Best performance and least fragile time-delayed controllers implemented on a 3-DOF helicopter

In this paper we propose two time-delayed controllers and perform experiments for the trajectory tracking problem of a 3-DOF helicopter. Due to the choice of their gains, one of them is called best performance controller since the closed-loop system tends to a desired reference as soon as possible and the other one is called least fragile controller since the controller gains are as far as possible from the boundary of the stability region. The results are compared with a PD controller tuned using linear quadratic regulation (LQR) techniques.