Practical tuning method for fractional order proportional and integral controllers

This thesis presents a new practical tuning method for fractional order proportional and integral controllers (FO-PI/PIalpha) for the first order plus delay time (FOPDT) class of systems. The tuning is optimal in the sense that the load disturbance rejection is optimized yet with a constraint on the maximum sensitivity. A generalized MIGO (Ms constrained Integral Gain Optimization), called the F-MIGO (Fractional-MIGO), has been developed for the FO-PI controllers. The F-MIGO method is then used to develop tuning rules for the FOPDT class of dynamic systems. The final developed tuning rules apply only the relative dead-time, tau, of the FOPDT model to determine the best fractional order (alpha) and at the same time to determine the best FO-PI gains (K, Ki). Experimental results in two lab platforms, Heat Flow Experiment and Rotary Flexible Joint, are reported using the tuning rules developed in this thesis. It has also been demonstrated that the tuning rule development procedure for FO-PI is not only valid for FOPDT systems but also applicable for other general classes of plants.