KR102059258B1 - LiDAR scanning device - Google Patents

Abstract

The present invention relates to a lidar scanning apparatus for measuring a distance, a direction, a speed, and the like to an object by irradiating the laser beam to the object and analyzing the laser beam reflected by the object.
Lidar scanning apparatus according to an embodiment of the present invention,
A transmitter for irradiating a laser beam; A mirror scanner which repeatedly rotates in a predetermined angle range so that the laser beam radiated from the transmitter is reflected in various directions; A multi-mirror that irradiates the laser beam reflected from the mirror scanner onto the object and receives the laser beam reflected from the object; A receiver configured to receive a laser beam reflected from the multi-faceted mirror; And a rotating motor for rotating the multi-faceted mirror.

Description

LiDAR scanning device {LiDAR scanning device}

The present invention relates to a lidar scanning apparatus for measuring a distance, a direction, a speed, and the like to an object by irradiating the laser beam to the object and analyzing the laser beam reflected by the object.

In general, a LIDAR system (Light Detection And Ranging system) can irradiate a laser to an object, analyze a laser beam reflected by the object, and measure and detect the distance, direction, and speed to the object. System.

The lidar system is utilized for applications such as weather observation, distance measurement, and the like, and has recently been used for technologies for autonomous vehicles, weather observation using satellites, unmanned robot sensors, and 3D image modeling.

The laser beam may be irradiated with a sine wave, a pulse wave, etc. according to a measuring method, and a lidar scanning device composed of a motor or a mirror is required to move the measuring point of the laser beam during 2D mapping or 3D shape measurement.

Recently, LiDAR has been in the spotlight as a sensor for measuring peripheral shape for a mobile platform. Taking autonomous vehicles and unmanned vehicles among mobile platforms, for example, the vehicle generally runs along the ground, so the object to be measured is mainly on the ground. Therefore, the autonomous vehicle rider does not need a wide measurement angle in the vertical direction, but a wide measurement area in the horizontal direction.

In addition, since there are many objects traveling at a high speed of 100 km or more in the driving environment of the vehicle, the measurement speed of the lidar may be fast to detect these objects.

1 is a perspective view illustrating a lidar scanning apparatus according to the prior art, and FIG. 2 is a view illustrating a measurement area of the lidar scanning apparatus of FIG. 1. The prior art of FIG. 1 is a lidar scanning device disclosed in US Patent US2014293263A1.

The lidar scanning device A shown in FIG. 1 includes a transmitter 35 and a receiver 40, a first axis scanning motor 20, a multi-faceted mirror 10 ′, a rotary table 50, and a second axis scanning. Motors (not shown) and the like. Here, the first axis is a horizontal rotation axis for scanning the vertical direction, and the second axis is a vertical rotation axis for scanning the horizontal direction.

The beam transmitted from the transmitting unit 35 is transmitted in the vertical direction at various heights by the multi-faceted mirror rotating around the first axis, and the beam reflected from the multi-faceted mirror while the rotating table 50 rotates around the second axis. Is transmitted in the vertical and horizontal directions. Thereafter, the transmitted beam is reflected at the object, and the beam reflected at the object is again reflected at the multi-faceted mirror and received at the receiver.

Such a lidar scanning device A can measure 360 degrees in the horizontal direction as in FIG. 2, and can measure up to 10 to 170 degrees in the vertical direction depending on the design of the multi-faced mirror.

However, since the conventional lidar scanning device A uses two motors for rotating the first axis and the second axis, the scanning speed is as low as several tens of Hz, which is not suitable for high speed scanning.

In addition, since the rotary table 50 itself rotates during the horizontal scanning, the transmitting unit 35, the receiving unit 40, the first axis scanning motor 20, and the multi-sided mirror 10 disposed above the rotating table 50. ') And various circuits are continuously subjected to centrifugal force due to rotation, which adversely affects the durability of these components, and thus there is a problem in that the horizontal scanning speed is limited.

3 is a view illustrating a lidar scanning apparatus according to the prior art, and FIG. 4 is a view illustrating a measurement area of the lidar scanning apparatus of FIG. 3. The prior art of FIG. 3 is “Design and characterization of a 256x64-pixel single-photon imager in CMOS for a MEMS based laser scanning time-of-flight sensor” (OSA Publishing, Vol. 20, Issue 11, pp. 11863-11881 (2012)) is a lidar scanning device.

The lidar scanning apparatus B shown in FIG. 3 includes a transmitter 1, a receiver 2, and a biaxial MEMS scanner 3. The lidar scanning device B of FIG. 3 uses a transmitter 1 composed of a plurality of lasers to widen the measurement area. The beam transmitted from the transmitter 1 is reflected by the biaxial MEMS scanner 3 in the vertical and horizontal directions to detect the object.

In the lidar scanning device B of FIG. 3, the direction in which the transmission beam is irradiated by the biaxial MEMS scanner 3 is changed, and the focus beam formed after the reception beam reflected from the object passes through the condensing lens 4. The position of is changed every time. Thus, the receiving unit 2 is composed of an M × N multi-channel receiving element or an image sensor so that all can be received separately according to the irradiation direction.

Since such a lidar scanning device B does not use a motor, the output of the transmitter 1 can be increased to about several tens of kHz, thereby enabling high-speed scanning. Accordingly, the above-described problem of the lidar scanning device A can be solved.

However, such a conventional lidar scanning device B, as shown in Fig. 4, is difficult to have a wide measuring angle of 50 degrees or more due to the angle limit of the biaxial MEMS scanner 3, and has a plurality of horizontal / vertical channels. The need for a receiver with (M × N pixels) increases the cost and complexity of the configuration.

United States Patent Application Publication US2014293263A1

Design and characterization of a 256x64-pixel single-photon imager in CMOS for a MEMS based laser scanning time-of-flight sensor (OSA Publishing, Vol. 20, Issue 11, pp. 11863-11881 (2012))

An object of the present invention is to provide a lidar scanning apparatus that can solve the problems of the above-described prior arts.

Lidar scanning apparatus according to an embodiment of the present invention,

A transmitter for irradiating a laser beam; A mirror scanner which repeatedly rotates in a predetermined angle range so that the laser beam radiated from the transmitter is reflected in various directions; A multi-mirror that irradiates the laser beam reflected from the mirror scanner onto the object and receives the laser beam reflected from the object; A receiver which receives the laser beam reflected from the multi-faceted mirror; And a rotating motor for rotating the multi-faceted mirror.

In the lidar scanning apparatus according to an embodiment of the present invention, the mirror scanner may be an actuator-based mirror scanner that repeatedly drives in a predetermined angle range.

In the lidar scanning apparatus according to the embodiment of the present invention, the mirror scanner may be any one of a resonance scanner, a MEMS mirror, a voice coil motor (VCM), and an optical phase array.

In the lidar scanning apparatus according to the embodiment of the present invention, the multi-faceted mirror may include a plurality of reflective mirrors having different inclinations.

In the lidar scanning apparatus according to the embodiment of the present invention, the plurality of reflective mirrors may partially overlap the measurement altitudes of the plurality of reflective mirrors.

In the lidar scanning apparatus according to the embodiment of the present invention, the receiver may be a single channel receiver composed of a single pixel or a multichannel receiver arranged in N × 1 pixels.

In a lidar scanning apparatus according to an embodiment of the present invention, the receiver is a single channel receiver, and the receiver further comprises a condenser lens for condensing a laser beam reflected from the multi-faceted mirror, wherein the laser beam is pulsed at the transmitter. And the transmitter, the receiver, and the mirror scanner are synchronized to measure a measurement altitude using a reflection angle of the mirror scanner.

Other specific details of embodiments according to various aspects of the present invention are included in the following detailed description.

According to an embodiment of the invention,

The multi-faceted mirror can be rotated by a rotating motor to emit a laser beam at a wide forward angle, thus widening the horizontal measurement range.

In addition, since the mirror scanner repeatedly drives in a predetermined angle range and reflects the laser beam to various vertical axis positions of the mirror, it is possible to increase the measuring altitude in the vertical direction.

In addition, since the rotating motor rotates only the multi-faceted mirror and the other components are not rotated by the rotating motor, the durability of the lidar scanning apparatus can be improved.

In addition, since the laser beam can be transmitted from the transmitter to the mirror scanner at a period of several hundred kHz or more, scanning can be performed at high speed in the vertical direction.

In addition, since a single laser diode is used and high-speed scanning can be performed even with a single channel receiver or an N × 1 multichannel receiver, configuration can be simplified and manufacturing costs can be reduced.

1 is a perspective view showing a lidar scanning device according to the prior art.
FIG. 2 is a view illustrating a measurement area of the lidar scanning apparatus of FIG. 1.
3 is a view illustrating a lidar scanning apparatus according to the prior art.
4 is a view illustrating a measurement area of the lidar scanning apparatus of FIG. 3.
5 is a diagram illustrating a lidar scanning apparatus according to an embodiment of the present invention.
6 is a diagram illustrating an example of a mirror scanner of a lidar scanning apparatus according to an embodiment of the present invention.
7 is a plan view showing an operating state of the lidar scanning apparatus according to an embodiment of the present invention.
FIG. 8 is a view for explaining a measurement altitude in the case where each of the reflective mirrors of the multi-sided mirror is formed at different inclinations.
9 and 10 illustrate an operation process of a lidar scanning apparatus according to an embodiment of the present invention.
11 to 13 illustrate a measurement area of a lidar scanning device according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the terms 'comprise' or 'have' are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof. Hereinafter, a lidar scanning apparatus according to an embodiment of the present invention will be described with reference to the drawings.

5 is a diagram illustrating a lidar scanning apparatus according to an embodiment of the present invention.

As shown in FIG. 5, a lidar scanning apparatus according to an exemplary embodiment of the present invention may include a transmitter 100, a mirror scanner 200, a multi-faceted mirror 300, a receiver 400, and a rotation motor 500. Include.

The transmitter 100 is formed to be spaced apart from the mirror scanner 200 by a predetermined distance, and irradiates a laser beam to the mirror scanner 200. The transmitter 100 may be used, for example, a laser diode LD, and may be formed in a single unit.

The mirror scanner 200 is formed to be spaced apart from the transmitter 100 for irradiating a laser beam at a predetermined distance, and reflects the laser beam irradiated from the transmitter 100 toward the mirror 300.

The mirror scanner 200 repeatedly drives the laser beam radiated from the transmitter 100 in a predetermined angle range so that the laser beam is reflected in various directions. Here, the repetitive driving may be, for example, the axis of rotation of the mirror scanner in a certain angle range. The mirror scanner 200 may rotate the laser beam to be reflected in a plurality of horizontal directions. However, the mirror scanner 200 is rotated to be reflected in a plurality of vertical directions because the horizontal direction is scanned by the rotation of the multi-faced mirror 300.

Such a mirror scanner 200 may be, for example, a small actuator based mirror scanner. Examples of small actuator-based mirror scanners include resonant scanners, MEMS mirrors, voice coil motors (VCMs), and optical phase arrays.

6 is a diagram illustrating an example of a mirror scanner of a lidar scanning apparatus according to an embodiment of the present invention.

The mirror scanner 200 according to an example, as shown in FIG. 6, serves as a rotation axis of the pair of permanent magnets 210, the electromagnetic mirror 220 disposed between the pair of permanent magnets, and the electromagnetic mirror. It may include a torsion bar 230 to perform. A coil is formed in the electromagnet mirror 220, and the magnetic field relationship between the permanent magnet 210 and the electromagnet mirror 220 changes according to a change in the direction of current flowing through the coil, and the electromagnet mirror 220 is affected by the changed magnetic field. The torsion bar 230 is rotated in a predetermined angle range using the rotation axis to reflect the laser beam emitted from the transmitter 100 in a plurality of vertical directions.

In the embodiment of the present invention, since the transmitter 100, the receiver 400, and the mirror scanner 200 are not parts rotated by the rotary motor 500, the laser diode constituting the transmitter 100 is several hundred kHz or more. The laser beam may be transmitted at a high speed at a periodic rate, and the mirror scanner 200 may reflect this to the multi-faced mirror 300 to perform high-speed scanning of the object.

In a mobile platform whose main purpose is to detect obstacles while driving, it is important to detect obstacles such as roads, vehicles, and people ahead. Therefore, it is more important to measure a relatively narrow range of vertical direction at high speed than drones and unmanned aerial vehicles, so it is preferable to use a small actuator-based mirror scanner 200 for vertical high-speed measurement. Of course, if necessary, the driving range of the mirror scanner 200 may be widened for wider vertical high speed measurement.

Meanwhile, at least one collimating lens C1 may be formed between the transmitter 100 and the mirror scanner 200. The collimating lens C1 is an optical lens that focuses a laser beam generated by a laser diode constituting the transmitter 100.

The multi-faceted mirror 300 irradiates the laser beam reflected from the mirror scanner 200 and receives the laser beam reflected from the object. The multi-faceted mirror 300 is formed of a predetermined number (n) reflective mirrors. For example, the multi-faceted mirror 300 may be formed of four reflective mirrors, and each reflective mirror performs a reflective mirror function of reflecting a laser beam reflected by the mirror scanner 200 and irradiating it in the horizontal and vertical directions. do.

FIG. 7 is a plan view illustrating an operating state of a lidar scanning apparatus according to an exemplary embodiment of the present invention, and FIG. 8 is a view illustrating a measurement altitude when each of the reflection mirrors of the multi-sided mirror is formed at different inclinations.

As shown in FIG. 7, when the multi-faceted mirror 300 rotates by the rotation of the rotary motor 500, the laser beam irradiated by the transmitter 100 and reflected by the mirror scanner 200 is applied to the multi-faceted mirror 300. It is reflected by the light at a predetermined angle and proceeds forward. As shown in FIG. 7C, the laser beam reflected toward the mirror scanner 200 according to the rotation of the multi-faced mirror 300 is noise processed.

As the number of mirrors of the multi-faceted mirror 300 increases, higher resolution or higher measurement speed may be realized. For example, when the multi-faced mirror 300 is composed of four reflective mirrors as shown in FIG. 5, the laser beam reflected from the mirror scanner 200 is irradiated with the measurement starting points of the four reflective mirrors slightly different. The resolution is four times, and when the laser beam is irradiated with the same measurement start point for the four reflection mirrors, the measurement speed for the object is four times. Here, the number of different measurement starting points is equal to the number of mirrors n, and the position of another starting point may be a position shifted by 1 / n of the horizontal axis angle resolution of the system when measured at the same starting point.

On the other hand, each of the reflective mirrors constituting the multi-faceted mirror 300 may have a different inclination. Here, the inclination of the reflection mirror means the angle θ formed between the vertical plane perpendicular to the bottom surface of the multi-faceted mirror and the reflection mirror.

The laser beam reflected by the mirror scanner 200 is reflected by a plurality of reflecting mirrors having different inclinations to measure various measurement altitudes. For example, as shown in FIG. 8, when there are four reflective mirrors having different inclinations, four measurement altitudes H1 to H4 can be measured each time the multi-faceted mirror 300 is rotated one time.

The receiver 400 receives the laser beam reflected from the multi-faceted mirror 300. The receiver 400 may be a multi-channel receiver having N × 1 pixels or a single channel receiver composed of one pixel.

9 and 10 are diagrams illustrating an operation process of a lidar scanning apparatus according to an embodiment of the present invention, and illustrate a reception position in the receiver 400. 9 and 10, the receiver 400 illustrates an N × 1 multichannel receiver.

As shown in FIG. 9, the laser beam reflected by the mirror scanner 200 is irradiated to the multi-faceted mirror 300 at the lowest altitude, reflected by the object, and then reflected by the multi-faceted mirror 300 to be multi-channel receiver 400. When received at, it is received in the top channel (pixel) of the multi-channel receiver 400 by geometric optical principle.

On the contrary, as shown in FIG. 10, when the laser beam is irradiated to the multi-faceted mirror 300 at the highest altitude and reflected from the object, the laser beam is reflected from the multi-faceted mirror 300 to be received by the multi-channel receiver 400. The channel is received at the lowest channel of the receiver 400.

As such, the position at which the laser beam is irradiated to the multi-faceted mirror 300 and the position received at the multi-channel receiver 400 are in a mutually opposite relationship.

In the above embodiment, since the focal position where the reception beam is formed varies depending on the vertical measurement altitude, the N × 1 multichannel receiver 400 is used, but the present invention is not limited thereto. The receiver 400 may be a single channel receiver. have. In this case, the receiver 400 additionally includes a condenser lens C2 for condensing the laser beam reflected from the multi-faceted mirror 300, and receives the laser beam received at all measurement altitudes through the proper design of the condenser lens C2. It can be received in one channel (pixel).

In this case, the laser beam is transmitted in the form of a pulse in the transmitter 100 and synchronizes the time of transmitting the laser beam with the time of receiving the laser beam at the receiver 400, and internally reflects the reflection angle of the mirror scanner 200 at the same time. Using drive signal feedback, measurements and altitudes can be specified. Then, the position, shape, etc. of the object are measured using the time difference of the laser beam measured at each angle.

The condenser lens C2 may be applied to the N × 1 multichannel receiver 400 as well as the single channel receiver.

Next, an operation process of the lidar scanning apparatus according to an embodiment of the present invention configured as described above will be described.

First, the transmitter 100 transmits a laser beam toward the mirror scanner 200. The laser beam may have various forms such as pulse wave, continuous wave,

The mirror scanner 200 reflects the laser beam radiated from the transmitter 100 toward the multi-faced mirror 300. The mirror scanner 200 reflects the laser beam to various vertical positions of the multi-faceted mirror 300 while repeatedly driving in a predetermined angle range.

The multi-faceted mirror 300 irradiates the laser beam reflected by the mirror scanner 200 toward the front on the basis of the incident angle / reflection angle principle. The multi-faceted mirror 300 may be irradiated with a laser beam at a wide front angle while being rotated by the rotation motor 500. For example, when the multi-faceted mirror 300 is composed of four reflective mirrors, the measurement angle in the horizontal direction may be 140 degrees or more.

The reflective mirrors constituting the multi-faceted mirror 300 may have a constant inclination of the surface or may be formed to be different from each other.

If the inclination of each side of the reflective mirror is constant, the measurement speed or resolution of the object may be increased. That is, as shown in FIG. 11, when the number of planes of the reflection mirror constituting the multi-faceted mirror 300 is four and the slope is constant, and the measurement starting point is different, the measurement points P1 to P4 measured by the respective reflection mirrors Since it is formed differently, it is possible to increase the horizontal axis measurement resolution for the object, and if the measurement start point is the same, since the same measurement point is measured four times in one rotation can increase the measurement speed.

If the inclination of each side of the reflective mirror is different, the resolution is relatively low, but the object can be measured at a wide measurement altitude. That is, as shown in FIG. 12, when the number of planes of the reflective mirrors constituting the multi-faceted mirror 300 is four and the inclination is different, four measurement altitudes H1 to H4 each time the multi-faceted mirror 300 is rotated one time. ) Can be measured.

On the other hand, even when the inclination of each side of the reflective mirror is different, by designing the inclination of each side so that the measurement altitude overlaps, it is possible to increase the resolution while measuring the object at a wide measurement altitude. That is, as shown in FIG. 13, in the overlapping measurement altitude portion D, the measurement speed or resolution with respect to the object may be increased, as in the case where the inclination of each surface of the reflection mirror is constant.

According to the lidar scanning apparatus according to the embodiment of the present invention as described above, since the multi-sided mirror is rotated by the rotating motor to irradiate the laser beam at a wide front angle, the horizontal measurement range can be widened.

In addition, since the mirror scanner repeatedly drives in a predetermined angle range and reflects the laser beam to various vertical axis positions of the mirror, it is possible to increase the measuring altitude in the vertical direction.

In addition, since the rotating motor rotates only the multi-faceted mirror and the other components are not rotated by the rotating motor, the durability of the lidar scanning apparatus can be improved.

In addition, since the laser beam can be transmitted from the transmitter to the mirror scanner at a period of several hundred kHz or more, scanning can be performed at high speed in the vertical direction.

In addition, since a single laser diode is used and high-speed scanning can be performed even with a single channel receiver or an N × 1 multichannel receiver, configuration can be simplified and manufacturing costs can be reduced.

As mentioned above, although an embodiment of the present invention has been described, those of ordinary skill in the art may add, change, delete or add components within the scope not departing from the spirit of the present invention described in the claims. The present invention may be modified and changed in various ways, etc., which will also be included within the scope of the present invention.

100: transmitter 200: mirror scanner
300: face mirror 400: receiver
500: rotary motor

Claims (7)

A transmitter for irradiating a laser beam;
A mirror scanner which repeatedly rotates in a predetermined angle range so that the laser beam radiated from the transmitter is reflected in various directions;
A multi-mirror that irradiates the laser beam reflected from the mirror scanner onto the object and receives the laser beam reflected from the object;
A multi-channel receiver configured to receive the laser beam reflected from the multi-faceted mirror;
A rotary motor for rotating the multi-faceted mirror,
The rotary motor rotates the multi-faceted mirror about a first axis,
When the laser beam reflected from the mirror scanner is irradiated to the first position of the multi-faceted mirror, the multi-channel receiver receives the laser beam reflected from the multi-faceted mirror in the first channel,
When the laser beam reflected from the mirror scanner is irradiated at the second position of the multi-faceted mirror, the multi-channel receiver receives the laser beam reflected from the multi-faceted mirror in a second channel,
When the position value of the first position is greater than the position value of the second position with respect to the first axis,
The position value of the first channel is smaller than the position value of the second channel with respect to the first axis.
Lidar scanning device.
The method according to claim 1, wherein the mirror scanner,
A rider scanning device, characterized in that the actuator-based mirror scanner repeatedly driving in a certain angle range.
The method of claim 2, wherein the mirror scanner,
Lidar scanning device, characterized in that any one of the resonance scanner, MEMS mirror, VCM (voice coil motor), Optical Phase Array.
The method according to claim 1, wherein the multi-sided mirror,
A lidar scanning device, characterized in that it comprises a plurality of reflective mirrors having different inclinations.
The method according to claim 4, wherein the plurality of reflective mirrors,
And an altitude measured by the plurality of reflective mirrors partially overlaps.
The method of claim 1, wherein the multi-channel receiving unit,
A lidar scanning apparatus, characterized in that the pixel is a multi-channel receiver arranged in N × 1.
The method according to claim 1,
The multi-channel receiver further includes a condenser lens for condensing a laser beam reflected from the multi-faceted mirror,
And the transmitter, the multi-channel receiver, and the mirror scanner are synchronized to measure a measurement altitude using a reflection angle of the mirror scanner.

Images