Coating Head MPC Control for Undulating Substrate Tracking
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Solution Overview
Problem
Existing coating methods fail to accurately follow the shape of substrates with large undulations or high moving speeds due to differences in control response delays between mechanisms, leading to inaccuracies in surface coating.
Innovation Solution
A control system incorporating a measurement sensor integrated with the coating head, multiple drive devices, and a control device that uses model predictive control to adjust positions based on real-time measurements, ensuring accurate tracking of substrate shapes by generating operation amounts for each drive device to maintain a constant distance and follow target trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two mechanisms are linked to operate together for moving the coating head in parallel direction and up-down direction, then the coating head can follow the substrate shape, but control response delay differences between the two mechanisms cause inaccurate following
Solution Approach 1:
The control system is divided into two independent model predictive control parts: a first control part for the parallel movement mechanism and a second control part for the up-down movement mechanism. Each control part independently calculates control commands based on its own dynamic characteristics, avoiding the response delay issues caused by linked control while achieving coordinated operation for accurate substrate shape following.
2Productivity
If the substrate moves at high speed or has large undulations, then productivity increases, but the control object becomes unable to accurately follow the surface shape
Solution Approach 1:
The model predictive control calculates future position commands in advance based on the substrate shape data and dynamic characteristics. By predicting and preparing control commands for upcoming positions, the system can respond quickly to high-speed movements and large undulations without sacrificing accuracy, as the control actions are pre-computed considering the system's dynamic limitations.
3Loss of time
If the measurement sensor is positioned to measure ahead of the processing point, then the system can anticipate surface variations, but the measurement point must be separated by a predetermined distance along the target trajectory
Solution Approach 1:
The measurement sensor acts as an intermediary that measures the substrate shape at a position separated by a predetermined distance along the target trajectory from the processing point. This advance measurement provides the control system with information about upcoming surface variations, allowing the model predictive control to calculate appropriate control commands in advance and maintain accurate following during high-speed operation.
Data Source
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AI summary
A measurement sensor is integrated with a control object so that a position separated from a process object by the control object along a target trajectory is a measurement point. A control device includes: a first generation unit that generates a first command position on a flat surface of the control object; a first control unit that generates a first operation amount using a model prediction control; a second generation unit that generates a second command position on a perpendicular axis that is perpendicular to the flat surface of the control object; and a second control unit that generates a second operation amount using the model prediction control. The second generation unit generates the second command position so that the distance between the control object and the surface of a physical object is constant, based on the measurement result of the measurement sensor and the first command position. The control object thereby follows the shape of the surface of the physical object with good precision.