Dead-time compensators (DTCs) are frequently regarded as being excessively sensitive to uncertainty in the loop delay. This claim, however, is based mostly on empirical studies rather than on any rigorous analysis. In particular, despite existing literature on the calculation of the delay margin, μd, there appears to be no study of the underlying reasons of such a sensitivity. In this paper we ...

Stability analysis in compliant mechanism (CM) design is of utmost importance. From a practical point of view, a CM that is unstable is of no significance (has no practical value). Three useful plots were considered in the evaluation of each of the dynamic models of nine configurations of compliant constant-force compression mechanisms (CCFCMs) for their stability characteristics, which include...

In this paper we propose a way to design continuous time Σ∆ modulators. The method is based on the Nyquist stability criterion. Based on this criterion we propose to use the vector gain margin as a robust stability margin. Using this margin as a design criterion we design a robustly stable modulator. Finally, we also show how this margin can be used to evaluate the relative stability of a desig...

Data transmission over bandlimited channels requires pulse shaping to eliminate or control Inter-Symbol Interference (ISI). A widely used filter for this purpose is the raised cosine filter which satisfies Nyquist’s first criterion. We design a phase compensator so that the square-root raised-cosine filter also satisfies Nyquist’s first criterion. Such a technique is particularly useful to acco...

It is shown that the classic Nyquist criterion can be extended in a straightforward way to feedback systems of fractional order. The proof this extension merely requires basic notions vector analysis and closed-loop system transfer functions. used not only ascertain stability fractional-order but also detect presence poles inside any given sector complex plane. test finally applied three exampl...

The application of ultrasonic guided wave methods to both nondestructive evaluation (NDE) and structural health monitoring (SHM) is becoming more prevalent as techniques to handle their multi-modal and dispersive nature are developed. There are several applications where it would be not only convenient but perhaps essential to interpolate arrays of measured guided wave signals. One application ...

Three matlab-based tools have been developed for the convenient assessment of stability conditions for linear and nonlinear systems. The first is a more helpful and definitive version of nyquist, which has features of automatic zooming (to show all crossings of the real axis and thus display the corresponding critical gain points) and which displays on the real axis a numeral (‘0’, ‘1’ etc.) th...

Three matlab-based tools have been developed for the convenient assessment of stability conditions for linear and nonlinear systems. The rst is a more helpful and deenitive version of nyquist, which has features of automatic zooming (to show all crossings of the real axis and thus display the corresponding critical gain points) and which displays on the real axis a numeral (`0', `1' etc.) that ...

With the rapid development of fractional calculus and active control techniques, stability of fractional-delay systems has been an increasing interest in engineering applications. For the local stability of an equilibrium of a linear dynamical system, the integral form of Mihkailov’s criterion, Nyquist criterion, and Stepan-Hassard’s criterion are probably among the most effective criteria. Thi...