Robust adaptive control of uncertain discrete-time systems (Q1295097)

Considering both external disturbances and unmodelled dynamics, the design of the controller here combines the backstepping technique with parameter projection. An intermediate constant is introduced in the normalizing term of the parameter estimator to allow for nonparametric uncertainties in the estimators properties. It is shown that the boundedness of the whole adaptive closed-loop system is guaranteed for any bounded initial conditions, set-point signals and external disturbances. The tracking error is bounded by a function of the size of the unmodelled dynamics, while in the ideal case (no disturbances and unmodelled dynamics) perfect tracking is ensured.