Adaptive sampling frequency for sampled-data control systems
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Authors
Farren, Merritt C.
Phillips, Charles A.
Subjects
Advisors
Dorf, Richard C.
Date of Issue
1960
Date
Publisher
Monterey, California: U.S. Naval Postgraduate School
Language
en_US
Abstract
Sampled-data control systems generally have fixed sampling
frequencies which must be set high enough to give satisfactory
performance for all anticipated conditions, A study is made
here of an adaptive system which varies the sampling frequency
by measuring a system parameter. It is shown, that a sampler
followed by a zero-order hold whose sampling period is controlled
by the absolute value of the first derivative of the
error signal will be a more "efficient" sampler than a fixed frequency sampler. That is, over a given time interval, fewer
samples are needed with the variable frequency system than with
a fixed frequency system while maintaining essentially the same
response characteristics. Analog computer studies of simple type 1 and type 2
sampled-data servo systems with error sampling and unity feedback
verified the method . Standard analog computer components were
used to set up a simulated servo system, a rate detector, absolute
value detector, a voltage controlled oscillator, and a
sampler and zero-order hold. The system described reduced the number of samples required
for response to a step input to about three-quarters that required
in a fixed sampling frequency system. Over a long period of time,
savings in the number of samples required can be expected to be
between twenty-five and fifty per cent. In many applications,
the saving produced by reducing the overall number of samples
required may outweigh the added complexity of the adaptive
sampling frequency system.
Type
Thesis
Description
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Department
Electrical Engineering
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Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.