Radar Directional Angle Correction Using Camera Input
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Solution Overview
Problem
Radar systems suffer from limited precision and systematic errors in estimating directional angles, particularly azimuth and elevation angles, which are exacerbated by object elevation and antenna calibration issues.
Innovation Solution
Utilize a camera with overlapping field of view to correct radar directional angle measurements by comparing simultaneous radar and camera detections, employing a common coordinate system and ground surface models to identify matching objects, and applying camera-derived directions to correct radar measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radar is used for detecting and monitoring objects, then detection capability is provided, but measurement precision of directional angles deteriorates due to systematic errors
Solution Approach 1:
The patent introduces a camera as an intermediary device to measure directional angles with higher precision. The camera serves as a mediator that provides accurate angular measurements which are then used to correct the radar's directional angle estimates, resolving the precision issue while maintaining radar detection capability
Solution Approach 2:
The patent implements a feedback mechanism where camera measurements of directional angles are continuously used to correct radar measurements. The correction values are calculated by comparing radar and camera angular measurements, then applied back to the radar system to improve its measurement accuracy over time
2Device complexity
If a one-dimensional antenna array is used in radar, then device complexity is reduced, but measurement precision of azimuth angle deteriorates due to broad side angle approximation
Solution Approach 1:
The camera acts as an intermediary that provides precise azimuth angle measurements independently of the radar's antenna array configuration. This allows the system to maintain the simple one-dimensional antenna array while achieving high azimuth angle precision through camera-based correction
Solution Approach 2:
The patent replaces the mechanical/angular measurement limitations of the radar's one-dimensional antenna array with an optical measurement system (camera). The camera's optical axis and image plane provide a different physical basis for angle measurement that is not constrained by the radar's antenna geometry
3Manufacturing precision
If radar antenna array is calibrated for a certain elevation angle, then manufacturing precision is improved for that angle, but measurement precision deteriorates for objects at different elevation angles
Solution Approach 1:
The camera provides a universal directional angle measurement capability that works accurately for objects at any elevation angle, unlike the radar which is optimized for a specific calibration angle. The camera's measurement function is not limited by elevation-specific calibration constraints
Solution Approach 2:
The patent changes the measurement parameter basis from radar's antenna phase measurements (which are elevation-dependent due to calibration) to camera's optical geometry measurements (which are not). This parameter change allows accurate angle measurement across all elevation angles without re calibration
Data Source
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AI summary
There is provided a method, an apparatus, and a system for estimating a corrected directional angle measured by a radar by using input from a camera. The method comprises receiving radar detections of one or more first objects in a scene and camera detections, which are simultaneous with the radar detections, of one or more second objects in the scene. Each radar detection is indicative of a first directional angle and a distance of a respective first object in relation to the radar, and each camera detection is indicative of a direction of a respective second object in relation to the camera. Further, a radar detection and a camera detection which are detections of a same object in the scene are identified by comparing the received radar detections to the received camera detections, and a corrected first directional angle for the identified radar detection is estimated by using the direction of the identified camera detection and the known positions and orientations of the radar and the camera.