KR102558838B1 - Apparatus and method for correcting optical alignment of lidar sensor - Google Patents

Abstract

The present invention relates to a light alignment correction device for a lidar sensor, comprising: a lidar sensor including an M*N photodetector array; and a control unit that measures received signal strength by processing light signals incident to each photodetector included in the M*N photodetector array, compares the received signal strength with a preset reference value to detect light alignment misalignment, and when the light alignment misalignment is detected, compares the received signal strength for each photodetector with a preset reference value in a predetermined order to find a new photodetector through which light is accurately incident and perform light alignment correction.

Description

Apparatus and method for correcting optical alignment of lidar sensor

The present invention relates to an apparatus and method for correcting light alignment of a lidar sensor, and more particularly, to an apparatus and method for correcting light alignment of a lidar sensor, which detects a light alignment misalignment of a lidar sensor during vehicle driving and automatically corrects optical alignment.

In general, a LIDAR (Light Detection and Ranging) sensor is a sensor that measures distance and detects an object using light, and LIDAR has a principle similar to that of radar.

However, radar emits electromagnetic waves to the outside and checks the distance and direction with electromagnetic waves that are re-received, but lidar has a difference in that it emits a pulse laser. That is, since a laser with a short wavelength is used, there is an advantage in that precision and resolution are high and even three-dimensional recognition is possible depending on the object.

For example, the lidar sensor is mounted on a bumper of a vehicle to sense objects or structures by sensing the front and rear of the vehicle. For reference, FIG. 1 is an exemplary view showing a field of view (FOV) of a lidar sensor mounted on a front/rear bumper of a vehicle.

Meanwhile, the lidar sensor is mainly mounted on the front bumper and must be exposed to the outside. This is because putting the lidar sensor into glass or other structures such as a vehicle body can significantly degrade the sensing performance of the sensor, so it is exposed and mounted to the outside.

For reference, as shown in FIG. 2, the lidar sensor includes a transmitter (laser transmission), a receiver (receives reflected laser), and a drive unit (drives a mirror rotation motor), and a cover is added to protect the sensor from external foreign substances. In addition, a heating wire is mounted on the cover, and the purpose of the heating wire is to remove moisture or snow attached to the surface of the cover.

In addition, the lidar sensor may be misaligned due to vibration or shock generated during vehicle driving. Therefore, there is a need for a method of detecting and correcting the misalignment of the light alignment of the LIDAR sensor.

The background art of the present invention is disclosed in Republic of Korea Patent Publication No. 2015-0009177 (registered on January 26, 2015, title of the invention: lidar sensor system).

According to one aspect of the present invention, the present invention was created to solve the above problems, and detects the light alignment misalignment of the lidar sensor when driving the vehicle and automatically corrects the light alignment of the lidar sensor. Its object is to provide a device and method for correcting light alignment.

An apparatus for compensating light alignment of a lidar sensor according to an aspect of the present invention includes a lidar sensor including an M*N photodetector array; and a control unit that processes an optical signal incident to each photodetector included in the M*N photodetector array to measure a received signal intensity, compares the received signal intensity with a preset reference value to detect optical alignment misalignment, and when the optical alignment misalignment is detected, compares the received signal intensity for each photodetector with a preset reference value in a predetermined order to find a new photodetector into which light is accurately incident and perform optical alignment correction.

In the present invention, the predetermined order is characterized in that the order of a photodetector having the closest peripheral distance to a photodetector having the farthest distance based on the most recently set photodetector before light alignment misalignment is detected.

In the present invention, the predetermined order is characterized in that, when optical alignment misalignment has occurred at least once previously, the order is set by additionally reflecting direction information in which the optical alignment misalignment occurred.

In the present invention, it is characterized in that the reference value is a received signal intensity value that can be measured when incident light is normally incident on any one photodetector.

In the present invention, when the received signal intensity measured by the most recently set photodetector among the M*N photodetector array is compared with a preset reference value, the control unit determines that optical alignment misalignment has occurred when the measured received signal intensity is not equal to or greater than the preset reference value.

In the present invention, the lidar sensor, the sensing light source for irradiating the sensing light; a light transmission reflector for reflecting the sensing light emitted from the sensing light source unit; a scanner unit that reflects the sensing light reflected from the light transmission reflector to a target and reflects incident light reflected from the target; a light-receiving lens through which incident light reflected from the scanner unit is transmitted and integrally formed with the light-transmitting reflector; a light receiving reflector for reflecting incident light passing through the light receiving lens; and a photodetector including the M*N photodetector array into which incident light reflected from the light receiving reflector is incident.

A light alignment correction method of a lidar sensor according to another aspect of the present invention includes the steps of measuring, by a control unit, a received signal strength by processing an optical signal incident to each photodetector included in an M*N photodetector array of a lidar sensor; detecting, by the control unit, light alignment misalignment by comparing the received signal strength with a preset reference value; and when the misalignment of the light is detected, the control unit compares the received signal intensity for each of the photodetectors with a preset reference value in a predetermined order to find a new photodetector into which light is accurately incident and perform optical alignment correction.

In the present invention, in the step of detecting the light alignment misalignment, the control unit determines that the light alignment misalignment has occurred when the received signal strength measured by the most recently set photodetector among the M*N photodetector array is compared with a preset reference value, when the measured received signal strength is not equal to or greater than the preset reference value.

In the present invention, in comparing the received signal strength with a preset reference value, the reference value is a received signal strength value that can be measured when incident light is normally incident on any one photodetector.

In the present invention, the predetermined order is characterized in that the order of a photodetector having the closest peripheral distance to a photodetector having the farthest distance based on the most recently set photodetector before light alignment misalignment is detected.

In the present invention, the predetermined order is characterized in that, when optical alignment misalignment has occurred at least once previously, the order is set by additionally reflecting direction information in which the optical alignment misalignment occurred.

According to one aspect of the present invention, the present invention detects the light alignment misalignment of the lidar sensor during vehicle driving so that the light alignment can be automatically corrected. Accordingly, it is possible to prevent deterioration in precision or resolution of sensing that may occur due to misalignment of light of the LIDAR sensor while driving the vehicle.

1 is an exemplary view showing a general FOV (Field of View) of a lidar sensor mounted on a front/rear bumper of a vehicle.
Figure 2 is an exemplary view shown to explain the schematic configuration of the previously released lidar sensor.
Figure 3 is an exemplary view schematically showing the internal configuration of the lidar sensor according to an embodiment of the present invention.
4 is an exemplary view showing a sensing light source unit, a light-receiving lens, and a light-receiving reflector of the lidar sensor in more detail in FIG. 3;
5 is an exemplary view showing a schematic configuration of an apparatus for compensating light alignment of a lidar sensor according to an embodiment of the present invention.
FIG. 6 is an exemplary diagram shown to explain the method of FIG. 5 , in which the control unit detects the light alignment misalignment and detects a new photodetector to which incident light is incident among the M*N photodetector array by the light alignment misalignment.
7 is a flowchart illustrating a method for correcting light alignment of a LiDAR sensor according to an embodiment of the present invention.

Hereinafter, an embodiment of an apparatus and method for correcting light alignment of a LiDAR sensor according to the present invention will be described with reference to the accompanying drawings.

In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

3 is an exemplary view schematically showing the internal configuration of a lidar sensor according to an embodiment of the present invention, and FIG. 4 is an exemplary view showing in more detail the sensing light source unit, light receiving lens, and light receiving reflector of the lidar sensor in FIG. 3.

As shown in FIGS. 3 and 4, the lidar sensor (or lidar sensing device) according to the present embodiment includes a sensing light source unit 10, a light transmission mirror 20, a scanner unit 30, a light receiving lens 40, a light receiving reflector 50, a light detection unit 60, and an M*N detector array 61.

The sensing light source unit 10 radiates sensing light.

The sensing light source unit 10 is disposed out of the light path of the light receiving lens 40 and the light receiving reflector 50. Since the sensing light source unit 10 is disposed out of the light path of the light receiving lens 40 and the light receiving reflector 50, it is possible to prevent the sensing light source unit 10 from blocking incident light in the light path (blackage effect). Therefore, it is possible to prevent a receiving blackage area (A) from being generated by the sensing light source unit 10 in the light path of the light receiving lens 40, thereby increasing light receiving efficiency. As the light receiving efficiency increases as described above, the maximum detection distance of the lidar sensor may be increased.

The sensing light source unit 10 includes a lens barrel 11 , a light source 13 and a light transmitting lens unit 15 . The barrel 11 is disposed out of the light passage of the light receiving lens 40 and may be formed in a cylindrical shape.

The light source 13 is installed inside the barrel 11. The light transmission lens unit 15 is installed on the output side of the light source 13 to collimate the sensing light emitted from the light source 13 . Since the light transmitting lens unit 15 collimates the sensing light into a parallel beam, the output of the sensing light can be improved.

The light transmission lens unit 15 includes a first light transmission lens 15a and a second light transmission lens 15b. The first light transmission lens 15a is installed inside the lens barrel 11, the second light transmission lens 15b is installed inside the lens barrel 11, and the sensing light passing through the first light transmission lens 15a is incident on the second light transmission lens 15b. Since the first light transmission lens 15a and the second light transmission lens 15b are installed inside the barrel 11, it is possible to prevent the first light transmission lens 15a and the second light transmission lens 15b from forming the reception blocking area A of the light receiving lens 40.

The light transmission reflector 20 reflects the sensing light emitted from the sensing light source unit 10 . A metal reflection layer (not shown) may be coated on the light transmission reflector 20 to improve light reflection efficiency.

The light transmitting reflector 20 is disposed in the optical path of the light receiving lens 40. At this time, since the light transmitting reflector 20 is disposed in the optical path of the light receiving lens 40, the reception blocking area A is as much as the width of the light transmitting reflector 20. Therefore, since the reception blocking area A is reduced in the light receiving lens 40, light reception efficiency can be increased. As the light reception efficiency increases, the maximum detection distance of the lidar sensing device can be further increased.

The scanner unit 30 reflects sensing light reflected from the light transmission reflector 20 to the target and reflects incident light reflected from the target. A reflective layer is also formed on the scanner unit 30 to improve light reflection efficiency.

The scanner unit 30 includes a scanner reflector 31 and a scanner driving unit 33 .

The scanner reflector 31 reflects the sensing light reflected from the light transmission reflector 20 toward the target and reflects the incident light reflected from the target to the light receiving lens 40 . The scanner driver 33 is connected to the scanner reflector 31 so as to rotate the scanner reflector 31 . Since the scanner driver 33 rotates the scanner reflector 31 , the reflection angle of the sensing light and the incident light may be changed according to the angle of the scanner reflector 31 .

A motor unit (not shown) may be applied as the scanner driving unit 33 . The motor unit may include an encoder (not shown) or may be connected to the encoder. The encoder measures the number of rotations, rotational speed, rotational angle, etc. of the motor unit and provides them to the control unit.

Incident light reflected from the scanner unit 30 is transmitted through the light receiving lens 40 , and the light receiving lens 40 is integrally formed with the light transmitting reflector 20 . The light-receiving lens 40 and the light-transmitting reflector 20 may be made of the same optical material, such as crystal, glass, or transparent synthetic resin. The light receiving lens 40 may be formed with an anti-reflection coating layer to prevent reflection of incident light. Since the light-receiving lens 40 and the light-transmitting reflector 20 are integrated into one optical module, the number of parts can be reduced. In addition, it is possible to prevent the reception shielding area A from being formed by the barrel 11 .

The light receiving reflector 50 reflects incident light passing through the light receiving lens 40 . A reflective layer (not shown) is also formed on the scanner unit 30 to improve light reflection efficiency.

Incident light reflected from the light receiving reflector 50 is incident to the light detector 60 . The photodetector 60 can detect the position and distance of the target according to the incident light.

In addition, the lidar sensor further includes an interference filter 63 and an M*N photodetector array 61 installed between the light receiving reflector 50 and the photodetector 60 . The interference filter 63 filters light of a specific wavelength, and since the interference filter 63 injects light of a certain wavelength into the photodetector 60, the position and distance of the target can be accurately detected by the photodetector 60. At this time, the photodetector 60 performs a photodetection operation based on the M*N photodetector array 61 .

Here, the M*N photodetector array 61 means that the photodetectors are arranged in M*N, and the incident light passing through the interference filter 63 is incident to any one of the M*N photodetector arrays 61. Accordingly, the photodetector 60 processes an optical signal incident to any one photodetector of the M*N photodetector array 61 .

In contrast to the present embodiment, conventionally, a 1*1 photodetector was used for the photodetector 60, and accordingly, if the optical alignment is distorted due to vibration or impact occurring during vehicle driving, that is, the 1*1 It was determined that the function of the lidar sensor was deteriorated or a failure occurred because the incident light was not accurately incident.

On the other hand, in the present embodiment, by applying the M*N photodetector array 61 to the photodetector 60, for example, assuming that a 10*10 photodetector array is applied to the photodetector 60 and incident light is incident to the 5*5 photodetector in a normal state, if the incident light is incident to the 6*6 photodetector due to a misalignment of the light, in this embodiment, the received signal intensity of the 5*5 photodetector is analyzed to determine the optical alignment. The misalignment is detected, and when the misalignment of light is detected, a new 6*6 photodetector through which the incident light is accurately incident is found, and the incident light signal is processed by the corresponding photodetector (ie, the 6*6 photodetector).

Accordingly, the present embodiment detects and corrects the misalignment of the light alignment even if the light alignment is distorted due to vibration or shock generated during vehicle driving, thereby allowing the LIDAR sensor to operate normally without deteriorating the sensing precision or resolution. There is an effect.

5 is an exemplary view showing a schematic configuration of an apparatus for correcting light alignment of a lidar sensor according to an embodiment of the present invention. As shown in FIG. 5, the apparatus for correcting optical alignment of a lidar sensor according to the present embodiment includes a lidar sensor 100 including an M * N photodetector array 61; and a control unit 200 performing optical alignment correction through the M*N photodetector array 61 .

Here, the controller 200 is a concept including the photodetector 60 .

The controller 200 detects a corresponding photodetector among the M*N photodetector array 61 to which the incident light passing through the interference filter 63 is incident. Accordingly, the control unit 200 processes an optical signal incident (or received) to any one of the M*N photodetector arrays 61, and measures the received signal strength through processing the optical signal.

In addition, the control unit 200 sequentially measures the received signal strengths of all the photodetectors included in the M*N photodetector array 61 in a designated order and compares them with a preset reference value (i.e., received signal strength that can be measured when incident light is normally incident).

At this time, the designated order is set in the order of the closest photodetector to the farthest photodetector based on the recently set photodetector (ie, the last photodetector set before the light alignment misalignment is detected). In addition, the designated order may be set by additionally reflecting direction information in which the optical alignment distortion occurs when the optical alignment deviation has already occurred at least once before.

The control unit 200 measures received signal strength from each photodetector of the M*N photodetector array 161 and compares it with a preset reference value to detect a misalignment of light. When the misalignment is detected, the control unit 200 measures the received signal strength from each photodetector and compares the received signal strength with the preset reference value to find a new photodetector through which incident light is accurately incident and process the light signal incident to the photodetector.

For example, FIG. 6 is an exemplary diagram shown in FIG. 5 to explain a method in which the control unit detects a light alignment misalignment and detects a new photodetector to which incident light is incident among the M*N photodetector arrays due to the light alignment misalignment. This occurs to detect incident light incident on any other photodetector (current photodetector in FIG. 6).

7 is a flowchart illustrating a method for compensating light alignment of a LiDAR sensor according to an embodiment of the present invention.

As shown in FIG. 7, when the lidar sensor starts operating, the control unit 200 applies (sets) the position value of the most recently set photodetector among the M*N photodetector array 161 applied to the lidar sensor (that is, the last photodetector set before light misalignment is detected) (that is, the position value of the most recently set photodetector among the M*N photodetector arrays) (S101).

Then, the controller 200 analyzes the received signal for the set photodetector (that is, the most recently set photodetector among the M*N photodetector array 161) (S102). That is, the controller 200 measures the received signal strength of the set photodetector (that is, the most recently set photodetector among the M*N photodetector array 161).

Accordingly, it is checked whether the received signal intensity for the set photodetector (i.e., the most recently set photodetector among the M*N photodetector array 161) is equal to or greater than a preset reference value (i.e., received signal intensity that can be measured when incident light is normally incident) (S103).

As a result of the check (S103), if the received signal intensity for the set photodetector (i.e., the most recently set photodetector among the M*N photodetector array 161) is equal to or greater than a preset reference value (i.e., received signal intensity that can be measured when the incident light is normally incident) (Yes in S103), it means that no light alignment misalignment has occurred.

Accordingly, the controller 200 applies the set position value of the photodetector among the M*N photodetector array 61 as it is (ie, maintains the setting) (S104).

However, as a result of the check (S103), if the received signal intensity for the set photodetector (i.e., the most recently set photodetector among the M*N photodetector array 161) is not greater than a preset reference value (i.e., received signal intensity that can be measured when the incident light is normally incident) (No in S103), it means that optical alignment misalignment has occurred.

Accordingly, the control unit 200 sequentially measures the received signal strength of all photodetectors included in the M*N photodetector array 61 according to a designated order, compares the received signal strength with a preset reference value (ie, the received signal strength that can be measured when the incident light is normally incident), finds a new photodetector (or the position value of the new photodetector) whose received signal strength is equal to or greater than the preset reference value (ie, the received signal strength that can be measured when the incident light is normally incident) and changes the setting (S1 05).

At this time, the designated order is set in the order of the closest photodetector to the farthest photodetector based on the recently set photodetector (ie, the last photodetector set before the light alignment misalignment is detected). In addition, the designated order may be set by additionally reflecting direction information in which the optical alignment distortion occurs when the optical alignment deviation has already occurred at least once before.

In addition, if the received signal strength of all photodetectors included in the M * N photodetector array 61 is sequentially measured in a designated order and compared with a preset reference value (ie, received signal strength that can be measured when incident light is normally incident), if a new photodetector (or position value of the new photodetector) whose received signal strength is equal to or greater than a preset reference value (ie, received signal strength that can be measured when incident light is normally incident) cannot be found, it is determined that the lidar sensor is out of order. Therefore, the control unit 200 may output an alarm to notify replacement of the lidar sensor.

The present invention has been described above with reference to the embodiments shown in the drawings, but this is only exemplary, and those skilled in the art to which the technology belongs will understand that various modifications and equivalent other embodiments are possible. Therefore, the technical protection scope of the present invention should be determined by the claims below. Implementations described herein may also be embodied in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed only in the context of a single form of implementation (eg, discussed only as a method), the implementation of features discussed may also be implemented in other forms (eg, an apparatus or program). The device may be implemented in suitable hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which is generally referred to as a processing device including, for example, a computer, microprocessor, integrated circuit or programmable logic device or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants ("PDAs") and other devices that facilitate communication of information between end-users.

10: sensing light source unit 11: barrel
13: light source 15: light transmission lens unit
15a: first light transmission lens 15b: second light transmission lens
20: light transmission reflector 30: scanner unit
31: scanner reflector 33: scanner driving unit
40: light receiving lens 50: light receiving reflector
60: photodetector unit 61: M * N photodetector array
63: interference filter 100: lidar sensor
200: control unit

Claims (11)

a lidar sensor including an M*N photodetector array; and
A control unit for measuring received signal strength by processing an optical signal incident to each photodetector included in the M*N photodetector array, comparing the received signal intensity with a preset reference value to detect light alignment misalignment, and comparing the received signal strength for each photodetector with a preset reference value in a pre-specified order to find a new photodetector through which light is accurately incident and perform light alignment correction;
The reference value is
Light alignment correction device of a lidar sensor, characterized in that the received signal intensity value that can be measured when the incident light is normally incident on any one photodetector.
The method of claim 1, wherein the predetermined order is,
Light alignment correction device of a lidar sensor, characterized in that the surrounding distance is set in the order of the photodetector with the closest distance to the photodetector with the farthest distance based on the most recently set photodetector before the optical alignment misalignment is detected.
The method of claim 2, wherein the predetermined order is,
If the light alignment misalignment has already occurred at least once before, the light alignment correction device of the lidar sensor, characterized in that the order is set by additionally reflecting the direction information in which the light alignment misalignment occurred.
delete The method of claim 1, wherein the control unit,
When the received signal strength measured by the most recently set photodetector among the M*N photodetector array is compared with a preset reference value,
Light alignment correction device of a lidar sensor, characterized in that it is determined that the optical alignment misalignment has occurred when the measured received signal strength is not equal to or greater than a preset reference value.
The method of claim 1, wherein the lidar sensor,
a sensing light source unit irradiating sensing light;
a light transmission reflector for reflecting the sensing light emitted from the sensing light source unit;
a scanner unit that reflects the sensing light reflected from the light transmission reflector to a target and reflects incident light reflected from the target;
a light-receiving lens through which incident light reflected from the scanner unit is transmitted and integrally formed with the light-transmitting reflector;
a light receiving reflector for reflecting incident light passing through the light receiving lens; and
Light alignment correction device of a lidar sensor, characterized in that it comprises a; photodetector including the M * N photodetector array into which the incident light reflected from the light receiving reflector is incident.
measuring, by a control unit, a received signal strength by processing an optical signal incident to each photodetector included in an M*N photodetector array of a lidar sensor;
detecting, by the control unit, light alignment misalignment by comparing the received signal strength with a preset reference value; and
When the light alignment misalignment is detected, the control unit compares the received signal strength for each of the photodetectors with a preset reference value in a predetermined order to find a new photodetector into which light is accurately incident and perform photoalignment correction; including,
In comparing the received signal strength with a preset reference value,
The reference value is
A light alignment correction method of a lidar sensor, characterized in that the received signal intensity value that can be measured when incident light is normally incident on any one photodetector.
The method of claim 7, wherein in the step of detecting the light alignment misalignment,
The control unit,
When the received signal strength measured by the most recently set photodetector among the M*N photodetector array is compared with a preset reference value,
When the measured received signal strength is not greater than or equal to a preset reference value, it is determined that optical alignment misalignment has occurred.
delete The method of claim 7, wherein the predetermined order,
A light alignment correction method of a lidar sensor, characterized in that the optical alignment correction method of the lidar sensor is set in the order of the photodetector with the closest distance to the photodetector with the farthest distance based on the most recently set photodetector before the optical alignment misalignment is detected.
The method of claim 10, wherein the predetermined order,
If the light alignment misalignment has already occurred at least once before, the light alignment correction method of the lidar sensor, characterized in that the order is set by additionally reflecting the direction information in which the light alignment misalignment occurred.

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