Smith Predictor Controller

R2026b

Discrete-time Smith dead-time compensator

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  • Smith Predictor Controller block

Libraries:
Simscape / Electrical / Control / General Control

Description

The Smith Predictor Controller block compensates for dead time by implementing a Smith dead-time PI control structure in discrete time. This diagram shows the equivalent circuit for the block.

Equations

The transfer function for a system with dead-time is

Gf(s)=Gp(s)e−τs,

where:

  • τ is the system dead time.

  • Gp(s) is the process model.

  • Gf(s) is prediction error filter.

Examples

DC Motor Control (Smith Predictor)

DC Motor Control (Smith Predictor)

A Smith Predictor speed-control structure for a DC motor. A PWM controlled four-quadrant Chopper is used to feed the DC motor. The Control subsystem includes the Smith predictor controller, and the PWM generation. A sensor measures the rotor speed with a delay of 5ms. The total simulation time (t) is 4 seconds. At t = 1.5 seconds, the load torque increases. At t = 2.5 seconds, the reference speed is changed from 1000 rpm to 2000 rpm.

Ports

Input

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Plant system reference signal.

Data Types: single | double

External reset signal (rising edge) for the integrator.

Data Types: Boolean

Plant system output signal.

Data Types: single | double

Output

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Control system output signal.

Data Types: single | double

Parameters

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Proportional gain, Kp, of the PI controller.

Integral gain, Ki, of the PI controller.

Value of the integrator at simulation start time.

Upper limit for the control output signal.

Lower limit for the control output signal.

Numerator of the system discretized transfer function. To determine the discrete transfer function, if you have a license for Control System Toolbox™, use the c2d function.

Denominator of the system discretized transfer function. To determine the discrete transfer function, if you have a license for Control System Toolbox, use the c2d function.

Number of samples of the dead time.

Time interval between samples. If the block is inside a triggered subsystem, inherit the sample time by setting this parameter to -1. If this block is in a continuous variable-step model, specify the sample time explicitly. For more information, see What Is Sample Time? and Specify Sample Time.

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"ee_sl_lib/General Control/Smith Predictor Controller"

Example: add_block("ee_sl_lib/General Control/Smith Predictor Controller","myModel/myBlock",MakeNameUnique="on")

References

[1] Velagic. J. "Design of Smith-like Predictive Controller with Communication with Communication Delay Adaptation."International Journal of Electrical, Computer, Energetic, Electronic and Communication Engineering. Vol 2, Number 11, 2008, pp. 2447-2481.

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2017b

See Also

Blocks