Marine Propulsion Control for Roll Stabilization at Low Speed
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Solution Overview
Problem
Smaller marine vessels lack effective stabilization systems to counteract environmentally-induced roll and pitch motions, which are uncomfortable and disruptive, as traditional stabilization devices are large, costly, and power-intensive, making them unsuitable for smaller vessels.
Innovation Solution
Utilizing propulsion devices to counteract roll and pitch motions by moving them in a way that targets the natural roll frequency of the vessel, without causing significant lateral movement, using drive movements and alternating thrust to stabilize the vessel without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional stabilization devices are used to counteract roll and pitch motions, then vessel stability is improved, but device size, cost, and power consumption increase significantly
Solution Approach 1:
The patent applies multi-functionality by using the vessel's existing propulsion devices for both their primary function (propulsion) and a secondary function (stabilization). The propulsion devices are controlled to counteract roll and pitch motions through alternating thrust patterns, eliminating the need for separate stabilization equipment while maintaining vessel stability.
Solution Approach 2:
The vessel's own propulsion system serves the dual purpose of propulsion and stabilization. By utilizing the existing propulsion devices and controlling them to generate counteracting forces, the system makes the vessel self-stabilizing without requiring external or additional stabilization hardware, thereby reducing device size and complexity.
2Stability of the object's composition
If traditional stabilization devices are installed on smaller vessels, then roll and pitch counteraction is achieved, but power consumption increases
Solution Approach 1:
The propulsion devices perform dual functions: propulsion and stabilization. By controlling the propulsion devices to alternate between left and right thrust patterns, the system generates rolling moments that counteract environmental roll forces while using the same devices for forward motion, thereby avoiding additional power consumption for dedicated stabilization equipment.
Solution Approach 2:
The stabilization mechanism employs periodic alternating thrust from the propulsion devices. The devices alternately generate thrust to the left and right in a periodic pattern, creating oscillating rolling moments that counteract the vessel's roll motion. This periodic action achieves stabilization without requiring continuous operation of separate stabilization systems, reducing overall power consumption.
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 method effectively stabilizes smaller marine vessels by counteracting environmentally-induced roll and pitch motions without the need for additional hardware, improving comfort and reducing power consumption, particularly effective at low speeds or during station keeping mode.
Implementation Method 1
determining a counteracting drive movement for at least one propulsion device based on the measured roll motion and the natural roll frequency of the marine vessel
Data Source
AI summary
A method of controlling attitude of a marine vessel includes measuring a roll motion of the marine vessel with an attitude sensor, and then determining that the roll motion exceeds a threshold roll where no corresponding steering input is present. The method further includes determining a counteracting drive movement for at least one propulsion device based on the measured roll motion and then controlling a steering actuator to move the at least one propulsion device to effectuate the counteracting drive movement so as to counteract an environmentally-induced roll motion of the marine vessel without effectuating a net change in heading and/or translation.