QFT LOOP SHAPING USING A FRACTIONAL INTEGRATOR - REAL-TIME APPLICATION TO A COUPLED-TANK SYSTEM

We propose to use a fractional order integrator (1/sa, a ε +) for simplifying the loop shaping in Quantitative Feedback Theory (QFT). The controller thus obtained is approximated to integer order in frequency domain by using Oustaloup's recursive approximation. The designed controller along with the prefilter is implemented realtime on a coupled-tank system and the experimental results are found to be satisfactory.