A control signal is a controller-generated input that drives an actuator or process to influence system behavior. In closed-loop control, the controller compares a desired state with feedback and produces a signal that reduces the difference. section 8.7
A PID controller shapes the signal through three complementary responses:
- Proportional action responds to the current error and tends to reduce rise time and steady-state error. section 8.7
- Integral action responds to error magnitude and duration, reducing steady-state error but potentially increasing overshoot and settling time. section 8.7
- Derivative action responds to the rate of error change, providing anticipatory control that can reduce overshoot and settling time. section 8.7
Room-temperature control
A thermostat compares the desired room temperature with the measured temperature. The resulting control signal turns a heater or air conditioner on or off, guiding the system toward the target while balancing rise time, overshoot, settling time, and steady-state error. section 8.7
