Adaptive Motion Compensation for Offshore Load Handling
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Solution Overview
Problem
Current motion compensation systems for offshore load lifting are limited by their bespoke nature, requiring significant re-engineering for different applications, and lack the precision needed for handling both topside and subsea loads, particularly due to vessel motion-induced resonance and complex wire dynamics in deep water operations.
Innovation Solution
An adaptive method for motion compensation that uses motion data and actuator performance parameters to generate a predicted motion model, allowing for real-time control adjustments and adaptation across various actuators and environments, including rotary, linear, and hybrid systems, to accurately position loads and maintain stable wire tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standardized motion compensation method is implemented, then adaptability to different actuators and environments is improved, but manufacturing precision and control accuracy may worsen due to the generic nature of the solution
Solution Approach 1:
The control method dynamically adapts to different actuator characteristics by continuously monitoring performance parameters and adjusting control signals in real-time. The system modifies control strategies based on actual actuator response, enabling a standardized approach to work effectively across diverse actuator types while maintaining precision through adaptive adjustment rather than fixed parameters
Solution Approach 2:
The system changes control parameters adaptively based on measured actuator performance. By monitoring parameters such as actuator response time, position accuracy, and force output, the control method adjusts control gains, feedforward terms, and compensation factors to optimize performance for each specific actuator configuration, resolving the contradiction between standardization and precision
2Measurement precision
If real-time control adjustments are made using predicted motion models, then positioning accuracy is improved, but device complexity increases due to additional sensors and processing requirements
Solution Approach 1:
The system performs preliminary actions by generating predicted motion models in advance based on actuator characteristics and environmental conditions. These predictions are calculated before actual positioning operations, allowing the control system to pre-compensate for expected errors and disturbances, thereby improving positioning accuracy without requiring complex real-time adjustments during critical operations
Solution Approach 2:
The method implements feedback mechanisms where sensor measurements of actual actuator performance and load position are continuously compared against predicted values. The differences (errors) are fed back to adjust the predicted motion model and control signals, creating a closed-loop system that improves accuracy progressively while managing complexity through iterative refinement rather than overly complex open-loop control
Data Source
Figure 1(a)~1(b)
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AI summary
There is proposed a method for adaptive motion compensation of a load [12] controlled by at least one first actuator [16, 30...] on a moving vessel [10], comprising the steps of: (a) obtaining motion data of the moving vessel [10] for a predefined first time interval [λ] in at least one first Degree of Freedom (DOF); (b) providing at least one geometric characteristic of said at least one first actuator [16, 30...]; (c) determining at least one performance parameter of said at least one first actuator [16, 30...]; (d) determining an initial position of said load [12]; (e) generating a predicted motion model of the moving vessel [10] for a predefined second time interval [λ]; (f) generating a control algorithm adapted to control said at least one first actuator [16, 30...], utilising said predicted motion model and at least one predicted performance parameter; (g) determining a first correction factor, and a second correction factor, (h) repeating steps (a) to (g) for each subsequent time interval [λ]. There is also proposed an adaptive controller adapted to execute the method.