Winding Drum Rotation Control for Precise Overhead Lift Stages
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Solution Overview
Problem
Existing overhead transport vehicles face challenges in accurately lifting or lowering a lift stage to a desired height due to individual differences in suspension member thickness, leading to potential deviations from the intended position.
Innovation Solution
The solution involves calculating individual values for the entire length of the suspension, diameter of the winding drum, and thickness of the suspension, and using these values to determine the rotation amount of the winding drum, approximated by a square function, to ensure precise lifting or lowering of the lift stage, even with individual differences in the overhead transport vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotation amount of the winding drum is determined using only the thickness of the suspension member, then the control process is simple, but the lifting/lowering accuracy deviates due to individual differences in suspension member thickness
Solution Approach 1:
The patent changes the parameters used for control calculation from only suspension member thickness to include entire length of suspension, diameter of winding drum, and thickness of suspension. By measuring these parameters at the actual installation position and using them in the rotation amount calculation, the system adapts to individual differences in each vehicle configuration, thereby improving lifting/lowering accuracy while maintaining control process simplicity through automated measurement and calculation.
2Manufacturing precision
If individual values for entire length of suspension, diameter of winding drum, and thickness of suspension are calculated and used, then lifting/lowering accuracy is improved, but the control process becomes more complex
Solution Approach 1:
The system performs self-measurement of the suspension members and winding drum parameters using sensors and measurement mechanisms integrated into the overhead transport vehicle. By automatically acquiring the entire length, diameter, and thickness values during installation or operation, and autonomously calculating the rotation amount based on these measured values, the system eliminates the need for manual measurement and complex external calibration processes, thereby improving accuracy without significantly increasing operational complexity.
Data Source
AI summary
An overhead transport vehicle includes a lift stage to transfer an article, a winding drum to overlap and wind a suspension attached to the lift stage, and a controller to control a rotation amount of the winding drum to control a lifting/lowering amount of the lift stage. The controller is configured or programmed to execute a first processing including calculating, as individual values of the overhead transport vehicle, an individual value of an entire length of the suspension, an individual value of a diameter of the winding drum, and an individual value of a thickness of the suspension, and a second processing including calculating a rotation amount of the winding drum with respect to a lifting/lowering amount of the lift stage.