SPIT System Plotting Interactive Tool

GUI to make Bode, Nyquist, and Nichols plots from Simulink models.

Choose a frequency range (in log units, so 4 means 10,000 Hz) and click the Bode button to plot the frequency response between Inports and Outports. Use the Results are in Hz, and the unity gain frequency is marked.

The attached image shows a control system with a plant (s^-2, such as a spring) and a controller (a lead compensator). Set the TF to show < output 3 / output 2 > and see that the open-loop transfer function has phase -101° at the unity gain frequency, and hence will be stable.

Jay Heefner and Torrey Lyons wrote earlier versions of SPIT. Jay and Torrey claimed no intellectual property rights, and I didn't develop it at work, so go ahead and use it however you want. Thanks, Jay & Torrey!