The robust stability of seesaw system with fuzzy logic control

A new design technique using a single fuzzy input variable instead of the design method of the switching line to reduce the control rules for a class of nonlinear systems is proposed. This technique only needs a single fuzzy input, and the deriving process is similar to the fuzzy sliding mode control (FSMC) principle, called the single-input quasi fuzzy sliding mode control (SQ-FSMC). First, choosing the Lyapunov function which is composed of the distance to the sliding surface, we shall provide a simple way to construct the control input to guarantee the asymptotic stability at the sliding phase even if the disturbance exists. Also, the advantage of the present approach is that the total number of rules is greatly reduced compared with that of two-dimensional FSMC. In addition, generations and tuning of control rules are more tractable. Other attractive feature of the approach includes the insensitivity to the uncertainties and disturbances. Furthermore, the approach is capable of dealing with the chattering problem inherent with the sliding mode control very well. Simulation results are presented to demonstrate these features of the present approach. Finally, a seesaw system subject to external disturbance and loading experimental results are given to show the effectiveness and feasibility of the approach.