Crane Load Sway Control Using Rotational Speed and Cable Length
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Solution Overview
Problem
Existing crane systems face challenges in automatically regulating the sway angle of loads during rotational movements around a vertical axis, as existing solutions do not effectively address the centrifugal force-induced oscillations, which persist even at zero acceleration or deceleration.
Innovation Solution
A regulation device that calculates and corrects the sway angle using the length of suspension cables, distance between the axis of rotation and the attachment point, and rotational speed, applying iterative processes and correction signals to the translational and rotational movements to minimize oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing anti-sway devices are used for translational movement, then sway control during linear movement is improved, but sway control during rotational movement remains ineffective
Solution Approach 1:
The control device is designed to handle both translational and rotational movements using a unified control strategy. The device calculates sway angles and generates correction signals that are applicable to both types of movement, making the system universal rather than specialized for only one movement type.
Solution Approach 2:
The control approach changes from directly measuring sway angles to calculating them indirectly using operational parameters (cable length, distance from rotation axis, rotational speed). This parameter transformation enables the system to adapt to different movement types by changing the calculation model rather than requiring different hardware.
2Measurement precision
If direct measurement of sway angle is implemented, then control precision is improved, but system complexity and measurement requirements increase
Solution Approach 1:
Instead of directly measuring the sway angle, the system uses operational parameters (cable length, distance from rotation axis, rotational speed) as intermediaries to calculate the sway angle. These parameters are already available from the crane's control system, eliminating the need for additional sensors and complex measurement equipment.
Solution Approach 2:
The patent replaces direct mechanical measurement systems with a computational approach. By substituting physical sensors with mathematical calculations based on operational parameters, the system achieves the same control precision without the complexity of additional measurement hardware.
3Manufacturing precision
If complex measurement and learning phases are required, then control accuracy is improved, but implementation time and operational complexity increase
Solution Approach 1:
The control device uses parameters that are already available from the crane's normal operation (cable length, distance from rotation axis, rotational speed). The system serves itself by utilizing existing operational data without requiring external measurement equipment or additional learning phases, thereby achieving control accuracy immediately upon implementation.
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
The solution allows for simple, quick, and effective damping of load oscillations along both horizontal and tangential axes during rotational and translational movements, reducing the need for complex measurements and learning phases, thereby enhancing safety and efficiency in load transfer.
Implementation Method 1
the particularity of a sway due to a rotational movement is that this sway has a component which is generated by the centrifugal force of the load during the rotation movement
Data Source
Figure 1~3
AI summary
The invention relates to a device (20) for controlling the movement of a load (15) suspended by cables (14) from a hook point (10) that is rotatable about a vertical axis (Z) and movable translationally along an axis of translation (X), the movement of rotation generating a first or sway angle (Tx) of the load (15) relative to the axis of translation (X). The device calculates the first or sway angle (Tx) and a speed (T'x) of the first or sway angle (Tx), the only input variables used being the length (L) of the cables (14), the distance (R) between the axis of rotation (Z) and the hook point (10) and the speed of rotation (Vy) of the hook point (10), while the acceleration (T"x) of the first or sway angle (Tx) is used as an internal variable.