ENTRIES TAGGED "gain factor"
Exploring the PID controller
In the previous parts of this series (Part 1, Part 2, Part 3, and Part 4), we introduced feedback as a design principle or paradigm, that can help to keep systems “on track”, even in the presence of uncertainty and change. In this post, we will begin to explore more closely what this all means in practice.
Consider the feedback loop shown in the Figure. The controlled system is a cache, and we have a controller that adjusts the size of the cache in order to maintain a desired cache hit rate. (Making the cache larger will result in a greater number of hits and hence will drive the hit rate up.) We also have a desired value for the hit rate as reference value or “setpoint” (supplied on the left). The tracking error is calculated as the difference between setpoint and actual hit rate and is provided as input to the controller.