An Experimental Study on Model Reference Adaptive Control of TRMS by Error-Modified Fractional Order MIT Rule

Model Reference Adaptive Control (MRAC) strategies find application in flight control because of changes in dynamics of flight conditions. This paper demonstrates an application of Fractional Order Adjustment Rule MRAC (FOAR-MRAC) with the modification of model error dead zone for adaptive control of Twin Rotor Multi-input multi-output System (TRMS). Here, we implement FOAR-MRAC structure with feedforward and feedback MIT rules by using a fractional order integrator. Previously, Vinage et al. have reported that MIT with fractional order integrator can improve tracking performance of MRAC. In the current experimental study, we modified model approximation error by using a piecewise linear, near-zero dead zone function and manage stability of adaptation process in practical application. Accordingly, when the control system response approximates to response of reference model, adaptation process is interrupted. This modification improves quasi-stabilization of updating rule by omitting low level errors and contributes to applicability of MRAC in real applications. An adaptive PID rotor control system is developed by integating the proposed FOAR-MRAC structure. Simulation and experimental results, obtained for TRMS setup, are presented to show effectiveness of the proposed method.