Editing Setpoint (control system) (section)

{{short description|Target value for the process variable of a control system}} 
{{About|setpoints in control theory||Set point (disambiguation){{!}}Set point}}
[[File:Set-point control.png|thumb|300px|[[Block diagram]] of a [[Negative feedback|negative feedback system]] used to maintain a setpoint in the face of a disturbance using error-controlled regulation. Positive error means feedback is too small (controller calls for an increase), and negative error means feedback is too large (controller calls for a decrease).]]

In [[cybernetics]] and [[control theory]], a '''setpoint''' ('''SP''';<ref name= Bequette/> also '''set point''') is the desired or target value for an essential variable, or [[Process variable|process value]] (PV) of a [[control system]],<ref name=Achterbergh/> which may differ from the actual measured value of the variable.  Departure of such a variable from its setpoint is one basis for error-controlled regulation using [[negative feedback]] for automatic control.<ref name=Ashby/> A setpoint can be any physical quantity or parameter that a control system seeks to regulate, such as temperature, pressure, flow rate, position, speed, or any other measurable attribute.

In the context of [[Proportional–integral–derivative controller|PID controller]], the setpoint represents the reference or goal for the controlled process variable. It serves as the benchmark against which the actual [[process variable]] (PV) is continuously compared. The [[Proportional–integral–derivative controller|PID controller]] calculates an error signal by taking the difference between the setpoint and the current value of the [[process variable]]. Mathematically, this error is expressed as:
:<math>e(t) = SP - PV(t),</math>
where <math>e(t)</math> is the error at a given time <math>t</math>, <math>SP</math> is the setpoint, <math>PV(t)</math> is the [[process variable]] at time <math>t</math>.

The PID controller uses this error signal to determine how to adjust the control output to bring the [[process variable]] as close as possible to the setpoint while maintaining stability and minimizing [[Overshoot (signal)|overshoot]].