A Rapid Maneuver Method with High Accuracy for Spacecraft Based on CMG and RW

The mission of ground tracking satellite requires not only the ability of large angle rapid maneuver, but also the ability of attitude stability with high accuracy during and after maneuver. A rapid maneuver method with high accuracy for spacecraft based on CMG and RW is proposed to solve this problem. By use of initial quaternions and target quaternions, a minimum path trajectory tracking algorithm is designed along the instantaneous Euler rotation axis. This algorithm requires that during the accelerating stage and the decelerating stage, the torque command is assigned to CMG system; however, during the constant-speed stage and after maneuver, the torque is assigned to RW system. Mathematical simulation indicates that, compared with the situation of just using CMG, the new method endows the spacecraft with the ability of rapid maneuver with high accuracy.

Download Full-text

Stellar magnetic imaging from spectropolarimetric data

Symposium - International Astronomical Union ◽

10.1017/s0074180900083091 ◽

1996 ◽

Vol 176 ◽

pp. 53-60 ◽

Cited By ~ 1

Author(s):

J.-F. Donati

Keyword(s):

Small Amplitude ◽

High Accuracy ◽

Spectral Lines ◽

New Method ◽

Doppler Imaging ◽

Magnetic Imaging ◽

Active Stars ◽

Surface Fields ◽

Very High

In this paper, I will review the capabilities of magnetic imaging (also called Zeeman-Doppler imaging) to reconstruct spot distributions of surface fields from sets of rotationnally modulated Zeeman signatures in circularly polarised spectral lines. I will then outline a new method to measure small amplitude magnetic signals (typically 0.1% for cool active stars) with very high accuracy. Finally, I will present and comment new magnetic images reconstructed from data collected in 1993 December at the Anglo-Australian Telescope (AAT).

Download Full-text

A Design of High-Accuracy Displacement Measurement Instrument from Principles of Optics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.2924 ◽

2012 ◽

Vol 170-173 ◽

pp. 2924-2928

Author(s):

Sheng Biao Chen ◽

Yun Zhi Tan

Keyword(s):

Measurement Instrument ◽

High Accuracy ◽

Mechanical Tests ◽

Total Reflection ◽

Displacement Measurement ◽

New Method ◽

Water Volume ◽

Water Drainage ◽

Accuracy Of Measurement ◽

Better Than

In order to measure the water drainage volume in soil mechanical tests accurately, it develop a new method which is based on principles of optics. And from both physical and mathematic aspects, it deduces the mathematic relationship between micro change in displacement and the increment projected on screen. The result shows that total reflection condition is better than refraction condition. What’s more, the screen could show the water volume micro variation clearly, so it can improve the accuracy of measurement.

Download Full-text

Barycentric prolate interpolation and pseudospectral differentiation

Numerical Algorithms ◽

10.1007/s11075-020-01057-7 ◽

2021 ◽

Author(s):

Yan Tian

Keyword(s):

Boundary Value Problem ◽

Convergence Rates ◽

Boundary Value ◽

High Accuracy ◽

Second Order ◽

New Method ◽

Numerical Examples ◽

Helmholtz Problem ◽

Collocation Scheme

AbstractIn this paper, we provide further illustrations of prolate interpolation and pseudospectral differentiation based on the barycentric perspectives. The convergence rates of the barycentric prolate interpolation and pseudospectral differentiation are derived. Furthermore, we propose the new preconditioner, which leads to the well-conditioned prolate collocation scheme. Numerical examples are included to show the high accuracy of the new method. We apply this approach to solve the second-order boundary value problem and Helmholtz problem.

Download Full-text

Large angle maneuver and high accuracy attitude pointing steering law for variable speed control momentum gyroscopes

Journal of the Franklin Institute ◽

10.1016/j.jfranklin.2021.02.019 ◽

2021 ◽

Author(s):

Feng Liu ◽

Yang Gao

Keyword(s):

Large Angle ◽

Speed Control ◽

High Accuracy ◽

Variable Speed ◽

Steering Law ◽

Variable Speed Control

Download Full-text

A New Method for Aggregate Proportion Design of Mixture

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.178-181.1250 ◽

2012 ◽

Vol 178-181 ◽

pp. 1250-1253

Author(s):

Yu Hua Li ◽

Kai Huang ◽

Ying Zhen Gao

Keyword(s):

Iterative Algorithm ◽

Accurate Result ◽

High Accuracy ◽

New Method ◽

Equation Method ◽

Normal Equation ◽

Improved Method ◽

Mixture Ratio ◽

Target Value ◽

Initial Target

When we make design of mixture ratio, we always use normal equation method (NEM), but the solution value of that method may doesn’t meet our demand. When we use the new method that proposed in this paper, we can solve the problem. The new method makes an improvement for NEM. By iterative algorithm, the new method uses the gradation data calculated by NEM as initial target value, canceling the relevant aggregate if the result of proportion is negative, and setting the gradation to the boundary value if the target value goes beyond limits. According to the adjusted object value, using NEM again, the new aggregate proportion can be solved. Then the new gradation of mixture will come into being the next target value. Finally, the accurate result will meet our need. The new improved method has good engineering applicability and high accuracy

Download Full-text

Adaptive Verspannung von Zahnstange-Ritzel-Antrieben*/Adaptive preloading for rack-and-pinion-drives

wt Werkstattstechnik online ◽

10.37544/1436-4980-2019-05-14 ◽

2019 ◽

Vol 109 (05) ◽

pp. 312-318

Author(s):

T. Engelberth ◽

A. Verl

Keyword(s):

Machine Tools ◽

Energy Demand ◽

High Accuracy ◽

Drive System ◽

New Method ◽

Large Machine ◽

Production Facilities

Zahnstange-Ritzel-Antriebe werden vorwiegend in großen Werkzeugmaschinen eingesetzt. Um die hohen Genauigkeitsanforderungen moderner Produktionsanlagen zu erreichen, werden diese Antriebe elektrisch verspannt. Die Verspannung ist konstant. Dieser Beitrag beschreibt eine neuartige Methode, die sogenannte adaptive Verspannung. Ziel ist es, den Energiebedarf und die Belastung des Antriebssystems durch Anpassung der Verspannung während des Betriebs zu reduzieren, ohne die Genauigkeit zu beeinflussen.   Rack-and-pinion-drives are mostly used in large machine tools. To achieve the high accuracy specifications of modern production facilities, these drives are electrically preloaded. The preload is constant. This article describes a new method of so-called adaptive preloading. The aim is to reduce energy demand and wear of the drive system by adjusting the preload during operation without affecting the accuracy.

Download Full-text