Stacker Crane Sway Detection and Transfer Control
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Solution Overview
Problem
Existing stacker crane control systems face inefficiencies due to theoretical estimation of swaying states, leading to delayed transfer operations and increased installation costs from requiring multiple sensors to detect swaying amounts along the entire lift height.
Innovation Solution
A stacker crane control system that includes a sway detection unit to detect a reference swaying amount at a specific height, a lifting height acquiring unit to monitor actual lifting heights, and a transfer control unit that converts the reference swaying amount into a lifting height swaying amount, allowing for transfer operations to start when the lifting height swaying amount is stable and within a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the waiting time is extended to ensure accurate transfer based on actual swaying conditions, then transfer reliability is improved, but operation efficiency deteriorates due to delayed transfer operations
Solution Approach 1:
The system continuously monitors the actual swaying amount of the mast using a sway detection unit and feeds this information back to the transfer control unit. This real-time feedback enables dynamic adjustment of the transfer timing, allowing operations to proceed as soon as swaying conditions are favorable, thus improving both reliability and efficiency without requiring extended waiting times
Solution Approach 2:
The patent replaces theoretical mechanical estimation of swaying with actual detection using sensors (optical sensors, accelerometers, or displacement sensors). This substitution provides accurate real-time data on mast swaying, enabling precise determination of optimal transfer moments without conservative delays
2Measurement precision
If multiple sensors are installed to detect swaying amounts along the entire lift height, then measurement precision is improved, but device complexity and installation cost increase
Solution Approach 1:
The patent extracts the swaying detection function to a single fixed position on the mast rather than distributing sensors throughout the lift height. By measuring swaying at one strategic location and using the detected parameters (swaying amount, frequency, amplitude) to represent the overall mast behavior, the system achieves sufficient measurement precision with minimal sensor deployment
Solution Approach 2:
A single sway detection unit performs multiple functions: detecting swaying amount, determining swaying frequency, and assessing overall mast stability. This multi-functional approach at one location replaces what would otherwise require multiple specialized sensors distributed throughout the system
3Device complexity
If theoretical parameters (lift weight, lifting height) are used to estimate swaying state, then device complexity is reduced, but measurement precision deteriorates causing inaccurate transfer timing
Solution Approach 1:
The patent replaces theoretical mechanical estimation based on lift parameters with actual physical measurement using sway detection sensors. The detected swaying parameters (actual swaying amount, frequency, amplitude) provide accurate real-time information about mast behavior, eliminating the inaccuracies inherent in theoretical models
Solution Approach 2:
Instead of relying on pre-calculated theoretical values, the system continuously measures actual mast swaying and feeds this information back to determine transfer timing. This feedback mechanism ensures that transfer decisions are based on real conditions rather than theoretical predictions, significantly improving accuracy
Data Source
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AI summary
A control system 1 includes: a sway detection unit 10 configured to detect a reference swaying amount X1 that is a swaying amount X of a mast 22 at a detection height H1, which is set to be greater than or equal to a height of a lowermost part 26a of a transfer apparatus 26 when a lift 24 is located at an upper limit of a lifting range E; a lifting height acquiring unit 14 configured to acquire lifting height information that indicates a lifting height H2, which is a height of the lift 24, at a plurality of points in time; and a transfer control unit 18 configured to control the transfer apparatus 26. The transfer control unit 18 converts the reference swaying amount X1 detected by the sway detection unit 10 into a lifting height swaying amount X2 that is a swaying amount of the mast 22 at the lifting height H2 indicated by the lifting height information, and starts a transfer operation of the transfer apparatus 26 if the lifting height swaying amount X2 is stably smaller than or equal to a predetermined determination threshold ΔX.