Fast Open Loop temperature control system
This process required fast risetime and steady control without feedback. I created an empirical model that was able to modify power profiles to produce the desired temperature profiles.
Batch CVD temperature control system
This batch processor needed to control temperature across a large physical space. I utilized five custom pyrometers to control temperature in seven power zones to enable process temperatures to remain constant within one degree C through the entire process space. This also included controlled startup to reduce thermal stresses to acceptable levels.
Single Wafer Temperature control system
Developed the PID algorithm for real time system running under the PDOS operating system. Did extensive testing and tuning, and added controlled ramping capability.
Disk Drive Spindle Motor Control
I wrote assembly language code for testing a wide variety of disk drive motors. Each drive motor has different characteristics and the tester needs to be configurable for each one. Due to the large volume, the tester needs to be small and inexpensive. The control system relies on back emf from the motor for its feedback. There was no other feedback path.
Wafer Indexer Motor Control
Deveveloped software for precisely positioning indexer to find wafers using a laser-based sensor. Developed tuning to make smooth starts & stops along with optimal speed and precision.