Patent Publication Number: US-2021165103-A1

Title: Sensor system

Description:
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; and 
     a 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; and 
     a 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. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a configuration of a left front sensor device according to an embodiment. 
         FIG. 2  illustrates a position of the left front sensor device of  FIG. 1  in a vehicle. 
         FIG. 3  illustrates a configuration of a sensor system including the left front sensor device of  FIG. 1 . 
         FIG. 4A  illustrates a translucent cover according to a comparative example. 
         FIG. 4B  illustrates a translucent cover according to a comparative example. 
         FIG. 5A  illustrates another example of a translucent cover in the sensor system of  FIG. 3 . 
         FIG. 5B  illustrates another example of a translucent cover in the sensor system of  FIG. 3 . 
         FIG. 6  illustrates another example of the left front sensor device of  FIG. 1 . 
         FIG. 7A  illustrates an operation of the left front sensor device of  FIG. 6 . 
         FIG. 7B  illustrates an operation of the left front sensor device of  FIG. 6 . 
     
    
    
     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&#39;s seat. 
       FIG. 1  illustrates a configuration of a left front sensor device  10  according to an embodiment. The left front sensor device  10  is disposed in a left front portion LF of the vehicle  100  illustrated in  FIG. 2 . The left front portion LF is an area located on the left of the center in a left-right direction of the vehicle  100  and ahead of the center in a front-rear direction of the vehicle  100 . 
     As illustrated in  FIG. 1 , the left front sensor device  10  includes a housing  11  and a translucent cover  12 . The housing  11  defines an accommodation chamber  13  together with the translucent cover  12 . The translucent cover  12  forms a part of the outer surface of the vehicle  100 . 
     The left front sensor device  10  includes a LiDAR sensor unit  14 . The LiDAR sensor unit  14  is disposed in the accommodation chamber  13 . 
     As illustrated in  FIG. 3 , the LiDAR sensor unit  14  includes a light emitting element  41  and a light receiving element  42 . The translucent cover  12  covers the light emitting element  41  and the light receiving element  42 . 
     The light emitting element  41  is configured to emit detecting light L 1  toward the outside of the vehicle  100 . As the detecting light L 1 , for example, infrared light having a wavelength of 905 nm can be used. As the light emitting element  41 , a semiconductor light emitting element such as a laser diode or a light emitting diode can be used. 
     The LiDAR sensor unit  14  may appropriately include an optical system (not illustrated) for irradiating the detecting light L 1  in a desired direction. The LiDAR sensor unit  14  may include a scanning mechanism (not illustrated) for changing the irradiating direction of the detecting light L 1  to scan a detection area. 
     The light receiving element  42  is configured to output a light receiving signal S 1  corresponding to the amount of incident light. As the light receiving element  42 , a photodiode, a phototransistor, a photo resistor, or the like can be used. The LiDAR sensor unit  14  may include an amplifier circuit (not illustrated) for amplifying the light receiving signal S 1 . 
     The light emitting element  41 , the light receiving element  42 , and the translucent cover  12  constitute a sensor system  1 . The sensor system  1  further includes a processor  20 . The processor  20  outputs a control signal S 0  for causing the light emitting element  41  to emit the detecting light L 1  at a desired timing. The processor  20  receives the light receiving signal S 1  outputted from the light receiving element  42 . 
     The processor  20  detects information in an outside area of the vehicle  100  based on the light receiving signal S 1  corresponding to reflected light L 2 . For example, the processor  20  can obtain a distance to an object associated with the reflected light L 2  based on the time period from the time when the detecting light L 1  is emitted in a certain direction to the time when the reflected light L 2  is 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 L 2 . Additionally or alternatively, information as to an attribute such as the material of the object associated with the reflected light L 2  can be acquired based on the difference in waveforms of the detecting light L 1  and the reflected light L 2 . 
     The translucent cover  12  has a plurality of flat portions  12   a . The processor  20  is configured to exclude positions corresponding to boundary portions  12   b  formed between the adjacent flat portions  12   a  from objects to be detected. 
       FIG. 4A  illustrates a translucent cover  12 A and a light emitting element  41 A according to a comparative example. In this example, the translucent cover  12 A has an arcuate cross section. The translucent cover  12 A and the light emitting element  41 A are disposed such that the center of curvature of the arcuate shape coincides with the center of light emission of detecting light L 0  emitted from the light emitting element  41 A, such as the light source position and the center of scan. 
     According to such an arrangement, the detecting light L 0  emitted from the light emitting element  41 A can pass through the translucent cover  12 A without being refracted regardless of the emitted direction. However, the shape of the translucent cover  12 A and the positional relationship with the light emitting element  41  may be a considerable constraint on the design of the sensor device. 
     In addition, as illustrated in  FIG. 4B , if the center of curvature of the arcuate shape does not coincide with the center of emission of the detecting light L 0 , the detecting light L 0  is greatly refracted by the curved surface of the translucent cover  12 A. 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 in  FIG. 3 , the detecting light L 1  emitted from the light emitting element  41  is allowed to pass through the flat portion  12   a  of the translucent cover  12 . 
     According to such a configuration, it is easy to cause the detecting light L 1  to enter the translucent cover  12  perpendicularly. In this case, the detecting light L 1  is not refracted when passing through the translucent cover  12 . For example, the detecting light L 1 A illustrated in  FIG. 3  is incident perpendicularly on the translucent cover  12 . Even if the translucent cover  12  and the light emitting element  41  are relatively displaced in the left-right direction from this state, the state in which the detecting light L 1 A is incident perpendicularly on the translucent cover  12  can be maintained. 
     In addition, even if the incident light is obliquely incident on the flat portion  12   a  as in the detecting light L 1 B illustrated in  FIG. 3 , the refraction amount of the detecting light L 1 B is small as compared with a case where the detecting light L 1 B is incident on the curved surface illustrated in  FIG. 4B . 
     However, by providing the flat portions  12   a  that can obtain such an advantageous effect, it is inevitable that the boundary portion  12   b  of the adjacent flat portions  12   a  is formed. In the boundary portion  12   b , the behavior of the detecting light L 1 C caused by the passage of the translucent cover  12  cannot be expected. Accordingly, the processor  20  is configured not to detect information based on the reflected light L 2  generated from the detecting light L 1 C emitted toward the boundary portion  12   b.    
     For example, when scanning in which the light emitting direction of the detecting light L 1  cyclically changes is performed, since the positional relationship between the light emitting element  41  and the boundary portion  12   b  is known, the processor  20  can grasp in advance at what timing the detecting light emitted is directed to the boundary portion  12   b . Accordingly, the processor  20  may be configured not to perform the information detection processing based on the light receiving signal S 1  corresponding to the reflected light generated by the detecting light L 1 C emitted at that timing. 
     Alternatively, in a case where a plurality of light emitting elements  41  are configured to emit the detecting light L 1  in various directions, since the positional relationship with the boundary portion  12   b  is also known, the processor  20  can grasp in advance which detecting light emitted from which light emitting element  41  is directed to the boundary portion  12   b . Accordingly, the processor  20  may be configured not to perform the information detection processing based on the light receiving signal S 1  corresponding to the reflected light generated by the detecting light L 1 C emitted from that light emitting element  41 . 
     Not only can the refraction when the detecting light L 1  passes through the translucent cover  12  be reduced, but also, since the position corresponding to the boundary portion  12   b  whose behavior is not expected is excluded from the information to be detected, it is possible to suppress the influence of the translucent cover  12  on the information detection. 
       FIG. 5A  illustrates an enlarged view of a boundary portion  12   b  of the translucent cover  12  surrounded by a chain line V in  FIG. 3 . The surface of the translucent cover  12  at the boundary portion  12   b  may be formed as an opaque portion  12   c  for at least the wavelength of the detecting light L 1  by 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 L 1  can be prevented from passing through the boundary portion  12   b , it is possible to prevent the occurrence of an unexpected behavior of the detecting light L 1  caused by the passage of the translucent cover  12 . In this case, even if no special processing is performed on the side of the processor  20 , the position corresponding to the boundary portion  12   b  can be excluded from the information to be detected. 
     Not only can the refraction when the detecting light L 1  passes through the translucent cover  12  be reduced, but also, since the position corresponding to the boundary portion  12   b  whose behavior is not expected is excluded from the information to be detected, it is possible to suppress the influence of the translucent cover  12  on the information detection. 
     As illustrated in  FIG. 5B , the surface of the translucent cover  12  at the boundary portion  12   b  may be formed as a curved surface  12   d.    
     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 portion  12   c  is minimized. Since the surface of the translucent cover  12  at the boundary portion  12   b  is formed as the curved surface  12   d , it is easy to perform the opacifying treatment while minimizing the area of the opaque portion  12   c . In addition, the molding workability of the translucent cover  12  (ease of removal from the mold or the like) is improved. 
     The functions of the processor  20  described 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 processor  20  may be disposed at any position in the vehicle. The processor  20  may 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 unit  14 . 
     As illustrated in  FIG. 1 , the left front sensor device  10  may include a lamp unit  15 . The lamp unit  15  is disposed in the accommodation chamber  13 . The lamp unit  15  is a device for emitting visible light to the outside of the vehicle  100 . Examples of the lamp unit  15  include 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 unit  15  is generally disposed at four corner portions of the vehicle  100 . The four corner portions are also portions where there are few obstacles when detecting information in an outside area of the vehicle  100 . By arranging the LiDAR sensor unit  14  so as to share the accommodation chamber  13  with the lamp unit  15 , it is possible to efficiently detect the information in the outside area of the vehicle  100 . 
     The left front sensor device  10  may include a sensor bracket  43  and a lamp bracket  53 . The sensor bracket  43  and the lamp bracket  53  are independent of each other. The LiDAR sensor unit  14  is supported by the sensor bracket  43 . The lamp unit  15  is supported by the lamp bracket  53 . 
     The left front sensor device  10  may include a sensor aiming mechanism  44  and a lamp aiming mechanism  54 . The sensor aiming mechanism  44  is a mechanism for adjusting a detecting reference direction of the LiDAR sensor unit  14 . The lamp aiming mechanism  54  is a mechanism for adjusting a lighting reference direction of the lamp unit  15 . 
     The sensor aiming mechanism  44  includes a first screw  441  and a second screw  442 . The first screw  441  and the second screw  442  can be operated from the outside of the housing  11 . 
     When the first screw  441  is operated, the posture of the sensor bracket  43  changes in the left-right direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the LiDAR sensor unit  14  changes in the left-right direction. When the second screw  442  is operated, the posture of the sensor bracket  43  changes in the up-down direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the LiDAR sensor unit  14  changes in the up-down direction. Each of the first screw  441  and the second screw  442  may be replaced with an actuator operated by an external control signal. 
     The lamp aiming mechanism  54  includes a first screw  541  and a second screw  542 . The first screw  541  and the second screw  542  can be operated from the outside of the housing  11 . 
     When the first screw  541  is operated, the posture of the lamp bracket  53  changes in the left-right direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the lamp unit  15  changes in the left-right direction. When the second screw  542  is operated, the posture of the lamp bracket  53  changes in the up-down direction about a fulcrum (not illustrated). As a result, the detecting reference direction of the lamp unit  15  changes in the up-down direction. Each of the first screw  541  and the second screw  542  may be replaced with an actuator operated by an external control signal. 
     Alternatively, as illustrated in  FIG. 6 , the left front sensor device  10  may include a common bracket  16 . The LiDAR sensor unit  14  and the lamp unit  15  are supported by the bracket  16 . 
     In this case, the left front sensor device  10  may include a swivel actuator  55 . The swivel actuator  55  may be controlled by the processor  20 . As illustrated in  FIG. 7A , the swivel actuator  55  changes the lighting reference direction of the lamp unit  15  in the left-right direction by causing the bracket  16  to pivot about a pivot shaft  16   a.    
     The detecting reference direction of the LiDAR sensor unit  14  supported by the common bracket  16  also changes in the same direction. Since the detectable range of the LiDAR sensor unit  14  is 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 unit  14  is necessary, the left front sensor device  10  may include a swivel actuator  45 , as illustrated in  FIG. 6 . The swivel actuator  45  may be controlled by the processor  20 . As illustrated in  FIG. 7B , the swivel actuator  45  changes the detecting reference direction of the LiDAR sensor unit  14  in the left-right direction by causing the LiDAR sensor unit  14  about a pivot shaft  16   b . As a result, it is possible to cancel the influence of the pivot movement of the bracket  16  by the swivel actuator  55 . 
     Since the detectable range of the LiDAR sensor unit  14  is relatively narrow in the up-down direction, it is preferable that the left front sensor device  10  independently includes a leveling actuator  46  and a leveling actuator  56 . The leveling actuator  46  changes the detecting reference direction of the LiDAR sensor unit  14  in the up-down direction. The leveling actuator  56  changes the detecting reference direction of the lamp unit  15  in 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 unit  14  may 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 device  10  illustrated in  FIG. 1  relative to the left-right direction may be mounted on a right front portion RF of the vehicle  100  illustrated in  FIG. 2 . The right front portion RF is an area located on the right of the center in the left-right direction of the vehicle  100  and ahead of the center in the front-rear direction of the vehicle  100 . 
     The configuration of the left front sensor device  10  is also applicable to a left rear sensor device. The left rear sensor device is mounted on a left rear portion LB of the vehicle  100  illustrated in  FIG. 2 . The left rear portion LB is an area located on the left of the center in the left-right direction of the vehicle  100  and behind the center in the front-rear direction of the vehicle  100 . The basic configuration of the left rear sensor device may be symmetric with the left-front sensor device  10  relative to the front-rear direction. 
     The configuration of the left front sensor device  10  is also applicable to a right rear sensor device. The right rear sensor device is mounted on a right rear portion RB of the vehicle  100  illustrated in  FIG. 2 . The right rear portion RB is an area located on the right of the center in the left-right direction of the vehicle  100  and behind the center in the front-rear direction of the vehicle  100 . 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.