Sonar Bearing Profile Maneuver Detection
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Solution Overview
Problem
Existing sonar technologies face challenges in detecting course and speed changes of targets in real-time, leading to sluggish data estimation and missed detections, especially during initial target maneuvers, due to reliance on filtered bearing angles over long periods.
Innovation Solution
A method that calculates two bearing profiles from recent and older bearing angles, determining an expected bearing angle, and comparing the difference to threshold values to automatically detect target maneuvers, with pre-filtering to smooth data and adapt processing periods based on noise and drift rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing angles from a previous, predetermined period of time are used for current target data estimate through filtering, then the target data estimation is stable and reliable when the target is moving steadily, but the estimation becomes sluggish and delayed after a target maneuver (course and/or speed change)
Solution Approach 1:
The patent applies dynamics by making the processing period adaptive rather than fixed. The system dynamically adjusts the length of the processing period based on the detected state of the target (steady motion vs. maneuvering). When a maneuver is detected, the processing period is shortened to reduce time delay, while during steady motion, a longer period maintains estimation reliability. This resolves the contradiction by allowing the system to switch between stability and responsiveness based on operational conditions.
Solution Approach 2:
The patent changes the parameter of processing period length based on the target's motion state. By monitoring bearing angle variations and detecting maneuvers, the system adjusts the processing period parameter to optimize performance. This parameter adaptation allows the system to maintain reliable estimates during steady motion while reducing time delays during maneuvers, effectively resolving the contradiction between reliability and responsiveness.
2Reliability
If conventional TMA methods are used to detect target maneuvers by monitoring convergence of target data estimates, then maneuvers can be detected when a convergent solution already exists, but maneuvers occurring shortly after track start cannot be detected
Solution Approach 1:
The patent applies preliminary action by detecting target maneuvers based on bearing angle variations before a convergent TMA solution is established. Instead of waiting for the target data estimation to converge (which may never happen if a maneuver occurs early), the system proactively monitors bearing angle changes and detects maneuvers in advance. This allows the system to identify maneuvers shortly after track start, resolving the contradiction between detection accuracy and early detection capability.
3Reliability
If the processing period is extended to improve target data estimation reliability, then good target data are provided during steady motion, but the system response to maneuvers becomes significantly slower
Solution Approach 1:
The patent resolves this contradiction by making the processing period dynamic rather than static. The system continuously monitors bearing angle variations and automatically adjusts the processing period length based on the target's motion state. During steady motion, a longer processing period ensures reliable target data estimation. When a maneuver is detected through bearing angle variation analysis, the processing period is automatically shortened to improve system response speed. This dynamic adaptation eliminates the need to choose between reliability and speed, as both are optimized for their respective operational contexts.
Data Source
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AI summary
The invention relates to a method for identifying changes of course and/or speed for a destination using a multiplicity of measured bearing angles (22) which are ascertained by virtue of the directionally selective reception of sound waves emitted from the destination using an arrangement of water borne sound pickups (86) in a sonar receiving installation. To this end, a first bearing profile (40) is calculated from a predetermined number k of most recently ascertained bearing angles, and a second bearing profile (42) is calculated from a predetermined number i of earlier bearing angles ascertained before the k bearing angles. An expected bearing angle (56, 58) for each of the two bearing profiles (40, 42) is calculated at a current time (54) and is used to form a bearing angle difference |d|. This bearing angle difference |d| can be compared with a plurality of threshold values C1, C2, wherein an intersection point (72) for the bearing profiles (40, 42) and an associated target manoeuvre time (74) are ascertained when one of the threshold values C1, C2 is reached and are output together with an information signal (75) relating to the identification of the target manoeuvre. The invention also relates to an apparatus for carrying out such a method.