Multi-IMU Ship Heading Control Under Wave-Induced Yaw
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Solution Overview
Problem
Existing ship maneuvering systems struggle to maintain a stable heading when navigating through waves due to the addition of yaw rates caused by wave motion, which disrupt the intended heading change, leading to inappropriate heading control.
Innovation Solution
A ship maneuvering system utilizing multiple inertial measurement units (IMUs) to estimate wave properties based on hull behavior and adjust heading control to account for wave influences, including predicting and compensating for wave-induced yaw rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If feedback control is performed using one IMU to hold heading, then the system is simple and easy to operate, but the heading cannot be appropriately held when waves are present because wave-induced yaw rate is added to the controlled yaw rate
Solution Approach 1:
The patent divides the single IMU into multiple IMUs positioned at different locations on the vessel. By segmenting the measurement function across multiple sensors, the system can distinguish between vessel-induced yaw rates and wave-induced yaw rates, thereby maintaining heading accuracy in wave conditions while preserving operational simplicity through automated multi-sensor fusion.
Solution Approach 2:
The patent introduces wave property estimation as an intermediary process between raw IMU measurements and heading control commands. The controller estimates wave properties (direction, period, height) from multiple IMU measurements and uses this intermediate information to compensate for wave-induced disturbances, enabling accurate heading control without increasing operational complexity.
2Reliability
If multiple inertial measurement units are used to estimate wave properties and compensate for wave influence, then heading accuracy is improved in wave conditions, but device complexity increases
Solution Approach 1:
The patent makes the multiple IMUs serve multiple functions: they simultaneously provide vessel attitude measurements for conventional heading control and wave property estimation for disturbance compensation. This multi-functionality justifies the increased device complexity by extracting maximum utility from each additional sensor, improving heading accuracy without adding dedicated separate systems.
Solution Approach 2:
The patent changes the operational parameters of the IMU system by utilizing measurements from multiple units with different spatial positions. By analyzing parameter variations (yaw rate differences) between IMUs at different locations, the system estimates wave properties and compensates for wave effects, transforming the complexity of multiple sensors into an advantage for disturbance rejection.
Data Source
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AI summary
A ship maneuvering system includes a plurality of inertial measurement units, and a controller configured or programmed to estimate a property of a wave received by a marine vessel based on a behavior of a hull of the marine vessel measured by the plurality of inertial measurement units, and perform a heading holding control with considering an influence of the wave of which the property is estimated.