  Dynamic surface control (DSC) method uses high gain filters to avoid the
"explosion of complexity" issue inherent in backstepping based controller
designs. As a result, the closed loop system and filter dynamics possess time
scale separation between them. This paper attempts to design a novel
disturbance observer based dynamic surface controller using contraction
framework. In doing so the steady state error bounds are obtained in terms of
design parameters which are exploited to tune the closed loop system
performance. The results not only show that DSC technique recover the
performance of a backstepping controller for a small range of filter parameter
but also derive the maximum bound for it. Furthermore the stability bounds are
also derived in the presence of disturbances and convergence of trajectories to
a small penultimate bound is proved. The convergence results are shown to hold
for less conservative choice of filter parameter and observer gain. The
effectiveness of the proposed controller is verified through simulation
example.
