  We consider controllable linear discrete-time systems with bounded
perturbations and present two methods to compute robust controlled invariant
sets. The first method tolerates an arbitrarily small constraint violation to
compute an arbitrarily precise outer approximation of the maximal robust
controlled invariant set, while the second method provides an inner
approximation. The outer approximation scheme is $\delta$-complete, given that
the constraint sets are formulated as finite unions of polytopes.
