A model reference adaptive control (MRAC) with smooth switching scheme was proposed for piecewise linear systems

and the method was utilized in turbofan engine control to avoid the discontinuity of control input. In this scheme

each sub-region of the operating envelope had its own MRAC controller

and smooth indicator function based smooth switching scheme was introduced to switch multiple controllers smoothly at the boundary of adjacent sub-regions. The Lyapunov stability analysis indicated that the proposed smooth switching scheme can guarantee the convergence of the closed-loop system during the controllers switching. The tracking error system was converted into a switched system to analyze the global stability of the closed-loop system. The advantage of the method was that the chattering of system output and instability caused by asynchronous switching can be eliminated. The simulation illustrates the effectiveness of the proposed control scheme in comparison with the existing MRAC controller with gain scheduling for turbofan engine.