Industrial problems
Typical control chains

Although the closed loop is more expensive than the open loop (cost of sensor and transmitter, often higher design costs), it is generally the only solution that can guarantee the performance required to meet ever-increasing quality demands. The open loop, on the other hand, is blind because the controller, the "brain" of the system, is not informed of its actual state. A well-tuned loop implies :

• components adapted to the function to be performed;

• a good control algorithm: a poor choice will lead to disappointing results; for example, opening the heater by simply amplifying the error may lead to a temperature that is too low, obtained moreover after oscillations that take a long time to dampen.

We will examine these points in turn.