Using Memoryless Output Feedback to Semiglobally Stabilize a Class of SISO Nonlinear Systems With Input Delay

Using the semiglobal control idea from the recent work (Wang and Lin, 2022), we present a different semiglobal method without invoking the dynamic extension technique to prove that in the single-input-single-output (SISO) case, certain nonaffine systems with input delay are semiglobally asymptotically stabilizable (SGAS) via
$n$
-dimensional memoryless output feedback. A dynamic output compensator is constructed and composed of an
$n$
-dimensional nonlinear observer and an observer-based controller, both of them with saturated states. As a consequence, an affine system in a lower triangular form with input delay is shown to be SGAS by
$n$
-dimensional memoryless output feedback. These results provide some answers to the open question in (Wang and Lin, 2022) where
$(2n-1)$
-dimensional output feedback controllers were found by a dynamic extension method: when and how to design delay-free,
$n$
-dimensional SGAS output feedback controllers for a significant class of SISO nonaffine systems?