نتایج جستجو برای: spacecraft

تعداد نتایج: 11066  

2007
Nicola Ceccarelli Andrea Garulli Antonio Giannitrapani Mirko Leomanni Fabrizio Scortecci

This paper deals with spacecraft autonomous navigation in deep space missions. The considered problem is that of spacecraft localization based on angular measurements. The dynamic model of the spacecraft accounts for several perturbing effects, such as Earth and Moon gravitational field asymmetry and errors associated with the Moon ephemerides. The measurement process is based on elevation and ...

2003
Puneet Singla John L. Crassidis John L. Junkins

In this paper, two different algorithms are presented for the estimation of spacecraft body angular rates in the absence of gyro rate data for a star tracker mission. In first approach, body angular rates are estimated with the spacecraft attitude using a dynamical model of the spacecraft. The second approach makes use of a rapid update rate of star camera to estimate the spacecraft body angula...

2011
Gerardo Cruz Xuebo Yang Avishai Weiss Ilya Kolmanovsky Dennis S. Bernstein

Torque-saturated control laws for spacecraft attitude control are considered. These control laws require no knowledge of the mass distribution of the spacecraft and thus are inertia-free. We examine two specific problems. In the first problem, the spacecraft has an arbitrary initial attitude and angular velocity, and the objective is to bring the spacecraft to rest with a specified attitude. In...

1998
Edward M. Murphy

Anderson, et al. have recently reported the discovery of an apparent anomalous, weak, long-range acceleration in the Pioneer 10/11 and Ulysses spacecraft. I believe that this result can be explained by non-isotropic radiative cooling of the spacecraft electronics through passive radiators on the spacecraft surface. These radiators are preferentially placed on the anti-solar side of the spacecra...

2004
Jae Jun Kim Brij N. Agrawal

This paper presents a slew maneuver control design of three-axis rotational flexible spacecraft. The focus of the work is to investigate the nonlinear effect of the three axis maneuver for a flexible spacecraft when a vibration suppression technique for linear systems such as input shaping is used in the control design. A simple method of slewing three-axis rotational spacecraft using input sha...

2013
Mark R. Krebs

ORBCOMM is a LEO communications spacecraft, providing global point to point packet messaging. Two are in operation now, and the rest of the (eventually 36) constellation design spacecraft are currently in integration and test. The ORBCOMM ACS mission is to point a communications antenna to nadir, while maintaining continuous Sun tracking via spacecraft yaw maneuvers. This mission is achieved us...

2011
Pearl Kurian

The aim is to develop vibration control of flexible spacecraft by adaptive controller. A case study will be carried out which simulates planar motion of flexible spacecraft as a coupled hybrid dynamics of rigid body motion and the flexible arm vibration. The notch filter and adaptive vibration controller, which updates filter and controller parameters continuously from the sensor measurement, a...

2000
Panagiotis Tsiotras Alexander Schleicher

We consider the problem of attitude and angular velocity stabilization of a rigid spacecraft subject to a single actuator failure. Only two pairs of gas jet actuators are available to perform the control objectives. Various controllers have been proposed for this problem in the case that the spacecraft is axisymmetric about one of its axis. In this paper the spacecraft under consideration is a ...

2003
Chi-Chang J. Ho

An innovative approach to automatic spacecraft docking using a computer vision-based control system is introduced. Precision control of the relative spacecraft velocity is required to achieve "soft" docking with a docking platform on a space station or on another spacecraft. We propose use of a computer vision system as a position and orientation sensor for obtaining feedback information used b...

2006
Darren T. Baird Robert Tolson

The Mars Global Surveyor spacecraft was initially placed into a high eccentricity, nearly polar orbit about Mars with a 45-hour period. To accomplish the science objectives of the mission, a 2-hour, circular orbit was required. Using a method known as aerobraking, numerous passes through the upper atmosphere slowed the spacecraft, thereby reducing the orbital period and eccentricity. To success...

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