Camera-to-Body Alignment Measurement for Guided Projectiles
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Solution Overview
Problem
Conventional navigation systems require costly and imprecise methods for measuring the rotation transform between a camera coordinate frame and a vehicle's body coordinate frame, often relying on expensive alignment devices like lasers or precision instruments.
Innovation Solution
A method involving a pure rolling motion of a body, captured images of a calibration target over a range of roll angles, and numerical optimization to estimate alignment and misalignment angles, eliminating the need for precise geometrical configuration or expensive alignment devices, using v-block mechanisms and sensors like inclinometers to measure roll angles and estimate rotational transforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional precision instruments or alignment devices are used to measure the rotation transform between camera and body coordinate frames, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical alignment devices with a computational approach using pure rolling motion and numerical optimization. Instead of using precision instruments to directly measure the rotation transform, the system uses a camera to capture images during rolling motion and computes the transform through optimization algorithms, substituting mechanical measurement systems with computational methods.
Solution Approach 2:
The system uses the body's own rolling motion to generate the calibration data needed for measurement. The pure rolling motion of the body itself creates the varying camera orientations relative to the calibration target, eliminating the need for external alignment devices to impose motion. The body serves its own calibration purpose through its natural rolling behavior.
2Measurement precision
If precision alignment devices are used to measure the rotation transform, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive precision alignment devices with inexpensive, readily available components: a standard camera, a simple calibration target with printed patterns, and basic rolling support mechanisms. These low-cost components perform the calibration function without requiring expensive specialized equipment, making the system economically viable.
Solution Approach 2:
The patent substitutes expensive mechanical alignment devices with a computational solution using image processing and numerical optimization. The rotation transform is determined through algorithmic processing of images captured during rolling motion, replacing costly physical alignment instruments with software-based computation.
3Measurement precision
If direct measurement methods are used to measure body orientation in the world coordinate frame, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces a calibration target as an intermediary element that mediates between the camera and the body coordinate frame. The calibration target provides a known reference structure that the camera observes, allowing the system to infer body orientation indirectly through image analysis rather than requiring direct measurement instruments.
Solution Approach 2:
The patent replaces direct mechanical orientation sensors with a vision-based indirect measurement system. Instead of using gyroscopes or other inertial sensors to directly measure body orientation, the system uses a camera to capture images of a calibration target and computes orientation through numerical optimization, substituting mechanical sensing with optical observation and computational analysis.
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
Accurately measures the camera-to-body rotational transformation with high precision, reducing costs and eliminating the need for expensive alignment devices, while providing repeatable results and differentiating between world-to-v-block and camera-to-body misalignments.
Implementation Method 1
capturing a series of images of an imaging device calibration target over a range of body roll angles
Data Source
AI summary
A technique is provided to measure an alignment of an imaging device of a guided projectile containing an imager and a world coordinate frame, and includes producing a pure rolling motion of a body of the projectile, capturing a series of images of an imaging device calibration target over a range of body roll angles of the rolling body, measuring the roll angles of the rolling body with respect to a world coordinate frame as defined by the imaging device calibration target, simultaneously estimating alignment angles of the imaging device and misalignment angles associated with an orientation of the body, and estimating a rotational transform between an imaging device coordinate frame and a body coordinate frame based on the estimated alignment angles and misalignment angles.