SetPoint

A setpoint, in control theory, is the desired value or trajectory for a process variable that a feedback control system aims to achieve. It serves as the reference input to the controller, and the units of the setpoint match those of the process variable being controlled.

In a closed-loop system, the measured process variable (PV) is compared with the setpoint (SP), and the difference, or error, drives the controller to generate a manipulated variable (MV) that adjusts the process toward the setpoint. The setpoint can be fixed for steady operation or time-varying for dynamic operation.

Setpoints can be simple fixed values or more complex time profiles. They may be stepped to a new level, ramped gradually, or scheduled to change with operating mode, time of day, or external conditions. Advanced control schemes may modify setpoints indirectly through feedforward actions, adaptive strategies, or multi-variable control.

Changing a setpoint produces a transient response as the system works to reduce error. The quality of tracking depends on controller tuning, system dynamics, disturbances, and any physical limits of the process. If the system cannot reach the setpoint due to constraints or saturation, steady-state error or performance degradation may result.

Common applications span many domains, including temperature and process control, HVAC, chemical processing, robotics, and automotive systems. The concept of a setpoint is central to designing and operating controllers that maintain or reach desired operating conditions.