Open-loop controller: Difference between revisions

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{{more footnotes|date=January 2015}}

In an '''open-loop controller''', also called a '''non-feedback controller''', the control action from the controller is independent of the "process output", which is the process variable that is being controlled.<ref name="auto">"Feedback and control systems" - JJ Di Steffano, AR Stubberud, IJ Williams. Schaums outline series, McGraw-Hill 1967</ref> It does not use [[feedback]] to determine if its output has achieved the desired goal of the input command or process "set point".

There are a large number of open loop controls, such as on/off switching of such as valves, machinery, lights, motors or heaters, where the control result is known to be approximately sufficient under normal conditions without the need for feedback. The advantage of using open loop control in these cases is the reduction in component count and complexity. However, an open-loop system cannot correct any errors that it makes or correct for outside disturbances, and cannot engage in [[machine learning]].

It does not use [[feedback]] to determine if its output has achieved the desired goal of the input or process "set point". An open-loop system cannot engage in [[machine learning]] and also cannot correct any errors that it could make. It will not compensate for disturbances in the process being controlled.

==Open-loop and closed-loop (feedback) control==