Tower Crane Autorotation Detection via Angular Monitoring
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Solution Overview
Problem
Tower cranes can enter unstable states during strong winds, leading to autorotation or oscillation, which can cause damage or collapse, and existing technologies lack real-time detection and preventive measures to address these instabilities.
Innovation Solution
A tower crane with a control/command unit connected to a motorized slewing system, mechanical slewing brake, and angular detector that activates a monitoring mode to detect autorotation or oscillation states based on orientation angle and speed thresholds, recording instability events and triggering alerts or corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mechanical slewing brake is deactivated to allow the rotating part to slew freely in the direction of the wind (out-of-service configuration), then the crane can be left without human supervision and oriented automatically, but the rotating part may enter unstable states such as autorotation or oscillation at high angular speeds
Solution Approach 1:
The control/command unit continuously receives angular position data from the angular detector and monitors the rotational behavior of the rotating part. When autorotation or oscillation patterns are detected through analysis of angular velocity variations, the system automatically activates the mechanical slewing brake to stop the unstable rotation, providing closed-loop feedback control for safety
Solution Approach 2:
The angular detector serves as an intermediary device that bridges the gap between the freely rotating rotating part and the control/command unit. It provides real-time angular position measurements that enable the control system to detect instability patterns without physically interfering with the free rotation, allowing monitoring while maintaining operational freedom
2Extent of automation
If the rotating part is released to rotate freely in strong winds, then the crane can operate autonomously, but damage or partial collapse may occur due to autorotation or oscillation states
Solution Approach 1:
The system implements automated feedback control by continuously monitoring angular position data from the angular detector and automatically activating the mechanical sleving brake when autorotation or oscillation is detected, enabling autonomous operation while protecting against wind-induced instability without human intervention
Solution Approach 2:
The control/command unit performs self-monitoring and self-protection functions by analyzing its own operational data from the angular detector and autonomously deciding when to activate the brake, making the system self-sufficient in detecting and preventing instability states during autonomous operation
3Device complexity
If traditional tower crane systems are used without real-time monitoring, then the device complexity is lower, but the ability to detect and prevent instability states is insufficient
Solution Approach 1:
The control/command unit is designed to perform multiple functions: it controls the motorized slewing system, monitors the mechanical brake status, processes angular position data from the angular detector, detects autorotation and oscillation patterns, and activates safety measures. This multi-functional approach integrates monitoring and control capabilities into an existing system component rather than adding separate dedicated systems
Solution Approach 2:
The system replaces complex mechanical monitoring mechanisms with electronic sensing and digital signal processing. The angular detector provides electronic angular position measurements that are processed by the control/command unit using algorithms to detect instability patterns, substituting mechanical gauges or physical indicators with electronic detection and computational analysis
Data Source
Figure 1~2
Figure 3~4
AI summary
Tower crane (1) comprising a tower (2) on which a rotating part (3) is pivotally mounted and configurable between a service configuration in which the rotating part is steerable in rotation by means of a motorized slewing system (40), and an out-of-service configuration in which the rotating part is free to rotate in order to orient itself in the direction of the wind, wherein a control/command unit (5) activates a monitoring mode in the out-of-service configuration to detect, based on variations in the angle of orientation or the angular velocity of the rotating part, whether the rotating part is in one of the following states of instability: - a state of autorotation corresponding to a rotary movement of the rotating part in a given direction over at least one complete revolution; or - a state of oscillation corresponding to a back-and-forth movement of the rotating part around the slewing axis.