Model-based specification of the flight software of an autonomous satellite

International audienceIn the framework of the AGATA program, we applied a model-based development process founded on a living UML specification to produce the RT-Java code of the AGATA onboard software. Derived from classical V-shaped production cycle, our development process benefited from several model-based engineering methods, such as model-debugging and automated code generation. Our resulting Y-shaped production cycle enabled an incremental development process that allowed us to start software validation early in the process. Despite the complexity of the AGATA onboard software we thereby manage to achieve its functional validation and were able to evaluate RT-Java (Real-Time Java Specification-RTSJ) for real-time space applications

A parametric study of vestibular stimulation during centrifugation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections."February 2006."Includes bibliographical references (p. 155-160).Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure to the health problems associated with long duration human spaceflight. Head-turns performed during centrifugation, however, trigger a disturbing vestibular response that is only qualitatively understood. In order to design an efficient incremental adaptation procedure, the present study investigates the quantitative aspect of the vestibular side effects associated with AG, in particular, the relationship among crosscoupled stimulation, vestibular response, and adaptation. We tested 20 young adults with supine right-quadrant yaw head-turns performed in a dark environment during short-radius centrifugation. We studied the changes in vestibular response and adaptation to head-turns at different levels of cross-coupled stimulation. Nine combinations of head-turn angle (20°, 40° or 80°) with centrifugevelocity (12, 19 or 30 rpm) were tested over two consecutive days.(cont.) There were four key findings: 1. All measures, except the slow-phase velocity (SPV) peak amplitude of the vestibulo-ocular reflex, decrease significantly between the two experimental days, which demonstrates that significant adaptation is achieved. 2. Large head-angles lead to longer vertical vestibulo-ocular reflex time-constants than smaller angles do, but do not lead to greater adaptation. 3. In the nose-up position, the perceived body-tilt is highly correlated with the true tilt of the gravito-inertial force at mid-chest level. 4. The SPV-peak amplitude and all subjective ratings except body-tilt show significant correlation with the intensity of the cross-coupled stimulus (CCS): the larger the CCS, the stronger the vestibular response.by Jeremie M. Pouly.S.M

Autonomous mission planning in space: mission benefits and real-time performances

International audienceIn the framework of the AGATA program we developped a ground tool to demonstrate thefeasibility and interest of autonomy for space systems. We used this demonstrator to study the impact of on-boardautonomy on both mission performances and real-time performances. We compared the results with respect tomission goals on different criteria for five levels of on-board autonomy. Our experimentation shows that missionbenefits increase with on-board autonomy level. In parallel we performed a real-time evaluation of the AGATAflight software for the higher level of autonomy. We were able to demonstrate that the central processing unit loadassociated to fully autonomous on-board mission planning is compatible with the actual Leon2 baseline