On the other hand, an effective sol

On the other hand, an effective solution that keeps the error state within the prescribed performance bounds is prescribed performance control (PPC) technology, which rst proposed by Bechlioulis and Rovithakis [18]. Subsequently, many scholars have theoretically studied PPC schemes for different nonlinear systems [19][28]. This method can be divided into two steps, the rst step is to transform the constrained tracking error dynamic system into an unconstrained equivalent transformation system; the second step is to prove that the transformation variable is bounded.