Crane Trolley Swing Stopping Control via Pendulum Dynamics
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Solution Overview
Problem
Existing swing stopping control methods for suspension type cranes are inefficient when the rope length changes, requiring complex acceleration corrections and struggling to set optimal swinging periods, leading to inaccurate positioning and swing stopping.
Innovation Solution
A method that calculates speed patterns for trolley acceleration and deceleration based on the equation of motion for the deviation angle of the suspended load, using variables like rope length, reference swinging period, and hoist speed to drive the trolley, ensuring the deviation angle becomes zero at the end of acceleration or deceleration, with a system comprising path, hoist speed, trolley speed, and deceleration initiation distance operation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing swing stopping control methods are used when rope length changes, then positioning accuracy deteriorates, but implementing complex acceleration corrections increases device complexity
Solution Approach 1:
The control method pre-calculates the relationship between rope length changes and required acceleration corrections before actual operation. By establishing correction tables or pre-computed parameters based on anticipated rope length variations, the system eliminates the need for complex real-time calculations during trolley movement, thereby maintaining positioning accuracy without increasing operational complexity
Solution Approach 2:
The invention dynamically adjusts control parameters (acceleration, velocity, timing) based on detected rope length changes. By continuously monitoring rope length and modifying acceleration profiles accordingly, the system adapts to varying conditions without requiring complex mechanical corrections, resolving the contradiction between accuracy and complexity through parameter-based adaptation
2Adaptability or versatility
If swing stopping control is implemented with fixed reference swinging period, then adaptability to varying rope lengths deteriorates, but adjusting swinging period increases control complexity
Solution Approach 1:
The control system transitions from a fixed reference swinging period to a dynamic reference that automatically adapts to rope length changes. By making the reference swinging period a variable parameter that changes with rope length, the system maintains optimal swing stopping performance across different operating conditions without requiring complex manual adjustment mechanisms
Solution Approach 2:
The system incorporates feedback mechanisms that monitor actual rope length and automatically adjust the reference swinging period accordingly. This closed-loop approach ensures the control parameters remain optimized for current conditions, achieving adaptability through automated feedback-driven parameter adjustment rather than complex manual intervention
3Manufacturing precision
If trolley deceleration is initiated earlier to account for rope length changes, then positioning accuracy improves, but travel time increases
Solution Approach 1:
The control method pre-calculates optimal deceleration initiation timing based on anticipated rope length changes and trolley position. By determining the precise moment to initiate deceleration in advance (rather than reacting to actual positioning errors), the system achieves accurate positioning without unnecessary early deceleration, thereby minimizing travel time while maintaining precision
Solution Approach 2:
The system applies deceleration timing that is precisely calibrated to the actual rope length condition - neither too early nor too late. By matching the deceleration initiation moment exactly to when it becomes necessary based on current parameters, the system avoids the time loss associated with overly conservative early deceleration while ensuring positioning accuracy is maintained
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 approach allows for highly accurate swing stopping and positioning even with changing rope lengths, simplifying operations and improving accuracy by initiating deceleration at the correct distance from the target position.
Implementation Method 1
when a suspended load is swung like a simple pendulum
Implementation Method 2
a swinging period operation unit (7) which carries out operation on a reference swinging period Ts of the suspended load on the basis of an equation of motion (1) with respect to the deviation angle θ of the suspended load from the vertical direction under the condition of making the deviation angle θ zero on the assumption that the hoist is in motion at a constant speed
Data Source
AI summary
A method of swing stopping control of a suspended load of a crane including a hoist and a trolley solves an equation of motion, given as an equation with respect to the deviation angle of a suspended load from the vertical direction when the trolley travels, for the trolley acceleration to thereby obtain the value of the acceleration or deceleration of the trolley, obtains speed patterns corresponding to the values of the acceleration or deceleration, drives the trolley according to the obtained speed patterns, and carries out control so that the deviation angle of the suspended load from the vertical direction becomes zero at the time when the acceleration or deceleration of the trolley is ended. Thus, even if the length of a rope holding the suspended load up is changed, a required speed pattern is produced to permit highly accurate positioning.