Crane Control System for Load Swing Suppression
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Solution Overview
Problem
Conventional crane control systems experience discontinuous acceleration and positional shifts of loads due to the influence of wire ropes, leading to unwanted swinging, especially when controlling actuators based on speed and directional signals from remote manipulation terminals.
Innovation Solution
A crane system that includes swivel angle, luffing angle, and extension/retraction length detection means, which converts target speed signals into target positions and computes the direction vector of the wire rope to generate operation signals for actuators, thereby stabilizing the boom control and reducing load swing by attenuating frequency components and using inverse dynamics models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the crane performs control using speed signal and directional signal from remote manipulation apparatus, then the crane can be manipulated intuitively without paying attention to actuator operating parameters, but discontinuous acceleration is caused so as to swing the load at the start or stop of movement
Solution Approach 1:
The control apparatus computes a target position of the boom tip based on the target speed signal before actuating the boom actuator. This preliminary computation of position from speed input allows the system to anticipate and smooth transitions, preventing discontinuous acceleration that would otherwise cause load swing while preserving intuitive manipulation.
2Device complexity
If the crane assumes the tip of the boom is always vertically above the load, then the control is simplified, but it is impossible to prevent the occurrence of a positional shift and/or swing of the load caused by the influence of a wire rope
Solution Approach 1:
The control apparatus introduces a wire rope length computation as an intermediary variable that accounts for the actual distance between the boom tip and the load. By computing the target boom tip position based on this intermediate wire rope length measurement, the system compensates for wire rope influence and achieves accurate load positioning without overly complicating the control structure.
3Ease of operation
If the crane controls actuators based on commands on the moving direction and speed of the load, then the manipulation is simplified, but the load swing cannot be prevented
Solution Approach 1:
The control apparatus computes the target position of the boom tip based on the target speed signal and then compares it with the actual boom tip position. This feedback mechanism allows the system to adjust actuator commands in real-time to prevent load swing, while maintaining the simplicity of load-centric manipulation for the operator.
Data Source
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AI summary
The invention addresses the problem of providing a crane and a crane control method that can suppress load swaying when controlling an actuator on the basis of the load. The invention is provided with a turntable camera (7b) that detects the current position coordinates p(n) of a load W with respect to a reference position, wherein the invention: converts a target speed signal Vd to target position coordinates p(n+1) of the load W with respect to the reference position; calculates the current position coordinates q(n) of a boom (9) with respect to the reference position from a turning angle θz(n), a hoisting angle θx(n), and an extension/contraction length lb(n); calculates a feed amount 1 of the wire rope and the directional vector e(n) of the wire rope from the current position coordinates p(n) of the load W and the current position coordinates (n) of the boom (9); calculates the target position coordinates q(n+1) of the boom (9) with regards to the target position coordinates (n+1) of the load W from the feed amount 1 and the directional vector e(n) of the wire rope; and generates an actuator operation signal Md on the basis of the target position coordinates q(n+1) of the boom (9).