Joe,
I envy your mechanical skills, facilities and execution. When I questioned the rotational speed, I didn't realize that the pinion was also worm drive. I hope it can stand up to the required braking torque. What size machine do you plan on using with this?
I'm certainly glad to see someone, besides myself, that recognizes the advantages of controlled yaw and are willing to pursue it. You will save a whole bunch of bucks over what I'm doing for my 16' machine with a commercial rotator, a Yaesu G-2800SDX, which has 180 Ft-Lb of rotational torque and 1800 Ft-Lb of braking torque. As you can see, braking torque is probably more significant.
I assume you're collaborating with Bill on the controller algorithm. I can see that a few modes need consideration.
Stow Mode:
The default mode. In no wind or high wind, yaw should turn the machine 90 deg. to the prevailing wind. When to come out of this mode should be based on wind speed that can produce usable power and yet, not be too high.
Operational Mode:
Yaw should track the average (perhaps, 5 min.) wind direction. This input could come from the site anemometer/wind vane or from a machine-mounted probe wind vane in front of the machine. I tend to favor a probe mounted vane to simplify the controller, since only a null-seeking controller for the relative wind direction is necessary.
Shut-down Mode:
When wind speed exceeds a predetermined value, the machine can be furled to 90 deg. This can be used in conjunction with variable pitch if available. Stow mode would then be activated.
I'm sure there are other satisfactory algorithms and I'd be interested in hearing about others you and/or Bill deem suitable.