摘要
An output expression of a class of dual-input single-output fuzzy controllers using pseudo trapezoid shaped membership function is given. By structure analysis it is proved that this class of fuzzy controllers is the sum of a global two-dimensional multi-level relay and a local linear or nonlinear proportional-integral or proportional-differential controller. And the output of this class of fuzzy controllers is a continuous, non-decreasing function of its input variables. These and other meaningful results derived from structure analysis based on the output expressions can guide the design of fuzzy controllers.