Crane Load Control Device for Skew Correction
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Solution Overview
Problem
Existing crane systems face challenges in accurately controlling the position and movement of freight containers due to issues like skew, list, and trim errors during loading and unloading, leading to inefficiencies and potential instability in container stacks.
Innovation Solution
A load control device with a four-point suspension system, optical sensors, and actuators that adjust load lines to correct linear displacement errors, using absolute encoder sensors for continuous monitoring and precise actuator control, enabling fast recovery from skew, list, and trim errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual adjustments are made by the crane operator to cancel out skew moment, then the operator can attempt to reduce skew oscillation, but the effectiveness is operator dependent and does not reliably reduce the time lost to skew oscillation
Solution Approach 1:
The patent replaces manual mechanical adjustments by the operator with an automated control system that uses sensors to detect container position and actuators to automatically adjust the spreader position, eliminating operator dependency and reliably reducing skew oscillation time
Solution Approach 2:
The patent implements a feedback control system where sensors continuously monitor the container's skew position and provide real-time data to the control system, which then automatically adjusts the spreader position to counteract skew oscillations, ensuring reliable and consistent correction
2Manufacturing precision
If the container is lowered while skew oscillations are present, then the landing accuracy is poor, but waiting for oscillations to die down takes many seconds or up to a minute
Solution Approach 1:
The patent applies preliminary anti-action by using the automated control system to counteract skew oscillations before the container is landed, actively correcting the position rather than passively waiting for oscillations to naturally dampen, thereby achieving both high landing accuracy and reduced waiting time
3Stability of the object's composition
If a 5-high stack of containers is not stable, then containers may be damaged and greater ground area and clearance space are demanded, but achieving stable stacking requires high landing accuracy
Solution Approach 1:
The patent uses feedback control to continuously monitor and adjust the container position during landing, ensuring high landing accuracy that enables stable 5-high stacking without requiring excessive ground area or clearance space
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution minimizes delays caused by container oscillations and ensures accurate positioning during landing, providing reliable and efficient automatic handling of containers across various weather conditions and crane types.
Implementation Method 1
an optical sensor for sensing a deflection position of an orthogonal axis of a container suspended under the spreader and light sources arranged on the spreader in a first straight line relative to an orthogonal axis of the container
Implementation Method 2
two or more actuators arranged attached to at least one load line for moving at least one said suspension point closer to or farther away from said imaginary centre line by shortening and/or lengthening the at least one load line
Data Source
AI summary
A control device and system for controlling a suspended load of a container crane with a trolley, a spreader and load lines arranged in a four point suspension for lifting a load and an optical sensor for sensing a deflection position of an orthogonal axis of a container suspended under the spreader. Two or more actuators are arranged attached to at least one load for moving at least one said suspension point closer to or farther away from an imaginary center line by shortening and/or lengthening the at least one load line.