Saturday, February 02, 2013

PID Control

I think it was Banerjee who asked me to write something about engineering, so that the engineers could beat me up. Here is my first try. It stems from the class in Control of Mobile Robots that I am taking from Coursera and Georgia Tech.
One of the most common control strategies for simple systems is so-called PID control, where the P stands for proportional, the I for integrating, and the D for derivative. The essence of the strategy is that you measure an error in your system behavior, and generate a correction control signal that is proportional to the error, its integral over time, and its derivative.
My quasi-philosophical question is this: does the value of this strategy have anything to do with the fact that so many laws of physics take the form of second order differential equations?
UPDATE: Second question. Suppose we replaced the Fed's Open Market Committee with a PID control robot which attempted to maintain a 2% inflation rate. What do think would happen?