The PID Algorithm
There is no single PID algorithm. Different fields using feedback control have probably used different algorithms ever since math was introduced to feedback control. This page is written for people in the process industries, for that is the only field in which I have experience. Even in that single field, which has been served by companies such as ABB (formerly Taylor), Bailey, Fisher, Foxboro, Honeywell, Moore Products, Yokogawa and others there is no standard algorithm. Perhaps years ago there was (or for most practical purposes was), but today there are many algorithms. Also there is no standard terminology. For the person interested in tuning controllers for the process industries it has become a bit more complicated, because the rules and procedures you would use to tune with one algorithm are not the ones you would use to tune with another. Also, with the added features available with computers, some of the configurations can become quite complex. This page does not begin to address those, but you certainly need to understand what your basic building block is.
