Projectile Gyroscope Compensation Using Image-Based Attitude Feedback
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Solution Overview
Problem
Current precision guided munitions rely on costly inertial measurement units (IMUs) and GPS for accurate attitude estimation, which is not feasible in GPS-denied environments, and low-cost IMUs have significant error shifts post-launch, affecting navigation accuracy.
Innovation Solution
A real-time compensation system for projectiles that includes a flight controller, imager device, and gyroscope, where the processor detects features in images and adjusts gyroscope compensation parameters based on sensed angular rates and image-derived rotation angles, allowing for accurate navigation without GPS and using low-cost IMUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-cost IMUs are used, then cost is reduced, but measurement precision deteriorates due to significant error shifts post-launch
Solution Approach 1:
The system uses a camera to capture images of the environment and detects feature points to determine the actual attitude of the projectile. This visual feedback is then used to compensate for gyroscope errors in real-time, creating a closed-loop system that maintains high measurement precision despite using low-cost IMUs
Solution Approach 2:
The patent introduces an image processing system as an intermediary to bridge the gap between low-cost IMU measurements and accurate attitude estimation. The camera and feature point detection algorithm serve as a mediator that provides corrective information to compensate for the inexpensive gyroscope's drift and errors
2Measurement precision
If GPS is used for navigation, then attitude estimation accuracy is improved, but the system becomes inoperable in GPS-denied environments
Solution Approach 1:
The system uses the projectile's own onboard camera and processing capabilities to perform self-calibration and attitude determination. By detecting feature points in the environment and calculating motion from these features, the system serves its own navigation needs without external GPS infrastructure
Solution Approach 2:
The patent replaces the GPS satellite-based electromagnetic system with an onboard optical-mechanical system using a camera and feature point tracking. This substitution enables navigation in GPS-denied environments by using local environmental features instead of satellite signals
3Measurement precision
If high-precision gyroscopes are used, then attitude estimation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The system merges the low-cost IMU with a camera system to create a hybrid navigation solution. By combining the inertial measurements with visual feature point tracking, the system achieves high precision without requiring expensive individual components
Solution Approach 2:
The patent dynamically changes the operational parameters of the gyroscope by applying real-time compensation based on camera-derived attitude information. This allows a low-cost gyroscope to operate at effective high-precision levels through parameter adjustment and error correction
Data Source
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AI summary
A real-time compensation system of a projectile includes at least one flight controller, at least one imager device, at least one gyroscope, and at least one processor. The at least one flight controller is configured to rotate the projectile about an axis between a first orientation and a second orientation. The at least one imager device is configured to capture a first image at the first orientation and a second image at the second orientation. The at least one gyroscope is configured to sense a first angular rate of the projectile as the projectile rotates from the first orientation to the second orientation. The at least one processor is configured to determine a first rotation angle based upon the first and second images and a second rotation angle based upon the angular rate sensed by the at least one gyroscope, and determine a gyroscope compensation parameter.