“…Generalized saturation functions (GSFs) are used in control design, which are defined as follows. Definition A function σ : R → R is said to be a GSF with bound ,if it is locally Lipschitz, non‐decreasing, and satisfies the following: - P1: x σ ( x ) > 0, ∀ x ≠ 0.
- | σ ( x )|≤ , ∀ x ∈ R .A strictly increasing continuously differentiable GSF, σ ( x ), has the following three properties (as proven in Lemma 1 of ).
- P3:The derivative of σ with respect to its argument (i.e., ) is positive and bounded, that is, there exist a constant such that , ∀ x ∈ R .
- P4: σ ( x ) is globally Lipschitz, that is,
- P5:
It is easy to check that t a n h ( x ) and are two GSFs satisfying P1–P5 with .…”