FRtool: A frequency response tool for CACSD in Matlab®

A control system can be designed either by applying a mathematical design method (the system theory approach) or by using a controller design tool (the CAD-approach). Graphical visually-interactive Computer Aided Design methods are nowadays quite attractive, especially for non-experts in control engineering. Matlab offers currently a controller design tool based on the root locus technique; time-delay systems have to be handled in a somewhat artificial way by approximating the dead-time with a rational transfer function. However time-delay systems can be tackled easily in the frequency-domain since the only influence of the dead-time is a shift in the phase. This paper thus presents a CAD-software based on the use of frequency charts as a controller design tool.