The control of uncertain non-linear discrete-time systems having stoch
astic cone-bounded non-linearities is considered. First, a quadratic p
erformance bound and a guaranteed-cost optimal state feedback controll
er are derived. Then, an auxiliary system is introduced. It is shown t
hat the quadratic optimal control for this auxiliary system is the sam
e as the guaranteed-cost control for the original system, and, therefo
re, the existence of the infinite-horizon guaranteed-cost controller c
an be based on the stabilizability and observability properties of the
auxiliary system. Finally, the stochastic boundedness of the controll
ed uncertain system is proved based on the properties of the auxiliary
system. (C) 1998 John Wiley & Sons, Ltd.