Camera Window Calibration for Boresight Shift Correction

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Solution Overview

Problem

The installation of a window over a camera assembly in autonomous vehicles causes a boresight shift, misaligning the optical axis with the mechanical axis due to refraction and misalignment, leading to reduced performance and accuracy in optical systems.

Innovation Solution

A calibration process using a diffractive optical element to determine and correct for the boresight shift by generating a transformation that maps pixel locations with and without the window, allowing for precise alignment and compensation for the shift, regardless of the window's optical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a window is installed over the camera assembly, then the camera is protected and can be used with various window designs, but boresight shift occurs causing misalignment between optical axis and mechanical axis

Engineering Contradiction:

Improvecamera protection and versatility with window designsVSAvoidalignment precision between optical axis and mechanical axis

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The calibration process is performed in advance to determine the boresight shift caused by the window. A transformation is pre-computed that maps pixel locations with the window to pixel locations without the window. This preliminary calibration allows the system to compensate for the window-induced misalignment before actual operation begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the optical parameters by applying a computed transformation to the pixel coordinates. This transformation adjusts the pixel locations to account for the refraction and misalignment caused by the window, effectively correcting the boresight shift through parameter modification rather than physical realignment.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a window is installed over the camera assembly, then various window designs can be used, but the optical performance is reduced due to refraction and misalignment

Engineering Contradiction:

Improvecompatibility with various window designsVSAvoidoptical performance and accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The calibration is performed in advance to characterize the specific window's effect on the optical system. By determining the boresight shift and computing the transformation beforehand, the system can compensate for this specific window's optical properties, maintaining measurement precision while allowing versatility in window design selection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a computational model (transformation) that replicates the effect of removing the window. By applying this transformation to pixel locations, the system effectively copies the ideal optical performance without the window while physically operating with the window installed, thus maintaining accuracy despite the window's presence.

Inventive Principle:

Principle #26Copying

3Ease of manufacture

If traditional calibration methods are used, then the process is simple, but high precision window installation is required to minimize boresight shift

Engineering Contradiction:

Improvesimplicity of calibration processVSAvoidwindow installation precision requirement

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of requiring precise installation, the method performs a preliminary calibration with the window actually installed. This approach shifts the precision requirement from the mechanical installation phase to the calibration phase, where software computation can achieve high precision without demanding tight mechanical tolerances during assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The solution replaces the mechanical precision requirement with a computational approach. Rather than relying on precise mechanical alignment during installation, the system uses software-based calibration and transformation to achieve the necessary alignment precision, substituting mechanical precision with computational correction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables accurate correction of boresight shift, ensuring the optical performance of camera assemblies is maintained even with various window designs, reducing the precision required for window installation and improving the reliability of autonomous systems.

Implementation Method 1

A calibration process using a diffractive optical element to determine and correct for the boresight shift

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

Boresight shift can be caused by additional refraction or misalignment caused by the optical properties of the additional layer

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS11812128B2Methods and systems for determination of boresight error in an optical system

Publication Date: 2023.11.07 MOTIONAL AD LLC

AI summary

Provided are methods for determination and correction of boresight shift caused by the installation of an optical layer over a camera assembly. Some methods described include performing a first calibration prior to installation of the window, performing a second calibration after installation of the window, and comparing the first and second calibrations to determine a transformation that corrects for the boresight shift. Systems and computer program products are also provided.