System with PI-controller:

Closed loop control systems Examples


This example shows how to examine the sensitivity of a closed-loop control system to time delays within the system.

Time delays are rarely known accurately, so it is often important to understand how sensitive a control system is to the delay value. Such sensitivity analysis is easily performed using LTI arrays and the InternalDelay property. For example, consider the notched PI control system developed in "PI Control Loop with Dead Time" from the example "Analyzing Control Systems with Delays." The following commands create an LTI model of that closed-loop system, a third-order plant with an input delay, a PI controller and a notch filter.

s = tf('s'); G = exp(-2.6*s)*(s+3)/(s^2+0.3*s+1); C = 0.06 * (1 + 1/s); T = feedback(ss(G*C), 1); notch = tf([1 0.2 1], [1 .8 1]); C = 0.05 * (1 + 1/s); Tnotch = feedback(ss(G*C*notch), 1);

Examine the internal delay of the closed-loop system Tnotch.

The 2.6-second input delay of the plant G becomes an internal delay of 2.6 s in the closed-loop system. To examine the sensitivity of the responses of Tnotch to variations in this delay, create an array of copies of Tnotch. Then, vary the internal delay across the array.

Tsens = repsys(Tnotch, [1 1 5]); tau = linspace(2, 3, 5); for j = 1:5; Tsens(:, :, j).InternalDelay = tau(j); end

The array Tsens contains five models with internal delays that range from 2.0 to 3.0.

Examine the step responses of these models.

The plot shows that uncertainty on the delay value has a small effect on closed-loop characteristics.



Share this article





Related Posts


Open loop control systems
Open loop control systems
Closed loop controller
Closed loop controller

Latest Posts
Control Systems Management
Control Systems…
The global economy has caused managers…
Applications of Control Systems Engineering
Applications…
Feedback control systems are widely used…
Closed loop function
Closed loop function
Analyze responses of a control system…
Access Control System definition
Access Control…
For example, a key card may act as an…
Programmable Automation
Programmable…
Programmable Automation Controller or…
Search
Featured posts
  • Examples of open loop control systems
  • Open loop control systems
  • Closed loop controller
  • Types of closed loop control system
  • What is closed loop control?
  • Closed loop control system project
  • Closed loop control
  • Closed loop control system definition
  • Closed loop control systems
Copyright © 2018 l www.oliver-control.com. All rights reserved.