Calibration system, calibration method, and calibration program

Abstract

This calibration system is used for calibrating a pair of optical sensors that form an overlapping area in a scanning field of view in which scanning orientations of optical scanning are rotated in opposite directions around parallel main shafts in a host vehicle, wherein, if the scanning orientations set symmetrically for each optical sensor are defined as reference orientations, and if the scanning orientations at which the same object is detected within the overlapping area by each optical sensor (40) are defined as detection orientations, a processor is configured to: monitor an angle deviation (Δθ) between detection angles (θL, θR) from the reference orientation to the detection orientation of the same object for each optical sensor; and calibrate a time difference imparted between reference scanning times (tL, tR) at which the reference orientations are scanned by each optical sensor to a corrected time difference (Δt) correlated with the monitored angle deviation (Δθ).

Description

Calibration system, calibration method, and calibration program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-99019 filed in Japan on June 19, 2024, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to calibration techniques for calibrating optical sensors in a host vehicle.

[0003] Patent Document 1 discloses a technology for calibrating and aligning LiDARs, which are optical sensors, in a host vehicle by utilizing the recognized positions of the same object detected by both LiDARs.

[0004] JP 2019-53034 A

[0005] The technology disclosed in Patent Document 1 makes it possible to match the recognition positions of the same object and spatially calibrate LiDARs. However, even when the recognition positions of the same object are matched, errors due to positional or axial misalignment of each LiDAR occur at the time of scanning. In other words, temporal calibration is difficult.

[0006] An object of the present disclosure is to provide a calibration system that spatiotemporally calibrates optical sensors. Another object of the present disclosure is to provide a calibration method that spatiotemporally calibrates optical sensors. Yet another object of the present disclosure is to provide a calibration program that spatiotemporally calibrates optical sensors.

[0007] The technical means of the present disclosure for solving the problems will be described below.

[0008] A first aspect of the present disclosure is a calibration system for calibrating a pair of optical sensors having a processor that forms an overlapping area in a scanning field of view in which scanning orientations by optical scanning rotate in opposite directions around parallel main axes in a host vehicle, wherein the processor is configured to: define a scanning orientation set symmetrically in each optical sensor as a reference orientation; define a scanning orientation in which each optical sensor detects the same target within the overlapping area as a detection orientation; monitor an angular deviation between detection angles from the reference orientation to the detection orientation of the same target in each optical sensor; and calibrate a time difference between reference scanning times for scanning the reference orientation in each optical sensor to a corrected time difference that correlates with the monitored angular deviation.

[0009] A second aspect of the present disclosure is a calibration method executed by a processor to calibrate a pair of optical sensors in a host vehicle, which form an overlapping area in a scanning field of view in which scanning orientations by optical scanning are rotated in opposite directions around parallel main axes, the method including: defining a scanning orientation set symmetrically in each optical sensor as a reference orientation; defining a scanning orientation in which each optical sensor detects the same target within the overlapping area as a detection orientation; monitoring an angular deviation between detection angles from the reference orientation to the detection orientation of the same target in each optical sensor; and calibrating a time difference between reference scanning times for scanning the reference orientation in each optical sensor to a corrected time difference correlated with the monitored angular deviation.

[0010] A third aspect of the present disclosure is a calibration program stored in a storage medium for calibrating a pair of optical sensors in a host vehicle that form an overlapping area in a scanning field of view in which the scanning orientations by optical scanning are rotated in opposite directions around parallel main axes, and includes instructions for causing a processor to execute the calibration, wherein the scanning orientations set symmetrically in each optical sensor are defined as reference orientations, and the scanning orientations in which each optical sensor detects the same target within the overlapping area are defined as detection orientations, and the program includes instructions for executing the following: monitoring the angular deviation between the detection angles from the reference orientation to the detection orientations of the same target in each optical sensor; and calibrating the time difference between the reference scanning times for scanning the reference orientation in each optical sensor to a corrected time difference that correlates with the monitored angular deviation.

[0011] In this way, the first to third aspects calibrate pairs of optical sensors that form overlapping areas in their scan fields of view by rotating their scan orientations in counter-rotating directions around parallel main axes on a host vehicle. Each of the optical sensors in the first to third aspects monitors the angular deviation between the detection angles from a symmetrically set reference orientation to the detection orientation at which the same target is detected within the overlapping area. This allows each optical sensor to calibrate the time difference between the reference scan times at which the reference orientation is scanned to a corrected time difference that correlates with the monitored angular deviation, thereby matching the scan times and scan positions for the same target. In other words, it is possible to spatially and temporally calibrate optical sensors.

[0012] FIG. 1 is a block diagram showing an overall configuration of an embodiment; FIG. 2 is a top view showing a host vehicle to which an embodiment is applied; FIG. 3 is a top view showing a pair of optical sensors according to an embodiment; FIG. 4 is a block diagram showing a functional configuration of a calibration system according to an embodiment; FIG. 5 is a flowchart showing a calibration flow according to an embodiment; FIG. 6 is a schematic diagram for explaining the calibration flow according to an embodiment; FIG. 7 is a schematic diagram for explaining the calibration flow according to an embodiment; FIG. 8 is a schematic diagram for explaining the calibration flow according to an embodiment;

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] The calibration system 1 according to one embodiment shown in FIG. 1 spatiotemporally calibrates a pair of optical sensors 40 mounted on a host vehicle 2 (see FIG. 2 ) and optically scanning the external environment. Here, the host vehicle 2 can be considered an ego-vehicle from a viewpoint centered on the host vehicle 2. The host vehicle 2 is a mobile object, such as an automobile, capable of traveling on a road surface with an occupant on board. Therefore, directions in the following description are defined based on the host vehicle 2 on an ideal road surface along a horizontal plane.

[0015] The host vehicle 2 is provided with an autonomous driving mode that is classified into levels according to the degree of manual intervention by the occupant in the dynamic driving task. The autonomous driving mode may be realized by autonomous driving control, such as conditional driving automation, high driving automation, or full driving automation, in which the system performs all dynamic driving tasks when activated. The autonomous driving mode may also be realized by advanced driving assistance control, such as driving assistance or partial driving automation, in which the occupant performs some or all of the dynamic driving tasks. The autonomous driving mode may be realized by either autonomous driving control or advanced driving assistance control, or by a combination of these, or by switching between them.

[0016] From such a perspective centered on the host vehicle 2, a moving body Tm (see FIG. 8 described later) that moves dynamically other than the host vehicle 2 can also be considered as another road user. The moving body Tm other than the host vehicle 2 may include at least one of the following types: automobiles, trucks, motorcycles, bicycles, autonomous robots, pedestrians, animals, etc.

[0017] 2, the optical sensors 40 are provided on the host vehicle 2 so as to form at least one pair that optically scans a specific direction (forward in the figure) in the external environment of the host vehicle 2. Each optical sensor 40 is a so-called LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging) that acquires optical information that can be used in the autonomous driving mode of the host vehicle 2.

[0018] 2 and 3 , each of the paired optical sensors 40 (hereinafter simply referred to as each optical sensor 40) is set with a scanning field of view Vs for optically scanning the outside world of the host vehicle 2. The scanning field of view Vs of each optical sensor 40 is a range of a field of view angle ψs, which is obtained by rotating the scanning orientation Rs of the optical scanning in opposite directions from the reference orientation Rsb around a main axis As that is parallel to each other along the up-down direction of the host vehicle 2. The scanning fields of view Vs of each optical sensor 40 partially overlap each other within the range of the substantially common field of view angle ψs, thereby forming an overlapping area Vsc (the dot-hatched portion in FIG. 2 ).

[0019] As shown in FIG. 3 , the reference direction Rsb in the scanning field of view Vs of each optical sensor 40 is set to a scanning direction Rs that is substantially symmetrical on both sides of the roll axis Ar, which is defined along the front-to-rear direction at the center of the width direction of the host vehicle 2. In particular, the reference direction Rsb in this embodiment represents the scanning direction Rs that determines the scanning start end Vss, which is opposite the scanning end Vse that forms the overlap area Vsc in the scanning field of view Vs of each optical sensor 40. As a result, when viewed from above the host vehicle 2, the scanning fields Vs of the pair of optical sensors 40 with a common field of view angle ψs can be said to be generally symmetrical with respect to the roll axis Ar. Furthermore, within the overlap area Vsc in the scanning field of view Vs of each optical sensor 40, the scanning direction Rs at which the same target Ts is detected by optical scanning is particularly defined as the detection direction Rsd.

[0020] 1, each of the optical sensors 40 has a common configuration, that is, a light emitting unit 400, a scanning unit 410, and a light receiving unit 420. The configuration of each of the units 400, 410, and 420 of one of the optical sensors 40 will be representatively described below.

[0021] The light-emitting unit 400 is mainly composed of a light-emitting element, such as a laser diode, that emits directional laser light in the infrared range. The light-emitting unit 400 projects irradiation light in the form of an intermittent pulse beam toward the outside of the host vehicle 2. The scanning unit 410 is mainly composed of a scanning mirror. The scanning unit 410 optically scans the irradiation light from the light-emitting unit 400 in a scanning direction Rs that corresponds to the swing rotation angle of the scanning mirror, which reflects the irradiation light from the light-emitting unit 400 into a scanning field of view Vs.

[0022] In each optical sensor 40, the scanning field of view Vs in one scanning frame is determined by changing the oscillating rotation angle of the scanning mirror in the scanning unit 410 in the forward direction from the starting angle to the terminal angle. Note that while the oscillating rotation angle of the scanning mirror in one scanning frame changes in the backward direction from the terminal angle to the starting angle, the projection of irradiation light by the light-emitting unit 400 is interrupted, and optical scanning within the scanning field of view Vs is stopped.

[0023] The light receiving unit 420 is configured by combining an integrated circuit with a light receiving element, such as a SPAD (Single Photon Avalanche Diode), that is highly sensitive to the irradiated light. The light receiving unit 420 receives reflected light from targets present in the scanning direction Rs within the scanning field of view Vs, at each light receiving pixel of the light receiving element, by re-reflection according to the swing rotation angle of the scanning unit 410. As a result, the light receiving unit 420 generates a light receiving signal for each light receiving pixel according to the scanning time and scanning position of the target in the scanning direction Rs for each scanning cycle repeated within one scanning frame. Therefore, the light receiving unit 420 in one scanning frame generates point cloud data Dp representing a group of scanning points associated with the scanning time and scanning position of the detected target, i.e., a scanning point cloud, based on the received signals generated for each scanning cycle across the scanning field of view Vs.

[0024] The calibration system 1 for calibrating each of these optical sensors 40 includes at least one dedicated computer. The calibration system 1 is connected to each of the optical sensors 40 via at least one of, for example, a local area network (LAN) line, a wire harness, an internal bus, or a wireless communication line. When the calibration system 1 includes multiple dedicated computers, the connections between these dedicated computers are similar.

[0025] The dedicated computer constituting the calibration system 1 may be a driving control ECU (Electronic Control Unit) that controls the driving of the host vehicle 2. The dedicated computer constituting the calibration system 1 may be a navigation ECU that navigates the driving route of the host vehicle 2. The dedicated computer constituting the calibration system 1 may be a locator ECU that estimates the self-state quantity of the host vehicle 2. The dedicated computer constituting the calibration system 1 may be an actuator ECU that controls the driving actuator of the host vehicle 2. The dedicated computer constituting the calibration system 1 may be an HCU (Human Machine Interface Control Unit (HMI)) that controls the presentation of information in the host vehicle 2. The dedicated computer constituting the calibration system 1 may be a computer other than the host vehicle 2 that constitutes an external center or mobile terminal that can communicate via the communication system of the host vehicle 2.

[0026] The dedicated computer constituting the calibration system 1 has at least one memory 10 and one processor 12. The memory 10 is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs, data, and the like. Here, "storage" may refer to accumulation in which data is retained even when the host vehicle 2 is powered off, or may refer to temporary storage in which data is erased when the host vehicle 2 is powered off. The processor 12 includes at least one type of core selected from a central processing unit (CPU), a graphics processing unit (GPU), a reduced instruction set computer (RISC)-CPU, a data flow processor (DFP), and a graph streaming processor (GSP).

[0027] In the calibration system 1, the processor 12 executes a plurality of instructions included in a calibration program stored in the memory 10 so as to spatially and temporally calibrate pairs of optical sensors 40. In this way, the calibration system 1 constructs a plurality of functional blocks for calibrating the scanning times and scanning positions of pairs of optical sensors 40. The plurality of functional blocks constructed in the calibration system 1 include a scanning block 100, a monitoring block 110, and an output block 120, as shown in FIG.

[0028] The calibration method in which the calibration system 1 spatially and temporally calibrates pairs of optical sensors 40 through the cooperation of these blocks 100, 110, and 120 is executed according to the calibration flow shown in Fig. 5. This calibration flow is executed repeatedly while the host vehicle 2 is running. Note that each "S" in this calibration flow represents a step executed by multiple commands included in the calibration program.

[0029] In S100 of Figure 5, the scanning block 100 (see Figure 4) acquires point cloud data Dp representing the scanning point cloud generated by each optical sensor 40 performing optical scanning across the scanning field of view Vs in the current scanning frame from the light receiving unit 420 of each optical sensor 40.

[0030] 5, the monitoring block 110 (see FIG. 4) monitors the angular deviation Δθ between the detected angles θL and θR based on the detected angles θL and θR from the reference direction Rsb to the detected direction Rsd of the same target Ts within the overlapping area Vsc of each optical sensor 40. Specifically, in S110, the monitoring block 110 extracts the detected angle θL by the left optical sensor 40 and the detected angle θR by the right optical sensor 40 from the corresponding point cloud data Dp in the upward view of the host vehicle 2 shown in FIG.

[0031] For this reason, in S110, the rotation direction of the scanning direction Rs from the reference direction Rsb, which is the scanning start end Vss of the scanning field of view Vs for each optical sensor 40, is defined as the positive direction of the detected angles θL, θR by each optical sensor 40. Furthermore, in this embodiment, the optical sensor 40 located on the left side in a top view of the host vehicle 2 is particularly selected as one of the optical sensors 40 to be calibrated. Therefore, the angle deviation Δθ monitored in S110 is defined according to the following equation 1 so that, assuming that the detected angle θL by the optical sensor 40 to be calibrated is a reference angle, the angle deviation Δθ is a positive (+) value when the detected angle θR by the other optical sensor 40 is smaller than the reference detected angle θL.

[0032] To monitor the angle deviation Δθ based on this principle, it becomes necessary to identify pairs of target scanning points Ps that detect the same target Ts as shown in Fig. 6 within the overlapping area Vsc of each optical sensor 40. Therefore, the monitoring block 110 in S110 of Fig. 5 monitors the angle deviation Δθ by matching multiple pairs of target scanning points Ps that detect the same target Ts from among the scanning point groups scanned by each optical sensor 40 within the overlapping area Vsc.

[0033] Here, multiple sets of target scanning points Ps are matched by searching using a nearest neighbor search method such as ICP (Iterative Closest Point) or bundle adjustment to minimize the error between the scanning points of each optical sensor 40 within the overlap area Vsc. At this time, for the scanning fields Vs of the optical sensors 40 that are symmetrical with each other, it is necessary to overlap the coordinate systems of the scanning point clouds to enable matching. Therefore, the scanning point cloud from the optical sensor 40 to be calibrated (the left side in this embodiment) is matched with the scanning point cloud from the other optical sensor 40 (the right side in this embodiment) by flipping the coordinate system left and right as shown in FIG. 7 . As a result, the angle deviation Δθ is variably adjusted as a coordinate transformation parameter to minimize the error between the scanning points, and can be said to be monitored as multiple sets of target scanning points Ps are matched.

[0034] In S110 of FIG. 5, prior to matching multiple sets of target scanning points Ps, the monitoring block 110 may exclude a mask area Vsm in which a moving object Tm other than the host vehicle 2 exists from the overlap area Vsc to be matched. At this time, the presence of the moving object Tm in the overlap area Vsc may be recognized by, for example, pattern matching and vector analysis of the point cloud data Dp acquired in the current scanning frame and the previous scanning frame. Therefore, as shown in FIG. 8, a mask area Vsm (the dot-hatched portion in FIG. 8) is set within the overlap area Vsc to surround the location of the recognized moving object Tm with a margin, and is excluded from the overlap area Vsc. Hereinafter, the overlap area Vsc from which the mask area Vsm has been excluded is referred to as the masked overlap area Vscm.

[0035] In S110 of FIG. 5, prior to the multiple-group matching of the target scanning points Ps, the monitoring block 110 may compensate for the movement of the host vehicle 2, which moves over time for each scanning period that determines the scanning orientation Rs, for the scanning point group of each optical sensor 40 within the masked overlap area Vscm. At this time, as shown in FIG. 9, the scanning positions of the scanning points within the masked overlap area Vscm by each optical sensor 40 are converted to virtual scanning positions going back to the specific time through a compensation process based on the movement vector (i.e., the amount and direction of movement) of the host vehicle 2 from the specific time. As a result, within the masked overlap area Vscm by each optical sensor 40, the scanning time of the scanning points at the compensated virtual scanning positions is set to the specific time, and these virtual scanning positions and the specific time are used for the multiple-group matching of the target scanning points Ps. Therefore, the specific time may be set, for example, to the scanning time for a specific scanning orientation Rs within the masked overlap area Vscm, or the scanning time for the reference orientation Rsb.

[0036] In S120 of FIG. 5 , the output block 120 (see FIG. 4 ) calibrates the time difference between the reference scanning times tL and tR at which each optical sensor 40 scans the reference direction Rsb. Specifically, as shown in FIG. 10 , the time difference between the reference scanning times tL and tR is calibrated to a corrected time difference Δt that is proportional to the angular deviation Δθ monitored in S110, and is output as calibration data Dc (see FIGS. 1 and 4 ). At this time, the calibration data Dc is output so as to represent a calibration command that shifts the reference scanning time tL of the reference direction Rsb by the optical sensor 40 to be calibrated (the left side in this embodiment) by the corrected time difference Δt, as shown in FIG. 10 . At the same time, the calibration data Dc is output so as to represent a calibration command that maintains the current reference scanning time tR of the reference direction Rsb by the other optical sensor 40 (the right side in this embodiment) that is different from the optical sensor to be calibrated.

[0037] Here, the output block 120 in S120 may calibrate the time difference between the reference scanning times tL and tR of each optical sensor 40 to a corrected time difference Δt that correlates with the angular deviation Δθ monitored in S110 as the angular deviation Δθ monitored in S110 increases outside the allowable range. In other words, while the angular deviation Δθ monitored in S110 is within the allowable range, the calibration in S120 may be skipped. Therefore, the allowable range of the angular deviation Δθ, which is the criterion for determining whether calibration is necessary in S120, may be set to a range equal to or less than the value of the upper limit deviation, which allows for achieving the lower limit accuracy of the scanning time and scanning position expected for the point cloud data Dp.

[0038] The calibration data Dc output by S120 is used to control the scanning unit 410 by shifting the reference scanning time tL of the reference orientation Rsb by the optical sensor 40 of the calibration target (the left side in this embodiment) by the correction time difference Δt, as shown in FIG. 10 . The output of the calibration data Dc by S120 may be stored in the memory 10 for use in controlling the scanning unit 410. In addition, the output of the calibration data Dc may be at least one of providing data to the driving control ECU in the host vehicle 2 and transmitting data to an external center via the communication unit of the host vehicle 2. When the execution of S120 is completed, the current scanning frame ends together with the current flow.

[0039] (Operations and Effects) The operations and effects of the present embodiment described above will be described below.

[0040] In this embodiment, a pair of optical sensors 40 that form an overlap area Vsc in a scan field of view Vs that rotates in counterclockwise directions about parallel main axes As in a host vehicle 2 in a scan direction Rs is calibrated. Each optical sensor 40 in this embodiment monitors the angular deviation Δθ between the detection angles θL and θR from a symmetrically set reference direction Rsb to a detection direction Rsd at which the same target Ts is detected within the overlap area Vsc. As a result, in each optical sensor 40, the time difference between the reference scan times tL and tR at which the reference direction Rsb is scanned is calibrated to a corrected time difference Δt that correlates with the monitored angular deviation Δθ, thereby allowing the scan times and scan positions for the same target Ts to be matched with each other. In other words, it is possible to spatially and temporally calibrate the optical sensors 40.

[0041] According to this embodiment, multiple pairs of target scanning points Ps at which the same target Ts are detected by each optical sensor 40 within the overlap area Vsc are matched. This allows each optical sensor 40 to accurately monitor the angular deviation Δθ between the detection angles θL, θR from the reference orientation Rsb to the detection orientation Rsd of the same target Ts. Therefore, it is possible to ensure spatial and temporal calibration accuracy by calibrating the time difference between the reference scanning times tL and tR to the corrected time difference Δt that correlates with the accurate angular deviation Δθ.

[0042] According to this embodiment, it is easier to accurately match multiple pairs of target scanning points Ps that detect the same target Ts between optical sensors 40 that share the same field of view angle ψs of the scanning field of view Vs around the principal axis As. This makes it possible to accurately monitor the angle deviation Δθ based on the detection orientation Rsd of the same target Ts in each optical sensor 40, and calibrate the time difference between the reference scanning times tL and tR to a corrected time difference Δt that correlates with the accurate angle deviation Δθ. Therefore, it is possible to improve the spatiotemporal calibration accuracy.

[0043] According to this embodiment, multiple pairs of target scanning points Ps detected by each optical sensor 40 for the same target Ts are matched from a group of scanning points within the overlap area Vsc that have been compensated for the movement of the host vehicle 2. This reduces the influence of time error and position error caused by the movement of the host vehicle 2 from the angle deviation Δθ between the detected angles θL and θR of each optical sensor 40. Therefore, the time difference between the reference scanning times tL and tR can be calibrated to a corrected time difference Δt that correlates with an accurate angle deviation Δθ from the standpoints of both time and position errors, thereby improving the spatiotemporal calibration accuracy.

[0044] According to this embodiment, multiple pairs of target scanning points Ps at which the optical sensors 40 detect the same target Ts are matched within an overlap area Vsc (in this embodiment, a masked overlap area Vscm) excluding a mask area Vsm where moving objects Tm other than the host vehicle 2 exist. This reduces the influence of time and position errors caused by the target scanning points Ps at which the optical sensors 40 detect the moving object Tm as the same target Ts from the angle deviation Δθ between the detection angles θL and θR of the optical sensors 40. Therefore, the time difference between the reference scanning times tL and tR can be calibrated to a corrected time difference Δt that correlates with an accurate angle deviation Δθ in terms of both time and position errors, thereby improving the spatiotemporal calibration accuracy.

[0045] According to this embodiment, as the angular deviation Δθ increases beyond the allowable range, the time difference between the reference scanning times tL and tR of each optical sensor 40 may be calibrated to a corrected time difference Δt that correlates with the angular deviation Δθ. This allows calibration to be skipped until the angular deviation Δθ increases to the point cloud data Dp, making it difficult to achieve the expected accuracy. This makes it possible to prevent the robustness of the system 1 from being deteriorated by calibration caused by disturbances.

[0046] (Other Embodiments) Although one embodiment has been described above, the present disclosure should not be construed as being limited to the embodiment described above, and can be applied to various embodiments within the scope that does not deviate from the gist of the present disclosure.

[0047] In a modified example, the dedicated computer constituting the calibration system 1 may have at least one of a digital circuit and an analog circuit as a processor. Here, the digital circuit is at least one of an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SOC), a programmable gate array (PGA), and a complex programmable logic device (CPLD). Furthermore, such a digital circuit may have a memory that stores a program.

[0048] In the modified example of S110, the reference direction Rsb may be set to a scanning direction Rs other than the scanning start end Vss in the scanning field of view Vs. In the modified example of S110, the process of excluding the mask area Vsm from the overlap area Vsc may be omitted. In the modified example of S110, the process of compensating for the scanning points due to the movement of the host vehicle 2 may be omitted. In the modified example of S120, regardless of the magnitude of the angular deviation Δθ, the time difference between the reference scanning times tL and tR may be calibrated to a corrected time difference Δt that correlates with the angular deviation Δθ. Of course, the calibration target in the modified example of S120 may be selected to be the optical sensor 40 on the right side of the host vehicle 2 when viewed from above.

[0049] In a modified example, the host vehicle 2 to which the calibration system 1 is applied may be, for example, an autonomous robot capable of transporting luggage or collecting information by autonomous driving or remote driving. In addition to the forms described so far, the above-mentioned embodiments and modified examples may be implemented in the form of a processing circuit (e.g., ECU, etc.) or a semiconductor device (e.g., semiconductor chip, etc.) as a calibration device that is configured to be mountable on the host vehicle 2 and has at least one processor 12 and one memory 10.

[0050] (Additional Remarks) This specification discloses the following technical ideas and their combinations. Note that the reference symbols in parentheses in this Additional Remarks section indicate the correspondence with the specific means described in the above detailed embodiments, and do not limit the technical scope of the present disclosure.

[0051] (Technical Idea 1) A calibration system for calibrating a pair of optical sensors (40) in a host vehicle (2), the calibration system having a processor (12) and forming an overlapping area (Vsc) in a scanning field of view (Vs) in which scanning orientations (Rs) by optical scanning are rotated in opposite directions around parallel main axes (As), wherein the processor is configured to: define the scanning orientations set symmetrically in each of the optical sensors as a reference orientation (Rsb), and define the scanning orientation at which each of the optical sensors detects the same target within the overlapping area as a detection orientation (Rsd); monitor the angular deviation (Δθ) between the detection angles (θL, θR) from the reference orientation to the detection orientation of the same target in each of the optical sensors; and calibrate the time difference given between reference scanning times (tL, tR) at which each of the optical sensors scans the reference orientation to a corrected time difference (Δt) that correlates with the monitored angular deviation.

[0052] (Technical Idea 2) The calibration system described in Technical Idea 1 includes monitoring the angular deviation by matching multiple pairs of target scanning points (Ps) at which each of the optical sensors detected the same target within the overlapping area, thereby monitoring the angular deviation between the detection angles from the reference orientation to the detection orientation of the same target in each of the optical sensors.

[0053] (Technical Idea 3) The calibration system according to Technical Idea 2, wherein monitoring the angular deviation includes monitoring the angular deviation between the optical sensors that have a common field of view angle (ψs) of the scanning field of view around the principal axis.

[0054] (Technical Idea 4) A calibration system according to Technical Idea 2 or 3, in which monitoring the angular deviation includes monitoring the angular deviation by matching multiple pairs of the target scanning points at which each of the optical sensors detects the same target from a group of scanning points compensated for the movement of the host vehicle within the overlapping area.

[0055] (Technical Idea 5) A calibration system described in any one of Technical Ideas 2 to 4, wherein monitoring the angular deviation includes monitoring the angular deviation by matching multiple pairs of the target scanning points where each optical sensor detects the same target within the overlapping area excluding a mask area (Vsm) where a moving body (Tm) other than the host vehicle exists.

[0056] (Technical Idea 6) A calibration system according to any one of Technical Ideas 1 to 5, wherein calibrating the time difference between the reference scanning times includes calibrating the time difference between the reference scanning times in each of the optical sensors to the corrected time difference as the angle deviation increases beyond the allowable range.

[0057] The above-mentioned technical concepts 1 to 6 may be understood as the respective technical concepts of the method and the program.

Claims

1. A calibration system for calibrating a pair of optical sensors (40) in a host vehicle (2) that form an overlap area (Vsc) in a scan field (Vs) in which scan orientations (Rs) by optical scanning are rotated in opposite directions around parallel main axes (As), the calibration system having a processor (12), wherein the processor is configured to: define the scan orientations set symmetrically in each of the optical sensors as a reference orientation (Rsb), and define the scan orientation at which each of the optical sensors detects the same target within the overlap area as a detection orientation (Rsd); monitor the angular deviation (Δθ) between the detection angles (θL, θR) from the reference orientation to the detection orientation of the same target in each of the optical sensors; and calibrate the time difference provided between reference scan times (tL, tR) at which each of the optical sensors scans the reference orientation to a corrected time difference (Δt) that correlates with the monitored angular deviation.

2. The calibration system of claim 1, wherein monitoring the angular deviation includes: matching multiple pairs of target scanning points (Ps) at which each of the optical sensors detects the same target within the overlapping area, thereby monitoring the angular deviation between the detection angles from the reference orientation to the detection orientation of the same target in each of the optical sensors.

3. The calibration system according to claim 2, wherein monitoring the angular deviation includes monitoring the angular deviation between the optical sensors that have a common field of view angle (ψs) of the scanning field of view around the principal axis.

4. The calibration system of claim 2, wherein monitoring the angular deviation includes monitoring the angular deviation by matching multiple pairs of the target scanning points at which each of the optical sensors detects the same target from a group of scanning points compensated for the movement of the host vehicle within the overlapping area.

5. The calibration system of claim 2, wherein monitoring the angular deviation includes monitoring the angular deviation by matching multiple sets of the target scanning points at which each of the optical sensors detects the same target within the overlapping area excluding a mask area (Vsm) where a moving object (Tm) other than the host vehicle exists.

6. A calibration system according to any one of claims 1 to 5, wherein calibrating the time difference between the reference scan times includes calibrating the time difference between the reference scan times in each of the optical sensors to the corrected time difference as the angular deviation increases outside the tolerance range.

7. A calibration method executed by a processor (12) for calibrating a pair of optical sensors (40) in a host vehicle (2) that form an overlapping area (Vsc) in a scanning field of view (Vs) in which scanning orientations (Rs) by optical scanning are rotated in opposite directions around parallel main axes (As), the calibration method comprising: defining the scanning orientations set symmetrically in each of the optical sensors as a reference orientation (Rsb), and defining the scanning orientation at which each of the optical sensors detects the same target within the overlapping area as a detection orientation (Rsd); monitoring the angular deviation (Δθ) between the detection angles (θL, θR) from the reference orientation to the detection orientation of the same target in each of the optical sensors; and calibrating the time difference provided between reference scanning times (tL, tR) at which each of the optical sensors scans the reference orientation to a corrected time difference (Δt) that correlates with the monitored angular deviation.

8. A calibration program stored in a storage medium (10) for calibrating a pair of optical sensors (40) in a host vehicle (2) that form overlapping areas (Vsc) in a scanning field of view (Vs) in which scanning directions (Rs) by optical scanning are rotated in opposite directions around parallel main axes (As), and the calibration program includes instructions for causing a processor (12) to execute the calibration, wherein the scanning directions set symmetrically in each of the optical sensors are defined as a reference direction (Rsb), and the scanning direction at which each of the optical sensors detects the same target within the overlapping area is defined as a detection direction (Rsd), monitoring the angular deviation (Δθ) between the detection angles (θL, θR) from the reference direction to the detection direction of the same target in each of the optical sensors, and calibrating the time difference given between reference scanning times (tL, tR) at which each of the optical sensors scans the reference direction to a corrected time difference (Δt) that correlates with the monitored angular deviation.

Images