Nonlinear Control Design Blockset

Nonlinear Control Design Blockset Startup

The Simulink system ncdtut1 contains the system shown above. You can open the system by typing ncdtut1 at the MATLAB prompt. The system was created just as any other Simulink system; you need not remodel any of your present Simulink systems to use the Nonlinear Control Design Blockset. You need simply to:

• Attach an NCD block to all signals you want to constrain. In ncdtut1, we attach an NCD block (square block with a step response display) to the plant output.
• Add input signals to the system for which you know what the output should look like. In ncdtut1, we input a step to the system since we know the desired step response characteristics of the system.
• Adjust the simulation Start time and Stop time appropriately. In ncdtut1, the step response should settle within 30 seconds, so making the simulation run to 50 seconds allows the step to go to completion. Since the Nonlinear Control Design Blockset optimization calls for many simulations of the system, you should make the simulation time as short as possible, but long enough to show dynamics of interest. You can change the Start time and Stop time through the Simulink Simulation parameters dialog created by selecting Parameters... from the Simulation menu.

Before continuing, MATLAB variables in the Simulink model must be initialized. At the MATLAB prompt, type

• zeta = 1;
  w0 = 1;
  Kint = 0.3;
  

We choose the initial value for Kint after plotting step responses of the linearized system for a few values of Kint.

A Control Design Example

Adjusting Constraints