This book presents new methodologies for the design and analysis of
adaptive control systems based on the backstepping approach. Our
emphasis is on - namic uncertain systems with nonsmooth nonlinearities,
such as backlash, de- zone, hysteresis and saturation, or time-varying
parameters, or interactions. The backstepping approach, a recursive
Lyapunov-based scheme, was p- posed in the beginning of 1990s. With this
method the construction of feedback controllawsandLyapunovfunctions
issystematic, followingastep-by-stepal- rithm. Backstepping can be used
to relax the matching condition, which blocked the traditional
Lyapunov-based design. A major advantage of backstepping is that it has
the ?exibility to avoid cancellations of useful nonlinearities and
achieve regulation and tracking properties. The technique was
comprehensively addressed by Krstic, Kanellakopoulos and Kokotovic in
[1]. However, there is still no monograph available to address
problems such as the handling of n- smooth nonlinearities, time varying
parameters and system interactions using this approach. Nonsmooth
nonlinearities such as dead-zone, backlash, hysteresis and satu- tion
are common in industrial control systems, such as mechanical, hydraulic,
biomedical, piezoelectric, and physical systems. Such nonlinearities are
usually poorlyknownandmayvarywithtime, andthey
oftenlimitsystemperformance.