  We propose a control protocol based on the prescribed performance control
(PPC) methodology for a quadrotor unmanned aerial vehicle (UAV). Quadrotor
systems belong to the class of underactuated systems for which the original PPC
methodology cannot be directly applied. We introduce the necessary design
modifications to stabilize the considered system with prescribed performance.
The proposed control protocol does not use any information of dynamic model
parameters or exogenous disturbances. Furthermore, the stability analysis
guarantees that the tracking errors remain inside of designer-specified
time-varying functions, achieving prescribed performance independent from the
control gains' selection. Finally, simulation results verify the theoretical
results.
