Page 17 - Adaptive Identification and Control of Uncertain Systems with Nonsmooth Dynamics

6 Adaptive Identification and Control of Uncertain Systems with Non-smooth Dynamics

is incorporated into backstepping control design and Nussbaum-type func-
tions are utilized to deal with the unknown control gains.
In Chapter 11, a robust output tracking control of non-linear pure-
feedback systems with unknown dead-zone is addressed. A coordinate
transform is introduced to reformulate pure-feedback systems into a canon-
ical form. By using an extended state observer (ESO), the unmeasurable
states and the lumped uncertainties including unknown functions and dead-
zone are all estimated, which are used in the control designs.
Part 4 is devoted to the modeling and control design of systems with
input saturation, which includes Chapter 12 to Chapter 15.
Chapter 12 introduces the dynamics and approximation of saturation,
imposed by the hardware constraints of the actuators in the control system.
Several examples with control input saturation are also reviewed.
In Chapter 13, an adaptive sliding mode control is proposed for an
electro-mechanical servo system with input saturation. The saturation is
reformulated as a smooth affine function, then the unknown saturation and
uncertainties are compensated by using an ESO. An adaptive sliding mode
control is then presented and validated in terms of comparative simulations.
Chapter 14 introduces a non-singular terminal sliding mode funnel
control for servo systems with unknown input saturation. A new funnel
variable is suggested and incorporated into adaptive control to make the
output tracking error fall into prescribe boundaries even in the presence of
unknown input saturation.
Chapter 15 presents an adaptive neural DSC for uncertain non-linear
systems with unknown input saturation. By using a smooth approximation
of input saturation, an NN is employed to approximate the lumped un-
known dynamics and the residual saturation dynamics. A DSC based on
the integral sliding mode is then proposed.
Part 5 including Chapter 16 to Chapter 19 addresses the modeling and
control for uncertain systems with hysteresis.
In Chapter 16, the dynamics and widely used models of hysteresis are
all presented, and several practical systems with hysteresis non-linearities are
reviewed.
In Chapter 17, an inverse model based compensation control using a
backlash-like hysteresis is presented for uncertain systems. The piecewise
linearly parametric representation is used, and then the characteristic pa-
rameters of the backlash and the unknown system coefficients are estimated
simultaneously. Then an inverse compensation control is given to achieve
tracking control response.