Search

Your search keyword '"Hocken, R."' showing total 45 results
Start Over Author "Hocken, R."
45 results on '"Hocken, R."'

5. Mismatch and the optimal control of linear systems with series time delays

Author

Hocken, R. D.

Subjects
629.8, Control systems & control theory
Abstract

A feature common to predictor control schemes for plants with time delays is the use of a plant model. Any difference between plant and model is referred to as mismatch. The presence of mismatch introduces extra parameters which in a parametric optimisation problem may be exploited to produce performance improvement. A study is undertaken of the mechanism and opportunities for such improvement. When the cost functional is quadratic a matched predictor control scheme is known to be optimal. However, it is important to determine a relationship between mismatch and degradation in performance. This will indicate the amount by which plant and model may differ before the performance of the control scheme becomes unacceptable. With this aim, algebraic expressions are obtained for the mismatched input and output. An examination of these expressions shows how mismatch effects the stability and performance of the control scheme. When the plant contains measurement delays, the optimal matched control scheme requires prior knowledge of an initial state. An alternative control scheme operating without this prior knowledge is suboptimal and may be improved by mismatch. The types of mismatch that could produce improvement are determined.

Published
1983

9. Dimensional stability

Author

Hocken, R and Justie, B

Subjects
Nonmetallic Materials
Abstract

The temporal stability of glass and glass-ceramic materials is important to the success of a large diffraction-limited telescope. The results are presented of an experimental study of the dimensional stability of glasses and glass ceramics being considered for substrates of massive diffraction-limited mirrors designed for several years of service in earth orbit. The purpose of the study was to measure the relative change in length of the candidate substrate materials, to the order of 5 parts in 10 to the 8th power, as a function of several years time. The development of monolithic test etalons, the development and improvement of two types of ultra-high precision interferometers, and certain aspects of tests data presently achieved are discussed.

Published
1976

19. Noncontacting optical probe.

Author

Jing, Fang-Sheng, Hartman, A. W., and Hocken, R. J.

Subjects
ELECTRONIC probes, MICROSCOPES, DETECTORS
Abstract

A description is given of an optical probe, consisting of an optical microscope with modified internal illumination, a dual chopper with its two edges straddling the image plane, and a dual area sensor mounted behind the chopper. An analysis shows that the sensitivity of this proximity probe is essentially the same as that of the Simon probe, while its linearity is much better. Also, its construction is much simpler. A prototype has shown resolution of 0.02 μm and linearity errors of 0.5 μm (at 100-μm range), respectively. [ABSTRACT FROM AUTHOR]

Published
1987
Full Text
View/download PDF

25. An Overview of Off-Line Robot Programming Systems

Author

Hocken, R. and Morris, G.

Abstract

The increasing use of robots in a variety of production applications has led to a rapid growth in the development of languages for off-line robot programming. In this paper we present a survey of the languages currently available for the off-line programming of robots, discuss performance measures that could be used to categorize these languages, point out current technological barriers to off-line robot programming, and make some predictions regarding future trends in this important area.

Published
1986
Full Text
View/download PDF

26. A Displacement Method for Machine Geometry Calibration

Author

Zhang, G., Ouyang, R., Lu, B., Hocken, R., Veale, R., and Donmez, A.

Abstract

It is shown that the volumetric errors of a three-axis machine tool or measuring machine can be determined by measuring the displacement error along 22 lines in the machine work zone. Pitch and yaw are derived from measuring the displacement error on two parallel lines for each axis. The squareness and straightness errors are determined by measuring two diagonals and one additional line. Roll errors are derived from the straightness errors on two parallel planes. Formulae for calculating these components of error and also the three-dimensional positioning error at any particular point are given. Experiments show that this method simplifies machine calibration, reduces the equipment needed, and can improve accuracy.

Published
1988
Full Text
View/download PDF

32. Tolerancing for Function

Author

Weill, R., primary, Clément, A., additional, Hocken, R., additional, Farmer, L.E., additional, Gladman, C.A., additional, Wirtz, A., additional, Bourdet, P., additional, Freckleton, J.E., additional, Kunzmann, H., additional, Ham, I., additional, Trumpold, H., additional, and Matthias, E., additional

Published
1988
Full Text
View/download PDF

44. Hybrid shear force feedback/scanning quantitative phase microscopy applied to subsurface imaging.

Author

Edward K, Farahi F, and Hocken R

Abstract

Quantitative phase microscopy allows for the study of the surface morphology and dynamics of transparent biological specimens. Although phase data often contains coupled subsurface information, decoupling the surface and subsurface components is often very difficult or impossible. We hereby present a simple procedure which exploits simultaneous obtained quantitative phase and shear-force feedback topography data to extract subsurface sample information. Our results reveal subsurface features in fabricated samples and fish erythrocytes.

Published
2009
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results