English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This paper describes relations between frequency measurement time and the stable operation of a pulse-drive servo system which is mainly used for servo drives in numerical control systems. The pulse-drive servo has two main characteristics; first, it has high reliability, because it has only one noncontact angular position detector removing mechanical faults; and second, it has high stability, because its control circuits are constructed only with logical and switching elements, eliminating the temperature, drifts of amplifiers. The velocity feedback signal, necessary for stable operation of the servo system, is obtained by measuring frequencies of feedback pulses. So the servo loop contains a time delay which is equivalent to the frequency measurement time and which causes unstable operation if the design is not done carefully. Two typical constructions of the pulse-drive servo are proposed here; one is PDS-1, which obtains the difference between the position error signal and the velocity feedback signal using a pulse counter; and the other is PDS-2, which obtains the difference using an adder circuit. It is shown that the characteristic equation of the servo system can be expressed by modified z transforms of transfer functions containing frequency measurement time as a parameter. Relations between frequency measurement time and stable operation of the servo are evaluated by root locus plots of the characteristic equation. And the results are compared with experimental data. The conclusion is drawn that PDS-2 is better for practical use because of its excellent stable operation.

Conditions for Stable Operation of Digital Servo Containing Frequency Measuring Circuit