- Properties of IMC
- IMC Designs for No Disturbance Lag
- Design for Processes with No Zeros Near the Imaginary Axis or in the Right Half of the s-Plane
- Design for Processes with Zeros Near the Imaginary Axis
- Design for Processes with Right Half Plane Zeros
- Problems with Mathematically Optimal Controllers
- Modifying the Process to Improve Control System Performance
- Software Tools for IMC Design
3.9 Software Tools for IMC Design
An important aid in the design of IMC controllers is the ability to display the time response of the loop transmission pq as in Figures 3.5 to 3.8. This can be done quite conveniently using Program CC, MATLAB with SIMULINK or Vissim, or similar types of software. We provide a MATLAB version 5.3.1 (or later) suite of m-files IMCTUNE.m on the web site for this text11 that allows the user to enter the process model and the portion of the model pm(s), inverted by the IMC controller in a convenient form. The program yields the output time response as one of its options under the Results and Simulations menu. IMCTUNE is also capable of producing PID controllers and of tuning the IMC controller to accommodate process uncertainty as described in Chapters 6 and 7. IMCTUNE requires the Optimization and Control System toolboxes in order to be used with MATLAB and SIMULINK.
To simplify the IMC design task, it is often convenient to convert a transfer function into time constant form wherein the numerator and denominator are factored into products of the form (± τs + 1), (τ2 s2 ± 2τζs + 1). This can be done in Program CC simply by the command tcf,g, where g is the transfer function that is desired in time constant form. MATLAB m-files, tcf.m and tfn.m, provided with the IMCTUNE software, provide the same functionality. Information on how to use tcf.m and tfn.m can be obtained by typing help, followed by the function name (e.g., help tcf).