Crystal Pulling Speed Deviation Correction via Recursive Filtering

The patent implements a feedback control system that continuously monitors the actual crystal pulling speed using an encoder and compares it to the nominal speed. A recursive algorithm with kinematic model filter processes the position data to detect speed deviations, and a fading average tracking filter with harmonic components corrects periodic errors. The control unit adjusts motor commands in real-time to compensate for worm gear-induced speed variations, maintaining pulling speed accuracy despite mechanical imperfections.

The patent replaces the reliance on high-precision mechanical worm gear components with a software-based solution. Instead of using expensive, high-quality gear components to achieve speed stability, the system uses a control unit with recursive algorithms and filtering methods to detect and correct speed deviations. This substitutes mechanical precision requirements with computational processing, reducing hardware costs and system complexity while maintaining or improving speed accuracy.

The patent introduces an intermediary computational layer between the motor control and the crystal pulling process. The recursive algorithm with kinematic model filter acts as a mediator that processes encoder position data and generates corrected motor commands. This intermediary system specifically addresses mechanical gear wear and quality issues by detecting periodic speed deviations and compensating for them through software, filling the gap left by conventional calibration methods that only address servo electronics drift.