KR102620781B1 - FMCW LiDAR SYSTEM USING HETEROGENEOUS SCANNERS - Google Patents

Abstract

The present invention relates to an FMCW LiDAR system using heterogeneous scanners. The optical system of FMCW Lidar is implemented by simultaneously using different types of polygon scanners and galvanometer scanners, and through this, a wide-angle and multi-channel laser can be output. This is about an FMCW LiDAR system using heterogeneous scanners that allows

Description

FMCW LiDAR system using heterogeneous scanners {FMCW LiDAR SYSTEM USING HETEROGENEOUS SCANNERS}

The present invention relates to an FMCW LiDAR system using heterogeneous scanners. More specifically, the optical system of FMCW (Frequency Modulated Continuous Wave) LiDAR is implemented by simultaneously using different heterogeneous polygon scanners and galvanometer scanners, and This is about an FMCW LiDAR system using heterogeneous scanners that can output wide-angle and multi-channel lasers.

LiDAR (Light Detection And Ranging) is a technology that can detect the distance, direction, speed, temperature, material distribution, and concentration characteristics of an object by shining a laser on the target. It has high energy density and short period. By utilizing the advantage of a laser that can generate pulse signals, it is used for more precise observation of physical properties in the atmosphere and distance measurement.

For example, LIDAR is mounted on aircraft, satellites, etc. and is used as an important observation technology for precise atmospheric analysis and observation of the global environment. It is also mounted on spacecraft and exploration robots as a means to supplement camera functions such as measuring distances to objects. It is being utilized.

In addition, a simple form of LiDAR technology has been commercialized on the ground for long-distance distance measurement and vehicle speed violation enforcement, and recently, laser scanners and 3D imaging for 3D reverse engineering and future unmanned cars. As it is used as a core technology for cameras, its utility and importance are gradually increasing.

Distance measurements using such LIDAR include pulsed TOF (time of flight), which measures the round trip time of a pulse, phase shift, which measures distance through the phase difference of the signal, and frequency difference after changing the frequency. Frequency modulation (FMCW) to extract distance information is being used.

The TOF method is a method of measuring distance by emitting a pulse signal from a laser and measuring the time for reflected pulse signals from objects within the measurement range to arrive at the receiver, and shows very excellent performance.

Despite these advantages, the TOF method requires a relatively large system size and high cost, so the phase shift or FMCW method is mainly used in low-cost distance measurement systems.

However, most FMCW lidars currently in use use galvanometer scanners or polygon scanners. FMCW lidars using galvanometer scanners have a maximum angle of about 50 degrees, so FMCW lidars that require wide angles are not suitable for use. A polygon scanner was used, and FMCW lidar using a polygon scanner had limitations in outputting vertical angles.

Therefore, the present invention proposes a method of implementing the optical system of FMCW LiDAR by simultaneously using different types of polygon scanners and galvanometer scanners, and thereby performing wide-angle and multi-channel laser output. In particular, a wide horizontal angle is realized using a polygon scanner, and a vertical angle is realized using a galvanometer scanner, enabling wide-angle and multi-channel laser output.

Next, we will briefly describe the prior inventions existing in the technical field of the present invention, and then describe the technical details that the present invention seeks to achieve differently compared to the prior inventions.

First, Korea Patent Publication No. 2015-0018787 (2015.02.24.) is a ranging apparatus; a reactive linkage mechanism having a first end connected to the ranging device and a second end connected to an object that moves the system through the environment; and an imaging device operatively coupled to one of the first end or the second end of the reactive linkage mechanism, wherein, when in use, acceleration of the object relative to the environment is achieved by the reactive linkage mechanism. A three-dimensional scanning beam and imaging system that translates into movement of a ranging device, increasing the field of view of the ranging device with respect to the environment, wherein the field of view of the ranging device overlaps the field of view of the imaging device. It is a prior invention regarding .

In addition, International Publication Patent No. WO2016/153233 (2016.09.29.) is a prior invention regarding a LiDAR device that measures the distance to a measurement object and the shape of the measurement object using optical means.

However, since the present invention implements the optical system of the FMCW lidar by simultaneously using a polygon scanner and a galvanometer scanner, the field of view of the distance measuring device is increased, and the field of view of the distance measuring device overlaps the field of view of the imaging device. Compared to Korean Patent Publication No. 2015-0018787 and International Publication Patent WO2016/153233, which emits a laser beam in a scanning manner for each direction within the angle of view and obtains reflected light separately for each direction to calculate the distance to the reflector. There is a difference in composition.

The present invention was created to solve the above problems, and is an FMCW using heterogeneous scanners that can perform wide-angle and multi-channel output of a laser to measure the distance to an object using two different types of scanners. The purpose is to provide a system.

Another purpose of the present invention is to provide an FMCW LiDAR system using heterogeneous scanners that can configure the optical system of the FMCW LiDAR using a polygon scanner and a galvanometer scanner.

In addition, the present invention provides an FMCW LiDAR system using heterogeneous scanners that can output wide-angle and multi-channel lasers by implementing a wide horizontal angle using a polygon scanner and a vertical angle using a galvanometer scanner. It has another purpose.

An FMCW LiDAR system using a heterogeneous scanner according to an embodiment of the present invention includes a laser emitting unit that emits a laser; a first scanner for implementing the vertical angle and angular resolution of the emitted laser; And a second scanner for implementing the horizontal angle and angular resolution of the laser transmitted through the first scanner; wide-angle and multi-channel laser through simultaneous application of the first and second scanners of different types. can be output as an object for distance measurement.

In addition, the FMCW LiDAR system using the heterogeneous scanner includes a lens that condenses and collimates the laser output from the laser emitting unit; a first driving motor that drives the mirror provided in the first scanner to rotate at a predetermined angle; a second driving motor that drives the second scanner to rotate in one direction at a preset speed; And a signal processing module that calculates the distance information of the object by referring to the reflected signal reflected and received by the object and the laser emitted from the laser emitting unit, wherein the second drive motor includes the second It may further include an encoder that detects the number of revolutions and speed of the drive motor.

In addition, the first scanner is a galvanometer scanner, and the mirror provided on the front is rotated by the first drive motor to output the laser emitted from the laser light emitting unit in multiple channels within a vertical angle of 30 degrees. , the second scanner is a polygon scanner formed on four sides, and can rotate in one direction by the second drive motor to output the laser output through the galvanometer scanner to the object at a horizontal angle of 120 degrees. there is.

In addition, the angular resolution of the galvanometer scanner is implemented by confirming the vertical position where the laser is currently output through the measurement value of a feedback sensor provided on one side of the galvanometer scanner, and the angular resolution of the polygon scanner is can be implemented by checking the horizontal position where the laser is currently output through the counter value of the encoder.

In addition, the FMCW LIDAR system using the heterogeneous scanner synchronizes the rotational feedback signal measured by the galvanometer scanner and the rotational position of the polygon scanner detected by the encoder, so that the galvanometer scanner and the polygon scanner By performing driving, wide-angle and multi-channel output of the laser to the object can be performed.

In addition, a method of driving an FMCW LiDAR system using a heterogeneous scanner according to an embodiment of the present invention includes the steps of emitting a laser through a laser emitting unit in an FMCW LiDAR system using a heterogeneous scanner; In the FMCW LiDAR system using the heterogeneous scanner, implementing the vertical angle and angular resolution of the emitted laser through a first scanner; And in the FMCW LiDAR system using the heterogeneous scanner, implementing the horizontal angle and angular resolution of the laser transmitted through the first scanner through a second scanner; including, the first scanner and the first scanner of different heterogeneous types. Through the simultaneous application of 2 scanners, wide-angle and multi-channel lasers can be output to the object for distance measurement.

In addition, the driving method includes, in the FMCW LiDAR system using the heterogeneous scanner, concentrating and collimating the laser output from the laser emitting unit through a lens and outputting the laser beam; Rotating a mirror provided in the first scanner at a predetermined angle using a first drive motor and outputting the laser focused and collimated through the lens to the second scanner; Rotating the second scanner in one direction at a preset speed using a second drive motor to output the laser input through the first scanner to the object; And calculating the distance information of the object by referring to the reflected signal reflected and received by the object and the laser emitted from the laser light emitting unit through a signal processing module, wherein the second driving motor includes, It may further include an encoder that detects the rotation speed and speed of the second drive motor.

In addition, the driving method, in the FMCW lidar system using the heterogeneous scanner, synchronizes the rotation feedback signal measured by the galvanometer scanner and the rotation position of the polygon scanner detected by the encoder, By driving the polygon scanner, wide-angle and multi-channel output of the laser to the object can be performed.

As described above, according to the FMCW Lidar system using a heterogeneous scanner of the present invention, the optical system of the FMCW Lidar is constructed by combining different types of polygon scanners and galvanometer scanners, and a wide By implementing horizontal angle and angular resolution and vertical angle and angular resolution using a galvanometer scanner, wide-angle and multi-channel output of the laser for measuring the distance of an object is possible.

However, the effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by those skilled in the art from this specification and the attached drawings.

Figure 1 is a block diagram showing in detail the configuration of an FMCW LiDAR system using heterogeneous scanners according to an embodiment of the present invention.
Figures 2 and 3 are diagrams to explain the output of a laser implemented at vertical and horizontal angles through a first scanner (galvanometer scanner) and a second scanner (polygon scanner) applied to the present invention.
Figure 4 is a diagram for explaining the configuration and operating principle of the encoder applied to the present invention.
Figure 5 is a flowchart showing in detail the operation process of the FMCW LIDAR system driving method using a heterogeneous scanner according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention may add, change, or delete other components within the scope of the same spirit, or create other degenerative inventions or this invention. Other embodiments that are included within the scope of the invention can be easily proposed, but this will also be said to be included within the scope of the invention of the present application.

In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described using the same reference numerals.

Figure 1 is a block diagram showing in detail the configuration of an FMCW LiDAR system using heterogeneous scanners according to an embodiment of the present invention.

As shown in Figure 1, the FMCW LiDAR system 100 using a heterogeneous scanner according to an embodiment of the present invention includes a laser light emitting unit 110, a lens 120, a first drive motor 130, and a first It includes a scanner 140, a second drive motor 150, a second scanner 160, etc.

In particular, the FMCW Lidar system 100 using a heterogeneous scanner applied to the present invention uses different types of scanners, a polygon scanner and a galvanometer scanner, and can implement a wide horizontal angle through the polygon scanner, Since the vertical angle can be realized through a nometer scanner, it has the advantage of being able to use wide-angle and multi-channel lasers.

The laser emitting unit 110 emits and outputs laser light under the control of a control module (not shown).

The lens 120 collects and collimates each laser output from the plurality of laser emitters 110 and outputs the laser beams to the first scanner 140. Here, the collimation means aligning the traveling direction of the laser to be parallel to the optical axis as a reference.

The first drive motor 130 drives the first scanner 140 under the control of a control module (not shown) to output the laser output from the lens 120 in the direction of the second scanner 160. do.

That is, the condensed and collimated laser output through the lens 120 can be converted to the vertical at a predetermined angle (for example, 30 degrees) and output to the second scanner 160.

For example, the first drive motor 130 is installed at the rear of the first scanner 140 and drives the mirror provided on one front side of the first scanner 140 to rotate at a predetermined angle, The laser output through the lens 120 is output vertically at a predetermined angle.

The first scanner 140 performs a function of implementing the vertical angle and angular resolution of the laser beam collected and collimated through the lens 120.

That is, the first scanner 140 is a galvanometer scanner, and the mirror provided on one side of the front is rotated at a predetermined angle by the first drive motor 130, and the laser light emitting unit 110 and The laser input through the lens 120 is output in multiple channels within a predetermined vertical angle (e.g., 30 degrees). At this time, the vertical angle is explained in the present invention as designed using 30 degrees as an example, but it is not limited to this and can be implemented in various ways.

The second drive motor 150 drives the second scanner 160 under the control of a control module (not shown) to divert the laser output at a predetermined vertical angle through the first scanner 140 to a wide horizontal angle. Make sure to output in the object direction.

That is, the laser input through the first scanner 140 can be converted to horizontal at a predetermined angle (for example, 120 degrees) and output.

For example, the second drive motor 150 is installed on the bottom of the second scanner 160 so that the second scanner 160, which is formed on four sides, can rotate in one direction at a preset speed. By driving, the laser input through the first scanner 140 is output at a wide angle.

At this time, the second drive motor 150 may further include an encoder 151 that detects the rotation speed and speed of the second drive motor 150.

The second scanner 160 functions to implement the horizontal angle and angular resolution of the laser transmitted through the first scanner 140.

That is, the second scanner 160 is a polygon scanner formed with four sides, and outputs through the first scanner 140 while rotating in a preset direction by the second drive motor 150. The laser is converted to the horizontal at a predetermined angle (e.g., 120 degrees) and output to the object.

Meanwhile, although not shown in FIG. 1, the FMCW LiDAR system 100 using the heterogeneous scanner refers to the reflected signal reflected and received by the object and the laser emitted from the laser emitting unit 110 to determine the It may further include a signal processing module that calculates distance information.

Figures 2 and 3 are diagrams to explain the output of a laser implemented at vertical and horizontal angles through a first scanner (galvanometer scanner) and a second scanner (polygon scanner) applied to the present invention.

As shown in FIGS. 2 and 3, the first scanner 140 implements the vertical angle and angular resolution of the laser focused and collimated through the lens 120, and the second scanner 160 The horizontal angle and angular resolution of the laser transmitted through the first scanner 140 are implemented.

At this time, the angular resolution of the first scanner (galvanometer scanner) is determined by checking the data measured by the feedback sensor (not shown) provided on one side of the first scanner (galvanometer scanner) in the control module (not shown). This can be implemented based on checking the vertical position where the laser is currently output.

In addition, the angular resolution of the second scanner (polygon scanner) is determined by checking the counter value measured by the encoder 151 provided in the second drive motor 150 in the control module (not shown), and through this, the current laser It can be implemented based on checking the output horizontal position.

To be more specific, in most FMCW lidars, the reference synchronization is chirp, and 1 point per chirp can be recorded on the screen (PointCloud).

For example, if a chirp of 10 kHz is used in the FMCW LiDAR system 100 using the heterogeneous scanner according to an embodiment of the present invention, 10,000 points per second can be displayed on the screen (PointCloud).

However, this is the number of the entire screen, not the value of the position where the laser is currently being fired.

In order to display the value of the position where the laser is currently shooting on the screen, you must know the position where the laser is currently output so that the value reflected by the object (i.e. the position) can be displayed on the screen. What is needed at this time is the horizontal position. This is the position value perpendicular to the value.

At this time, in order to know the vertical position value, the current position is confirmed through the sensor provided in the first scanner 140, and by placing a point on the confirmed position value, the vertical position can be confirmed.

Similarly, in order to know the position value corresponding to the horizontal, check the current position through the encoder 151 provided in the second drive motor 150 that drives the second scanner 160, and place a point on the confirmed position value. You can check the horizontal position.

Meanwhile, in the FMCW LiDAR system 100 using the heterogeneous scanner, synchronization of the first scanner 140 and the second scanner 160 is essential in order to output a laser in a wide angle and multi-channel direction in the object direction.

To this end, in the present invention, the rotational feedback signal measured by the first scanner 140 is synchronized with the rotational position of the second scanner 160 detected by the encoder 151, so that the first scanner 140 and The second scanner 160 is driven.

At this time, the synchronization signal is, for example, horizontal field of view (FOV) start, end -> first line movement in vertical field of view (FOV) -> horizontal field of view (FOV) start, end -> second line movement in vertical field of view (FOV). -> Horizontal field of view (FOV) start and end -> Vertical field of view (FOV) The first scanner 140 and the second scanner 160 must be driven in synchronization in the form of movement of the third line, etc. on the screen ( In other words, it is possible to spray laser accurately on PointCloud.

Figure 4 is a diagram for explaining the configuration and operating principle of the encoder applied to the present invention.

The second drive motor 150 that drives the polygon scanner applied to the present invention is equipped with an encoder 151.

The encoder 151 may use an incremental encoder, an absolute encoder, etc., but in the present invention, as shown in Figures 4 (a) and (b), an optical incremental encoder or It is desirable to apply a magnetic incremental encoder.

As shown in (c) of FIG. 4, the encoder outputs position information in A-phase, B-phase, and index (Z-phase). At this time, the signal corresponding to one wheel is the index, the value for one position out of 360 degrees is displayed as A phase and B phase, and the phase difference between A phase and B phase is 90 degrees. The reason for doing this is to increase resolution and to know the direction of rotation of the motor. In addition, if only phase A is used, 1024 units can be output in one wheel, but if both A and B phases are used simultaneously, it can be disassembled into 4096 units, which is 4 times more.

Next, an embodiment of the FMCW LiDAR system driving method using a heterogeneous scanner according to the present invention configured as described above will be described in detail with reference to FIG. 5. At this time, the order of each step according to the method of the present invention may be changed depending on the usage environment or a person skilled in the art.

Figure 5 is a flowchart showing in detail the operation process of the FMCW LIDAR system driving method using a heterogeneous scanner according to an embodiment of the present invention.

As shown in FIG. 5, the FMCW LiDAR system 100 using a heterogeneous scanner according to an embodiment of the present invention performs a step of emitting a laser through the laser emitting unit 110 (S100).

In addition, the FMCW LiDAR system 100 using the heterogeneous scanner performs the step of concentrating and collimating the laser output through the step S100 through the lens 120 and outputting the laser (S200).

In addition, the FMCW LiDAR system 100 using the heterogeneous scanner rotates the mirror provided on one side of the galvanometer scanner, which is the first scanner 140, at a predetermined angle through the first drive motor 130, The laser beam collected and collimated through the lens 120 in step S200 is output to the second scanner 160 (S300).

That is, the vertical angle and angular resolution of the laser are implemented through the first scanner 140 and output to the second scanner 160.

Subsequently, the FMCW LiDAR system 100 using the heterogeneous scanner rotates the polygon scanner, which is the second scanner 160, in one direction at a preset speed through the second drive motor 150, in step S300. A step of outputting the laser input through the first scanner 140 as an object is performed (S400).

That is, by implementing the horizontal angle and angular resolution of the laser transmitted through the first scanner 140 through the second scanner 160 and outputting it as an object, wide-angle and multi-channel scanning is achieved through simultaneous application of different types of scanners. The laser is output to the object of distance measurement.

At this time, as described above, the rotational feedback signal measured by the first scanner 140 and the rotational position of the second scanner 160 detected by the encoder 151 of the second drive motor 150 must be synchronized.

The laser output to the object at a wide angle and in multiple channels through step S400 is reflected by the object, and the signal processing module of the FMCW LIDAR system processes the reflected reflection signal and the laser light emitting unit 110 through step S100. A step is performed to calculate the distance information of the object by referring to the laser emitted from (S500).

As such, the present invention combines different types of polygon scanners and galvanometer scanners to construct the optical system of FMCW lidar, implements a wide horizontal angle and angular resolution using a four-sided polygon scanner, and uses a galvanometer scanner. Because it implements vertical angle and angular resolution, wide-angle and multi-channel output of the laser for measuring the distance of an object is possible.

In the attached drawings, in order to more clearly express the technical idea of the present invention, components that are unrelated or less relevant to the technical idea of the present invention are briefly expressed or omitted.

In the above, the configuration and features of the present invention have been described based on the embodiments according to the present invention, but the present invention is not limited thereto, and various changes or modifications may be made within the spirit and scope of the present invention. It is obvious to those skilled in the art, and therefore, it is stated that such changes or modifications fall within the scope of the appended patent claims.

100: FMCW lidar system
110: laser emitting unit
120: lens
130: first driving motor
140: 1st scanner (galvanometer scanner)
150: 2nd drive motor
151: encoder
160: 2nd scanner (polygon scanner)

Claims (10)

A laser light emitting unit that emits a laser;
a first scanner for implementing the vertical angle and angular resolution of the emitted laser;
a second scanner for implementing the horizontal angle and angular resolution of the laser transmitted through the first scanner;
Through simultaneous application of the first and second scanners of different types, a wide-angle and multi-channel laser is output to the object of distance measurement;
a lens that condenses and collimates the laser output from the laser emitting unit;
a first driving motor that drives the mirror provided in the first scanner to rotate at a predetermined angle;
a second driving motor that drives the second scanner to rotate in one direction at a preset speed; and
It includes a signal processing module that calculates the distance information of the object by referring to the reflected signal reflected and received by the object and the laser emitted from the laser emitting unit,
The second driving motor further includes an encoder that detects the rotation speed and speed of the second driving motor,
The encoder uses an optical incremental encoder and a magnetic incremental encoder, and the A phase and B phase, which are values for one position out of 360 degrees corresponding to one rotation, are used simultaneously to decompose the resolution into 4096 points. FMCW LiDAR system using heterogeneous scanners.
delete In claim 1,
The first scanner is,
As a galvanometer scanner, a mirror provided on the front is rotated by the first drive motor to output the laser emitted from the laser light emitting unit in multiple channels within a vertical angle of 30 degrees,
The second scanner is,
It is a polygon scanner formed on four sides, and rotates in one direction by the second drive motor to output the laser output through the galvanometer scanner to the object at a horizontal angle of 120 degrees. FMCW Lidar System.
In claim 3,
The angular resolution of the galvanometer scanner is implemented by confirming the vertical position where the laser is currently output through the measurement value of a feedback sensor provided on one side of the galvanometer scanner,
The angular resolution of the polygon scanner is an FMCW lidar system using a heterogeneous scanner, characterized in that it is implemented by checking the horizontal position where the laser is currently output through the counter value of the encoder.
In claim 3,
The FMCW LiDAR system using the heterogeneous scanner is,
By synchronizing the rotational feedback signal measured by the galvanometer scanner and the rotational position of the polygon scanner detected by the encoder, the galvanometer scanner and the polygon scanner are driven, so that the wide angle of the laser to the object and an FMCW LiDAR system using heterogeneous scanners, characterized by performing multi-channel output.
In an FMCW LiDAR system using a heterogeneous scanner, emitting a laser through a laser emitter;
In the FMCW LiDAR system using the heterogeneous scanner, implementing the vertical angle and angular resolution of the emitted laser through a first scanner;
In the FMCW LiDAR system using the heterogeneous scanner, implementing the horizontal angle and angular resolution of the laser transmitted through the first scanner through a second scanner;
outputting a wide-angle and multi-channel laser to an object to be measured for distance through simultaneous application of different types of first and second scanners;
In the FMCW LiDAR system using the heterogeneous scanner, concentrating and collimating the laser output from the laser emitting unit through a lens and outputting it;
In the FMCW LiDAR system using the heterogeneous scanner, the mirror provided in the first scanner is rotated at a predetermined angle through a first drive motor, and the laser focused and collimated through the lens is output to the second scanner. step;
In the FMCW LiDAR system using the heterogeneous scanner, rotating the second scanner in one direction at a preset speed through a second drive motor to output the laser input through the first scanner to the object; and
In the FMCW LiDAR system using the heterogeneous scanner, calculating distance information of the object by referring to the reflected signal reflected and received by the object and the laser emitted from the laser emitting unit through a signal processing module; Includes,
The second driving motor further includes an encoder that detects the rotation speed and speed of the second driving motor,
The encoder applies an optical incremental encoder and a magnetic incremental encoder, and is characterized by realizing a resolution of 4096 by simultaneously using the A phase and B phase, which are values for one position out of 360 degrees corresponding to one rotation. How to operate the FMCW LiDAR system using heterogeneous scanners.
delete In claim 6,
The first scanner is,
As a galvanometer scanner, a mirror provided on the front is rotated by the first drive motor to output the laser emitted from the laser light emitting unit in multiple channels within a vertical angle of 30 degrees,
The second scanner is,
It is a polygon scanner formed on four sides, and rotates in one direction by the second drive motor to output the laser output through the galvanometer scanner to the object at a horizontal angle of 120 degrees. How to operate the FMCW lidar system.
In claim 8,
The angular resolution of the galvanometer scanner is implemented by confirming the vertical position where the laser is currently output through the measurement value of a feedback sensor provided on one side of the galvanometer scanner,
The angular resolution of the polygon scanner is implemented by checking the horizontal position where the laser is currently output through the counter value of the encoder.
In claim 8,
The driving method is,
In the FMCW LiDAR system using the heterogeneous scanner, the rotation feedback signal measured by the galvanometer scanner and the rotation position of the polygon scanner detected by the encoder are synchronized to drive the galvanometer scanner and the polygon scanner. An FMCW LiDAR system driving method using a heterogeneous scanner, characterized in that wide-angle and multi-channel output of the laser to the object is performed.