing of the light source and the detection time of the light detection unit using the detection signal.

[0015] Here, the control unit controls the light source to emit pulsed light when a detection signal is input from the encoder.

[0016] In addition, the control unit controls the light source to emit pulsed light at each rotational position of the reflector.

[0017] In addition, the control unit controls the light detection unit to detect reflected light during at least a portion of the output section of the detection signal.

[0018] In addition, the mirror is made of a polyhedron with multiple reflective surfaces arranged on its side.

[0019] In addition, the reflector and the encoder are coupled to the rotation axis of the motor and rotate together with the rotation axis.

[0020] Additionally, the encoder is a magnetic encoder comprising a multi-pole magnet and a Hall sensor, or an optical encoder comprising a slit member having a plurality of slits and a photodiode.

[0021] In addition, the present invention provides a control method for a LiDAR device comprising the steps of: a light source emitting pulsed light; a reflector reflecting the pulsed light and transmitting it to an object; the pulsed light being reflected by the object; the reflector reflecting the reflected light from the object and transmitting it to a light detection unit; the light detection unit detecting the reflected light; a motor rotating the reflector; an encoder detecting the rotational position of the reflector and outputting a detection signal; and a control unit controlling the emission timing of the light source and the detection time of the light detection unit using the detection signal. Effects of the invention

[0023] According to the present invention, even if the motor does not rotate at a constant speed, the encoder detects a specific rotational position of the reflector, and the control unit controls the light source to emit pulsed light at the detected specific rotational position, thereby not only improving the horizontal resolution of the lidar device but also enabling the use of a relatively low-spec motor in the lidar device, which can reduce the manufacturing cost of the lidar device.

[0024] In addition, according to the present invention, by detecting reflected light only during a specific detection time when the light-sensing unit is highly likely to receive reflected light, it is possible to block the detection of noise signals that are unnecessary for object detection and to reduce the data capacity for detection signal processing.

[0025] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0027] FIG. 1 is a schematic block diagram of a lidar device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a reflector, motor, and encoder of a lidar device according to an embodiment of the present invention. FIG. 3 is a graph illustrating, respectively, a detection signal (a) output by an encoder according to a specific rotational position of a reflector, an emission signal (b) of a light source output by a control unit according to the detection signal, and a detection signal (c) in which a light detection unit detects reflected light during a specific section of the output section of the detection signal in a lidar device according to an embodiment of the present invention. FIG. 4 is a flowchart of a control method for a lidar device according to an embodiment of the present invention. Specific details for implementing the invention

[0028] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts unrelated to the explanation have been omitted to clearly explain the present invention, and the same reference numerals have been used for identical or similar components throughout the specification.

[0029] In this specification, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0031] FIG. 1 is a schematic block diagram of a lidar device according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of a reflector, motor, and encoder of a lidar device according to an embodiment of the present invention.

[0032] As illustrated in FIG. 1, a lidar device according to an embodiment of the present invention may be configured to include a light source (110), a light detection unit (120), a reflector (130), a motor (140), an encoder (150), and a control unit (160).

[0033] The light source (110) emits pulsed light toward the reflector (130) to detect an object, and the light detection unit (120) detects the reflected light that returns after the pulsed light is reflected from the object.

[0034] A lidar device according to an embodiment of the present invention detects an object by measuring the time difference between pulsed light and reflected light and calculating the distance from the lidar device to the object.

[0035] The light source (110) may be a single-channel light source that emits single-channel pulse light or a multi-channel light source that emits multiple pulse lights of different channels.

[0036] The reflector (130) has a plurality of reflective surfaces and reflects pulsed light emitted from the light source (110) to transmit it to an object, and reflects the reflected light that is reflected back from the object to transmit it to the light detection unit (120). Here, the reflector (130) may be formed as a polyhedron with a plurality of reflective surfaces arranged on its sides. For example, as shown in FIG. 2, the reflector may be formed as a hexahedron with reflective surfaces provided on each of its four sides.

[0037] The reflector (130) can rotate 360 ​​degrees by the rotational force of the motor (140).

[0038] The light source (110) is positioned to face the reflective surface provided in the reflector (130) and emits pulsed light toward the reflective surface. Here, the light source (110) may be positioned on a printed circuit board.

[0039] Although not illustrated in the drawings, the lidar device according to an embodiment of the present invention may further include a collimation lens positioned between the light source (110) and the reflector (130) to improve the directivity of the pulsed light emitted from the light source (110).

[0040] Here, the collimation lens prevents the pulse light emitted from the light source (110) from being scattered or dispersed while reaching the reflective surface of the mirror (130).

[0041] The light source (110) is positioned at a certain distance from the reflector (130) so as not to be affected by vibrations caused by the rotation of the reflector (130).

[0042] The light detection unit (120) is positioned to face the reflective surface of the reflector (130) and receives reflected light reflected from the reflective surface.

[0043] The motor (140) rotates the mirror (130) 360 degrees, and the encoder (150) detects the rotation position, i.e., the rotation angle of the mirror (130) and outputs a detection signal.

[0044] Here, the encoder (150) may be formed in the shape of a disc having a center of rotation. Additionally, the encoder (150) may be a magnetic encoder including a multi-pole magnet (151) and a Hall sensor (152) as shown in FIG. 1, or an optical encoder including a slit member in which a plurality of slits are arranged radially and a photodiode, but is not limited thereto, and it is sufficient if it is an encoder capable of detecting the rotational position of the mirror (130).

[0045] A magnetic encoder detects the rotation angle of a mirror (130) by detecting the direction of a rotating multi-pole magnet (151) using a Hall sensor (152). Here, the multi-pole magnet (151) may consist of four or more poles and be arranged radially. Additionally, an optical encoder detects the rotation angle of a mirror (130) by detecting light that has passed through a slit using a photodiode.

[0046] The reflector (130) and encoder (150) are coupled to the rotation axis of the motor (140) and rotate together with the rotation axis (141).

[0047] Referring to FIG. 2, an encoder (150) is coupled to a base plate (143), and a motor (140) is coupled to the encoder (150). Then, a reflector (130) has a receiving space formed to accommodate the motor (140) and the encoder (150), and the bottom is open so that the motor (140) and the encoder (150) can be inserted into this receiving space.

[0048] Here, when the motor (140) and encoder (150) are accommodated in the receiving space of the reflector (130), the reflector (140) and the motor (150) are joined through the flange (142) on the upper part of the motor.

[0049] The control unit (160) receives a detection signal from the encoder (150) and uses the received detection signal to control the emission timing of the light source (110) and the detection time of the light detection unit (120).

[0050] Specifically, the control unit (160) controls the light source (110) to emit pulsed light when a detection signal is input from the encoder (150). Additionally, the control unit (160) controls the light source (110) to emit pulsed light at each rotational position of the reflector (130).

[0051] The control unit (160) controls the light detection unit (120) to detect reflected light during at least a portion of the output section of the detection signal.

[0053] FIG. 3 is a graph illustrating, respectively, a detection signal (a) output by an encoder according to a specific rotational position of a reflector, an emission signal (b) of a light source output by a control unit according to the detection signal, and a detection signal (c) in which a light detection unit detects reflected light during a specific section of the output section of the detection signal in a lidar device according to an embodiment of the present invention.

[0054] In Figure 3, the horizontal axis represents time, and the vertical axis represents the magnitude of the signal (voltage).

[0055] First, referring to FIG. 3(a), the encoder (150) detects specific rotation positions of the mirror (130) at regular or irregular intervals when the mirror (130) rotates. At this time, when the mirror (130) is rotated using a relatively low-spec motor (150), the mirror (130) does not rotate at a constant speed, so the intervals of specific rotation positions may be irregular.

[0056] And, the encoder (150) outputs a high-level detection signal whenever it detects a specific rotational position of the mirror (130). At this time, the high-level detection signal may be sustained for a certain period of time.

[0057] Next, referring to FIG. 3 (a) and (b), the control unit (160) receives a detection signal from the encoder (150) and controls the light source (110) so that a pulse light is emitted whenever a high-level detection signal is input or at a certain interval of input of a high-level detection signal. For example, as shown in the drawing, the control unit (160) can control the light source so that a pulse light is emitted whenever an odd-numbered high-level detection signal is input (indicated by an arrow).

[0058] Additionally, the control unit (160) outputs a high-level output signal to the light source (110) when a high-level detection signal is input from the encoder (150). Then, the light source (110) emits pulsed light according to the output signal received from the control unit (160). In the example described above, the control unit (160) can output a high-level output signal to the light source (110) when an odd-numbered high-level detection signal is input. At this time, due to a delay in the signal path, the rising time of the detection signal and the rising time of the output signal may differ. That is, the rising time of the output signal may be delayed compared to the detection signal. Although this signal delay value corresponds to a very short time in the order of a few microseconds, the signal delay problem can be resolved by reflecting this in advance in the output timing of the output signal.

[0059] In this way, the lidar device according to the embodiment of the present invention can improve the horizontal resolution of the lidar device by allowing the use of a relatively low-spec motor in the lidar device, even if the motor (140) does not rotate at a constant speed, by the encoder (150) detecting a specific rotational position of the reflector (130) and the control unit (160) controlling the light source (110) so that a pulsed light is emitted at the detected specific rotational position.

[0060] Next, referring to FIG. 3 (a) and (c), the control unit (160) controls the light detection unit (120) to detect reflected light that has been reflected back from an object during at least a portion of the output section of the high-level detection signal output by the encoder (150) during a specific detection time. At this time, the output section of the high-level detection signal is a section in which the light detection unit (120) is relatively likely to receive reflected light that has been reflected back from an object, and the first part of the output section has a higher probability of detection than the second part.

[0061] And, the light detection unit (120) receives reflected light simultaneously or sequentially during a specific detection time and outputs a high-level detection signal. Here, the light detection unit (120) detects reflected light only during a specific detection time and does not operate during other times. For example, as shown in the drawing, the light detection unit (120) can be controlled to detect reflected light during the section (hatched area) from the rising point of the high-level detection signal output by the encoder (150) to the halfway point of the output section. At this time, the light detection unit (120) can detect at least one reflected light with a different detection time depending on the distance from the object.

[0062] In this way, the lidar device according to the embodiment of the present invention can block the detection of noise signals unnecessary for object detection and reduce the data capacity for detection signal processing by detecting reflected light only during a specific detection time when the light detection unit (120) is highly likely to receive reflected light.

[0064] FIG. 4 is a flowchart of a control method for a lidar device according to an embodiment of the present invention.

[0065] Hereinafter, with reference to FIGS. 1 to 4, a control method for a lidar device according to an embodiment of the present invention will be described.

[0066] First, a light source (110) emits pulsed light toward a reflector (130) to detect an object (S10). At this time, the light source (110) is positioned to face a reflective surface provided in the reflector (130) and emits pulsed light toward the reflective surface.

[0067] Next, the reflector (130) reflects the pulsed light and transmits it to the object (S20). Then, the pulsed light is reflected by the object (S30).

[0068] Next, the reflector (130) reflects the reflected light reflected by the object and transmits it to the light detection unit (120) (S40). Then, the light detection unit (120) detects the reflected light (S50).

[0069] A lidar device according to an embodiment of the present invention detects an object by measuring the time difference between pulsed light and reflected light and calculating the distance from the lidar device to the object.

[0070] Next, the motor (140) rotates the mirror (130) 360 degrees (S60). Then, the encoder (150) detects the rotation position of the mirror (130) and outputs a detection signal (S70).

[0071] Next, the control unit (160) receives a detection signal from the encoder (150) and uses this detection signal to control the emission timing of the light source (110) and the detection time of the light detection unit (120) (S80).

[0072] At this time, the control unit (160) controls the light source (110) to emit pulsed light when a detection signal is input from the encoder (150). Additionally, the control unit (160) controls the light source (110) to emit pulsed light at each rotational position of the reflector (130).

[0073] The control unit (160) controls the light detection unit (120) to detect reflected light during at least a portion of the output section of the detection signal.

[0074] In this way, the control method of the lidar device according to the embodiment of the present invention can improve the horizontal resolution of the lidar device and reduce the manufacturing cost of the lidar device by enabling the use of a relatively low-spec motor in the lidar device. This is achieved by the encoder (150) detecting a specific rotational position of the reflector (130) even when the motor (140) does not rotate at a constant speed, and the control unit (160) controlling the light source (110) so that a pulsed light is emitted at the detected specific rotational position.

[0075] In addition, the control method of the lidar device according to an embodiment of the present invention can block the detection of noise signals unnecessary for object detection and reduce the data capacity for detection signal processing by detecting reflected light only during a specific detection time when the light detection unit (120) is highly likely to receive reflected light.

[0077] Although an embodiment of the present invention has been described above, the concept of the present invention is not limited to the embodiments presented in this specification. Those skilled in the art who understand the concept of the present invention may easily propose other embodiments within the scope of the same concept by adding, changing, deleting, or adding components, and such embodiments shall also be considered to fall within the scope of the concept of the present invention. Explanation of the symbols

[0079] 110: Light source 120: Photodetector 130: Reflector 140: Motor 150: Encoder 160: Control unit

Claims

Claim 1 A LiDAR device comprising: a light source emitting pulsed light; a light detection unit detecting reflected light that is reflected back from an object by the pulsed light; a mirror having a plurality of reflective surfaces, reflecting the pulsed light to the object and reflecting the reflected light to the light detection unit; a motor for rotating the mirror; an encoder for detecting the rotational position of the mirror and outputting a detection signal; and a control unit for controlling the emission timing of the light source and the detection time of the light detection unit using the detection signal, wherein the control unit controls the pulsed light to be emitted from the light source when the detection signal is input from the encoder, and controls the light detection unit to detect the reflected light during the first half of the output section of the detection signal. Claim 2 delete Claim 3 In claim 1, the control unit controls the light source to emit the pulse light at each certain rotational position of the reflector. Claim 4 In claim 1, the control unit controls the light detection unit to detect the reflected light during at least a portion of the output section of the detection signal. Claim 5 In claim 1, the reflector is a LiDAR device comprising a polyhedron having a plurality of reflective surfaces arranged on its side. Claim 6 In claim 1, the reflector and the encoder are coupled to the rotation axis of the motor and rotate together with the rotation axis in a lidar device. Claim 7 In claim 1, the encoder is a magnetic encoder lidar device comprising a multi-pole magnet and a Hall sensor. Claim 8 In claim 1, the encoder is a lidar device that is an optical encoder comprising a slit member having a plurality of slits formed therein and a photodiode. Claim 9 A method for controlling a LiDAR device comprising: a step in which a light source emits a pulsed light; a step in which a reflector reflects the pulsed light and transmits it to an object; a step in which the pulsed light is reflected by the object; a step in which the reflector reflects the reflected light reflected by the object and transmits it to a light detection unit; a step in which the light detection unit detects the reflected light; a step in which a motor rotates the reflector; a step in which an encoder detects the rotational position of the reflector and outputs a detection signal; a step in which a control unit controls the emission timing of the light source and the detection time of the light detection unit using the detection signal; and a step in which the control unit controls the light detection unit to detect the reflected light during the first half of the output section of the detection signal, wherein the step of controlling the detection time of the light detection unit is a step in which the control unit controls the pulsed light to be emitted from the light source when the detection signal is input from the encoder.

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