阅读说明：本技术 激光雷达传感器及其控制方法 (Laser radar sensor and control method thereof ) 是由 金庆麟 曹圣恩 金元谦 金荣信 于 2019-04-19 设计创作，主要内容包括：本发明提供了一种具有驱动电机的激光雷达传感器及其控制方法,在激光雷达传感器中,该驱动电机的整体部分被覆盖在扫描镜的倾斜面下,所述扫描镜具有开放的底面和A形截面。所述驱动电机的旋转轴可以连接到背衬面的底部,所述背衬面形成在所述倾斜面的下方,磁体可以形成在一个或多个的所述背衬面和支承面的底部,所述支承面连接到所述扫描镜的所述倾斜面,以及霍尔传感器可以对应于形成所述磁体的位置,而形成在所述激光雷达传感器的底面上。(In a laser radar sensor, an entire portion of a driving motor is covered under an inclined surface of a scanning mirror having an open bottom surface and an A-shaped cross-section. A rotation shaft of the driving motor may be coupled to a bottom of a backing surface formed below the inclined surface, a magnet may be formed at a bottom of one or more of the backing surface and a support surface coupled to the inclined surface of the scanning mirror, and a hall sensor may be formed on a bottom surface of the laser radar sensor corresponding to a position where the magnet is formed.)

1. A lidar sensor having a drive motor, an integral part of which is covered under an inclined surface of a scanning mirror having an open bottom surface and an A-shaped cross-section,

wherein a rotation shaft of the driving motor is connected to a bottom of a back surface formed below the inclined surface,

a magnet is formed at the bottom of one or more of the backing surface and a support surface connected to the inclined surface of the scan mirror, an

A hall sensor is formed on a bottom surface of the laser radar sensor corresponding to a position where the magnet is formed.

2. The lidar sensor of claim 1, wherein the inclined surface of the scanning mirror is inclined with respect to a bottom surface of the lidar sensor,

one side of the backing surface is horizontally connected to the bottom of the inclined surface,

the bearing surface is connected to the top of the inclined surface and the other side of the backing surface at a prescribed angle, and

the inclined surface, the backing surface and the bearing surface form the a-shaped cross-section.

3. The lidar sensor according to claim 2, wherein the backing surface is formed at a height of: a height reflecting a height including a height of a main body of the driving motor and a length of the rotation shaft.

4. The lidar sensor of claim 3, wherein the backing surface is formed at a height corresponding to a specified gap such that when the drive motor is connected to the backing surface, the open bottom surface of the scanning mirror is not in contact with the bottom surface of the lidar sensor to which the drive motor is attached.

5. The lidar sensor of claim 1, further comprising:

a motor drive unit configured to rotate the scan mirror connected to the drive motor at a specified speed; and

a control unit configured to calculate an angle of rotating the driving motor or the scanning mirror based on a rotation speed and time from a reference position to which the magnet is attached, and to control an output of the laser light by distinguishing between a scanning region and a non-scanning region based on the calculated angle.

6. The lidar sensor according to claim 5, wherein the control unit scans an object in front of the lidar sensor by outputting a laser scanning signal when the calculated angle corresponds to the scanning area, and does not output the laser scanning signal when the calculated angle corresponds to the non-scanning area.

7. A control method of a laser radar sensor comprises the following steps:

detecting, by a control unit of the lidar sensor, a sensing signal indicative of a reference position of a scanning mirror;

resetting, by the control unit, current position information to the reference position when the sensing signal is detected;

rotating the scanning mirror at a designated speed while performing laser scanning by the control unit;

calculating, by the control unit, an angle of rotation of the scanning mirror based on the speed of rotation and time from the reference position;

checking, by the control unit, whether the calculated angle has become a specified scan angle;

continuously performing, by the control unit, laser scanning and calculation of a scanning angle while rotating the scanning mirror at the specified speed until the calculated angle becomes the specified scanning angle; and

performing, by the control unit, laser scanning in a scanning area and ending laser scanning in a non-scanning area based on the calculated scanning angle.

8. The control method of claim 7, wherein the sensing signal comprises: a signal obtained when a hall sensor senses the formation of a magnet at one face of the bottom of the scan mirror.

9. The control method according to claim 7, wherein the reference position is set as a start position of the scanning area,

wherein the control unit immediately starts laser scanning when the sensing signal indicating the reference position is detected.

10. The control method according to claim 7, wherein the reference position is set to a position different from a start position of the scanning area,

wherein, when the sensing signal indicating the reference position is detected, the control unit calculates a start position of the scanning area from the reference position and starts laser scanning at the calculated start position of the scanning area.

11. The control method of claim 7, wherein the specified scan angle comprises: one or more of an angle corresponding to a start position of the scan area and an angle corresponding to an end position of the scan area.

Technical Field

The present invention relates to a lidar (light detection and ranging) sensor and a control method thereof, and more particularly, to a lidar sensor that is reduced in size by changing the structure of a driving unit including a rotating mirror (or a scanning mirror) and a driving motor to rotate the rotating mirror, and to provide a rotation detection method of a rotating mirror suitable for the changed structure of the driving unit and a control method thereof.

Background

In general, a lidar sensor refers to a sensor that measures a distance and senses an object using light. Lidar sensors have similar principles as radars.

The radar transmits and receives electromagnetic waves to and from the outside to check a distance and a direction, and the laser radar sensor transmits pulse laser light. That is, since the laser radar sensor uses short-wavelength laser light, the laser radar sensor can have high accuracy and resolution to recognize an object in a three-dimensional manner.

For example, a lidar sensor may be mounted on a vehicle bumper and sense an object or structure by monitoring the front/rear area of the vehicle. For reference, fig. 1 shows a field of view (FOV) of a lidar sensor mounted on a front/rear bumper of a vehicle.

The lidar sensor is typically mounted on the front bumper and needs to be exposed to the outside. When the lidar sensor is mounted in another structure, such as a vehicle body or glass, the sensing performance of the sensor may be significantly degraded. Therefore, the lidar sensor should be installed outside the vehicle.

For reference, as shown in fig. 2, the lidar sensor includes: a transmitter that transmits laser light, a receiver that receives reflected laser light, and a driver that drives a mirror rotating motor. Further, the lidar sensor includes a cover for protecting the sensor from foreign substances. A hot wire (hot wire) is mounted on the cover body, and the hot wire is used to remove moisture or snow attached to the surface of the cover body.

However, since existing lidar sensors have a much larger volume than other sensors attached to the vehicle, the volume of the lidar sensors may become a burden when multiple lidar sensors are attached to an autonomous vehicle. Therefore, a technique capable of downsizing the laser radar sensor is required.

The prior art of the present invention is disclosed in korean patent No. 10-2018-0003238 entitled "optical system of lidar sensor" published on 9.1.2018.

Disclosure of Invention

Embodiments relate to a laser radar sensor that is reduced in size by changing a structure of a driving unit including a rotating mirror (or a scanning mirror) and a driving motor to rotate the rotating mirror, and provide a rotation detecting method of the rotating mirror and a control method thereof that are suitable for the changed structure of the driving unit.

In one embodiment, a lidar sensor is provided having a drive motor, an integral portion of which is covered under an inclined surface of a scan mirror having an open bottom surface and an a-shaped cross-section. A rotation shaft of the driving motor may be coupled to a bottom of a backing surface formed below the inclined surface, a magnet may be formed at a bottom of one or more of the backing surface and a support surface coupled to the inclined surface of the scanning mirror, and a hall sensor may be formed on a bottom surface of the laser radar sensor corresponding to a position where the magnet is formed.

The inclined surface of the scan mirror may be inclined with respect to a bottom surface of the lidar sensor, one side of the backing surface may be horizontally connected to a bottom of the inclined surface, the support surface may be connected to a top of the inclined surface and the other side of the backing surface at a designated angle, and the inclined surface, the backing surface, and the support surface may form the a-shaped cross-section.

The backing surface may be formed at the following height: a height reflecting a height including a height of a main body of the driving motor and a length of the rotation shaft.

The backing surface may be formed at a height corresponding to a designated gap such that when the driving motor is connected to the backing surface, the open bottom surface of the scanning mirror is not in contact with the bottom surface of the lidar sensor to which the driving motor is attached.

The lidar sensor may further include: a motor drive unit configured to rotate the scan mirror connected to the drive motor at a specified speed; and a control unit configured to calculate an angle of rotating the driving motor or the scanning mirror based on a rotation speed and time from a reference position to which the magnet is attached, and to control an output of the laser light by distinguishing between a scanning region and a non-scanning region based on the calculated angle.

The control unit may scan an object in front of the lidar sensor by outputting a laser scanning signal when the calculated angle corresponds to the scanning area, and not output the laser scanning signal when the calculated angle corresponds to the non-scanning area.

In another embodiment, a method of controlling a lidar sensor may include: detecting, by a control unit of the lidar sensor, a sensing signal indicative of a reference position of a scanning mirror; resetting, by the control unit, current position information to the reference position when the sensing signal is detected; rotating the scanning mirror at a designated speed while performing laser scanning by the control unit; calculating, by the control unit, an angle of rotation of the scanning mirror based on the speed of rotation and time from the reference position; checking, by the control unit, whether the calculated angle has become a specified scan angle; continuously performing, by the control unit, laser scanning and calculation of a scanning angle while rotating the scanning mirror at the specified speed until the calculated angle becomes the specified scanning angle; and performing, by the control unit, laser scanning in a scanning area and ending laser scanning in a non-scanning area based on the calculated scanning angle.

The sensing signal may include: a signal obtained when a hall sensor senses the formation of a magnet at one face of the bottom of the scan mirror.

The reference position may be set as a start position of the scanning area. When the sensing signal indicating the reference position is detected, the control unit immediately starts laser scanning.

The reference position may be set to a position different from a start position of the scanning area. When the sensing signal indicating the reference position is detected, the control unit calculates a start position of the scanning area from the reference position, and starts laser scanning at the calculated start position of the scanning area.

The specified scan angle may include: one or more of an angle corresponding to a start position of the scan area and an angle corresponding to an end position of the scan area.

Drawings

Fig. 1 shows a field of view (FOV) of a lidar sensor mounted on a front/rear bumper of a vehicle.

Fig. 2 shows a schematic configuration of an existing lidar sensor.

Fig. 3A and 3B show the basic operation of a prior art mirror rotation lidar sensor.

Fig. 4A and 4B show, in a comparative manner, the structure of a conventional mirror rotation lidar sensor and the structure of a mirror rotation lidar sensor according to an embodiment of the present invention.

Fig. 5 shows a schematic configuration of a mirror rotation lidar sensor according to an embodiment of the invention.

FIG. 6 is a flow chart of a method of operation of a mirror rotation lidar sensor according to an embodiment of the invention.

Detailed Description

Some example embodiments may be illustrated in the figures as functional blocks, units and/or modules, as is common in the respective arts. Those of ordinary skill in the art will appreciate that the functional blocks, units and/or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, processors, hardwired circuits, memory elements, wired connections, and so forth. When implemented by a processor or similar hardware, these functional blocks, units and/or modules may be programmed and controlled using software (e.g., code) to perform the various functions discussed herein. Alternatively, each functional block, unit and/or module may be implemented by dedicated hardware for performing the specified function, or as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed processors and associated circuitry) for performing other functions. Each functional block, unit and/or module of some example embodiments may be physically separated into two or more interactive and discrete functional blocks, units and/or modules without departing from the scope of the present inventive concept. Furthermore, the functional blocks, units and/or modules of some exemplary embodiments may be physically combined into more complex functional blocks, units and/or modules without departing from the scope of the inventive concept.

Hereinafter, a lidar sensor and a control method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be noted that the drawings are not to precise scale and that the thickness of lines or the size of parts may be exaggerated for illustrative and clarity. Further, the definition of terms used herein takes the functions of the present invention into consideration and may be changed according to the custom or intention of a user or a user. Therefore, terms should be defined throughout the present disclosure.

Fig. 3A and 3B show the basic operation of a prior art mirror rotation lidar sensor.

As shown in fig. 3A, the mirror rotation lidar sensor may perform laser scanning in a specified scanning area (e.g., at a scanning angle of 145 degrees) in front of the lidar sensor.

As shown in fig. 3B, the mirror rotation lidar sensor may include: a rotating mirror (or scanning mirror) coupled to the top of the drive motor; a laser emitter located at the top of the rotating mirror and capable of emitting laser light (e.g., pulse-type laser light) vertically toward the inclined surface of the rotating mirror; and the emitted laser can be reflected by the inclined surface of the rotating mirror and output forwards.

The output laser light (or the emitted laser light) may be reflected by collision with an object (or a detection object) in front of the lidar sensor, and the laser light reflected from the object (or the received laser light) may be reflected upward by an inclined surface of the rotating mirror (or the scanning mirror) and received by the laser receiver through a light receiving lens above the rotating mirror.

Fig. 4A and 4B show, in a comparative manner, the structure of a conventional mirror rotation lidar sensor and the structure of a mirror rotation lidar sensor according to an embodiment of the present invention.

Fig. 4A is a schematic cross-sectional view of a conventional mirror-rotating lidar sensor, and fig. 4B is a schematic cross-sectional view of a mirror-rotating lidar sensor according to an embodiment of the present invention.

Referring to fig. 4A, the existing mirror rotating lidar sensor may include a rotating mirror (or scanning mirror) 101 connected to the top of a drive motor 102. The turning mirror may have the shape of a right triangle with all sides closed and one side tilted.

An encoder 104 may be attached to a rotating shaft that connects the driving motor 102 and the rotating mirror 101, and an encoder detector 103 may be attached to an end of the encoder 104 and used to detect rotation of the encoder 104 using a hole formed in the encoder 104.

Therefore, since the existing mirror rotation lidar sensor requires all the heights and volumes of the reflection drive motor 102, the encoder 104, the encoder detector 103, and the rotation mirror 101, the entire height and volume of the lidar sensor is inevitably increased.

Referring to fig. 4B, the mirror rotation lidar sensor according to an embodiment of the present invention may include: a rotating mirror (or scanning mirror) 201 having an open bottom surface and an a-shaped cross section; a drive motor 202 located in the rotating mirror 201 and covered by the rotating mirror 201; and a rod (bar) (or backing surface) 205 connected to the top of the rotation shaft of the driving motor 202. The rotating mirror 201 may include: a surface inclined with respect to a bottom surface of the laser radar sensor; a back surface having one side connected to the inclined surface in a horizontal direction to be connected to a rotation shaft of the driving motor; and a bearing surface connected to the top of the inclined surface and the other side of the backing surface and formed at a designated angle (e.g., a right angle). Thus, the inclined face, the backing face and the bearing face may form an a-shaped cross-section.

At this time, the rotating mirror 201 may not be limited to the a-shaped cross-sectional structure but may have only the inclined surface. In such a structure having only the inclined surface, the driving motor 202 may be covered under the inclined surface.

More specifically, the driving motor 202 may be connected to a rod (or a bearing surface) 205 formed therein through an open bottom surface of the rotating mirror 201. The lever 205 can basically function as a connection portion that connects the driving motor 202 to the inside of the rotating mirror 201.

By reflecting the height of the drive motor 202 (i.e., the height including the drive motor main body height and the rotation shaft length), the height at which the lever 205 is formed can be set to a greater or lesser height.

However, when the driving motor 202 and the lever 205 are connected to each other, the open bottom surface of the rotating mirror 201 may be slightly separated from the bottom surface of the laser radar sensor so that the open bottom surface of the rotating mirror 201 does not contact the bottom surface of the laser radar sensor (i.e., the surface to which the driving motor 202 is attached).

Further, a magnet 204 may be formed or attached to the bottom inside of the vertical surface of the rotating mirror 201, and a hall sensor 203 may be formed on the bottom surface of the lidar sensor to which the driving motor is attached, corresponding to the position where the magnet 204 is formed or attached.

However, the positions where the magnet 204 and the hall sensor 203 are formed may be changed according to the shape of the rotating mirror 201.

When the rotating mirror 201 has no vertical surface or only an inclined surface, the magnet 204 may be formed inside the bottom of the inclined surface or the rod 205. Therefore, the position of the hall sensor 203 can also be changed.

Accordingly, since the mirror-rotating lidar sensor according to an embodiment of the present invention may reflect only the height of the rotating mirror 201, the overall volume of the lidar sensor may be reduced as compared to the existing lidar sensor.

In the present embodiment, the rotation of the rotary mirror 201 or the drive motor 202 can be detected by using the magnet 204 and the hall sensor 203 instead of the encoder 104 and the encoder detector 103. Therefore, the mirror rotation lidar sensor according to the present embodiment needs to perform laser scanning in a different manner from the existing mirror rotation lidar sensor.

A schematic configuration of the mirror-rotation lidar sensor in which the structure of the drive unit (i.e., the connection structure of the drive motor, the rotating mirror, and the rotation sensor) is changed is described with reference to fig. 5 and 6, and an operation method of the mirror-rotation lidar sensor suitable for the configuration is described.

Fig. 5 shows a schematic configuration of a mirror rotation lidar sensor according to an embodiment of the invention.

As shown in fig. 5, the mirror-rotating lidar sensor according to an embodiment of the present invention may include a sensor unit 210, a motor driving unit 220, and a control unit 230.

The sensor unit 210 may include a hall sensor 203 for sensing a magnet 204 attached to the rotating mirror (or scanning mirror) 201.

In one embodiment, a plurality of magnets 204 may be attached according to the detection position (e.g., the start position and the end position of the scanning area).

The motor driving unit 220 may rotate the rotary mirror 201 connected to the driving motor 202 at a designated speed according to the control of the control unit 230.

By rotating the drive motor 202 at a specified speed, the control unit 230 can calculate the angle of rotating the drive motor 202 or the rotating mirror 201 based on the rotation speed and time from the reference position of the attached magnet.

By calculating the angle by which the drive motor 202 or the rotating mirror 201 rotates, the control unit 230 can distinguish between a scanning region and a non-scanning region and determine whether to output laser light. The scanning area may indicate an area for scanning the object by outputting the laser scanning signal to the front of the laser radar sensor, and the non-scanning area may indicate an area where the laser scanning signal is not output at the rear of the laser radar sensor.

FIG. 6 is a flow chart of a method of operation of a mirror rotation lidar sensor according to an embodiment of the invention.

Referring to fig. 6, in step S101, the control unit 230 may check whether a sensing signal of the hall sensor is detected.

When the sensing signal of the hall sensor is detected (yes in step S101), the control unit 230 may reset the position information of the scanning mirror or the driving motor in step S102. For example, the control unit 230 may set the rotation angle corresponding to the reference position to 0 degree.

That is, when the sensing signal of the hall sensor is detected, the control unit 230 may determine that the scanning mirror or the driving motor is at a reference position (e.g., a start position of the scanning area).

In step S103, the control unit 230 can rotate the scanning mirror or the drive motor at a specified speed while performing laser scanning.

For example, when the reference position is set as the start position of the scanning area, the control unit 230 may immediately start performing the laser scanning. On the other hand, when the reference position is set to another position not corresponding to the start position of the scanning area, the control unit 230 may start the laser scanning at the start position of the scanning area calculated from the reference position.

Further, in step S104, the control unit 230 may calculate an angle (or a scanning angle) by which the drive motor 202 or the rotating mirror (or the scanning mirror) 201 rotates, based on the rotation speed of the reference position at which the rotation angle is set to 0 degrees and the time.

In step S105, the control unit 230 may check whether the calculated angle has become a specified scanning angle, that is, an angle corresponding to the end position of the scanning area.

In steps S103 to S105, until the calculated angle becomes a specified scanning angle corresponding to the end position of the scanning area (no in step S105), the control unit 230 can rotate the scanning mirror or the drive motor at a specified speed while continuously performing laser scanning and calculating the scanning angle.

Then, in step S106, when the calculated angle becomes a specified scanning angle corresponding to the end position of the scanning area (yes in step S105), the control unit 230 may determine that the current area is a non-scanning area, continuously rotate the scanning mirror 201, and end the laser scanning.

That is, when the laser radar sensor rotates the scanning mirror 201 by 360 degrees, the scanning area and the non-scanning area can be repeated. Therefore, in the non-scanning region, the control unit 230 may continuously rotate the scanning mirror 201 but not perform the laser scanning.

In step S107, the control unit 230 calculates a scanning area and a non-scanning area from the reference position, and repeatedly starts and ends the processing of laser scanning until the operation of the laser radar sensor ends. At this time, the control unit 230 may calculate a rotation angle based on the time and the rotation speed of the motor, and calculate a scanning region and a non-scanning region based on the rotation angle.

As described above, the present embodiment can reduce the size of the laser radar sensor to rotate the rotating mirror by changing the structure of the drive unit including the rotating mirror (or the scanning mirror) and the drive motor, and provide a rotation detection method of the rotating mirror suitable for the structure of the drive unit.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.