Vessel Azimuth Control with Speed-Adaptive Gains and Vibration Suppression
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Solution Overview
Problem
Conventional vessel automatic steering systems face instability due to vessel-speed-dependent azimuth control responsiveness and inability to effectively suppress disturbances outside the control band, leading to vibrations and reduced sailing comfort.
Innovation Solution
A vessel-azimuth control apparatus with an azimuth command generator, angular velocity controller, and vibration suppression controller that converts user interface signals into commands, processes actual vessel data, and generates final steering angle commands to stabilize vessel azimuth control, regardless of vessel speed, by attenuating vibrations outside the control band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed gains are used for feedback and feedforward controllers, then the control system is simple to implement, but the azimuth control responsiveness varies with vessel speed and may become unstable
Solution Approach 1:
The patent applies dynamics by making the controller gains variable rather than fixed. The feedback controller gain and feedforward controller gain are adjusted dynamically based on vessel speed, allowing the control system to adapt to changing operational conditions. This resolves the contradiction by maintaining stability across different speeds while avoiding excessive complexity through a structured gain adjustment mechanism.
Solution Approach 2:
The patent changes the parameter of controller gains from fixed values to speed-dependent variable values. By adjusting the feedback gain and feedforward gain according to vessel speed, the system maintains optimal performance across the operating range. This parameter change approach allows the system to adapt to speed variations without requiring a completely complex restructured controller.
2Device complexity
If the control band is fixed, then the controller design is simple, but vibrations outside the control band cannot be suppressed leading to reduced sailing comfort
Solution Approach 1:
The patent segments the control system into multiple functional components: a feedback controller for stability, a feedforward controller for performance, and a vibration suppression controller for disturbance rejection. Each component operates with appropriate gain characteristics, allowing the system to address both stability and vibration suppression without excessive overall complexity.
Solution Approach 2:
The vibration suppression controller acts as an intermediary component that processes the control signal and adds vibration suppression functionality without fundamentally redesigning the entire control system. This mediator approach allows vibration suppression to be added while maintaining the existing feedback and feedforward control structures.
3Ease of manufacture
If conventional controllers are used, then the system is easy to implement, but azimuth control performance degrades at low vessel speeds
Solution Approach 1:
The patent changes the gain parameters of the feedback and feedforward controllers based on vessel speed. At low speeds, the gains are adjusted to provide sufficient control authority for effective azimuth changes, while at high speeds the gains are reduced to prevent excessive responsiveness. This parameter adjustment maintains good control performance across all speeds while keeping the implementation relatively simple through a structured gain schedule.
Data Source
AI summary
A vessel-azimuth control apparatus is configured in such a way that an azimuth controller generates and outputs an angular velocity command, based on an azimuth command from an azimuth command generator and an actual azimuth, in such a way that an angular velocity controller generates and outputs a steering angle command, based on the angular velocity command, a vessel speed, and an actual angular velocity, and in such a way that a vibration suppression controller outputs a final steering angle command, based on the steering angle command.