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A block diagram of a PID controller in a feedback loop. r(t) is the desired process variable (PV) or setpoint (SP), and y(t) is the measured PV. The distinguishing feature of the PID controller is the ability to use the three control terms of proportional, integral and derivative influence on the controller output to apply accurate and optimal ...
Nicolas Minorsky (born Nikolai Fyodorovich Minorsky, Russian: Николай Федорович Минорский; 23 September [O.S. 11 September] 1885 – 31 July 1970) was a Russian American control theory mathematician, engineer [1] and applied scientist.
The Ziegler–Nichols tuning (represented by the 'Classic PID' equations in the table above) creates a "quarter wave decay". This is an acceptable result for some purposes, but not optimal for all applications. This tuning rule is meant to give PID loops best disturbance rejection. [2]
Classical control theory uses the Laplace transform to model the systems and signals. The Laplace transform is a frequency-domain approach for continuous time signals irrespective of whether the system is stable or unstable.
PID controller (proportional-integral-derivative controller), a control concept used in automation; Piping and instrumentation diagram (P&ID), a diagram in the process industry which shows the piping of the process flow etc. Principal ideal domain, an algebraic structure; Process identifier, a number used by many operating systems to identify a ...
Process control instrumentation and designation (names, numbers, unique tag identifiers), including: Valves and their types and identifications (e.g. isolation, shutoff, relief and safety valves, valve interlocks) Control inputs and outputs (sensors and final elements, interlocks)
A typical application is a PID controller fed by a flow meter and using a control valve as the final control element. The DCS sends the setpoint required by the process to the controller which instructs a valve to operate so that the process reaches and stays at the desired setpoint. (see 4–20 mA schematic for example).
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 PID controller, the setpoint represents the reference or goal