louboutin pas cher How Do PID Controllers Work

Integral (Reset)
Tuning of PID Controller Terms
The P, I and D terms need [url=http://www.rtnagel.com/louboutin.php]louboutin pas cher[/url] to be "tuned" to suit the dynamics ofthe process [url=http://www.1855sacramento.com/moncler.php]moncler sito ufficiale[/url] being controlled. Any of the terms described abovecan cause the process to be unstable, or very slow to control,if not correctly set. These days temperature control usingdigital PID controllers have automatic auto-tune functions.During the auto-tune period the PID controller controls thepower to the process and measures the rate of change, overshootand [url=http://www.vivid-host.com/barbour.htm]barbour uk outlet[/url] response time of the plant. This is often based on theZeigler-Nichols method [url=http://www.sandvikfw.net/shopuk.php]hollister outlet sale[/url] of calculating controller term values.Once the auto-tune period is completed the P, I & D values arestored and used by the [url=http://www.rtnagel.com/airjordan.php]nike air jordan pas cher[/url] PID controller.
Example: Temperature Control using a Digital PIDcontroller
The following section examines PID controller theory andprovides further explanation of the question `how do PIDcontrollers [url=http://www.mansmanifesto.fr]doudoune moncler[/url] work'.
A PID (Proportional Integral Derivative) controller [url=http://www.ilyav.com/uggpascher.php]ugg pas cher[/url] is a commoninstrument used in industrial control applications. A can be used for regulation of speed, temperature, flow, pressureand other process variables. Field mounted PID controllers canbe placed close to the sensor or the control regulation deviceand be monitored centrally using a SCADA system.
Proportional (Gain)
PID Controller Theory
The error is acted upon by the three (P, I & D) termssimultaneously:
b>What is a PID controller?
A PID controller (sometimes called a three term controller)reads the sensor signal, normally from a thermocouple or RTD,and converts the measurement to engineering units e.g. DegreesC. It then subtracts the measurement from a desired setpoint todetermine an error.
The error is integrated (averaged) over a period of time, andthen multiplied by a constant I, and added to the currentcontrol output. I [url=http://www.mquin.com/giuseppezanotti.php]giuseppe zanotti pas cher[/url] represents the steady state error of thesystem and will remove setpoint / measured value errors. Formany applications Proportional + Integral control will besatisfactory with good stability and at the desired setpoint.
The error is multiplied by a negative (for reverse action)proportional constant P, and added to the current output. Prepresents the band over which a controller's output isproportional to [url=http://www.rtnagel.com/airjordan.php]jordan pas cher[/url] the error of the system. E.g. for a heater, acontroller with a proportional band of 10 deg C and a setpointof 100 deg C would have an output of 100% up to 90 deg C, 50% at95 Deg C and 10% at 99 deg C. If the temperature overshoots thesetpoint value, the heating power would be cut back further.Proportional only control can provide a stable processtemperature but there will always be an error between therequired setpoint and the [url=http://www.davidhabchy.com]barbour outlet[/url] actual [url=http://www.achbanker.com/home.php]hollister france[/url] process temperature.
A typical PID temperature controller application could be tocontinuously vary a regulator which can alter a processtemperature. This may be a pulsed switching device forelectrical heaters or [url=http://www.davidhabchy.com]barbour sale[/url] by opening and closing a gas valve. A heatonly PID temperature controller uses a reverse output action,i.e. more power is applied when the temperature is below thesetpoint and less power when above. PID control for injectionand extrusion applications often employ additional coolingcontrol outputs and usually require multiple controllers.
Derivative (Rate)
The rate of change of the error is calculated with respect totime, multiplied by another constant D, and added to the output.The derivative term is used to determine a controller's responseto a change or disturbance of the process temperature (e.g.opening an oven door). The larger the derivative term, the morerapidly the controller will respond to changes in the processvalue.
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