Crane Vibration Control via Dynamic Frequency Filtering
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Solution Overview
Problem
Conventional cranes fail to effectively reduce vibrations related to the resonance frequency of horizontal swing and the natural frequency of telescopic booms during operational maneuvers, leading to increased oscillations and instability in load handling.
Innovation Solution
A crane system that generates filtered control signals for actuators, attenuating frequency components corresponding to the resonance frequency of the load's horizontal swing and the natural frequencies of the telescopic boom in both luffing and swiveling directions, with adjustable attenuation rates based on the luffing angles to minimize vibration transmission to the boom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a notch filter is applied to the frequency of vibration in each operational direction based on a vibration model, then the vibration of the carried load is reduced, but the vibration of the boom itself that varies depending on luffing angles cannot be reduced
Solution Approach 1:
The patent applies dynamic filtering by computing resonance frequencies based on real-time operational parameters (luffing angles, suspension length) rather than using fixed notch filters. The filter characteristics are continuously adjusted according to the current boom configuration, enabling effective vibration reduction across varying luffing angles while maintaining adaptability to different operational conditions
Solution Approach 2:
The invention changes the parameters of the filter based on luffing angles and operational state. By computing resonance frequencies dynamically and adjusting filter characteristics accordingly, the system adapts to different boom configurations and operational directions, resolving the limitation of fixed notch filters that cannot handle varying vibration characteristics across different luffing angles
2Speed
If acceleration is applied when a load is carried, then the load moves, but vibratory forces cause the load to vibrate as a simple or double pendulum
Solution Approach 1:
The system applies preliminary anti-action by computing the resonance frequency of the load pendulum vibration in advance and applying a notch filter to attenuate this specific frequency component in the control signal. This prevents the vibratory forces from being transmitted to the load, allowing smooth acceleration without inducing pendulum oscillations
Solution Approach 2:
The invention converts the harmful vibratory forces into a controllable parameter by identifying the resonance frequency and using it as the center frequency for the notch filter. By targeting the specific problematic frequency for attenuation, the system transforms the understanding of the harmful vibration into a precise control strategy that eliminates the issue while maintaining load movement
3Productivity
If the crane operates with telescopic boom, then lifting capability is enhanced, but deflection of structural components causes additional vibrations
Solution Approach 1:
The patent segments the vibration control strategy by identifying and treating different vibration sources separately. It computes and filters the resonance frequency of the load pendulum vibration and the natural frequency of the telescopic boom deflection as distinct frequency components. This segmented approach allows targeted attenuation of each vibration type without interfering with the lifting capability provided by the telescopic boom
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 system efficiently reduces vibrations associated with the resonance frequency of horizontal swing and the natural frequency of the telescopic boom, enhancing operational stability and reducing oscillations during luffing and swiveling operations.
Implementation Method 1
a resonance frequency of a swing of a load in a horizontal direction is computed based on a suspension length of a wire rope via which the load is suspended from a leading end of a telescopic boom, a natural frequency of the telescopic boom in a luffing direction is computed
Implementation Method 2
the filtered control signal for the actuator is generated according to a luffing manipulation of the telescopic boom, the filtered control signal being a signal in which a frequency component in any frequency range is attenuated at any rate with reference to the resonance frequency of the load and a frequency component in any frequency range is attenuated at any rate with reference to the natural frequency of the telescopic boom in the luffing direction
Data Source
AI summary
The resonant frequency ωx(n) of horizontal shaking of a suspended load W suspended from the distal end of a telescopic boom 9 via wire ropes 14·16 is calculated on the basis of the suspension length Lm(n)·Ls(n) of the wire ropes 14·16; the characteristic frequency ωy(n) in the raising and lowering direction of the telescopic boom 9 is calculated; and, in accordance with an operation for raising and lowering the telescopic boom 9, the filtering control signal Cd(n) of an actuator is generated in which a frequency component in a discretionary frequency range is attenuated at a discretionary ratio with reference to the resonant frequency ωx(n) of the suspended load W, and in which a frequency component in a discretionary frequency range is attenuated at a discretionary ratio with reference to the characteristic frequency ωy(n) in the raising and lowering direction of the telescopic boom 9.