WO2022138088A1

WO2022138088A1 - Sensor system

Info

Publication number: WO2022138088A1
Application number: PCT/JP2021/044581
Authority: WO
Inventors: 高範難波; 誠晃佐藤; 清隆望月
Original assignee: 株式会社小糸製作所
Priority date: 2020-12-25
Filing date: 2021-12-03
Publication date: 2022-06-30
Also published as: JPWO2022138088A1

Abstract

A sensor system (1) includes: a sensor for outputting point group information including position information of an object, distance information to the object, and a reflection intensity from the object; a dirt determining unit (31) for detecting dirt on the basis of the point group information; a shutter (20) which covers a surface of a transmissive portion on the opposite side to a light emitting unit (11) by means of a reference surface (21a), and which is capable of switching between a closed state and an open state; and a reference information recording unit (32) in which reference information, being the point group information acquired with the shutter (20), when clean, in the closed state, is recorded. The dirt determining unit (31) determines that dirt is attached when the point group information acquired with the shutter (20) in the closed state differs from the reference information.

Description

Sensor system

The present invention relates to a sensor system.

A cleaner system equipped with a cleaner is known from Patent Document 1 and the like.

Japanese Patent Application Laid-Open No. 2001-171491

By the way, in the sensor mounted on the vehicle, the output of the sensor changes as the vehicle travels. If dirt such as mud or dust adheres to the sensor, the output of the sensor does not change even though the vehicle is running. Therefore, based on such a difference, it can be determined that dirt has adhered to the region where the output of the sensor does not change when the vehicle is running.
However, such a dirt determination method cannot be used while the vehicle is stopped. Further, such a dirt determination method cannot be used for a sensor that does not move with respect to the ground, such as a surveillance camera.

Therefore, the present invention provides a sensor system that can detect the adhesion of dirt even if the sensor is stationary with respect to the ground.

The sensor system according to one aspect of the present invention is
Based on a light emitting unit that emits light within a predetermined range through a transmissive unit that transmits light, a light receiving unit that receives light reflected by the light emitted from the light emitting unit that hits an object, and light received by the light receiving unit. A sensor having a point group information output unit that outputs point group information including position information of the object, distance information to the object, and reflection intensity from the object.
A stain determination unit that detects stains adhering to the transmission portion based on the point cloud information, and a stain determination unit.
A shutter that can be switched between a closed state in which the reference surface covers the surface of the transmissive portion opposite to the light emitting portion and an open state in which the reference surface does not cover the transmissive portion.
It has a reference information recording unit that records reference information, which is the point cloud information acquired when the shutter is closed while the transmission unit is clean.
When the point cloud information acquired when the shutter is closed is different from the reference information, the dirt determination unit determines that dirt is attached.

It is a system block diagram of a sensor system. It is a sectional view of a camera. It is a flowchart of the process executed by a sensor system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience of explanation, the description of the member having the same reference number as the member already described in the description of the embodiment will be omitted. Further, the dimensions of each member shown in this drawing may differ from the actual dimensions of each member for convenience of explanation.

Further, in the description of the present embodiment, for convenience of explanation, "horizontal direction", "front-back direction", and "vertical direction" are appropriately referred to. These directions are relative directions set for the vehicle. Here, the "vertical direction" is a direction including the "upward direction" and the "downward direction". The "front-back direction" is a direction including the "forward direction" and the "rear direction". The "left-right direction" is a direction including "left direction" and "right direction".

FIG. 1 is a system block diagram of the sensor system 1 according to the embodiment of the present invention. As shown in FIG. 1, the sensor system 1 includes a LiDAR 10 (an example of a sensor), a shutter 20, a dirt determination unit 31, and a reference information recording unit 32.

FIG. 2 is a cross-sectional view of LiDAR 10. As shown in FIG. 2, the LiDAR 10 includes a light emitting unit 11, a light receiving unit 12, an outer lens 13 (an example of a transmissive unit), and a housing 14. An opening is provided in front of the housing 14, and an outer lens 13 covers this opening. A light emitting unit 11 and a light receiving unit 12 are provided inside the space composed of the housing 14 and the outer lens 13.

The light emitting unit 11 emits light within a detection region (predetermined range) defined in front of the LiDAR 10. The light emitting unit 11 emits light in order toward a plurality of points in the detection region. The light emitted from the light emitting unit 11 and reflected by the object in the detection region passes through the outer lens 13 and is incident on the light receiving unit 12. The light receiving unit 12 outputs the detection result corresponding to the detection of the reflected light to the point cloud information output unit 15.
The point cloud information output unit 15 (see FIG. 1) outputs point cloud information including position information, distance information, and reflection intensity information for a plurality of points in the detection area.

The position information is information indicating at which point (called a detection point) in the detection region the light emitted from the light emitting unit 11 and reflected toward the light receiving unit 12 is reflected, and the position of the detection point. ..
For example, the detection region is divided in advance into a matrix such as 10000 × 10000, the light emitting unit 11 is configured to emit light to points in the divided region, and the light emitting unit 11 is located at the upper right of these plurality of points. It is assumed that the light is emitted in order from the point to the point located in the lower left. In this case, the position information indicating to which point the light is received in the order in which the light is received is included is included. In this case, the point cloud information output unit 15 outputs a pair of information consisting of distance information and reflection intensity information in order, and the order in which these information is output is the position information.
Alternatively, the light emitting unit 11 may include a light source and a mirror whose direction can be changed, and can be configured so that the direction in which the light emitting unit 11 emits light can be specified by the direction of the mirror. In this case, the direction in which the light reflected by the mirror travels becomes the position information. The position information in this case can be expressed by a horizontal angle and a vertical angle in the direction in which the light travels. The point cloud information output unit 15 outputs point cloud information including position information of a detection point based on the direction of the mirror of the light emitting unit 11, distance information, and reflection intensity information.

The distance information is information indicating the distance between the light receiving unit 12 and the object existing at the detection point. The distance information is calculated based on the speed of light and the time from when the light emitting unit 11 emits light toward the detection point until the light receiving unit 12 receives the reflected light from the detection point.
The reflection intensity information is information indicating the intensity of light when the light receiving unit 12 receives the reflected light from this detection point.

The shutter 20 is attached to the LiDAR 10. The shutter 20 has a shielding member 21 and a shutter driving unit 22 for driving the shielding member 21.
The shutter 20 can switch between two states, a closed state in which the shielding member 21 covers the outer lens 13, and an open state in which the shielding member 21 does not cover the outer lens 13. The shielding member 21 has a reference surface 21a facing the surface of the outer lens 13 in the closed state. In other words, the closed state is a state in which the reference surface 21a covers the surface of the outer lens 13 opposite to the light emitting portion 11. The open state is a state in which the outer lens 13 is not covered by the reference surface 21a. In the closed state, the shielding member 21 does not need to cover the entire surface of the outer lens 13. In the closed state, the shielding member 21 may cover at least the region of the outer lens 13 through which the light incident on the light receiving portion 12 is transmitted. In FIG. 2, the shield member 21 in the closed state is shown by a solid line, and the shield member 21 in the open state is shown by a two-dot chain line.

In the illustrated example, the shielding member 21 is attached via the hinge component 23. The shutter drive unit 22 switches between a closed state and an open state by rotating the shielding member 21 around the axis of the hinge component 23. The shutter drive unit 22 can be configured by a motor, an actuator, or the like.
Further, the shutter 20 is in an open state in a normal state, and is configured to be in a closed state only when the shutter drive unit 22 is operated. For example, an elastic member such as a spring constantly exerts a force on the shielding member 21 to open the shielding member 21. When the closed state is desired, the shutter driving unit 22 exerts a driving force that overcomes the elastic restoring force of the elastic member to bring the elastic member into the closed state.

Returning to FIG. 1, the reference information recording unit 32 records the reference information which is the point cloud information acquired when the shutter 20 is closed while the outer lens 13 (transmission unit) is in a clean state. Specifically, the reference information is point cloud information obtained based on the light reflected by the reference surface 21a (see FIG. 2) when the shutter 20 is closed and the outer lens 13 is clean.

Next, a method for determining stains by the stain determination unit 31 will be described. FIG. 3 is a flowchart of the process executed by the sensor system 1. As shown in FIG. 3, first, the dirt determination unit 31 of the sensor system 1 determines whether or not the shutter 20 is in the closed state (step S01). If the shutter 20 is in the open state (step S01: No), an error is output as the stain determination cannot be executed, and the process ends.
If the shutter 20 is in the closed state (step S01: Yes), the dirt determination unit 31 operates the LiDAR 10 to acquire point cloud information from the point cloud information output unit 15 (step S02). The point cloud information acquired at this time is called the judgment target point cloud information.

Next, the dirt determination unit 31 reads the reference information from the reference information recording unit 32 (step S03). Further, the dirt determination unit 31 compares the determination target point cloud information with the reference information and determines whether or not they are different (step S04). When it is determined that the determination target point cloud information is different from the reference information (step S04: Yes), the stain determination unit 31 determines that the stain is attached (step S05). When it is determined that the determination target point cloud information does not differ from the reference information (step S04: No), the stain determination unit 31 determines that no stain is attached (step S06).

As described above, the point cloud information includes position information, distance information, and reflection intensity information. The dirt determination unit 31 identifies the point cloud information whose position information matches from the determination target point cloud information and the reference information, and compares the distance information and the reflection intensity information of the specified point cloud information.
For example, when the order of the data indicates the position information, the first distance information in the reference information and the first distance information in the determination target point cloud information are compared. Further, the first reflection intensity information in the reference information and the first reflection intensity information in the determination target point cloud information are compared.
Alternatively, when the point group information includes the position information as the horizontal angle and the vertical angle, the horizontal angle of the reference information and the horizontal angle of the judgment target point group information match, and the vertical angle of the reference information The distance information of the reference information and the distance information of the judgment target point group information, which match the vertical angle of the judgment target point group information, are compared. In addition, the reflection intensity information of the reference information and the reflection intensity information of the judgment target point cloud information are compared.

If dirt is not attached to the outer lens 13, the light emitted from the light emitting unit 11 is reflected by the reference surface 21a. When dirt is attached to the outer lens 13, the light emitted from the light emitting unit 11 is reflected by the dirt. Since the dirt is located closer to the light receiving portion 12 than the reference surface 21a, the distance information when the dirt is attached is shorter than the distance information when the dirt is not attached. Further, since the dirt reflects the light from the light emitting unit 11 diffusely, the reflection intensity information when the dirt is attached is lower than the reflection intensity information when the dirt is not attached. Alternatively, when the reference surface 21a is configured so that the reflectance of the reference surface 21a is different from the reflectance of the dirt, the reflection intensity information when the dirt is attached is the reflection intensity when the dirt is not attached. Different from information.

Therefore, for example, when the number of point cloud information in which the compared distance information differs by a predetermined value or more is a predetermined number or more, the dirt determination unit 31 determines that the two are different, and dirt is attached to the outer lens 13. Can be configured to determine.
Further, when the number of point cloud information in which the compared reflection intensity information differs by a predetermined value or more is equal to or more than a predetermined number, the stain determination unit 31 determines that the two are different, and determines that the outer lens 13 is dirty. It can be configured to determine.
Further, when the compared distance information is different by a predetermined value or more and the number of point cloud information in which the compared reflection intensity information is different by a predetermined value or more is a predetermined number or more, the stain determination unit 31 is different from each other. It can be configured to determine that the outer lens 13 is dirty and to determine that the outer lens 13 is dirty.
Alternatively, when the number of abnormal points is more than a predetermined number based on the position information of the point cloud information (called an abnormal point) in which the compared distance information differs by a predetermined value or more, dirt adheres to the position of these abnormal points. It can be configured to determine that. It should be noted that the identification of the abnormal point may be different from the compared reflection intensity information by a predetermined value or more, the compared distance information is different by a predetermined value or more, and the compared reflection intensity information is different by a predetermined value or more. May be.

As described above, according to the sensor system 1 of the present embodiment, it is possible to determine whether or not dirt has adhered to the sensor that does not move with respect to the ground.
Further, since the dirt can be determined by using the shutter 20 that protects the sensor when the sensor is not in use, the sensor system 1 has both a member that protects the sensor and a member for determining dirt. It can be configured simply.

When the sensor system 1 is mounted on the vehicle, for example, when the switch for turning off the power of the vehicle is activated, the shutter 20 is switched to the closed state, and then the dirt determination shown in FIG. 3 is executed. Can be configured to Alternatively, when the occupant operates the switch while the vehicle is stopped, the shutter 20 is switched to the closed state, and the dirt determination can be executed. Alternatively, when the sensor system 1 is mounted on a vehicle capable of automatic driving using a sensor, the shutter 20 is switched to the closed state when the occupant of the vehicle switches from the automatic driving mode to the manual driving mode, and a dirt determination is made. Can be configured to run.

Further, when the sensor system 1 is mounted on a structure installed on the ground such as a surveillance camera, the shutter 20 can be periodically switched to the closed state to execute the dirt determination. For example, it can be configured to execute the dirt determination at a fixed time of the day, such as 5 am when the traffic is light.

A shutter closing sensor 24, which is a mechanical contact switch, may be used to determine whether or not the shutter 20 is in the closed state (see FIG. 2). When the shielding member 21 is in the open state, the movable portion 24a of the shutter closing sensor 24 does not come into contact with the shielding member 21. When the shielding member 21 is in the closed state, the movable portion 24a of the shutter closing sensor 24 is pushed by the shielding member 21 and outputs a signal indicating that the shutter 20 is in the closed state. It is possible to determine the closed state of the shutter 20 according to the distance information of the LiDAR 10, but if the LiDAR 10 is dirty, it becomes difficult to make an accurate determination. Therefore, it is preferable to use a sensor other than the sensor that is the target of dirt determination to determine whether or not the shutter 20 is in the closed state.

In the closed state of the shutter 20, it is preferable that a gap is provided between the reference surface 21a of the shielding member 21 and the outer lens 13 so as not to come into contact with each other. If the shutter 20 is closed with dirt attached to the outer lens 13, the dirt on the outer lens 13 also adheres to the reference surface 21a. This is because it is difficult to accurately determine the stain because the determination is made using the dirty reference surface 21a at the time of the stain determination.

When the shutter 20 is in the closed state, the reference surface 21a is preferably separated from the outer lens 13 by at least 0.1 mm or more. This is because if the reference surface 21a and the light emitting unit 11 are too close to each other, normal point cloud information may not be obtained due to diffused reflection due to short-distance emission.

The reflectance of the reference surface 21a of the shutter 20 may be 50% or less. The reflectance of the reference surface 21a of the shutter 20 is preferably 30% or less, more preferably 20% or less, still more preferably 10% or less. Since the reference surface 21a is located near the light emitting portion 11 in the closed state of the shutter 20, the reflection intensity of the light reflected by the reference surface 21a tends to increase. Therefore, it is preferable that the reflectance of the reference surface 21a is low.

The stain determination unit 31 may be configured to emit light to the light emitting unit 11 with a weaker output when the shutter 20 is in the closed state than when the shutter 20 is in the open state.

When the sensor system 1 is mounted on the vehicle, it is preferable that the dirt determination unit 31 closes the shutter 20 when the stop signal indicating that the vehicle is stopped is acquired from the vehicle. It is preferable that the shutter 20 is in the open state so that external information can be acquired by the sensor when the vehicle is running, and the shutter 20 can be switched to the closed state when the vehicle is stopped.

In the above-described embodiment, an example in which the sensor system 1 is mounted on a vehicle has been described, but the present invention is not limited to this example.
The present invention is applied to a sensor that is attached to an installation object installed on the ground such as a traffic light or a street light and acquires traffic information such as the speed and number of vehicles passing there, or a sensor system 1 having a surveillance camera. You may.

Further, in the above-described embodiment, the shutter 20 having the shielding member 21 that rotates around the hinge component 23 has been described, but the present invention is not limited to this example. For example, the shutter may be configured such that the shielding member slides to move to a position that covers the outer lens, or that the shutter can be switched from the wound open state such as a roll screen to the closed state that covers the outer lens.

Although the embodiments of the present invention have been described above, it goes without saying that the technical scope of the present invention should not be construed in a limited manner by the description of the present embodiments. It is understood by those skilled in the art that the present embodiment is merely an example, and various embodiments can be modified within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and the equivalent scope thereof.

This application is based on a Japanese patent application filed on December 25, 2020 (Japanese Patent Application No. 2020-217244), the contents of which are incorporated herein by reference.

According to the present invention, there is provided a sensor system capable of detecting the adhesion of dirt even if the sensor is stationary with respect to the ground.

1 Sensor system 11 Light emitting unit 12 Light receiving unit 13 Outer lens 14 Housing 15 Point cloud information output unit 20 Shutter 21 Shielding member 21a Reference surface 22 Shutter drive unit 23 Hinge parts 24 Shutter closing sensor 24a Movable unit 31 Dirt determination unit 32 Reference information recording unit

Claims

Based on a light emitting unit that emits light within a predetermined range through a transmissive unit that transmits light, a light receiving unit that receives light reflected by the light emitted from the light emitting unit that hits an object, and light received by the light receiving unit. A sensor having a point group information output unit that outputs point group information including position information of the object, distance information to the object, and reflection intensity from the object.
A stain determination unit that detects stains adhering to the transmission portion based on the point cloud information, and a stain determination unit.
A shutter that can be switched between a closed state in which the reference surface covers the surface of the transmissive portion opposite to the light emitting portion and an open state in which the reference surface does not cover the transmissive portion.
It has a reference information recording unit that records reference information, which is the point cloud information acquired when the shutter is closed while the transmission unit is clean.
The dirt determination unit is a sensor system that determines that dirt is attached when the point cloud information acquired when the shutter is in the closed state is different from the reference information.
The sensor system according to claim 1, wherein the reflectance of the reference plane is 50% or less.
The sensor system according to claim 1, wherein the reference surface is at least 0.1 mm or more away from the transmissive portion when the shutter is in the closed state.
The sensor system according to claim 1, wherein the dirt determination unit emits light to the light emitting unit with a weaker output when the shutter is in the closed state than when the shutter is in the open state.
The sensor system according to claim 1, wherein the dirt determination unit closes the shutter when a stop signal indicating that the vehicle is stopped is acquired from the vehicle.