Crane Lift-Off Control Using Filtered Load Feedback
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Solution Overview
Problem
Conventional dynamic lift-off control devices in cranes require complex control mechanisms, leading to prolonged lift-off times due to the combination of winch and derricking actuators, which complicates the process and increases the time needed to suppress load swing during dynamic lift-off.
Innovation Solution
A dynamic lift-off control device that includes a load detection unit and a control unit to manage the winch and boom hoisting using a control signal with a filter to dampen specific frequency components, allowing for quick lift-off while suppressing load swing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dynamic lift-off control uses winch and derricking actuators in combination, then load swing is suppressed, but dynamic lift-off time increases due to complicated control
Solution Approach 1:
The patent extracts and removes the derricking actuator from the control system, relying solely on the winch actuator to perform dynamic lift-off. This simplification eliminates the complexity of coordinating multiple actuators while maintaining load swing suppression through optimized winch control algorithms that calculate appropriate winding speeds based on boom length and load characteristics
Solution Approach 2:
The patent changes the control parameters by using load detection unit data (load weight, boom angle) to dynamically adjust the winch winding speed. The control unit calculates optimal winding speed profiles that account for the specific load and configuration, enabling single-actuator control to achieve the same stability效果 that previously required coordinated multi-actuator control
2Productivity
If dynamic lift-off control is simplified to reduce complexity, then operational speed increases, but load swing suppression may be compromised
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously receives data from the load detection unit regarding load weight and boom angle, and adjusts the winch winding speed in real-time based on this feedback. This closed-loop control ensures load swing suppression is maintained even with simplified single-actuator control, while the automated nature of the feedback loop maintains high operational speed
Solution Approach 2:
The control unit performs preliminary calculations of the optimal winding speed profile before initiating dynamic lift-off, based on pre-input or pre-detected parameters such as load weight and boom length. This preliminary action allows the system to execute the lift-off operation quickly without complex real-time adjustments, while still maintaining stability through the pre-planned control trajectory
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 device enables rapid and efficient dynamic lift-off of suspended loads with reduced load swing by utilizing a load detection unit and a control unit with a frequency-dampening filter, enhancing operational efficiency and safety.
Implementation Method 1
a filter for dampening a frequency component in a predetermined range is applied
Data Source
AI summary
A dynamic lift-off control device that is mounted on a crane including a boom and a winch for winding a wire rope and that controls dynamic lift-off of a suspended load, wherein: the dynamic lift-off control device comprises a load detection unit that detects a load acting on the boom, and a control unit that controls a winding action of the winch and a hoisting action of the boom; and the control unit controls the hoisting of the boom by using a control signal, which is generated on the basis of the change over time in the value detected by the load detection unit and to which a filter for attenuating a frequency component in a prescribed range, to suppress swaying of the suspended load is applied.