Feedback stability of discrete-time, linear time-varying systems

The paper proposes a method for feedback stability evaluation for discrete-time, linear time-varying control systems. It is assumed that the time-varying system can be described by linear matrices operators, equivalent to general discrete-time, time-varying state space model with nonzero input-output delay. The main used tools are Bode diagrams approximated for time-varying systems, using power spectral density properties, discrete Fourier transform and singular value decomposition of the system operator.