Implementation of an open-loop control technique for high-speed micropositioning in a single-point diamond turning process

Optical systems typically use galvanometers (aka galvos) and scanners. Galvos move optical elements such as mirrors, quasi-statically, from one static position to another, and an important figure of merit is their step-settle relaxation time. Scanners move in an oscillatory fashion, typically at the device resonant frequency. MEMS devices, which have many advantages and are often used in such optical systems, are typically high Q devices. Moving from one position to another for a galvo or one frequency/amplitude to another for scanners, can take many periods to settle following the ring down. During these transitions, the optical system is inactive and the time is not being efficiently used. In this article we show how a novel class of open loop control algorithms can be used to rapidly change position, frequency and amplitude, typically in well under the period of the device. We show how the MEMS designer can excite, with complete, high-speed control, a vibrational mode of the system. We call this modal engineering, the ability to control the modes of the system in a practical, fast way. This control of the modes is accomplished with open loop control algorithms.

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An energy saving open-loop control technique for flexible manipulators

2011 IEEE International Conference on Mechatronics and Automation ◽

10.1109/icma.2011.5985694 ◽

2011 ◽

Cited By ~ 1

Author(s):

Akira Abe ◽

Kazuma Komuro

Keyword(s):

Energy Saving ◽

Open Loop ◽

Control Technique ◽

Flexible Manipulators ◽

Open Loop Control ◽

Loop Control

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Turbulent boundary layer under the control of different schemes

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2017.0038 ◽

2017 ◽

Vol 473 (2202) ◽

pp. 20170038 ◽

Cited By ~ 3

Author(s):

Z. X. Qiao ◽

Y. Zhou ◽

Z. Wu

Keyword(s):

Boundary Layer ◽

Turbulent Boundary Layer ◽

High Speed ◽

Control Strategies ◽

Local Maximum ◽

Open Loop ◽

Open Loop Control ◽

Feed Forward ◽

Loop Control ◽

Combined Feed

This work explores experimentally the control of a turbulent boundary layer over a flat plate based on wall perturbation generated by piezo-ceramic actuators. Different schemes are investigated, including the feed-forward, the feedback, and the combined feed-forward and feedback strategies, with a view to suppressing the near-wall high-speed events and hence reducing skin friction drag. While the strategies may achieve a local maximum drag reduction slightly less than their counterpart of the open-loop control, the corresponding duty cycles are substantially reduced when compared with that of the open-loop control. The results suggest a good potential to cut down the input energy under these control strategies. The fluctuating velocity, spectra, Taylor microscale and mean energy dissipation are measured across the boundary layer with and without control and, based on the measurements, the flow mechanism behind the control is proposed.

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