Space systems design (spacecraft, satellites, space stations and their equipment)
Ghasem Kahe; Mehdi Alemi Rostami
Volume 15, English Special Issue , May 2022, , Pages 45-53
Abstract
Diversity in both hardware and software plays an essential and unmatched role in increasing the reliability of redundant systems, especially in safety and mission critical applications. The onboard computer of satellites and the flight computer of spacecrafts, which are ultra-reliable systems, utilize ...
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Diversity in both hardware and software plays an essential and unmatched role in increasing the reliability of redundant systems, especially in safety and mission critical applications. The onboard computer of satellites and the flight computer of spacecrafts, which are ultra-reliable systems, utilize various hardware platforms for their redundant architecture to resolve a common cause failure (CCF) problem. Furthermore, the software is also developed by separate teams based on different software platforms to mitigate the specification and design flaws, and implementation mistakes. This paper focuses on modelling the diversity of redundant architectures in space systems using CCF modelling and Markov reliability analyzing. The proposed scheme is explored in two types of applications: mission critical applications (with long mission time) and safety critical applications (with short mission time). Analytical and simulation results show the effectiveness of diversity in increasing the reliability of these systems. Since a significant percentage of all failures appear as common cause failures, which restrict reliability improvement through similar redundant modules, achieving ultra-reliability necessitates considering diversity in these systems.
Morteza Tayefi; Ghasem Kahe; Mijtaba Mehrafrooz
Volume 12, Issue 4 , December 2019, , Pages 69-77
Abstract
Sounding rockets provide a useful platform for the aerospace research activities in which carry out a research payload to the space and recover it in the ground. In the flight path, it does scientific experiments and acquire the result for more analysis in the ground. All of the well-known aerospace ...
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Sounding rockets provide a useful platform for the aerospace research activities in which carry out a research payload to the space and recover it in the ground. In the flight path, it does scientific experiments and acquire the result for more analysis in the ground. All of the well-known aerospace centers around the world use frequently the various forms of sounding rocket to test and evaluate their sensitive space components. Actually, space qualification process of a space module is completed sometimes through a real space flight using the sounding rocket. In this paper the performance of a MEMS based inertial measurement unit (IMU) is investigated. The investigation result shows that using appropriate filtering, MEMS based IMU can measure appropriately the dynamic behavior of the sounding rocket. These data may be used for further identification and validation tests.
Ghasem Kahe; Maysam Mohammadi-Amin; Arash Sefidan Benisi
Volume 10, Issue 1 , June 2017, , Pages 1-13
Abstract
Various strategies have been developed to increase the safety of spacecraft crews, among which the Launch Abort System has been widely considered by the space centers across the world. The launch abort system should be able to carry the crew module away from the failed launcher or rocket in a short time ...
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Various strategies have been developed to increase the safety of spacecraft crews, among which the Launch Abort System has been widely considered by the space centers across the world. The launch abort system should be able to carry the crew module away from the failed launcher or rocket in a short time in accordance with the predetermined profile and recover the crew module on the ground. While the main part of the vehicle flight consists of the tracking, reorientation, and settling phase; attitude control in the flight path is done via the roll and pitch channel. Non-linear dynamic inversion flight control is considered for the attitude control of the LAS. Tracking the predetermined profile for the angle of attack as well as the sideslip angle and maintaining the stability of the vehicle in the flight path are considered as the control objectives based on the requirements. Simulations and analytical evaluations indicate the outperformance of the proposed controller for the attitude control of LAS in line with the predetermined profile.
