David A. Kahn

Bio: David A. Kahn is an academic researcher from Calspan Corporation. The author has contributed to research in topics: Distributed parameter system & Nonlinear system. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.

An Analysis of Relay Servomechanisms

Abstract: THE METHODS of analysis and synthesis of linear servomechanism loops have been developed to the point where they have become a common and useful tool. Comparable advances have not been made in the case of relay-type control although the latter is of great importance in many engineering fields. The reason for this failure is that the differential equations governing a relay-controlled system are nonlinear in nature and cannot be solved by conventional means. Nevertheless, it is possible to analyze such a system by accepting something less than a finite analytic expression for the solution of the governing differential equation. Application of Laplace transform theory to this problem yields the response expressed as a series of terms from which the system behavior may be found. The information obtainable in this manner indicates whether the system under consideration is stable or unstable and gives relations among the circuit parameters which must hold if the response of the system is periodic. This method is not restricted to cases of intermittently applied constant torque as in previous treatments but is applicable to any controlled object whose unilateral transfer function can be written, as for example a motor, a vacuum-tube circuit, or a complete servomechanism loop.

Relay feedback systems - established approaches and new perspectives for application

Abstract: Relay feedback systems belong, since long, to rather classical topics of the control theory and engineering. While they were first used as robust and simple switching elements in the automatic control, over time, they experienced different periods of renewed interest regarding both the theoretical analysis and applications. Examples here are the automatic tuning of the simple feedback controllers, delta-sigma modulators for analog-digital converters, robust relaybased controls, nonlinear systems analysis and identification, and others. One of the remarkable features when using relays in feedback is appearance of the stable limit cycles. The structural and parametric conditions for the stable limit cycles, their prediction, and controllability of magnitude and frequency already found answers, to the large part, in the former research, driven by both theoretical curiosity and application requirements. This brief tutorial paper is summarizing the basic principles of relay feedback systems, discuss several characteristics interesting for applications, and address some perspectives of further use for the system identification. A case-specific study of estimating the unknown backlash, hidden within two-mass systems, is demonstrated along with experimental example, based on provoking the controllable drifting limit cycles by the non-ideal relay in the velocity feedback loop.

A Survey of Discontinuous Temperature Control Methods for Electric Space Heating and Cooling Processes II-Selected Bibliography

Abstract: Some 219 selected references on electric space heating and cooling, automatic temperature control, and allied subjects, are listed in the order in which they appear in the text of Part I. They are also classified under subject headings.

Application of Electronic Differential Analyzers to Engineering Problems

Abstract: The basic elements comprising an electronic differential analyzer are described. Fundamental concepts employed in the application of electronic differential analyzers to engineering problems are discussed, and an effective method of studying complicated dynamic systems is demonstrated. Data are presented on the types of problems which such machines are known to be capable of solving and on the extent to which they are being used in research, development and industrial organizations.