Sensor system

A light emitting element emits detecting light toward an outside area of a vehicle. A light receiving element outputs a light receiving signal corresponding to reflected light. A processor detects information of the outside area on the basis of the light receiving signal. A translucent cover forms a part of an outer surface of the vehicle, and has a plurality of flat portions allowing passage of the detecting light. The processor excludes, from the information to be detected, a position corresponding a boundary portion between adjacent ones of the flat portions.

FIELD

The presently disclosed subject matter relates to a sensor system adapted to be installed in a vehicle.

BACKGROUND

In order to realize driving support technology of the vehicle, a sensor for detecting information in an outside area of the vehicle shall be mounted on a vehicle body. Examples of such sensors include LiDAR (Light Detection and Ranging) sensors (see Patent Document 1, for example).

The LiDAR sensor includes a light emitting element and a light receiving element. The light emitting element emits detecting light toward an outside area of the vehicle. The detecting light is reflected by an object that situates in the outside area of the vehicle, and incident on the light receiving element as reflected light. The light receiving element outputs a signal based on the reflected light. Based on the signal, information in the outside area of the vehicle is detected.

CITATION LIST

Patent Document

Patent Document 1: Japanese Patent Publication No. 2010-185769 A

SUMMARY

Technical Problem

For the purpose of protection from dirt and flying stones, the LiDAR sensor is covered with a translucent cover forming a part of the outer surface of the vehicle. Accordingly, the detecting light passes through the translucent cover and is directed to the outside of the vehicle. The translucent cover refracts the detecting light. As a result, there is a difference between a point on an extension line of the detecting light incident on the translucent cover and a point at which the detecting light emitted from the translucent cover reaches. This difference affects the detection of information in the outside area of the vehicle.

Accordingly, it is demanded to suppress the influence of the translucent cover, that allows the passage of light for detecting the external information of the vehicle, on the detection of the information.

Solution to Problem

In order to meet the demand described above, a first illustrative aspect of the presently disclosed subject matter provides a sensor system adapted to be installed in a vehicle, comprising:a light emitting element configured to emit detecting light toward an outside area of the vehicle;a light receiving element configured to output a signal corresponding to reflected light;a processor configured to detect information of the outside area on the basis of the signal; anda translucent cover configured to form a part of an outer surface of the vehicle, and having a plurality of flat portions configured to allow passage of the detecting light,wherein the processor is configured to exclude, from the information to be detected, a position corresponding a boundary portion between adjacent ones of the flat portions.

According to such a configuration, not only can the refraction when the detecting light passes through the translucent cover be reduced, but also, since the position corresponding to the boundary portion whose behavior is not expected is excluded from the information to be detected, it is possible to suppress the influence of the translucent cover on the information detection.

The sensor system according to the first illustrative aspect may be configured such that a surface of the translucent cover at the boundary portion is made opaque for at least a wavelength of the detecting light.

According to such a configuration, since the detecting light can be prevented from passing through the boundary portion, it is possible to prevent the occurrence of an unexpected behavior of the detecting light caused by the passage of the translucent cover.

In order to meet the demand described above, a second illustrative aspect of the presently disclosed subject matter provides a sensor system adapted to be installed in a vehicle, comprising:a light emitting element configured to emit detecting light toward an outside area of the vehicle;a light receiving element configured to output a signal corresponding to reflected light;a processor configured to detect information of the outside area on the basis of the signal; anda translucent cover configured to form a part of an outer surface of the vehicle, and having a plurality of flat portions configured to allow passage of the detecting light,wherein a surface of the translucent cover at a boundary portion between adjacent ones of the flat portions is made opaque for at least a wavelength of the detecting light.

According to such a configuration, since the detecting light can be prevented from passing through the boundary portion, it is possible to prevent the occurrence of an unexpected behavior of the detecting light caused by the passage of the translucent cover. In this case, even if no special processing is performed on the side of the processor, the position corresponding to the boundary portion can be excluded from the information to be detected. In addition, since the refraction when the detecting light passes through the translucent cover can be reduced, it is possible to suppress the influence of the translucent cover on the information detection.

The sensor system according to the second illustrative aspect may be configured such that a surface of the translucent cover at the boundary portion is curved.

It is desirable that the area excluded from the target of information detection is minimized. Accordingly, it is desirable that the area of the opaque portion is minimized. Since the surface of the translucent cover at the boundary portion is formed as a curved surface, it is easy to perform the opacifying treatment while minimizing the area of the opaque portion. In addition, the molding workability of the translucent cover (ease of removal from the mold or the like) is improved.

The sensor system according to the first and second illustrative aspects may be configured such that the light emitting element and the light receiving element are parts of either a LiDAR sensor unit or a TOF camera unit.

As used herein, the term “sensor unit” means a constituent unit of a component that can be distributed by itself as a single unit while providing a desired information detecting function.

As used herein, the term “driving support” means control processing that at least partially performs at least one of driving operation (steering operation, acceleration, deceleration), monitoring of a driving environment, and backup of driving operation. That is, the term “driving support” means not only the partial driving support such as braking function for collision avoidance and assisting function for lane-keeping, but also a full self-driving operation.

DESCRIPTION OF EMBODIMENTS

Examples of embodiments will be described below in detail with reference to the accompanying drawings. In each of the drawings used in the following description, the scale is appropriately changed in order to make each member have a recognizable size.

In the accompanying drawings, an arrow F represents a forward direction of the illustrated structure. An arrow B represents a rearward direction of the illustrated structure. An arrow U represents an upward direction of the illustrated structure. An arrow D represents a downward direction of the illustrated structure. An arrow L represents a leftward direction of the illustrated structure. An arrow R represents a rightward direction of the illustrated structure. The terms “left” and “right” used in the following descriptions represent the left-right directions when viewed from the driver's seat.

FIG.1illustrates a configuration of a left front sensor device10according to an embodiment. The left front sensor device10is disposed in a left front portion LF of the vehicle100illustrated inFIG.2. The left front portion LF is an area located on the left of the center in a left-right direction of the vehicle100and ahead of the center in a front-rear direction of the vehicle100.

As illustrated inFIG.1, the left front sensor device10includes a housing11and a translucent cover12. The housing11defines an accommodation chamber13together with the translucent cover12. The translucent cover12forms a part of the outer surface of the vehicle100.

The left front sensor device10includes a LiDAR sensor unit14. The LiDAR sensor unit14is disposed in the accommodation chamber13.

As illustrated inFIG.3, the LiDAR sensor unit14includes a light emitting element41and a light receiving element42. The translucent cover12covers the light emitting element41and the light receiving element42.

The light emitting element41is configured to emit detecting light L1toward the outside of the vehicle100. As the detecting light L1, for example, infrared light having a wavelength of 905 nm can be used. As the light emitting element41, a semiconductor light emitting element such as a laser diode or a light emitting diode can be used.

The LiDAR sensor unit14may appropriately include an optical system (not illustrated) for irradiating the detecting light L1in a desired direction. The LiDAR sensor unit14may include a scanning mechanism (not illustrated) for changing the irradiating direction of the detecting light L1to scan a detection area.

The light receiving element42is configured to output a light receiving signal S1corresponding to the amount of incident light. As the light receiving element42, a photodiode, a phototransistor, a photo resistor, or the like can be used. The LiDAR sensor unit14may include an amplifier circuit (not illustrated) for amplifying the light receiving signal S1.

The light emitting element41, the light receiving element42, and the translucent cover12constitute a sensor system1. The sensor system1further includes a processor20. The processor20outputs a control signal S0for causing the light emitting element41to emit the detecting light L1at a desired timing. The processor20receives the light receiving signal S1outputted from the light receiving element42.

The processor20detects information in an outside area of the vehicle100based on the light receiving signal S1corresponding to reflected light L2. For example, the processor20can obtain a distance to an object associated with the reflected light L2based on the time period from the time when the detecting light L1is emitted in a certain direction to the time when the reflected light L2is detected. Further, by accumulating such data as to the distance in association with the detecting position, it is possible to acquire information as to the shape of the object associated with the reflected light L2. Additionally or alternatively, information as to an attribute such as the material of the object associated with the reflected light L2can be acquired based on the difference in waveforms of the detecting light L1and the reflected light L2.

The translucent cover12has a plurality of flat portions12a. The processor20is configured to exclude positions corresponding to boundary portions12bformed between the adjacent flat portions12afrom objects to be detected.

FIG.4Aillustrates a translucent cover12A and a light emitting element41A according to a comparative example. In this example, the translucent cover12A has an arcuate cross section. The translucent cover12A and the light emitting element41A are disposed such that the center of curvature of the arcuate shape coincides with the center of light emission of detecting light L0emitted from the light emitting element41A, such as the light source position and the center of scan.

According to such an arrangement, the detecting light L0emitted from the light emitting element41A can pass through the translucent cover12A without being refracted regardless of the emitted direction. However, the shape of the translucent cover12A and the positional relationship with the light emitting element41may be a considerable constraint on the design of the sensor device.

In addition, as illustrated inFIG.4B, if the center of curvature of the arcuate shape does not coincide with the center of emission of the detecting light L0, the detecting light L0is greatly refracted by the curved surface of the translucent cover12A. That is, not only high accuracy is required for the positioning of the component, but also the information sensing accuracy is likely to be affected by the positional deviation caused by vibration or aging.

On the other hand, in the present embodiment illustrated inFIG.3, the detecting light L1emitted from the light emitting element41is allowed to pass through the flat portion12aof the translucent cover12.

According to such a configuration, it is easy to cause the detecting light L1to enter the translucent cover12perpendicularly. In this case, the detecting light L1is not refracted when passing through the translucent cover12. For example, the detecting light L1A illustrated inFIG.3is incident perpendicularly on the translucent cover12. Even if the translucent cover12and the light emitting element41are relatively displaced in the left-right direction from this state, the state in which the detecting light L1A is incident perpendicularly on the translucent cover12can be maintained.

In addition, even if the incident light is obliquely incident on the flat portion12aas in the detecting light L1B illustrated inFIG.3, the refraction amount of the detecting light L1B is small as compared with a case where the detecting light L1B is incident on the curved surface illustrated inFIG.4B.

However, by providing the flat portions12athat can obtain such an advantageous effect, it is inevitable that the boundary portion12bof the adjacent flat portions12ais formed. In the boundary portion12b, the behavior of the detecting light L1C caused by the passage of the translucent cover12cannot be expected. Accordingly, the processor20is configured not to detect information based on the reflected light L2generated from the detecting light L1C emitted toward the boundary portion12b.

For example, when scanning in which the light emitting direction of the detecting light L1cyclically changes is performed, since the positional relationship between the light emitting element41and the boundary portion12bis known, the processor20can grasp in advance at what timing the detecting light emitted is directed to the boundary portion12b. Accordingly, the processor20may be configured not to perform the information detection processing based on the light receiving signal S1corresponding to the reflected light generated by the detecting light L1C emitted at that timing.

Alternatively, in a case where a plurality of light emitting elements41are configured to emit the detecting light L1in various directions, since the positional relationship with the boundary portion12bis also known, the processor20can grasp in advance which detecting light emitted from which light emitting element41is directed to the boundary portion12b. Accordingly, the processor20may be configured not to perform the information detection processing based on the light receiving signal S1corresponding to the reflected light generated by the detecting light L1C emitted from that light emitting element41.

Not only can the refraction when the detecting light L1passes through the translucent cover12be reduced, but also, since the position corresponding to the boundary portion12bwhose behavior is not expected is excluded from the information to be detected, it is possible to suppress the influence of the translucent cover12on the information detection.

FIG.5Aillustrates an enlarged view of a boundary portion12bof the translucent cover12surrounded by a chain line V inFIG.3. The surface of the translucent cover12at the boundary portion12bmay be formed as an opaque portion12cfor at least the wavelength of the detecting light L1by applying opacification treatment. Examples of the opacifying treatment include treatment for making a surface into a state like frosted glass by forming fine unevenness, treatment for performing coating on the surface, and the like.

According to such a configuration, since the detecting light L1can be prevented from passing through the boundary portion12b, it is possible to prevent the occurrence of an unexpected behavior of the detecting light L1caused by the passage of the translucent cover12. In this case, even if no special processing is performed on the side of the processor20, the position corresponding to the boundary portion12bcan be excluded from the information to be detected.

Not only can the refraction when the detecting light L1passes through the translucent cover12be reduced, but also, since the position corresponding to the boundary portion12bwhose behavior is not expected is excluded from the information to be detected, it is possible to suppress the influence of the translucent cover12on the information detection.

As illustrated inFIG.5B, the surface of the translucent cover12at the boundary portion12bmay be formed as a curved surface12d.

It is desirable that the area excluded from the information to be detected is minimized. Accordingly, it is desirable that the area of the opaque portion12cis minimized. Since the surface of the translucent cover12at the boundary portion12bis formed as the curved surface12d, it is easy to perform the opacifying treatment while minimizing the area of the opaque portion12c. In addition, the molding workability of the translucent cover12(ease of removal from the mold or the like) is improved.

The functions of the processor20described later may be realized by a general-purpose microprocessor cooperating with a memory, or may be realized by a dedicated integrated circuit such as a microcontroller, an FPGA, and an ASIC.

The processor20may be disposed at any position in the vehicle. The processor20may be provided as a part of a main ECU responsible for central control processing in the vehicle, or may be provided as a part of a sub-ECU interposed between the main ECU and the LiDAR sensor unit14.

As illustrated inFIG.1, the left front sensor device10may include a lamp unit15. The lamp unit15is disposed in the accommodation chamber13. The lamp unit15is a device for emitting visible light to the outside of the vehicle100. Examples of the lamp unit15include a headlamp unit, a clearance lamp unit, a direction indicator lamp unit, and a fog lamp unit. As used herein, the term “lamp unit” means a constituent unit of a component that can be distributed by itself as a single unit while providing a desired lighting function.

The lamp unit15is generally disposed at four corner portions of the vehicle100. The four corner portions are also portions where there are few obstacles when detecting information in an outside area of the vehicle100. By arranging the LiDAR sensor unit14so as to share the accommodation chamber13with the lamp unit15, it is possible to efficiently detect the information in the outside area of the vehicle100.

The left front sensor device10may include a sensor bracket43and a lamp bracket53. The sensor bracket43and the lamp bracket53are independent of each other. The LiDAR sensor unit14is supported by the sensor bracket43. The lamp unit15is supported by the lamp bracket53.

The left front sensor device10may include a sensor aiming mechanism44and a lamp aiming mechanism54. The sensor aiming mechanism44is a mechanism for adjusting a detecting reference direction of the LiDAR sensor unit14. The lamp aiming mechanism54is a mechanism for adjusting a lighting reference direction of the lamp unit15.

The sensor aiming mechanism44includes a first screw441and a second screw442. The first screw441and the second screw442can be operated from the outside of the housing11.

When the first screw441is operated, the posture of the sensor bracket43changes in the left-right direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the LiDAR sensor unit14changes in the left-right direction. When the second screw442is operated, the posture of the sensor bracket43changes in the up-down direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the LiDAR sensor unit14changes in the up-down direction. Each of the first screw441and the second screw442may be replaced with an actuator operated by an external control signal.

The lamp aiming mechanism54includes a first screw541and a second screw542. The first screw541and the second screw542can be operated from the outside of the housing11.

When the first screw541is operated, the posture of the lamp bracket53changes in the left-right direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the lamp unit15changes in the left-right direction. When the second screw542is operated, the posture of the lamp bracket53changes in the up-down direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the lamp unit15changes in the up-down direction. Each of the first screw541and the second screw542may be replaced with an actuator operated by an external control signal.

Alternatively, as illustrated inFIG.6, the left front sensor device10may include a common bracket16. The LiDAR sensor unit14and the lamp unit15are supported by the bracket16.

In this case, the left front sensor device10may include a swivel actuator55. The swivel actuator55may be controlled by the processor20. As illustrated inFIG.7A, the swivel actuator55changes the lighting reference direction of the lamp unit15in the left-right direction by causing the bracket16to pivot about a pivot shaft16a.

The detecting reference direction of the LiDAR sensor unit14supported by the common bracket16also changes in the same direction. Since the detectable range of the LiDAR sensor unit14is relatively wide in the left-right direction, the influence on the information detection is relatively small even if the detecting reference direction changes.

However, if strict adjustment of the detecting reference direction of the LiDAR sensor unit14is necessary, the left front sensor device10may include a swivel actuator45, as illustrated inFIG.6. The swivel actuator45may be controlled by the processor20. As illustrated inFIG.7B, the swivel actuator45changes the detecting reference direction of the LiDAR sensor unit14in the left-right direction by causing the LiDAR sensor unit14about a pivot shaft16b. As a result, it is possible to cancel the influence of the pivot movement of the bracket16by the swivel actuator55.

Since the detectable range of the LiDAR sensor unit14is relatively narrow in the up-down direction, it is preferable that the left front sensor device10independently includes a leveling actuator46and a leveling actuator56. The leveling actuator46changes the detecting reference direction of the LiDAR sensor unit14in the up-down direction. The leveling actuator56changes the detecting reference direction of the lamp unit15in the up-down direction.

The above embodiments are merely illustrative to facilitate understanding of the presently disclosed subject matter. The configuration according to each of the above embodiments can be appropriately modified or improved without departing from the gist of the presently disclosed subject matter.

The LiDAR sensor unit14may be replaced with a TOF (Time of Flight) camera unit. The TOF camera unit includes a light emitting element and a light receiving element. Detecting light emitted from the light emitting element is reflected by an object that situates in the outside area of the vehicle, and incident on the light receiving element as reflected light. The distance to the object can be calculated based on the time period from the time when the detecting light is emitted from the light emitting element to the time when the reflected light is incident on the light receiving element. By associating information as to the calculated distance with each pixel of a two-dimensional image acquired by the camera while scanning the detecting light two-dimensionally, it is possible to acquire information as to the shape of the object.

A right front sensor device having a configuration symmetrical with the left front sensor device10illustrated inFIG.1relative to the left-right direction may be mounted on a right front portion RF of the vehicle100illustrated inFIG.2. The right front portion RF is an area located on the right of the center in the left-right direction of the vehicle100and ahead of the center in the front-rear direction of the vehicle100.

The configuration of the left front sensor device10is also applicable to a left rear sensor device. The left rear sensor device is mounted on a left rear portion LB of the vehicle100illustrated inFIG.2. The left rear portion LB is an area located on the left of the center in the left-right direction of the vehicle100and behind the center in the front-rear direction of the vehicle100. The basic configuration of the left rear sensor device may be symmetric with the left-front sensor device10relative to the front-rear direction.

The configuration of the left front sensor device10is also applicable to a right rear sensor device. The right rear sensor device is mounted on a right rear portion RB of the vehicle100illustrated inFIG.2. The right rear portion RB is an area located on the right of the center in the left-right direction of the vehicle100and behind the center in the front-rear direction of the vehicle100. The basic configuration of the right rear sensor device may be symmetrical with the above-mentioned left rear sensor device relative to the left-right direction.

The present application is based on Japanese Patent Application No. 2018-148279 filed on Aug. 7, 2018, the entire contents of which are incorporated herein by reference.