This script demonstrates optimal tuning of a cascade PI control system. SYSTUNE is used to select gains for two controllers in a DC drive: the inner PI current controller and the outer PI speed controller. The submissions serves educational purposes. Please be aware that there is plenty of similar (if not identical in their design) examples out there, e.g. http://blogs.mathworks.com/seth/2014/04/03/control-system-tuning-without-guess-or-stress/ or http://www.mathworks.com/help/robust/examples/control-of-a-linear-electric-actuator.html .