PID Autotuning Design VI

Owning Palette: PID VIs

Requires: Full Development System

Implements autotuning using the tuning method associated with the polymorphic instance you select. This VI generates PID parameters based on the Stimulus signal and Response signal you specify. You can use this VI to generate initial parameters when you do not have sufficient information about the system you want to tune. You must manually select the polymorphic instance to use.

Example

Use the pull-down menu to select an instance of this VI.

Select an instance PID Autotuning Design (Auto)PID Autotuning Design (Ziegler-Nichols)PID Autotuning Design (Cohen-Coon)PID Autotuning Design (Chien-Hrones-Reswick)PID Autotuning Design (Internal Model Control)

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PID Autotuning Design (Auto)

Note  By default, this instance uses the Ziegler-Nichols tuning method. However, if your model does not have delay, Ziegler-Nichols tuning does not work. In this case, the VI automatically switches to internal model control to estimate the response.

	Ziegler-Nichols Speed specifies the desired response performance of the PID parameters. 0 Fast—(Default) Specifies a fast response performance. Faster response generally results in a smaller rise time. 1 Normal—Specifies a normal response performance. 2 Slow—Specifies a slow response performance. Slower response generally results in less overshoot.
	Type of Controller specifies which parameters to return as the PID gains. 0 P—(Default) Specifies to return only the proportional parameters. 1 PI—Specifies to return the proportional and integral parameters. 2 PID—Specifies to return the proportional, integral, and derivative parameters.
	Stimulus signal specifies an array that represents the stimulus signal.
	Response signal specifies an array that represents the response signal.
	closed-loop? specifies whether the system is a closed-loop system. If you set closed-loop? to TRUE, this VI estimates open-loop parameter values based on the closed-loop values it identifies from the input signals.
	dt (s) specifies the�interval, in seconds, at which this VI is called. If dt (s) is less than or equal to zero, this VI uses an internal timer with a one millisecond resolution. The default is 0.
	Controller Gain (K) specifies an initial value for the controller gain, which this VI uses to calculate the integral time (Ti, min) component of PID gains. The default is 0.
	stimulus operating point returns the calculated stimulus offset for the plant.
	response operating point returns the calculated response offset for the plant.
	PID gains returns the calculated PID gains values for the plant. proportional gain (Kc) returns the proportional gain of the controller. integral time (Ti, min) returns the integral time in minutes. derivative time (Td, min) returns the derivative time in minutes.
	Plant Parameters returns the calculated gain, time constant, and dead time of the plant. Plant Gain (K) returns the calculated process gain (K). Time Constant (T) returns the calculated time constant (T), in seconds. Dead Time (L) returns the calculated dead time (L), in seconds.

PID Autotuning Design (Ziegler-Nichols)

Note  This instance uses the Ziegler-Nichols tuning method.

	Ziegler-Nichols Speed specifies the desired response performance of the PID parameters. 0 Fast—(Default) Specifies a fast response performance. Faster response generally results in a smaller rise time. 1 Normal—Specifies a normal response performance. 2 Slow—Specifies a slow response performance. Slower response generally results in less overshoot.
	Type of Controller specifies which parameters to return as the PID gains. 0 P—(Default) Specifies to return only the proportional parameters. 1 PI—Specifies to return the proportional and integral parameters. 2 PID—Specifies to return the proportional, integral, and derivative parameters.
	Stimulus signal specifies an array that represents the stimulus signal.
	Response signal specifies an array that represents the response signal.
	closed-loop? specifies whether the system is a closed-loop system. If you set closed-loop? to TRUE, this VI estimates open-loop parameter values based on the closed-loop values it identifies from the input signals.
	dt (s) specifies the�interval, in seconds, at which this VI is called. If dt (s) is less than or equal to zero, this VI uses an internal timer with a one millisecond resolution. The default is 0.
	Controller Gain (K) specifies an initial value for the controller gain, which this VI uses to calculate the integral time (Ti, min) component of PID gains. The default is 0.
	stimulus operating point returns the calculated stimulus offset for the plant.
	response operating point returns the calculated response offset for the plant.
	PID gains returns the calculated PID gains values for the plant. proportional gain (Kc) returns the proportional gain of the controller. integral time (Ti, min) returns the integral time in minutes. derivative time (Td, min) returns the derivative time in minutes.
	Plant Parameters returns the calculated gain, time constant, and dead time of the plant. Plant Gain (K) returns the calculated process gain (K). Time Constant (T) returns the calculated time constant (T), in seconds. Dead Time (L) returns the calculated dead time (L), in seconds.

PID Autotuning Design (Cohen-Coon)

Note  This instance uses the Cohen-Coon tuning method.

	Type of Controller specifies which parameters to return as the PID gains. 0 P—(Default) Specifies to return only the proportional parameters. 1 PI—Specifies to return the proportional and integral parameters. 2 PID—Specifies to return the proportional, integral, and derivative parameters.
	Stimulus signal specifies an array that represents the stimulus signal.
	Response signal specifies an array that represents the response signal.
	closed-loop? specifies whether the system is a closed-loop system. If you set closed-loop? to TRUE, this VI estimates open-loop parameter values based on the closed-loop values it identifies from the input signals.
	dt (s) specifies the�interval, in seconds, at which this VI is called. If dt (s) is less than or equal to zero, this VI uses an internal timer with a one millisecond resolution. The default is 0.
	Controller Gain (K) specifies an initial value for the controller gain, which this VI uses to calculate the integral time (Ti, min) component of PID gains. The default is 0.
	stimulus offset returns the calculated stimulus offset for the plant.
	response offset returns the calculated response offset for the plant.
	PID gains returns the calculated PID gains values for the plant. proportional gain (Kc) returns the proportional gain of the controller. integral time (Ti, min) returns the integral time in minutes. derivative time (Td, min) returns the derivative time in minutes.
	Plant Parameters returns the calculated gain, time constant, and dead time of the plant. Plant Gain (K) returns the calculated process gain (K). Time Constant (T) returns the calculated time constant (T), in seconds. Dead Time (L) returns the calculated dead time (L), in seconds.

PID Autotuning Design (Chien-Hrones-Reswick)

Note  This instance uses the Chien-Hrones-Reswick tuning method.

	Tuning specifications specifies which formula to use to convert the model to PID parameters. This input provides formulas for 0% and 20% overshoot. 0 Regulator - 0% 1 Regulator - 20% 2 Servo - 0% 3 Servo - 20%
	Type of Controller specifies which parameters to return as the PID gains. 0 P—(Default) Specifies to return only the proportional parameters. 1 PI—Specifies to return the proportional and integral parameters. 2 PID—Specifies to return the proportional, integral, and derivative parameters.
	Stimulus signal specifies an array that represents the stimulus signal.
	Response signal specifies an array that represents the response signal.
	closed-loop? specifies whether the system is a closed-loop system. If you set closed-loop? to TRUE, this VI estimates open-loop parameter values based on the closed-loop values it identifies from the input signals.
	dt (s) specifies the�interval, in seconds, at which this VI is called. If dt (s) is less than or equal to zero, this VI uses an internal timer with a one millisecond resolution. The default is 0.
	Controller Gain (K) specifies an initial value for the controller gain, which this VI uses to calculate the integral time (Ti, min) component of PID gains. The default is 0.
	stimulus offset returns the calculated stimulus offset for the plant.
	response offset returns the calculated response offset for the plant.
	PID gains returns the calculated PID gains values for the plant. proportional gain (Kc) returns the proportional gain of the controller. integral time (Ti, min) returns the integral time in minutes. derivative time (Td, min) returns the derivative time in minutes.
	Plant Parameters returns the calculated gain, time constant, and dead time of the plant. Plant Gain (K) returns the calculated process gain (K). Time Constant (T) returns the calculated time constant (T), in seconds. Dead Time (L) returns the calculated dead time (L), in seconds.

PID Autotuning Design (Internal Model Control)

Note  This instances uses internal model control to estimate the response.

	Desired Time Constant (tau_c) specifies a time constant value at which you want the system to perform after you close the loop. This VI uses this value to adjust the PID gains according to the internal model control method and as appropriate for a first-order model with delay.
	Type of Controller specifies which parameters to return as the PID gains. 0 P—(Default) Specifies to return only the proportional parameters. 1 PI—Specifies to return the proportional and integral parameters. 2 PID—Specifies to return the proportional, integral, and derivative parameters.
	Stimulus signal specifies an array that represents the stimulus signal.
	Response signal specifies an array that represents the response signal.
	closed-loop? specifies whether the system is a closed-loop system. If you set closed-loop? to TRUE, this VI estimates open-loop parameter values based on the closed-loop values it identifies from the input signals.
	dt (s) specifies the�interval, in seconds, at which this VI is called. If dt (s) is less than or equal to zero, this VI uses an internal timer with a one millisecond resolution. The default is 0.
	Controller Gain (K) specifies an initial value for the controller gain, which this VI uses to calculate the integral time (Ti, min) component of PID gains. The default is 0.
	stimulus offset returns the calculated stimulus offset for the plant.
	response offset returns the calculated response offset for the plant.
	PID gains returns the calculated PID gains values for the plant. proportional gain (Kc) returns the proportional gain of the controller. integral time (Ti, min) returns the integral time in minutes. derivative time (Td, min) returns the derivative time in minutes.
	Plant Parameters returns the calculated gain, time constant, and dead time of the plant. Plant Gain (K) returns the calculated process gain (K). Time Constant (T) returns the calculated time constant (T), in seconds. Dead Time (L) returns the calculated dead time (L), in seconds.

Example

Refer to the Autotuning PID Offline VI in the labview\examples\control\PID directory for an example of using the PID Autotuning Design VI.

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