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EP-4617711-B1 - LASER DEVICE, CALIBRATION OF LASER DEVICE AND VERIFICATION OF RADAR ALIGNMENT CALIBRATION

EP4617711B1EP 4617711 B1EP4617711 B1EP 4617711B1EP-4617711-B1

Inventors

  • ABBRUZESE, Gianmarco
  • ROEMHILD, Torsten

Dates

Publication Date
20260506
Application Date
20240312

Claims (6)

  1. A method of verifying calibration of automotive radar alignment, comprising: replacing (S80) a radar sensor of a vehicle with a verification device (10) having the same physical orientation with respect to the vehicle as the radar sensor; providing, via reflection by respective first (24) and second (25) reflecting surfaces of the verification device, a first laser beam (26) and a second laser beam (27), wherein the first and second reflecting surfaces are adjacent to each other and are such that the first laser beam and the second laser beam are spaced apart in laterally spaced parallel planes, each plane perpendicular to a ground plane (34) on which the vehicle is positioned, and such that the first laser beam is at a first elevation angle with respect to the ground plane, and the second laser beam is at a second elevation angle with respect to the ground plane, wherein the difference between the first elevation angle and the second elevation angle is at least 2 degrees, and wherein the verification device comprises recesses for accommodating first (21) and second (22) laser sources for the respective first and second laser beams; irradiating (S82) a target screen (70) with the first laser beam and the second laser beam, determining a first target position (74) at which the first laser beam is incident on the target screen, and determining a second target position (75) at which the second laser beam is incident on the target screen; and determining an orientation of the radar sensor by comparing the first target position with a first reference position (71) associated with the incidence of a first reference laser beam on the target screen from the verification device at a reference orientation, and comparing the second target position with a second reference position (72) associated with the incidence of a second reference laser beam on the target screen from the verification device at the reference orientation; determining misalignment of the radar sensor using the difference between the determined orientation and the reference orientation; configuring the calibration of the radar sensor to compensate for determined misalignment.
  2. A method according to claim 1, wherein the target screen (70) is arranged such that the intersection of the boresight of the verification device (10) with the target screen is at the midpoint (73) of a line joining the first reference position (71) and the second reference position (72).
  3. A method according to claim 2, further comprising: measuring a first difference between an offset (77) between the first target point (74) and the second target point (75) in a first direction, and an offset between the first reference point and the second reference point in the first direction; determining a pitch of the verification device, relative to the reference orientation, using the first difference; measuring a second difference between an offset (78) between the first target point and the second target point in a second direction, and an offset between the first reference point and the second reference point in the second direction; determining a yaw of the verification device, relative to the reference orientation, using the second difference; wherein the first direction and second direction are perpendicular to each other and the second direction is perpendicular to the ground plane (34).
  4. A verification device (10) for verifying calibration of alignment of an automotive radar, comprising: a frame (12); and mounting means (14a-c) for mounting to the verification device to a vehicle; wherein the mounting means are configured to mate with receiving means on the vehicle for receiving a radar sensor at a reference orientation, such that when the radar sensor is detached from the receiving means and the mounting means are attached to the receiving means, the verification device has the reference orientation; wherein the frame comprises a first surface (24) for receiving and reflecting a first laser beam (26) from a first laser source, and a second surface (25) for receiving and reflecting a second laser beam (27) from a second laser source, wherein the first and second reflecting surfaces are adjacent to each other and arranged such that the verification device outputs a reflected first laser beam and a reflected second laser beam in laterally spaced parallel planes, each plane perpendicular to a ground plane (34) on which the vehicle is positioned, wherein the first and second surfaces have angles of inclination, with respect to the ground plane, which are offset from each other by at least 2 degrees, such that the reflected first and second beams have different angles of elevation; wherein the frame comprises recesses for accommodating the first and second laser sources.
  5. A verification device according to claim 4, wherein the frame (12) comprises aluminium.
  6. A method of calibrating a verification device according to claim 4 or claim 5, the method comprising: using the verification device (10) to reflect and output first and second laser beams (40, 41); (S50) positioning a target screen (70) at a first distance (M1) from the verification device; (S52) determining the points of incidence (46, 47) of the reflected first and second laser beams on the target screen; (S54) positioning the target screen at a second distance (M2) from the verification device; (S56) determining the points of incidence (48, 49) of the reflected first and second laser beams on the target screen; (S58) determining the difference in elevation and azimuth of the reflected first and second laser beams using the points of incidence of the reflected first and second laser beams on the target screen at the first and second distances, and the difference (D) between the first and second distances; and (S62) outputting calibration data defining the expected configuration of first and second reflected laser beams output by the verification device when the verification device is mounted to a vehicle at the reference orientation, wherein the first distance (M1) and the second distance (M2) are measured using two or more reference lasers (42, 43).

Description

Field The present disclosure relates to estimating sensor misalignment, and particularly to verifying the calibration of the alignment of automotive radars. The present disclosure relates to a device for outputting one or more laser beams for use in determining automotive radar alignment. The present disclosure also relates to methods of calibrating the laser device, and of verifying radar calibration. Background Many vehicles are equipped with radar systems in order to detect nearby obstacles or other vehicles, to enable autonomous driving functions to be performed, or to provide information to a driver. The radars are usually mounted to vehicles via brackets. The fitting of such brackets to a vehicle, and the fitting of radars to the brackets, creates a chain of manufacturing tolerances which is such that in practice, a radar's position may deviate from its optimum position after mounting. In such cases, the radar is considered to be misaligned from its design specification. Moreover, the deviation may differ from vehicle to vehicle. There is therefore a need to check each vehicle, after production, to check for deviations in the alignment of the radars and to calibrate the vehicle to take any misalignment into account. Such a process is referred to herein as end-of-line calibration. Once deviations are identified, the vehicle's processors are calibrated to accommodate the determined deviations, for example by applying necessary mathematical offsets to radar signals. For example, if it is determined that the radar is elevated or has an azimuthal offset, with respect to the road surface and direction, from its ideal expected configuration, the frame of reference for radar calculations can be adjusted by reprogramming the vehicle's processors in order to compensate for this elevation deviation, so that the position of a detected object is calculated with respect to the true road surface and direction. A problem arises, however, if the process of checking for deviations is itself subject to inaccuracies. In such circumstances, it is difficult to fully compensate for radar misalignment, as the ground truth for the radar's positioning is not known accurately. Laser-based techniques are conventionally used to mitigate this problem by seeking to optimise the accuracy of end-of-line calibration techniques. Such techniques, applicable in particular to front-looking radars, involve the mounting of a laser to the radar so that the radar alignment can be observed via the position of a co-aligned laser beam on a measurement chart. The mounting of the laser to the radar is complex, however, and difficulties may arise if there is insufficient space surrounding the radar installation to accommodate the laser. Further, mounting structures which are used are often heavy and the mounting itself can cause further radar misalignment, such as a change in elevation associated with the radar sinking under the weight of the mounting structure. However, many radars are positioned behind a cover or fascia to conceal their appearance, which either prevents or complicates access to such radars to fit laser-mounting structures. There are also no known solutions to calibrate corner-concealed radars which have recently been installed on vehicle bumpers. US2005/222746 discloses an adaptive cruise control sensor subsystem alignment tool for a vehicle, comprises gauge pins with respective distal ends, arranged to define a plane with known orientation to illumination axis, defined by an illumination source. The point at which a visible laser light beam strikes a reference surface can reveal the alignment of the sensor sub-assembly with respect to the vehicle. BENDIX: "Instructions for the Vertical and Lateral Alignment of Bendix Radar Sensors" discloses a system for vehicle radar sensor vertical and lateral alignment. US2014022115 discloses an apparatus for aligning forward-facing radar sensors in vehicles, comprising a receiver flag positioned in front of the forward-facing radar sensor, and laser beams perpendicular to the thrust line of the vehicle. The present disclosure presents apparatus and methods to improve the ease and accuracy of verifying the calibration of radar alignment. Accuracy of 0.1° of error in any direction can be achieved. According to a first aspect, there is provided a method of verifying calibration of automotive radar alignment, comprising replacing a radar sensor of a vehicle with a verification device having the same physical orientation with respect to the vehicle as the radar sensor, providing, via reflection by respective first and second surfaces of the verification device, a first laser beam and a second laser beam, wherein the first and second reflecting surfaces are adjacent to each other and are such that the first laser beam and the second laser beam are spaced apart in laterally spaced parallel planes, each plane perpendicular to a ground plane on which the vehicle is positioned, and such that the first