Stereo Camera Calibration for Aircraft Ground Collision Avoidance
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Solution Overview
Problem
Current aircraft ground collision avoidance systems face challenges in accurately detecting obstacles due to camera installation costs, calibration complexities, and mechanical flexure, which affect the reliability of stereoscopic and structure from motion methods used for 3D tracking.
Innovation Solution
A collision avoidance system utilizing a pair of cameras mounted on the vertical stabilizer with power-on self-calibration capabilities, using existing feature points on the aircraft to adjust stereo calibration matrices, and employing stereoscopic and structure from motion techniques for obstacle detection, providing a cost-effective and reliable solution for day and night operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple cameras are mounted on different parts of the aircraft (fuselage, wings, stabilizers), then the field of view coverage is improved, but the device complexity and calibration difficulty increase due to mechanical flexure and relative movement between cameras
Solution Approach 1:
The patent consolidates multiple cameras onto a single rigid structure (the vertical stabilizer), eliminating the problem of relative movement between cameras caused by mechanical flexure. This merging approach maintains comprehensive field of view coverage while simplifying the system by ensuring all cameras move together as a single unit, thus resolving the contradiction between coverage and complexity.
Solution Approach 2:
The vertical stabilizer serves as a universal mounting platform for all cameras, performing the dual function of structural support and rigid camera positioning. This multi-functional use of the stabilizer structure eliminates the need for separate mounting mechanisms on flexible surfaces, reducing overall system complexity while maintaining coverage.
2Area of stationary object
If cameras are mounted on flexible surfaces (wings, horizontal stabilizers), then the field of view is expanded, but the measurement precision deteriorates due to mechanical flexure causing relative movement between cameras
Solution Approach 1:
By mounting all cameras on the rigid vertical stabilizer structure, the patent eliminates mechanical flexure between cameras. The stabilizer acts as a single rigid platform that maintains fixed relative positions between all cameras, ensuring precise 3-D tracking measurements while still providing comprehensive field of view through strategic camera placement and orientation.
3Reliability
If external camera systems are installed on aircraft, then collision avoidance capability is improved, but the manufacturing cost increases due to high retrofit installation costs
Solution Approach 1:
The patent combines multiple camera functions and mounting structures into a single integrated system on the vertical stabilizer, reducing the number of separate installation tasks. This consolidation lowers retrofit costs by requiring a single mounting location while maintaining comprehensive collision avoidance capability through the coordinated operation of multiple cameras on the rigid stabilizer structure.
4Measurement precision
If stereoscopic techniques are used with multiple cameras, then 3-D tracking accuracy is improved, but the device complexity increases due to calibration requirements and processing demands
Solution Approach 1:
By mounting all cameras on the rigid vertical stabilizer, the patent creates a stable reference frame that simplifies calibration. The fixed relative positions of cameras on the rigid structure eliminate the need for complex dynamic calibration, reducing processing complexity while maintaining high 3-D tracking accuracy through stereoscopic techniques.
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
The system effectively estimates time to collision and provides aural or graphical cues to pilots, enhancing safety by reducing calibration costs and mechanical flexure-related errors, while ensuring accurate obstacle detection and collision avoidance during aircraft ground maneuvers.
Implementation Method 1
the machine vision processing unit is configured to process the image data captured by the cameras using stereoscopic and structure from motion (SFM) techniques to detect an obstacle that is near or in the path of the aircraft
Implementation Method 2
the machine vision processing unit is configured to process the image data captured by the cameras using stereoscopic and structure from motion (SFM) techniques
Data Source
AI summary
A collision avoidance system comprises a pair of video cameras mounted to a vertical stabilizer of the aircraft, a machine vision processing unit, and a system to inform the pilots of a potential collision. The machine vision processing unit is configured to process image data captured by the video cameras using stereoscopic and structure from motion techniques to detect an obstacle that is near or in the path of the aircraft. Estimates of the range to the object and the rate of change of that range are computed. With the range and range rate, a time to collision can be estimated toward every point of the aircraft. A pilot warning can be sounded based on the nearness of the potential collision. A method of calibrating the video cameras using existing feature points on the top of the aircraft is initiated in response to power being turned on.