Axis misalignment determining apparatus

An axis misalignment determining apparatus is configured to determine an axis misalignment in a sensor mounted on a vehicle by using a determining member mounted on the vehicle. The axis misalignment determining apparatus is provided with: a storage configured to store therein a result of detection of the determining member by the sensor in a condition in which there is no axis misalignment, as a detection result in a normal case; an acquirer configured to detect the determining member by using the sensor and configured to obtain it as a present detection result; and a determinator configured to determine whether or not there is an axis misalignment in the sensor by comparing the present detection result with the detection result in the normal case.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-197221, filed on Oct. 10, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

Embodiments of the present disclosure relate to an axis misalignment determining apparatus configured to determine an axis misalignment or an axis deviation in a sensor mounted on a vehicle.

2. Description of the Related Art

For this type of apparatus, there is known an apparatus configured to determine an axis misalignment (i.e., a misalignment or deviation in a detection direction) in various sensors, such as, for example, a radar and LiDAR (Light Detection and Ranging or Laser Imaging Detection and Ranging), which are mounted on a vehicle. For example, Japanese Patent Application Laid Open No. 2016-053563 (Patent Literature 1) discloses a technology/technique in which a ratio of the number of recognitions of a preceding vehicle by using both a radar and a camera with respect to the number of recognitions of the preceding vehicle by using at least the camera is calculated, and in which an axis misalignment in a vertical plane, which occurs in the radar, is detected in accordance with a value of the calculated ratio.

The axis misalignment in the sensor may occur during running of the vehicle and during parking in which the vehicle is left for a long time. It is thus normally preferable to perform the detection of the axis misalignment immediately after the vehicle starts to run. In the technology/technique disclosed in the Patent Literature 1, however, the axis misalignment cannot be detected until detection results of the radar and the camera are sufficiently stored. Thus, the axis misalignment cannot be detected if the vehicle does not run, and even after the vehicle starts to run, it takes a certain time to detect the axis misalignment, which is technically problematic.

SUMMARY

In view of the aforementioned problems, it is therefore an object of embodiments of the present disclosure to provide an axis misalignment determining apparatus configured to determine an axis misalignment in a sensor mounted on a vehicle.

The above object of embodiments of the present disclosure can be achieved by an axis misalignment determining apparatus configured to determine an axis misalignment in a sensor mounted on a vehicle by using a determining member mounted on the vehicle, the axis misalignment determining apparatus provided with: a storage configured to store therein a result of detection of the determining member by the sensor in a condition in which there is no axis misalignment, as a detection result in a normal case; an acquirer configured to detect the determining member by using the sensor and configured to obtain it as a present detection result; and a determinator configured to determine whether or not there is an axis misalignment in the sensor by comparing the present detection result with the detection result in the normal case.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an axis misalignment determining apparatus according to an embodiment will be explained with reference to the drawings. In the embodiment, an explanation is given to an apparatus configured to determine an axis misalignment in a LiDAR mounted on a vehicle.

Firstly, an entire configuration of the axis misalignment determining apparatus according to the embodiment will be explained with reference toFIG. 1.FIG. 1is a block diagram illustrating the configuration of the axis misalignment determining apparatus according to the embodiment.

As illustrated inFIG. 1, an axis misalignment determining apparatus10according to the embodiment is configured to be, for example, a part of an electronic control unit (ECU) mounted on a vehicle, and is provided with a LiDAR point cloud acquirer110, a LiDAR point cloud storage120, an axis misalignment determinator130, and a nozzle controller140, as processing blocks physically or logically realized therein.

The LiDAR point cloud acquirer110is a specific example of the “acquirer” in Supplementary Notes described later, and is configured to obtain a point cloud (i.e., a plurality of points indicating positions of a detected object), which is a detection result of a LiDAR20configured to detect an object in the surroundings of the vehicle. The LiDAR point cloud storage120is a specific example of the “storage” in Supplementary Notes described later, and is configured to store therein the point cloud obtained by the LiDAR point cloud acquirer110. The axis misalignment determinator130is a specific example of the “determinator” in Supplementary Notes described later, and is configured to determine whether or not there is an axis misalignment in the LiDAR20by comparing a point cloud in a normal case stored in the LiDAR point cloud storage120and a present point cloud. The nozzle controller140is a specific example of the “position controller” in Supplementary Notes described later, and is configured to control a position of a washer nozzle30, which is provided to wash the LiDAR20.

Next, a specific arrangement configuration of the LiDAR20and the washer nozzle30described above will be explained with reference toFIG. 2toFIG. 5.FIG. 2is a top view illustrating an example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 3is a front view illustrating the example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 4is a side view illustrating the example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 5is a top view illustrating a normal position of the washer nozzle.

As illustrated inFIG. 2toFIG. 4, the LiDAR20is mounted in a part of a vehicle body50(e.g., a bumper part, etc.) via a LiDAR mounting mechanism25. The LiDAR20is a specific example of the “sensor” in Supplementary Notes described later. The washer nozzle30is mounted in a position in which the washed nozzle30can wash an optical surface20aof the LiDAR20, i.e., a surface of the LiDAR20on which laser light is received and emitted. The washer nozzle30is mounted in a part of the vehicle body50via a washer nozzle mounting mechanism35, which is different from the LiDAR mounting mechanism25. As described above, the LiDAR20and the washer nozzle30are mounted by the respective mounting mechanisms that are independent of each other, i.e., by the LiDAR mounting mechanism25and the washer nozzle mounting mechanism35. Thus, even if there is an axis misalignment (i.e., a position deviation) in the LiDAR20, the washer nozzle30does not have the same axis misalignment. In other words, the LiDAR20and the washer nozzle30do not deviate integrally.

As illustrated inFIG. 5, the washer nozzle30is configured to be extendable, and the position of the washer nozzle30can be controlled by the nozzle controller140. Specifically, the washer nozzle30is configured to move between a position in which its end portion overlaps on the optical surface20aof the LiDAR20, as illustrated inFIG. 2toFIG. 4, and a position in which the end portion does not overlap the optical surface20aof the LiDAR20, as illustrated inFIG. 5. In other words, the washer nozzle30is configured to move between the position that can be detected by the LiDAR20(refer toFIG. 2toFIG. 4) and the position that cannot be detected by the LiDAR20(refer toFIG. 5). Hereinafter, the position as illustrated inFIG. 2toFIG. 4will be referred to as a “determination position”, and the position as illustrated inFIG. 5will be referred to as a “normal position”.

The washer nozzle30according to the embodiment is a specific example of the “determining member” in Supplementary Notes described later, and is a member whose position is to be detected by the LiDAR20in determining the axis misalignment in the LiDAR20. Thus, when the position of the washer nozzle30is to be detected, the washer nozzle30may be moved to the determination position. On the other hand, if the washer nozzle30is always in the determination position, the presence of the washer nozzle30may reduce detection accuracy of a target that is to be originally detected by the LiDAR20(e.g., an obstacle in the surroundings of the vehicle, etc.). The washer nozzle30according to the embodiment is thus configured to move to the normal position, which is out of a detection range of the LiDAR20. The washer nozzle30is moved to the determination position, not only in determining the axis misalignment in the LiDAR20but also in washing the optical surface20aof the LiDAR20, which is an original function of the washer nozzle30.

Then, an arrangement configuration of an axis misalignment determining apparatus according to a modified example will be explained with reference toFIG. 6toFIG. 9.FIG. 6is a top view illustrating the modified example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 7is a front view illustrating the modified example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 8is a side view illustrating the modified example of the arrangement configuration of the LiDAR and the washer nozzle.FIG. 9is a side view illustrating a configuration the washer nozzle having a high reflective material;

As illustrated inFIG. 6toFIG. 8, the washer nozzle30may be mounted above the LiDAR20. Even in this case, it is possible to provide the washer nozzle30with the same function as that when the washer nozzle30is mounted beside the LiDAR20as illustrated inFIG. 2toFIG. 5. In other words, a mounting position of the washer nozzle30according to the embodiment is not particularly limited, and the washer nozzle30may be extendable in any direction with respect to the optical surface20aof the LiDAR20.

As illustrated inFIG. 9, the washer nozzle30may have a high reflective material200(e.g., a high reflective paint, a retro-reflective material, etc.) in a position opposed to the optical surface20aof the LiDAR30. In this case, the laser light from the LiDAR20is reflected with high reflectivity, and it is thus possible to detect the position of the washer nozzle30, i.e., a point cloud corresponding to the washer nozzle30.

Next, a normal position storage operation performed by the axis misalignment determining apparatus10according to the embodiment, i.e., an operation of storing the detection result of the LiDAR20in the normal case, will be explained with reference toFIG. 10.FIG. 10is a flowchart illustrating a flow of the normal position storage operation by the axis misalignment determining apparatus according to the embodiment.

As illustrated inFIG. 10, in the normal position storage operation, firstly, it is determined whether or not an axis misalignment determinable flag is OFF (step S11). The axis misalignment determinable flag may be a flag for determining whether or not the axis misalignment determining apparatus10is in a condition in which the axis misalignment determining apparatus10can determine the axis misalignment in the LiDAR20. If the axis misalignment determinable flag is ON (the step S11: NO), it can be determined that the detection result of the LiDAR20in the normal case is already stored. The subsequent process is thus omitted, and a series of operation steps is ended.

On the other hand, if the axis misalignment determinable flag is OFF (the step S11: YES), the washer nozzle30is operated in a washer no-jet mode (in other words, in a mode in which the washing is not performed) (step S12). Specifically, the extension of the washer nozzle30may be controlled by the nozzle controller140, so that the washer nozzle30is moved from the normal position to the determination position.

Then, information about the point cloud corresponding to the position of the washer nozzle30(hereinafter referred to as “point cloud information” as occasion demands) is stored as the normal position (step S13). Specifically, the LiDAR position cloud acquirer110may obtain the point cloud information corresponding to the washer nozzle30located in the determination position, and may store the point cloud information obtained by the LiDAR point cloud storage120, as the normal position.

After the above process is ended, the axis misalignment determinable flag is set to ON (step S14). After that, it is possible to determine whether or not there is an axis misalignment in the LiDAR20on the basis of the stored normal position. The aforementioned normal position storage operation is to be performed in a condition in which there is no axis misalignment in the LiDAR20. It is thus preferable to perform the normal position storage operation, for example, in factory shipping of the vehicle, or immediately after calibration of the LiDAR20, or in similar situations.

Next, an axis misalignment determination operation performed by the axis misalignment determining apparatus10according to the embodiment, i.e., an operation of determining the axis misalignment in the LiDAR20, will be explained with reference toFIG. 11.FIG. 11is a flowchart illustrating a flow of the axis misalignment determination operation by the axis misalignment determining apparatus according to the embodiment.

As illustrated inFIG. 11, in the axis misalignment determination operation, it is firstly determined whether or not the axis misalignment determinable flag is ON (step S21). If the axis misalignment determinable flag is OFF (the step S21: NO), the aforementioned normal position storage operation is not normally ended, and the axis misalignment of the LiDAR20cannot be determined at this point. The subsequent process is thus omitted, and a series of operation steps is ended. If the axis misalignment determinable flag is ON (the step S21: YES), it is determined whether or not a driving support of the vehicle is in operation (step S22). The driving support herein may indicate driving support control using the detection result of the LiDAR20, and may exemplify a driving support in which an obstacle in the surroundings of the vehicle is detected by using the LiDAR20and in which a driving route for automatically avoiding the obstacle is set. The LiDAR20is used while operating the driving support, and thus, the axis misalignment determination operation may inhibit the function of the LiDAR, i.e., there is a possibility that the driving support is not normally performed. Thus, if it is determined that the driving support is in operation (the step S22: YES), the subsequent process is omitted, and the series of operation steps is ended. The series of operation steps may be started again from the beginning after a lapse of a predetermined period from the end.

If it is determined that the driving support is not in operation (the step S22: NO), the washer nozzle30is operated in the washer no-jet mode (step S23). In other words, as in the step S12in the normal position storage operation (refer toFIG. 10), the extension of the washer nozzle30may be controlled by the nozzle controller140, so that the washer nozzle30is moved from the normal position to the determination position.

Then, the point cloud information corresponding to the washer nozzle30is stored as a present position (step S24). Specifically, as in the step S13in the normal position storage operation (refer toFIG. 10), the LiDAR position cloud acquirer110may obtain the point cloud information corresponding to the washer nozzle30located in the determination position, and may store the point cloud information obtained by the LiDAR point cloud storage120, as the present position.

Then, the point cloud information is compared between the normal position and the present position (step S25). Specifically, the axis misalignment determinator130may read the point cloud information indicating the normal position and the point cloud information indicating the present position, which are stored in the LiDAR point cloud storage120, and may compare the two point informations. The axis misalignment determinator130compares the point cloud information indicating the normal position and the point cloud information indicating the present position, and determines whether or not there is a difference between the two point cloud informations (step S26). More specifically, the axis misalignment determinator130may store therein, e.g., a predetermined threshold value for eliminating a detection error, and may determine there is a difference between the present position and the normal position if the difference between the point cloud information indicating the normal position and the point cloud information indicating the present position is greater than or equal to the predetermined threshold value. On the other hand, it is determined that the present invention does not have the difference from the normal position if the difference between the point cloud information indicating the normal position and the point cloud information indicating the present position is not greater than or equal to the predetermined threshold value.

As a result of the determination, if it is determined that the present position has the difference from the normal position (the step S26: YES), the axis misalignment determinator140sets an axis misalignment flag to ON (step S27). On the other hand, if it is determined that the present position has no difference from the normal position (the step S26: NO), the axis misalignment determinator140sets an axis misalignment flag to OFF (step S28). The axis misalignment flag may be a flag indicating whether or not there is an axis misalignment in the LiDAR20, and if it is ON, an announcement process for an occupant of the vehicle (e.g., an alarm or a waning indicating that there is an axis misalignment in the LiDAR20, etc.) is performed.

Now, the comparison of the point cloud information will be specifically explained with reference toFIG. 12andFIG. 13.FIG. 12is a conceptual diagram illustrating an example of a point cloud in the normal case and a point cloud in the axis misalignment when the LiDAR is viewed from right above.FIG. 13is a conceptual diagram illustrating an example of the point cloud in the normal case and the point cloud in the axis misalignment when the LiDAR is viewed from the side.

As illustrated inFIG. 12, suppose that the point cloud corresponding to the washer nozzle30is detected in black circle positions inFIG. 12in the normal case, from a viewpoint in which the LiDAR20is viewed from right above. Then, if the axis misalignment in the LiDAR20occurs in a horizontal left direction, the point cloud corresponding to the washer nozzle30may be detected in white circle positions inFIG. 12. In other words, the axis misalignment occurs in the LiDAR20, whereas the position of the washer nozzle30does not change. Thus, a relative position of the washer nozzle30as viewed from the LiDAR20changes in accordance with the axis misalignment in the LiDAR20. As a result, it is detected that the point cloud information in the normal case is apparently different from the point cloud information after the axis misalignment.

As illustrated inFIG. 13, suppose that the point cloud corresponding to the washer nozzle30is detected in a black circle position inFIG. 13in the normal case, from a viewpoint in which the LiDAR20is viewed from the side. Then, if the axis misalignment in the LiDAR20occurs in a vertical upward direction, the point cloud corresponding to the washer nozzle30may be detected in a white circle position inFIG. 13. In other words, the position of the washer nozzle30viewed from the LiDAR20is deviated downward by an amount of the upward axis misalignment in the LiDAR20. As described above, it is possible to determine the axis misalignment in the LiDAR20by comparing the point cloud information in the normal case and the point cloud information after the axis misalignment. It is also possible to determine to what extent and in which direction the axis misalignment in the LiDAR20occurs, from a deviated direction and a deviated distance of the point cloud.

Next, a technical effect of the axis misalignment determining apparatus10according to the embodiment will be explained.

According to the axis misalignment determining apparatus10in the embodiment, as explained above, it is possible to determine the axis misalignment in the LiDAR20, from the detection result of the washer nozzle30by using the LiDAR20. Particularly in the embodiment, the LiDAR20and the washer nozzle30are mounted by the mounting mechanisms that are independent of each other, i.e., by the LiDAR mounting mechanism25and the washer nozzle mounting mechanism35. Thus, even if there is an axis misalignment (i.e., a position deviation) in the LiDAR20, the washer nozzle30does not have the same axis misalignment. It is thus possible to accurately determine the axis misalignment in the LiDAR20on the basis of the relative position of the washer nozzle30as viewed from the LiDAR20.

The member for detecting the axis misalignment in the LiDAR20may be another member other than the washer nozzle30. Any member that is in the detection range of the LiDAR20and that does not have the integral axis misalignment with the LiDAR20, i.e., a member having such a relative position to the LiDAR20that does not change due to any factor other than the axis misalignment in the LiDAR20, can be also used to determine the axis misalignment in the LiDAR20. The washer nozzle30, however, is a member originally mounted in the position that can be detected by the LiDAR20, in order to wash the optical surface20aof the LiDAR20. Thus, the use of the washer nozzle30makes it possible to avoid an increase in cost and an increase in size and complication of the apparatus.

In the embodiment, an example of the determination of the axis misalignment in the LiDAR20is explained; however, the target of the determination of the axis misalignment may be various sensors (e.g., a radar, a camera, etc.) other than the LiDAR20mounted on the vehicle. The existing technique/technology can be used, as occasion demands, to compare detection results of the various sensors, i.e., to determine whether or not there is a difference between the normal position and the present position.

Various aspects of the present disclosure derived from the embodiment explained above will be explained hereinafter.

An axis misalignment determining apparatus described in Supplementary Note 1 is an axis misalignment determining apparatus configured to determine an axis misalignment in a sensor mounted on a vehicle by using a determining member mounted on the vehicle, the axis misalignment determining apparatus provided with: a storage configured to store therein a result of detection of the determining member by the sensor in a condition in which there is no axis misalignment, as a detection result in a normal case; an acquirer configured to detect the determining member by using the sensor and configured to obtain it as a present detection result; and a determinator configured to determine whether or not there is an axis misalignment in the sensor by comparing the present detection result with the detection result in the normal case.

According to the axis misalignment determining apparatus described in Supplementary Note 1, it is determined whether or not there is an axis misalignment in the sensor by comparing the result of the detection of the determining material by the sensor in the condition in which there is no axis misalignment, i.e., the detection result in the normal case, and the result of the detection of the determining member by the present sensor, i.e., the present detection result. Specifically, if there is a significant difference between the detection result in the normal case and the present detection result, it is determined that there is an axis misalignment in the sensor. If there is little difference between the detection result in the normal case and the present detection result, it is determined that there is no axis misalignment in the sensor. The “condition in which there is no axis misalignment” may mean a condition in which a detection direction of the sensor is as intended in design. It is thus preferable that the detection result in the normal case is stored in factory shipping or immediately after calibration.

Particularly in this aspect, the determining member mounted on the vehicle is used as a determination reference of the axis misalignment. It is thus possible to determine the axis misalignment, extremely easily and accurately, for example, in comparison with when an object that is outside the vehicle is used as a reference. It is also sufficient to compare the detection result in the normal case, i.e., the detection result in the past, and the present detection result. It is thus not necessary to store, for example, a large amount of detection results of the sensor, and the axis misalignment can be determined in a short time.

In an aspect of the axis misalignment determining apparatus described in Supplementary Note 2, it is further provided a position controller configured to move the determining member between a normal position, which is out of a detection range of the sensor, and a determination position, which is in the detection range of the sensor.

According to this aspect, if the axis misalignment in the sensor is not determined, the determining member can be moved out of the detection range of the sensor. It is thus possible to avoid inhibiting an original function of the sensor (e.g., recognition of an object that is outside the vehicle, etc.) due to regular presence of the determining member in the detection range of the sensor.

In another aspect of the axis misalignment determining apparatus described in Supplementary Note 3, the sensor and the determining member are separately mounted on the vehicle by using respective mounting mechanisms that are independent of each other.

According to this aspect, when there is an axis misalignment in the sensor, it is possible to prevent the determining member from having the same misalignment. Thus, the position of the determining member as the determination reference does not change even when there is an axis misalignment in the sensor. It is therefore possible to accurately determine the axis misalignment in the sensor by using the detection result of the determining member.

In the axis misalignment determining apparatus described in Supplementary Note 4, it is further provided with a high reflective material, which is provided in a position of the determining material opposed to the sensor and which has higher reflectivity than that of the determining member.

According to the axis misalignment determining apparatus described in Supplementary Note 4, detection accuracy of the determining member by the sensor is improved. It is thus possible to more accurately determine the axis misalignment in the sensor.

In the axis misalignment determining apparatus described in Supplementary Note 5, the determining member is a washer nozzle configured to wash the sensor.

According to the axis misalignment determining apparatus described in Supplementary Note 5, it is not necessary to separately provide an exclusive part as the determining member. It is thus possible to prevent complication and an increase in size of the apparatus, and an increase in manufacturing cost.