PID CONTROL

摘要

If you can't tell a PID feedback loop from spaghetti, don't worry: you are not alone. People are mystified by the full spelling of the acronym PID, which stands for proportional integral derivative. These terms are borrowed from calculus so it is little wonder that people are frightened at the thought of grappling with the complexities of feedback control. If you were to call a PID loop a compensator instead, nobody apart from the most pedantic academic could take issue with you. OK, some engineers can get quite technical and start talking about lead-lag compensation and suchlike, but the principle is the same. A PID controller examines signals from sensors placed in a process, called feedback signals. When a feedback signal is received, it is compared with the desired value, or set-value, and a calculation is made of what the necessary response is in order to make the feedback signal - also known as the 'error' signal because of its deviation from the set-value - match the set-value.