Start with a concrete task: understand the signals, read a plot or compare two tunings. Each material includes a diagram, a short example and a next step in the lab.
After reading. You will be able to explain what the controller changes, what the plot shows and how to test a tuning.
Tell SP, PV and MV apart
Imagine a heater: you want 60 °C, but the sensor reads 55 °C. SP is the target temperature and PV is the measurement. Their difference, an error of 5 °C, tells the controller how far the process is from the target.
The controller changes MV: power in percent. The temperature then changes, the sensor measures again and the cycle repeats. The PID explanation shows how P, I and D contribute to that action.
Reading the loop: the target is 60 °C and the measurement is 55 °C. The controller changes power, not the measurement itself. Arrows show signal direction.
Read the plot after a setpoint change
In the sketch, SP steps from 40 to 60 °C. PV approaches the target gradually and first goes above it. That excursion is called overshoot.
MV reacts before the temperature. Read both plots: reaching SP quickly may require abrupt output movement. The simulation lesson helps you find these signals on an actual stand.
Illustrative curves, not a PIDLAB simulation result. Above: SP/PV temperature in °C. Below: MV power in %. Compare the timing of changes, not line heights on different scales.
Check whether a tuning improved
A testable question: will a smaller Ti reduce residual error without extra oscillation? First run A with the baseline tuning. Then restore the initial state, change only Ti and repeat the same SP step.
The result is a comparison of plots and conditions, not just a new set of coefficients. The tuning material explains how to assess overshoot, settling and output limits.
