Substrate Transfer Robot Velocity Control for Misalignment Correction
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Solution Overview
Problem
Existing substrate transfer systems, such as those described in PTL 1, lack specific methods for modifying the wafer transfer path to correct positional misalignment, leading to potential inaccuracies in substrate placement and fluctuations in hand velocity.
Innovation Solution
A control device for a substrate transfer robot that modifies the target position of the hand based on positional misalignment information, employing first and second velocity controls to accurately place the substrate while minimizing hand velocity fluctuations. The first velocity control maintains a constant velocity as the hand approaches the target, and the second velocity control gradually decreases the hand's velocity to stop at the modified target position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the target position is modified to correct positional misalignment, then manufacturing precision is improved, but hand velocity fluctuation occurs
Solution Approach 1:
The patent applies dynamics by implementing two-stage velocity control that adapts to the modified target position. The first velocity control maintains constant velocity for a portion of the movement, while the second velocity control applies deceleration with a slope matching the original velocity profile. This dynamic adjustment of velocity parameters ensures the hand reaches the modified target position with minimal velocity fluctuation, resolving the contradiction between position correction accuracy and velocity stability.
Solution Approach 2:
The patent changes velocity parameters dynamically based on the modification amount. By calculating the modification amount and adjusting the velocity profile accordingly (constant velocity period followed by deceleration with matched slope), the system maintains hand velocity stability while achieving accurate substrate placement at the modified target position.
2Manufacturing precision
If the target position is modified based on positional misalignment, then substrate placement accuracy is improved, but transfer path deviation increases
Solution Approach 1:
The patent uses feedback from the positional misalignment detection to modify the target position. The modification amount is calculated based on the detected misalignment, and the velocity control parameters are adjusted accordingly. This feedback mechanism ensures the hand reaches the corrected target position accurately while maintaining velocity stability, balancing placement accuracy with transfer path predictability.
3Stability of the object's composition
If velocity control is adjusted to suppress hand velocity fluctuation, then operational stability is improved, but positioning time may increase
Solution Approach 1:
The patent implements dynamic velocity control with two stages: constant velocity maintenance followed by deceleration with a slope matching the original velocity profile. This dynamic approach allows the hand to travel efficiently at constant velocity for most of the distance, then decelerate smoothly at the appropriate point, minimizing positioning time while maintaining velocity stability and achieving accurate placement at the modified target position.
Data Source
AI summary
A control device controls a substrate transfer robot including a hand, a joint, and a joint motor. The control device modifies a target position of the hand when it places substrate at transfer destination, based on positional misalignment information indicating misalignment of substrate. To change a position at which the hand places the substrate to target position after modification, the control device performs first velocity control and second velocity control. In first velocity control, velocity of hand that is approaching target position before modification with the velocity decreasing is made constant by correcting. In second velocity control, velocity of hand decreases by slope equal to the slope of velocity of the hand immediately before first velocity control and hand is stopped at target position after modification. Time during which the first velocity control is performed increases as a magnitude of change in the target position due to the modification increases.