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Vallely, D. P.

Publications and source records attributed to Vallely, D. P..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Rocket engine health monitoring and control - Some connections and their implications

SSME health-monitoring and health-managing subsystems are presently discussed with a view to the ways in which their design objectives influence each other. Analytical results based on the application of system-theoretic concepts to the analysis of a general health monitoring/control architecture are presented; an effort is made to illuminate and quantify the tradeoffs in question. Attention is given to SSME simulation results that illustrate the conceptual framework employed.

Helmicki, Arthur J.↗
NASA NTRS1978

Floating-point system quantization errors in digital control systems

This paper considers digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. A quantization error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. The program can be integrated into existing digital simulations of a system.

Phillips, C. L.↗
NASA NTRS1974

Implementation of digital filters for minimum quantization errors

In this paper a technique is developed for choosing programing forms and bit configurations for digital filters that minimize the quantization errors. The technique applies to digital filters operating in fixed-point arithmetic in either open-loop or closed-loop systems, and is implemented by a digital computer program that is based on a digital simulation of the system. As an output the program gives the programing form required for minimum quantization errors, the total bit configuration required in the filter, and the location of the binary decimal point at each quantizer within the filter.

Phillips, C. L.↗
NASA NTRS1973

Limit cycles resulting from quantization in digital control systems.

The existence of quantizer-induced limit cycles in digital control systems is a well-known phenomenon. This paper reports the results of an investigation into the discrete describing function technique which is applicable not only to the quantizer nonlinearity but also to any nonlinearity in an otherwise linear discrete system. First a general expression is developed for the discrete describing function that is applicable to any nonlinearity. The describing function is then obtained for the quantizer nonlinearity. Finally, the use of the discrete describing function is illustrated by an example of a digital control system.

Phillips, C. L.↗