An extended nonlinear disturbance observer (ENDOB)-based fuzzy sliding mode control approach is proposed for single-input and single-output systems with matched and mismatched uncertainties/disturbances. and it is extended to the general $n$ th order systems. By integrating the mismatched disturbance estimation and its derivative into the sliding mode surface. an ENDOB-based SMC metho... https://allfixelectricales.shop/product-category/gas-safety-valve/