PID

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PID

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PID

(1) (Process IDentifier) A temporary number assigned by the operating system to a process or service.

(2) (Proportional-Integral-Derivative) The most common control methodology in process control. It is a continuous feedback loop that keeps the process flowing normally by taking corrective action whenever there is any deviation from the desired value ("setpoint") of the process variable (rate of flow, temperature, voltage, etc.). An "error" occurs when an operator manually changes the setpoint or when an event (valve opened, closed, etc.) or a disturbance changes the load, thus causing a change in the process variable.

The PID controller receives signals from sensors and computes corrective action to the actuators from a computation based on the error (proportional), the sum of all previous errors (integral) and the rate of change of the error (derivative). See PAC.


Inputs from a PID
The large white boxes are Opto 22 SNAP PACs, which are programmable automation controllers that are processing the PID loops in Chevron's research facility in Richmond, Virginia. The wires come from thermocouples that sense pipe temperature in a laboratory test that analyzes the best way to break down crude oil. The PACs determine when to raise and lower the temperature, and the three modules with the black sockets send digital signals to the heaters (cables not connected in this image). (Image courtesy of Opto 22, www.opto22.com)
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References in periodicals archive ?
Also, the satisfactory performance of the developed PSO-based Fuzzy gain scheduling PID controller was addressed above.
The lower layer is a simple PID controller. The addition operator combines the initial value with the output-4[K.sub.P], [DELTA][K.sub.I] and [DELTA][K.sub.D] of the fuzzy controller.
When the track reference is a step signal with magnitude 1 [degrees] which lasts for 10 s, the ADRC controller has a good dynamic performance compared to the conventional PID controller. As shown in this figure, compared to the conventional PID controller, the ADRC controller has nearly no any overshoot and can more easily reach stabilization state with much shorter adjusting time.
The controller is mainly composed of three parts, such as the PID controller, backstepping controller, and runaway protection module for controlling the attitude and position of the unmanned aerial vehicle so that the UAV can reach the desired state from the initial state.
In order to associate with the PID controller, we will call this "the tuning step", because we find the controller's parameters that guarantee positive invariance and [lambda]-contractivity.
The SMC controller uses a PID controller as the sliding surface and it was implemented successfully into the Arduino Board.
* continuous PID controller and a pulse-width modulator;
The Simulink model of the conventional PID controller as shown in Figure 10 is used in both the position and current controllers, but their gain values [K.sub.p], [K.sub.i] and [K.sub.d] differ according to the position and current magnitude of the working ranges.
The hot water inlet temperature (60oC) is maintained with [+ or -] 0.50C variation using an in built digital PID controller. The cold water is supplied at the room temperature.
For a typical PID controller, the controller output signal u(t) can be written as the following in time and s domain [18]:
In the current work, the Fractional Order PID controller is designed as follows: