Partial feedback linearization is applied to a harmonically excited beam wi
th one-sided spring to reduce vibration amplitudes while keeping the contro
l effort small. Vibration amplitudes are reduced by globally stabilizing th
e small amplitude 1-periodic solution which is one of the coexisting soluti
ons. As the 1-periodic solution represents a natural solution of the uncont
rolled system, no control effort will be needed once the system vibrates in
the 1-periodic response. To control the multi-degree-of-freedom (d.o.f.) b
eam system to the 1-periodic solution, only one actuator is used that contr
ols one (d.o.f.). The behaviour of the other d.o.f.s is eventually describe
d by the zero dynamics. Whether these d.o.f.s converge to the 1-periodic so
lution depends on the stability of the zero dynamics. The global asymptotic
stability of the non-autonomous zero dynamics can be partially determined
by a frequency domain technique known as the circle criterion. However, the
circle criterion does not guarantee stability at all actuator positions al
ong the beam (C) 1999 Academic Press.