We consider a point pattern matching problem occuring in astronautics: Given are pictures from a camera with unknown orientation, showing a section of the starry sky. We want to determine the orientation of the camera by matching the constellations in the pictures with a star catalogue. This problem occurs for satellite attitude determination with star eld sensors. We present a new solution, wh...

In this paper, an adaptive attitude control algorithm is developed based on neural network for a satellite using four reaction wheels in a tetrahedron configuration. Then, an attitude control based on feedback linearization control is designed and uncertainties in the moment of inertia matrix and disturbances torque have been considered. In order to eliminate the effect of these uncertainties, ...

Stephen Hodgart received a Ph.D. degree from the University of Surrey. He has been with the Surrey Space Centre, since its inception and the launch of their first satellite, UoSAT-1 in 1981. He is currently visiting Reader at the University of Surrey. He was responsible for the first practical low-cost active magnetic and passive gravity gradient control attitude system for a low earth orbiting...

A higher-order perturbation theory for the rotation of a uniaxial satellite under gravity-gradient torque demonstrates that known special configurations of the attitude dynamics at which the satellite rotates, on average, as in a torque-free state, are only the result of an early truncation of the secular frequencies of motion. In addition to providing a deeper insight into the dynamics, the hi...

A new attitude sensor is proposed that consists of a single global positioning system (GPS) antenna mounted on a turntable with its phase center offset from the turntable's spin axis. It is being considered as a means of sensing 3-axis attitude information. It is attractive because its GPS receiver could have a low number of channels and, therefore, be smaller and use less power. The system sen...

Control laws for an integrated power/attitude control system (IPACS) for a satellite using variable-speed singlegimbal control moment gyroscopes (VSCMGs) are introduced. Whereas the wheel spin rates of the conventional CMGs are constant, the VSCMGs are allowed to have variable speeds. Therefore, VSCMGs have extra degrees of freedom and can be used to achieve additional objectives, such as energ...

In the normal operation conditions of a pico satellite, conventional Unscented Kalman Filter (UKF) gives sufficiently good estimation results. However, if the measurements are not reliable because of any kind of malfunction in the estimation system, UKF gives inaccurate results and diverges by time. This study, introduces Robust Unscented Kalman Filter (RUKF) algorithms with the filter gain cor...

Accurate estimates for the drag coefficients of a satellite are important in reducing the biases in densities derived from satellite drag measurements as well as explicitly reducing the errors in orbit prediction. This develops a approach to estimate the drag coefficient for debris objects with known shape models.This paper focuses on rocket bodies in particular. The attitude and angular veloci...