Crane Control Device Vibration Suppression via Real-Time Frequency Identification
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Solution Overview
Problem
Tower cranes experience vibrations during slewing movements due to their mechanical structure, leading to unstable speed perception for operators and difficulties in precise positioning, especially at low speeds, as existing solutions either sacrifice responsiveness or require complex mathematical modeling and additional hardware.
Innovation Solution
A method and control device that automatically calculate the natural frequency and damping rate of the crane system in real-time using motor torque and current values, generating a speed reference profile that suppresses vibrations by convolving the operator's signal with a frequency elimination signal, allowing for smooth and jerk-free slewing without the need for a detailed mathematical model or additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive vibration reduction methods (fluid coupling, eddy current brake) are used, then vibrations in the structure are reduced, but the speed of the drive motor or drive axle is influenced by torque resulting from vibrations, sacrificing responsiveness
Solution Approach 1:
The control device continuously monitors actual speed and compares it with the speed reference value, using the speed deviation and its derivative to calculate corrective torque commands. This closed-loop feedback mechanism compensates for vibration-induced speed fluctuations while maintaining responsive control, as the system actively counteracts disturbances rather than passively absorbing them
Solution Approach 2:
The system uses readily available sensor data (speed measurements) and motor parameters to generate vibration compensation without requiring additional sensors or complex external systems. The control algorithm self-adjusts by calculating torque commands based on measured speed deviations, making the system self-sufficient in combating vibrations
2Measurement precision
If detailed mathematical modeling of the crane structure is performed to suppress vibrations, then vibration control precision is improved, but device complexity and commissioning effort increase significantly
Solution Approach 1:
The system replaces complex, permanent mathematical models of the crane structure with simple, empirically determined parameters (natural frequency and damping ratio) that are automatically identified through brief test movements. This approach achieves effective vibration control without requiring detailed structural modeling, reducing system complexity while maintaining control precision
Solution Approach 2:
The control system dynamically adjusts the speed reference profile based on identified parameters (natural frequency and damping ratio) rather than relying on fixed mathematical models. By changing the temporal characteristics of the speed profile to avoid resonant frequencies, the system achieves vibration suppression with minimal computational complexity
3Measurement precision
If additional sensors are installed to measure vibrations and natural frequencies, then vibration detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The existing speed sensors and motor control systems perform multiple functions: they not only control motor speed but also provide data for vibration analysis and natural frequency identification. By analyzing speed deviations and torque fluctuations from normal operation, the system extracts vibration information without requiring dedicated vibration sensors
Solution Approach 2:
The system uses its own operational data (speed measurements, motor current) to identify vibration characteristics and natural frequencies. No external measurement systems are needed, as the crane's own operational signals provide sufficient information for parameter identification and control
4Manufacturing precision
If the speed reference profile is optimized to eliminate vibrations, then positioning precision is improved, but the flexibility to respond to operator commands may be reduced
Solution Approach 1:
The speed reference profile is dynamically adjusted based on the current operating state and identified parameters. The system generates optimized speed profiles that adapt to different movement conditions and operator commands, maintaining positioning precision while preserving flexibility through real-time parameter adjustment rather than fixed pre-programmed sequences
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 reduces structural stresses, noise, and energy wastage by the crane, enabling full torque availability for smooth movements, with the system adapting to changing mechanical properties and simplifying commissioning processes.
Implementation Method 1
calculating, from the operator signal and the natural frequency and the damping rate, a speed reference profile for the motor which actively suppresses oscillations at the natural frequency of the structure of the crane system
Data Source
Figure 1a~2
Figure 3~5
Figure 6a~7
AI summary
The invention relates to a method and a control device for the low-vibrational control of the movement, by means of a motor (20), of a moveable crane element (14, 16, 18) such as a crane jib (18) in a crane system (10), said crane element being made to vibrate at a natural frequency (fEIG) and having a damping ratio (?). Said moveable crane element (14, 16, 18) is controlled by a control signal (VSOLL), the spectrum of which is substantially free from natural frequencies (fEIG) of the crane system (10), and the control signal (VSOLL) is calculated from an operator signal (SBED) of an operator, taking into account system parameters of the crane system (10). So as to reduce vibrations in a rotating tower crane structure during the pivoting movement and to simplify configuration of the control device in a method and control device of the type referred to initially, the system parameters in the form of the natural frequency (fEIG) and the damping ratio (?) of the crane system (10) are automatically calculated during operation, and the control signal (VSOLL) is calculated in real-time, as an active speed-reference profile (VSOLL), from the operator signal (SBED) of the operator as well as from the calculated natural frequency (fEIG) and the damping ratio (?) of the crane system (10).