Stable Solution of Tracking and Dynamic ReconstructionProblems under Measuring State Coordinates at Discrete Times

We consider the dynamic input reconstruction problem for a system of ordinary differential equations and the problem of tracking a trajectory of a system affected by an unknown disturbance by a trajectory of another system. The input action is assumed to be an unbounded function, namely, an element of the space of square integrable functions. Two solution algorithms robust under informational disturbances and computational errors and well designed for computer implementation are suggested. Upper bounds for their convergence rates are established. The algorithms are based on constructions of feedback control theory and operate under conditions of (inaccurate) system state measuring at discrete times.