Sensor angular alignment
Methods, apparatus, and systems for sensor alignment include acquiring a translational vector, a first calibration point location and a second calibration point location, determining an expected rotational orientation in response to the translational vector, the first calibration point location and the second calibration point location, capturing an image of the a first calibration point and the second calibration point, determining a first position of the first calibration point and a second position of the second calibration point in response to the image, calculating a calculated rotational orientation in response to the first position of the first calibration point and the second position of the second calibration point, determining a calibration value in response to the calculated rotational orientation, storing the calibration value and controlling a vehicle in response to the calibration value and a subsequent image.
1 . An apparatus comprising:
a camera configured to capture a first image of a first field of view;
a data interface configured to receive a translational vector, a first location of a first calibration point and a second location of a second calibration point and wherein the first calibration point and the second calibration point are within the first field of view;
a processor configured to determine an expected rotational orientation in response to the first location of the first calibration point and the second location of the second calibration point, to determine a first position of the first calibration point within the first image and a second position of the second calibration point within the first image, to determine a calculated rotational orientation in response to the first position of the first calibration point within the first image and the second position of the second calibration point within the first image; and to generate a calibration value in response to the calculated rotational orientation;
a memory configured to store the calibration value; and
a vehicle controller configured to control a host vehicle in response to the calibration value and a subsequent image captured by the camera.
2 . The apparatus of claim 1 wherein the translational vector, the first location of the first calibration point and the second location of the second calibration point are coordinates within a three dimensional coordinate system and wherein the processor is further operative to convert the translational vector, the first location of the first calibration point and the second location of the second calibration point into a two dimensional coordinate system.
3 . The apparatus of claim 1 wherein the translational vector is transmitted from a calibration station to the data interface via a wireless network.
4 . The apparatus of claim 1 wherein the translational vector is determined in response to a vehicle design parameter and a vehicle orientation within a calibration environment.
5 . The apparatus of claim 1 wherein the first calibration point and the second the second calibration point are located on a calibration target within the first field of view.
6 . The apparatus of claim 1 wherein a two point algorithm is used to compute the calculated rotational orientation.
7 . The apparatus of claim 1 wherein the processor is further operative to determine a subsequent calculated rotational orientation in response to an error of the calculated rotational orientation being greater than a threshold value.
8 . The apparatus of claim 1 wherein the first position of the first calibration point and the second position of the second calibration point are determined within the two dimensional coordinate system.
9 . The apparatus of claim 1 further including an inertial measurement unit for measuring a vehicle attitude and wherein the vehicle attitude and the translational vector are used to calculate the expected rotational orientation.
10 . A method comprising:
capturing, by a first camera, a first image of a first field of view;
receiving, by a data interface, a translational vector, a first location of a first calibration point and a second location of a second calibration point and wherein the first calibration point and the second calibration point are within the first field of view;
determining, by a processor, an expected rotational orientation in response to the first location of the first calibration point and the second location of the second calibration point, to determine a first position of the first calibration point within the first image and a second position of the second calibration point within the first image, to determine a calculated rotational orientation in response to the first position of the first calibration point within the first image and the second position of the second calibration point within the first image; and to generate a calibration value in response to the calculated rotational orientation;
storing, in a memory, the calibration value; and
controlling, by a vehicle controller, a host vehicle in response to the calibration value and a subsequent image captured by the camera.
11 . The method of claim 10 further including translating the translational vector, the first calibration point location and the second calibration point location from a three dimensional coordinate system to a two dimensional coordinate system.
12 . The method of claim 10 including predetermining the translational vector in response to a vehicle dimension and a camera position.
13 . The method of claim 10 , including determining the translational vector in response to the image and a lidar depth map.
14 . The method of claim 10 , including determining the translational vector in response to a vehicle attitude value detected by an inertial measurement unit.
15 . The method of claim 10 , including determining the calculated rotational orientation in response to a two point algorithm.
16 . The method of claim 10 , including recalculating the calibration value in response a subsequent angular difference between a subsequent calculated rotational orientation and the calculated rotational orientation exceeding a threshold value.
17 . The method of claim 10 wherein the first calibration point and the second calibration point are located on a calibration target within a manufacturing calibration test station.
18 . The method of claim 10 , wherein the calculated rotational orientation is determined in response to a small angle approximation.
19 . A camera calibration system comprising:
an optical sensor for capturing a two dimensional image of a field of view;
a network interface for receiving a translational vector, a first location of a first calibration point and a second location of a second calibration point and wherein the first calibration point and the second calibration point are within the field of view;
a processor for determining an expected rotational orientation in response to the first location of the first calibration point and the second location of the second calibration point, for determining a first position of the first calibration point within the two dimensional image and a second position of the second calibration point within the two dimensional image, for determining a calculated rotational orientation in response to the first position of the first calibration point within the two dimensional image and the second position of the second calibration point within the two dimensional image; and for generating a calibration value in response to the calculated rotational orientation;
a memory for storing the calibration value; and
a vehicle controller for controlling a host vehicle in response to the calibration value and a subsequent two dimensional image captured by the optical sensor.
20 . The camera calibration system of claim 19 , wherein the translational vector, the first location of the first calibration point and the second location of the second calibration point are coordinates within a three dimensional coordinate system and wherein the processor is further operative to convert the translational vector, the first location of the first calibration point and the second location of the second calibration point into a two dimensional coordinate system.