Active Rider Block Tagline System for Shipboard Crane Pendulation
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Solution Overview
Problem
Current control systems for slewing pedestal cranes, such as the Rider Block Tagline System (RBTS) and Pendulation Control System (PCS), are not entirely successful in limiting pendulation to acceptable magnitudes under all standard operating conditions, particularly in high sea-states, and require significant operator dexterity and crane machinery performance beyond standard marine crane design capabilities.
Innovation Solution
The Pendulation Control System with Active Rider Block Tagline System (PCS-with-ARBTS) combines attributes of RBTS and PCS, featuring active control of the rider block to optimally partition ship motion cancellation commands between the crane's primary and RBTS drive systems, and implements active swing damping through the rider block, eliminating the need for active swing damping in the primary crane drive system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a Rider Block Tagline System (RBTS) is incorporated into the crane, then the pendulum length is reduced and payload stability is improved, but the device complexity and operator skill requirements increase significantly
Solution Approach 1:
The crane system is segmented by introducing a rider block that divides the original single pendulum into two separate pendulums: one from the boom tip to the rider block, and another from the rider block to the payload. This segmentation reduces the effective pendulum length for the payload, thereby improving stability while distributing the complexity across modular components (rider block, taglines, lift line) that can be controlled independently.
Solution Approach 2:
The rider block serves as an intermediary component between the boom and the payload. It acts as a mediator that actively controls the payload's position and orientation by adjusting the taglines and lift line lengths, thereby improving payload stability without requiring the entire crane system to be overly complex. The rider block absorbs much of the control complexity.
2Ease of operation
If automated control is implemented for the RBTS to reduce operator burden, then the ease of operation improves, but the device complexity and control system requirements increase
Solution Approach 1:
The automated control system incorporates feedback mechanisms that continuously monitor the positions of the rider block and payload, and adjust the tagline and lift line lengths accordingly. This feedback-based control automates the complex coordination required by the RBTS, improving ease of operation while managing system complexity through intelligent control algorithms rather than mechanical complexity.
Solution Approach 2:
The patent replaces manual mechanical control with automated control systems that use sensors, processors, and actuators to manage the RBTS. This substitution of mechanical operator dexterity with electronic control systems improves ease of operation while consolidating complexity into integrated control units rather than distributed mechanical linkages.
3Stability of the object's composition
If the rider block is actively controlled to dampen payload swing, then the payload stability improves, but the drive system speed requirements and energy consumption increase
Solution Approach 1:
The active swing damping control employs periodic adjustments to the tagline and lift line lengths, applying small corrective forces at critical moments in the payload's oscillation cycle. This periodic action effectively dampens swings without requiring continuous high-speed operation of the drive systems, thereby reducing energy consumption while maintaining payload stability.
Solution Approach 2:
The system changes the parameters of the control system by actively adjusting the lengths of the taglines and lift line in response to payload swing conditions. These parameter changes enable dynamic damping of payload oscillations without requiring the drive systems to operate at maximum speeds continuously, thus reducing energy consumption while improving stability.
4Reliability
If the crane is designed to handle high sea-state conditions, then the reliability and operational capability improve, but the machinery performance requirements exceed standard marine crane capabilities
Solution Approach 1:
By segmenting the payload support system into a rider block with separate taglines and lift line, the crane can independently control different segments to counteract ship motions. This segmentation allows the system to handle high sea-state conditions more reliably by addressing oscillations at multiple levels without requiring proportionally higher power from the main drive systems.
Solution Approach 2:
The system incorporates dynamic control capabilities where the rider block and its associated lines can actively adjust their configuration in real-time to adapt to changing sea conditions. This dynamic adaptability improves operational reliability in high sea states without requiring the crane machinery to have excessive power margins, as the system optimizes its response to actual conditions rather than being over-designed for worst-case scenarios.
Data Source
AI summary
The inventive control system, as typically embodied, includes sensing mechanisms, a computational processing unit, and an algorithm for processing inputs and generating outputs to control a rotating pedestal crane equipped with a Rider Block Tagline System (RBTS). Typical inventive embodiments uniquely feature a processing algorithm that distributes various control modes that operate not only through the crane's hoisting, luffing, and slewing mechanisms but also through the crane's RBTS; the inventive algorithm thereby effectuates motion compensation and pendulation damping with respect to the crane. This algorithmic allocation of control represents a more efficient crane anti-pendulation methodology than conventional methodologies; in particular, the inventive methodology exerts significantly greater control of the payload while exacting significantly less burden upon the hoisting, luffing, and slewing mechanisms of the crane.