Fractional Order PID Controller Using Recursive Least Square Algorithm in MIMO Systems

In this paper a new Fractional order PID controller (FOPID) using RLS algorithm is proposed to obtain precise nonlinear control model. The parameters of the FOPID can identify using Recursive Least Square (RLS) algorithm. The RLS algorithm, on the contrary of its usual application as an identification method, is used in the proposed controller to update the PID gains forcing the system to behave like a desired reference model. Unlike other techniques, the proposed fractional order PID controller has the advantage that it does not impose restrictions on the system structure such as being stable, square, minimum phase, nor almost restrict positive real. Since stability is a vital issue in the evaluation of control systems, therefore stability analysis of the proposed approach can develop using Lyapunov stability theory.