Ladar Backtracking of Wake Turbulence for Point-of-Origin Estimation
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Solution Overview
Problem
Current weapon-locating radar systems face delays and inaccuracies in detecting and tracking incoming projectiles due to assumptions of ballistic trajectories, which can be disrupted by factors like wind, maneuvering, or low radar cross-sections, leading to less effective counter-fire.
Innovation Solution
A weapon-locating ladar system that uses flow field measurements to backtrack the wake turbulence of airborne targets, allowing for more accurate estimation of the point-of-origin by illuminating the wake with a laser beam and processing spatially resolved radial velocity and derivatives to compute backward trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler radar is used to detect and track the hardbody of the projectile, then the system can provide 3D position and radial velocity measurements, but there is a delay in detection and tracking establishment due to the narrow field-of-view scan and low radar cross-section of certain projectiles
Solution Approach 1:
The patent uses wake turbulence as an intermediary medium to detect the projectile's trajectory. Instead of directly detecting the projectile hardbody with radar, the system detects the wake turbulence left by the projectile, which provides continuous trajectory information without the detection delays associated with direct hardbody detection.
Solution Approach 2:
The system performs preliminary detection of the wake turbulence before the projectile reaches the impact zone. By detecting and tracking the wake turbulence trail left by the projectile, the system can establish the trajectory early in the projectile's flight path, reducing the time delay before counter-fire can be directed.
2Measurement precision
If ballistic trajectory assumptions are used to backtrack the projectile path, then the system can estimate the point-of-origin, but the accuracy is reduced when the projectile does not follow a pure ballistic trajectory due to wind, maneuvering, or boosting
Solution Approach 1:
The patent transitions from static ballistic trajectory assumptions to dynamic wake turbulence tracking. The wake turbulence naturally follows the actual projectile path regardless of whether it is ballistic, maneuvering, or boosted, allowing the system to adapt to different trajectory types without requiring separate models or assumptions.
Solution Approach 2:
The patent replaces the mechanical calculation-based ballistic trajectory backtracking with an optical detection method that directly measures the wake turbulence flow field. This substitution allows the system to capture the actual trajectory as it occurs, including all deviations from pure ballistic motion, without requiring complex mechanical calculations or assumptions.
3Area of stationary object
If the radar beam scans a large field-of-regard to detect incoming projectiles, then the system can cover more area, but the narrow instantaneous field-of-view causes delays in detecting the projectile when it emerges from behind terrain features
Solution Approach 1:
The wake turbulence detection provides continuous trajectory information along the entire wake path. Once the wake is detected at any point, the system can continuously track it back to the origin without the intermittent scanning delays of traditional radar, maintaining continuous useful action throughout the backtracking process.
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 approach enhances the accuracy of point-of-origin estimation and counter-fire effectiveness by extending detection closer to the source, accommodating non-ballistic trajectories, and compensating for wind velocities, thereby improving the precision of counter-fire measures.
Implementation Method 1
The laser energy backscattered from molecules, aerosols and particulate matter in the volume of air in and around the wake trailing the airborne target is detected
Implementation Method 2
The weapon-locating system uses Doppler radar to detect the hardbody of the projectile and then track the position of the hardbody forwards
Data Source
Figure 1a~1c
Figure 2
Figure 3a
AI summary
A weapon-locating ladar system estimates a backward trajectory of an airborne target by using flow field measurements to follow the wake turbulence trailing the airborne target from a position at which the target is detected backwards until the wake is no longer observable. The system may use the backward trajectory to estimate the point-of-origin of the target. The system may also use the flow field measurements along the backward trajectory to classify the target. Target classification may be used to refine the point-of-origin estimate, to influence counter-fire or to adapt the flow field measurements.