Motion Compensation Arm with Flexible Modeling
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Solution Overview
Problem
Existing movement compensation systems for floating bodies, such as ships and drilling platforms, face challenges in maintaining stable contact due to wave-induced movements, which can lead to instability and unsafe conditions, especially when simplifying assumptions of rigid connections and ideal joints are not met, causing vibrations and deformations that affect control quality.
Innovation Solution
A system with a movable arm equipped with actuators and a sensor device that compensates for unwanted movements by determining and accounting for arm deformation and vibration, using a combination of measuring sensors and kinematic models to improve stability and control quality during docking operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simplifying assumptions of rigid connections and ideal joints are made in motion compensation systems, then device complexity is reduced, but control quality and stability deteriorate due to unaccounted vibrations and deformations
Solution Approach 1:
The patent changes the modeling parameters from idealized rigid connections to flexible connections with elastic elements. The arm structure is modeled with spring-damper elements that account for real-world deformations and vibrations, allowing the control system to compensate for these effects and maintain stability.
Solution Approach 2:
The patent implements feedback by measuring the actual positions and orientations of arm components using sensors (such as optical encoders or external cameras) and using this information to update the kinematic model. This closed-loop approach allows the system to account for deviations caused by flexibility and bearing play, improving control quality.
2Reliability
If wave-induced movements are compensated using traditional control systems, then contact establishment between floating bodies is improved, but control stability deteriorates due to arm vibrations and deformations
Solution Approach 1:
The patent segments the arm structure into multiple rigid bodies connected by flexible elements. Each segment (e.g., boom, jib, counterjib) is modeled separately with its own mass, inertia, and elastic properties. This allows the control system to independently analyze and compensate for vibrations and deformations in different parts of the structure.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating damping elements in the flexible connection models. These dampers are designed to counteract the vibrations and oscillations that occur during arm movement, providing passive vibration suppression before the control system acts on them.
3Manufacturing precision
If the arm structure is designed to be rigid to minimize deformation, then manufacturing precision is improved, but device complexity and cost increase due to the need for stronger materials and structures
Solution Approach 1:
The patent substitutes complex mechanical rigidity requirements with a computational model. Instead of designing the arm to be perfectly rigid through expensive materials and over-engineering, the system uses a flexible multibody model with spring-damper elements to represent the arm's elastic behavior. This allows standard, less expensive materials to be used while maintaining control accuracy through software compensation.
Data Source
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Figure 3
AI summary
Disclosed is a system comprising a floating body, in particular a ship, which has an arm, in particular a gangway. The system comprises a motion compensation device for compensating the movement of the arm. Preferably, a sensor is provided with which the position of the head of the gangway relative to the ship can be determined more precisely. In particular, deformations and/or vibrations of the gangway can be detected via the sensor.