Figure 1 illustrates the block diagram of a linear servo PID control system. And as mentioned at the beginning of the article, PID stands for Proportional, Integral, and Derivative. These refer to ...

Citations: Lariviere, Martin, G Cachon. 1999. An Equilibrium Analysis of Linear, Proportional and Uniform Allocation of Scarce Capacity. IIE Transactions. (9)835-849.

The valves are termed proportional because output flow is not exactly linear in relation to input current. Despite their nonlinear response, the valves are an inexpensive way to control position ...