  In this paper, a robust adaptive backstepping-based controller is developed
for positioning the spool valve of Electro-Hydraulic Servo System (EHSS) with
parameter fluctuations. Artificial Bee Colony (ABC) algorithm is utilized to
drive the parameters of the proposed controller to a good neighbourhood of the
solution space. The optimization problem is formulated such that both the
tracking error and control signal are minimized concurrently. The results show
that the proposed controller guarantees the uniform ultimate boundedness of the
tracking error and control signal. Moreover, illustrative simulations validate
the potentials and robustness of the proposed schemes in the presence of
uncertainties. The proposed controller is also compared with sliding mode
control.
