Crane Boom Swing Suppression via Modified Triangular Wave Control
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Solution Overview
Problem
Existing crane control systems fail to effectively suppress the swing of a suspended load due to response delays in the drive device, leading to inaccurate motion control.
Innovation Solution
A crane system that incorporates a control unit to input a control command with a pattern for swing suppression, including modified triangular waves and rectangular waves in the jerk pattern to correct response delays in the drive device, ensuring accurate motion control of the boom and reduction of swing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional drive device is used without response delay correction, then the control system is simple, but the swing suppression accuracy deteriorates
Solution Approach 1:
The control unit pre-calculates and applies correction values for response delay before the actual movement occurs. By anticipating the drive device's delayed response and compensating in advance through modified acceleration patterns, the system achieves accurate swing suppression without requiring complex real-time feedback mechanisms.
Solution Approach 2:
The invention modifies the acceleration command parameters by superimposing correction values that account for the drive device's response characteristics. This parameter adjustment transforms the conventional control approach into one that compensates for delays, improving swing suppression accuracy while maintaining the existing drive device hardware.
2Productivity
If the boom moves at high speed or large angle, then productivity is improved, but residual swing increases due to centrifugal forces
Solution Approach 1:
The control unit applies preliminary counter-actions by superimposing correction values that oppose the centrifugal forces generated during high-speed or large-angle boom movement. This anticipatory compensation prevents residual swing from developing, allowing high productivity operations without compromising load stability.
Solution Approach 2:
The invention dynamically adjusts the acceleration command by adding time-varying correction values that adapt to the boom's movement conditions. As the boom moves at different speeds or angles, the correction values dynamically compensate for changing centrifugal forces, maintaining load stability throughout the transportation process.
3Measurement precision
If response delay correction is applied, then swing suppression accuracy is improved, but control calculation complexity increases
Solution Approach 1:
The control unit performs the complex calculation work in advance by pre-determining the correction values based on the drive device's known response characteristics. This preliminary calculation approach achieves accurate motion control without requiring complex real-time computations during actual operation, balancing precision with computational feasibility.
Data Source
AI summary
A crane includes a boom that suspends a suspended load, a drive device that drives the boom, and a control unit that controls the drive device, the control unit inputting a control command including a pattern for swing suppression to the drive device, to cause the drive device to execute a swing suppression drive, and, when a value of the control command is converted into a command value of acceleration of the boom, the pattern for swing suppression includes a modified triangular wave including, in consecutive order, a first gradient portion that changes with a predetermined gradient in either a positive or negative direction, an offset portion in which the command value is displaced in a direction opposite to the change in the first gradient portion, and a second gradient portion that changes with a predetermined gradient in the direction opposite to the change in the first gradient portion.