On the invariance of trajectories under perturbations in linear dynamic control systems

For a linear, nonstationary, completely controllable dynamical system with multipoint conditions on the state, we consider a problem on the independence of the state (trajectory) of the system of external perturbations and possible changes in the parameters of the system (internal perturbations). The problem is to construct a control for the perturbed system under which the state of the perturbed system is identical to the state of the unperturbed system. We compare controls for the unperturbed and perturbed systems at the same states of the systems.