Combination of sliding mode controller and PI controller using fuzzy logic controller

This paper proposes an approach to combine a sliding mode controller (SMC) and a PI controller using a fuzzy logic controller. An SMC can give good transient performance. However, the steady state performance is poor due to the presence of discontinuous control which causes chattering. On the other hand, a PI controller can offer zero steady state error. Hence, combining these two controllers by a fuzzy logic controller can combine their advantages and remove their disadvantages. Although the PI sub-system has one order higher than the SMC subsystem, the closed-loop system stability under the control of this fuzzy logic controller can still be proved by applying a new proposed method. An illustrative example shows that good transient and steady state responses can be obtained by applying the proposed controller.