Vessel Azimuth Gain Control Using Online Frequency Response
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Solution Overview
Problem
Existing vessel azimuth control apparatuses require excessive memory capacity and calculation time for information processing, making them costly and unable to instantaneously adjust vessel parameters in response to changing conditions such as vessel speed.
Innovation Solution
The proposed vessel azimuth control apparatus includes an azimuth command generation unit, yaw-angle and yaw-angular-velocity detection units, a steering-angle detection unit, an azimuth control unit, a steering-angle control unit, and a control gain adjustment unit that calculates frequency responses to adjust the control gain online, reducing the need for extensive memory and computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SQP algorithm is used to identify vessel parameters by accumulating steering-angle commands and bow-azimuth data, then parameter identification accuracy is improved, but memory capacity and calculation time requirements increase excessively
Solution Approach 1:
The patent extracts only the essential frequency response characteristics from vessel operation data, discarding the need to accumulate and process large volumes of raw steering-angle and bow-azimuth data. By focusing on frequency response parameters directly, the system achieves accurate parameter identification without the computational burden of the SQP algorithm.
Solution Approach 2:
Instead of using complex optimization algorithms (SQP) to infer parameters from accumulated data, the patent inverts the approach by directly measuring frequency response characteristics from operational data and deriving vessel parameters from these measurements, similar to how physical parameters are determined in experimental modal analysis.
2Reliability
If vessel parameters are recalculated when vessel speed changes to optimize control gain, then control performance is improved, but the system cannot instantaneously adjust due to excessive calculation time
Solution Approach 1:
The system continuously monitors frequency response characteristics from ongoing vessel operations and automatically updates parameter estimates without requiring external intervention or complex recalculation procedures. The control apparatus self-adjusts by extracting frequency response data from current operations and updating parameters in real-time.
Solution Approach 2:
The patent changes the approach from recalculating parameters using complex optimization algorithms to directly updating parameters based on frequency response measurements. This allows rapid parameter adaptation when vessel speed or operating conditions change, as frequency response characteristics can be quickly extracted and processed.
3Device complexity
If a simple first-order model is used for vessel identification, then calculation complexity is reduced, but the model cannot represent vessels with yawing vibration and overshooting behavior
Solution Approach 1:
The patent transitions from using fixed, simple first-order models to dynamically adapting higher-order models that can represent complex vessel behaviors. The system identifies appropriate model orders and parameters based on frequency response characteristics, allowing the model structure itself to adapt to the specific vessel being controlled.
Solution Approach 2:
The system performs preliminary frequency response analysis to determine the appropriate model order and characteristics before applying the identification algorithm. By pre-assessing the frequency response data, the system can select suitable model complexities that accurately represent the vessel's dynamic behavior without unnecessary computational overhead.
Data Source
AI summary
The objective is to obtain an azimuth control apparatus and an azimuth control method that require no excessive memory capacity and calculation time for information processing and can cope with a disturbance by adaptively adjusting a control gain while calculating changing vessel parameters online. The vessel azimuth control apparatus hasan azimuth control unit that outputs a steering-angle command signal for making a vessel turn to an azimuth to which the vessel should travel, based on an azimuth command signal generated by an azimuth command generation unit, a yaw-angle signal, and a yaw-angular-velocity signal,a steering-angle control unit that controls a rudder based on the steering-angle command signal, anda control gain adjustment unit that calculates respective frequency responses of the yaw-angle signal and the yaw-angular-velocity signal to a steering-angle signal outputted by a steering-angle detection unit and then adjusts a control gain of the azimuth control unit.