Motion Compensating Gangway Contact Control
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Solution Overview
Problem
Motion compensating gangways face inaccuracies in positioning due to errors in motion reference unit measurements, leading to unstable engagement with offshore structures and potential imbalance issues, which complicates operation and design.
Innovation Solution
A motion compensating gangway with a control unit that utilizes both motion reference unit and sensor signals to control actuators, enabling precise positioning and force management at the distal end, using joints and actuators for telescopic, luffing, and slewing directions, and employing a contact mode with negative feedback loops to maintain steady contact with the offshore structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion reference unit measurements are used for active motion compensation, then the distal end can be positioned relative to the offshore structure, but positioning inaccuracies occur due to measurement errors
Solution Approach 1:
The patent implements a feedback control mechanism where a sensor at the distal end detects the actual contact condition with the offshore structure and feeds this information back to the control unit. The control unit then adjusts the actuator commands based on this feedback to correct positioning errors caused by MRU measurement inaccuracies, ensuring stable engagement.
Solution Approach 2:
The system uses the sensor feedback to automatically correct its own positioning errors without external intervention. The control unit processes the sensor signals and autonomously adjusts the actuator commands to maintain accurate positioning and stable contact, making the system self-correcting against measurement errors.
2Reliability
If additional safety measures like dynamic gripping mechanisms are added, then safety level is improved, but device complexity increases
Solution Approach 1:
The patent uses sensor feedback to monitor the contact condition between the distal end and the offshore structure. This feedback enables the control system to detect and respond to engagement issues, providing safety through intelligent control rather than mechanical complexity.
Solution Approach 2:
The patent replaces complex mechanical safety mechanisms (such as dynamic gripping mechanisms) with an intelligent control system that uses sensor feedback and software-based motion compensation. This substitution maintains safety and reliability while significantly reducing mechanical complexity.
3Stability of the object's composition
If passive mode is used to minimize movement between distal end and landing portion, then engagement stability improves, but the gangway may enter imbalance state due to uncounteracted loads
Solution Approach 1:
The patent implements a dynamic control mode that actively adjusts actuator commands based on real-time sensor feedback. This dynamic approach maintains engagement stability while continuously counterbalancing loads and preventing imbalance states, unlike static passive mode.
Solution Approach 2:
The control unit uses sensor feedback to continuously monitor the gangway's state and adjust actuator commands to maintain both engagement stability and force balance. This feedback mechanism prevents the imbalance issues that occur in passive mode by actively compensating for load changes.
Data Source
Figure 1
Figure 2
AI summary
A motion compensating gangway (1) comprises a proximal end (4), a distal end (8), a walkway (2) between these, an actuator (26, 28, 30) for moving the distal end (8) relative to the proximal end (4) upon command from a control unit, at least one sensor (32) for determining a condition of contact between the distal end (8) and a separate structure, and a contact mode wherein the control unit controls the distal end (8) position relative to the proximal end (4), based on at least a signal from a motion reference unit and a signal from the sensor.