“…In Kaddissi, Kenne´, and Saad (2007), system parameters were identified based on the recursive least squares method and nonlinear backstepping approach was studied for a hydraulic servo system. Quantitative feedback control was used for a three axis hydraulic road simulator to reproduce the random input signal (Kim, Xuan, and Kim 2008). It illustrated a tracking performance of the closed-loop control system, but it need to know the system's transfer function.…”