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Aerospace Launch Vehicles (ALVs), used for launching artificial satellites and space stations to Earth orbits, usually encounter with failure in navigation systems . In these cases, survival of an ALV during accurate payloads injection in orbits is one of the most critical issues for Guidance and Control systems.An important challenge for safety of Aerospace Launch Vehicle (ALV) is their reliability against all types of faults. There is a requirement for on-board fault detection without deteriorating the performance of ALV. In this paper, a new software sensor is proposed for fault detection and compensation based on symmetrical behavior of the yaw and pitch channels of an ALV. For this purpose, using identification techniques on the yaw channel, a new software sensor is developed as an online rigid dynamic predictor for the pitch channel. The proposed software sensor is employed to generate the residual of estimation error as an indicator of predefined faults. The main novelty of this software sensor is online tuning of the virtual sensor against unforeseen variations in the parameters of the vehicle. Robustness of the new control system in the presence of asymmetric behavior is investigated. The efficiency of the proposed fault tolerant method is illustrated through simulations.

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Considering uncertainties in the design process is one of the most important factors to achieve reasonable and reliable results. In this article, a collaborative structure, which is a multidisciplinary design optimization, is combined with a robust design approach to design an optimum and robust launch vehicle, while considering the effects of uncertainties. First, a liquid-fuel vehicle is designed under two disciplines to send a 1200 kg mass to the 750 km orbit from the earth surface with 50.7◦ orbital inclination, using the collaborative structure. It should be said that the first discipline includes three subsystems that are engine design, geometry design and estimating the mass. Also, the second discipline includes three subsystems that are pitch program, aerodynamic calculations and trajectory simulation. Then, the optimum collaborative output is combined with the robust design in a multi-objective model to achieve the final vehicle configuration. The results show that the calculated mass of the first stage of the project using the collaborative robust design process is 3 tons heavier than the calculated mass using optimum collaborative design approach and the engines working time is increased. The overall size of the launch vehicle is increased too. The outputs of each subsystem have been evaluated and also, the overall results have been compared with another design process, i.e. MDF. This comparison shows the acceptable accuracy of the proposed approach.