Ship Heading Control Using IMU-Based Wave Yaw Compensation
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Solution Overview
Problem
Existing ship maneuvering systems face challenges in maintaining accurate heading control due to yaw rates generated by waves, which interfere with the intended steering angles, leading to deviations from the target heading.
Innovation Solution
Incorporating multiple inertial measurement units (IMUs) to estimate wave properties based on hull behavior, allowing the system to adjust steering angles to compensate for wave-induced yaw rates and maintain proper heading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one inertial measurement unit (IMU) is used to detect heading, then the device complexity is low, but the measurement precision deteriorates due to inability to distinguish wave-induced yaw from steering-induced yaw
Solution Approach 1:
The patent divides the single IMU function into multiple specialized IMUs: one IMU detects the steering angle input, while another IMU detects the actual yaw rate of the hull. This segmentation allows the system to separately measure steering-induced yaw and wave-induced yaw, improving heading detection precision by distinguishing between intentional steering and wave interference.
Solution Approach 2:
The patent introduces an intermediary calculation process that uses the difference between the steering angle detected by the first IMU and the actual yaw rate detected by the second IMU to estimate wave-induced yaw. This intermediary approach allows the system to isolate and compensate for wave effects without requiring direct wave measurement, thereby improving measurement precision while managing device complexity.
2Reliability
If feedback control is performed based on single IMU heading detection, then the control system is simple, but the reliability deteriorates when waves are present due to added yaw rate from waves
Solution Approach 1:
The patent implements a dual-loop feedback control system. The first feedback loop uses the steering angle from the first IMU to calculate the expected yaw rate. The second feedback loop compares this expected yaw rate with the actual yaw rate from the second IMU to estimate wave-induced yaw. This layered feedback approach improves heading holding reliability by continuously compensating for wave effects while maintaining a structured control architecture.
Solution Approach 2:
The patent performs preliminary estimation of wave-induced yaw by comparing the steering angle input with the actual hull yaw rate before final heading control is applied. This preliminary action allows the system to pre-compensate for wave effects in the control calculation, improving reliability in wave conditions by addressing wave interference before it affects the final heading control decision.
Data Source
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 based on an influence on the marine vessel caused by the wave of which the property was estimated.