Shipborne Radar Target Estimation via Stationary Reference Filtering
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Solution Overview
Problem
Conventional target object movement estimating devices suffer from accuracy degradation due to disturbances in location measurement data, particularly when the ship's movement state changes rapidly, leading to temporary precision loss and delayed recovery in estimation accuracy.
Innovation Solution
The device uses a stationary point reference target object location, independent of the ship's movement, for filtering, and selectively switches between this location and target object relative location based on GNSS accuracy, employing a filtering module that includes a Kalman filter or αβ tracker for smoothing and estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If smoothing is performed using a recursive digital filter to reduce disturbance influence, then estimation stability is improved, but estimation accuracy degrades due to delay in the movement estimation result
Solution Approach 1:
The patent segments the estimation process into two independent parts: one for stability (smoothing filter using stationary point reference location) and one for accuracy (relative location information). By separating these functions, the system maintains estimation stability while preserving accuracy through the use of unsmoothed relative location data for certain calculations.
Solution Approach 2:
The patent introduces a switching mechanism as an intermediary that selectively combines outputs from the smoothing filter and raw measurement data. This intermediary component allows the system to switch between filtered and unfiltered data based on current operational conditions, thereby resolving the contradiction between stability and accuracy.
2Ease of operation
If location measurement data is created based on ship location and radar signals, then target tracking is achieved, but accuracy degrades when ship movement state changes rapidly
Solution Approach 1:
The patent extracts the ship's movement influence from the location measurement data by using stationary point reference location. By removing the ship movement component, the system obtains target location information that is independent of ship motion, thereby maintaining estimation precision even when ship movement state changes rapidly.
Solution Approach 2:
Instead of calculating target location directly from ship-relative radar coordinates (which embeds ship movement), the patent inverts the approach by first establishing a stationary reference frame and then expressing target location relative to this fixed point, effectively eliminating ship movement from the measurement equation.
3Measurement precision
If stationary point reference target object location is used for filtering, then ship movement influence is removed, but system complexity increases due to switching between different location types
Solution Approach 1:
The patent implements a dynamic switching mechanism that adaptively selects between stationary point reference location and ship-relative location based on current operational conditions. This dynamic approach allows the system to maintain high estimation accuracy while managing complexity through context-dependent operation rather than fixed architecture.
Data Source
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AI summary
The disclosure provides a target object movement estimating device which can output a movement estimation result which is less influenced by a change of a movement state of the device. A target object movement estimating module (6) provided to a radar device includes a target object relative coordinate acquisition module (61), a stationary point reference target object coordinates acquisition module (62), and a filtering module (64). The target object relative coordinate acquisition module (61) is carried in a ship, and acquires relative coordinates (Trx, Try) indicative of a relative location of a target object with respect to the ship location based on a radar echo. The stationary point reference target object coordinates acquisition module (62) acquires stationary point reference coordinates (Tax, Tay) indicative a location of the target object with respect to a stationary point, based on the relative coordinates (Trx, Try) and the ship location. The filtering module (64) is inputted with the stationary point reference coordinates (Tax, Tay), and then estimates movement information on the target object.