  If embedded with command filter properly, the implementation of backstepping
design could be dramatically simplified. In this paper, we introduce a command
filter with time-varying gain and integrate it with backstepping design,
resulting in a new set of backstepping control algorithms with low complexity
even for high-order strict-feedback systems. Furthermore, with the aid of
"softening" sign function based compensator, zero-error output tracking is
ensured while at the same time maintaining prescribed transient performance.
Numerical simulation is carried out to verify the effectiveness and benefits of
the proposed method.
