This paper studies high performance robust motion control of linear motors
that have a negligible electrical dynamics. A discontinuous projection base
d adaptive robust controller (ARC) is constructed. Since only output signal
is available for measurement, an observer is first designed to provide exp
onentially convergent estimates of the unmeasurable states. This observer h
as an extended filter structure so that on-line parameter adaptation can be
utilized to reduce the effect of the possible large nominal disturbances.
Estimation errors that come from initial state estimates and uncompensated
disturbances are effectively dealt with via certain robust feedback at each
step of the ARC backstepping design. The resulting controller achieves a g
uaranteed output tracking transient performance and a prescribed final trac
king accuracy. In the presence of parametric uncertainties only, asymptotic
output tracking is also achieved. The scheme is implemented on a precision
epoxy core linear motor. Experimental results are presented to illustrate
the effectiveness and the achievable control performance of the proposed sc
heme. (C) 2001 Elsevier Science Ltd. All rights reserved.