Crane Control System With Notch Filter For Load Swing Suppression
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Solution Overview
Problem
Conventional cranes face challenges in reliably stopping loads at predetermined locations while suppressing load swing, due to variations in working radius, suspension length, and load weight, which can result in collisions with obstacles.
Innovation Solution
A crane system incorporating an actuator, a generation unit for creating deceleration and constant-speed control signals, a filter unit for filtering these signals, and a control unit that uses a notch filter to control the actuator, allowing for precise deceleration and stopping of loads while minimizing swing, by calculating resonance frequencies and adjusting control signals based on load dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deceleration control is used, then the load can be decelerated, but the load swing cannot be suppressed and reliable stopping at predetermined location cannot be achieved
Solution Approach 1:
The patent applies vibration control by generating a control signal that includes a vibration component at the resonance frequency of the load swing. The vibration suppression control unit detects the load swing frequency and generates a control signal that actively counteracts the swing by applying vibrational forces at the resonant frequency, thereby suppressing load swing during deceleration and enabling reliable stopping at the predetermined location.
2Reliability
If deceleration is started early to ensure stopping at predetermined location, then stopping reliability improves, but productivity decreases due to extended operation time
Solution Approach 1:
The control unit calculates the appropriate deceleration start position in advance based on the current speed, distance to the predetermined location, and load characteristics. This preliminary calculation allows the system to initiate deceleration at the optimal moment, ensuring accurate stopping at the predetermined location while minimizing the deceleration distance and time, thus maintaining productivity.
3Object-generated harmful factors
If filtering control signal is applied to suppress swing, then load swing is reduced, but the complexity of the control system increases
Solution Approach 1:
The patent implements feedback control by using the load swing frequency detected during operation to dynamically adjust the control signal. The vibration suppression control unit continuously monitors the load swing and generates a control signal that feeds back the detected frequency information, allowing the system to adaptively suppress swing without requiring complex pre-programming or multiple fixed-frequency filters.
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 effectively decelerates and stops loads at predetermined locations while suppressing swing, enhancing safety by preventing collisions with obstacles and ensuring precise control.
Implementation Method 1
the resonance frequency is calculated on the basis of the suspension length of the hook... the notch filter has a characteristic that an attenuation rate becomes higher as a frequency approaches a resonance frequency
Implementation Method 2
the filter may be a notch filter. The notch filter has a characteristic that an attenuation rate becomes higher as a frequency approaches a resonance frequency
Data Source
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AI summary
This crane is provided with: a operable functional unit; an actuator for driving the operable functional unit; a generation unit that, in control of causing the operable functional unit to automatically stop, generates a first control signal including a first deceleration signal section composed of a control signal for decelerating a speed of the operable functional unit from a first speed to a second speed and a first constant-speed signal section composed of a control signal for maintaining the speed of the operable functional unit at the second speed; a filter unit for filtering at least the first deceleration signal section in the first control signal to generate a second control signal; and a control unit that controls the actuator so as to decelerate the operable functional unit on the basis of the second control signal, then controls the actuator so as to maintain the speed of the operable functional unit at the second speed, and controls the actuator so as to zero the speed of the operable functional unit when a load suspended from the crane has been moved to a location satisfying a prescribed condition.