  This paper addresses the problem of tracking control for an unknown nonlinear
system with time-varying bounded disturbance subjected to prescribed
Performance and Input Constraints (PIC). Since simultaneous prescription of PIC
involves a trade-off, we propose an analytical feasibility condition to
prescribe feasible PIC which also yields feasible initial state space as
corollary results. Additionally, an approximation-free controller is proposed
to guarantee that the tracking performance adheres to the prescribed PIC. The
effectiveness of the proposed approach is demonstrated through numerical
examples.
