New insights on stability of sampleddata systems with timedelay Abstract   This paper analyses the stability of sampleddata systems with timedelay. By employing a twosided loopedfunctional approach, some improved conditions are derived to guarantee the stability of the system under consideration. Then, based the conditions, some intrinsic relationships between sampleddata period and time delay are obtained. From the illustrative example being solved by the proposed approach, it is observed that the results obtained are significantly better than those obtained by existing methods. More importantly, from the simulation being carried out, it is discovered that, contrary to the findings in previous studies, timedelays in a system may enlarge the interval of sampleddata periods and accelerate the rate of convergence of the system states, rather than deteriorate the system performance.

On Stability of Current Controlled Drives with Delay in Feedback Path Mechatronic systems nowadays heavily depend on current regulated electromechanical actuators. The current regulation is achieved with proportional and integral controllers that execute every PWM period. However, growing embedded algorithm complexity is causing feedback sampling to be delayed inadvertently. This research paper demonstrates the impact of delayed sampling on the stability of the closedloop system from a discrete control system perspective. A currentcontrolled DC motor drive system with increasing delay in the feedback path is evaluated under varying system parameters are studied. Analysis, simulation, and experimental results are presented with good correlation on the effect of delayed sampling in the feedback system of a current regulated drive.