GM 2019-04-266 Dec 2019 13:55
More on the Camera calibration theme.
GM
THREE-DIMENSIONAL ALIGNMENT OF RADAR AND CAMERA SENSORS 2019-04-26
As previously noted, vehicles increasingly include sensor systems such as radar sensors and camera sensors. In autonomous vehicles or vehicles with autonomous features (eg, autonomous parking), 360-degree coverage around the vehicle with more than one sensor facilitates the acquisition of supplementary information through sensor fusion. However, sensor fusion (ie, a combination of data acquired by each sensor) requires geometric alignment of the individual sensors that share the FOV. If the sensors are not aligned, the detection of a frame of reference that is converted to other sensors by one sensor will be projected at the wrong coordinates. For example, radar detections that are converted to the camera coordinate system are projected at the wrong image coordinates. Therefore, the distance (in pixels) between the projected position and the actual image position is a measure of the sensor's misalignment.
Embodiments of the systems and methods described in detail herein relate to 3D alignment of radar sensors and camera sensors. Specifically, the conversion parameters between the radar and the camera are determined to align the two types of sensors geometrically. Then, the radar detection converted to the camera reference frame is projected onto the target image at the correct image coordinates. In the exemplary embodiment described in detail herein, corner reflectors are used to determine the conversion parameters. In radar systems, corner reflectors appear as strong point targets, where all reflected energy comes from near the apex. By inserting a light emitting diode (LED) in the vertex of the corner reflector, the image coordinates of the LED in the image acquired by the camera can be aligned with the vertex detection performed by the radar system, as described in detail above.
According to an exemplary embodiment, FIG. 1 is a block diagram of a vehicle 100 that performs 3D alignment of a radar sensor 110 and a camera sensor 120. The exemplary vehicle 100 shown in FIG. 1 is a car 101. In addition to the radar 110 and the camera 120, the vehicle 100 may include additional sensors (eg, lidar, additional radar, additional cameras), where the FOV is guided to cover the sides and rear of the vehicle 100. The vehicle 100 includes a controller 130 for aligning the radar 110 and the camera 120. For example, the controller 130 may be a stand-alone controller or may be part of one of the sensors or part of the automation system of the vehicle 100. The controller 130 includes a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or grouped) and memory executing one or more software or firmware programs, a combination logic circuit, and / Or other suitable components that provide the described functionality.
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