Journal of Space Science and Technology
Year:2016 | Volume:9 | Issue:1|Papers Count:8

The purpose of this paper is to present a genetic algorithm (as a software) to optimize engine main parameters through the application of "genetic algorithm" and also introduced the new and modified thermodynamic cycles with analysing their performance. This software objective function is to achieve the highest and optimum level of 'final velocity'. In this study, the strategy of using fuel booster turbo pump and 2nd stage fuel pump is followed primarily to moderate the effect of cavitation on pumps. Although the use of booster pumps increase the weight, arise pumps' rpm and possibility to reduce the tanks pressure came with a decrease in weight of propulsion system. The developed software is applied to Russian RD-180 engine in construction of propulsion system of first stage of ATLAS IIIB LV, and experimental results have been demonstrating the improvement of engine performance which results from a multi-variable sensitivity study on a staged-combustion engine will be highlighted. This algorithm is under the limitation of constraints to control the critical variation of combustion pressure, turbine rpm, and pumps cavitation margin and turbine temperature. Results show that, supply flow rate of gas generation from 2nd stage of fuel pump and divide flow rate of exhaust of fuel booster turbine to 2nd stage of fuel pump and combustion chamber, will increase the final velocity of launch vehicle.

Recently, many researchers are examining the possibility of the small satellites or micro satellites, because small satellites are easier and faster to develop and thereby, provide increased launch opportunities. In this paper designing and experimental testing of three axis agility satellite simulator - equipped with pyramid configuration of SGCMG- with implementation of PID and feedback quaternion strategies are presented. These control strategies in the two different control gains and two different type of maneuvering about single and three axis are presented. First actuators and simulator of satellite have introduced and control strategies are simulated in Matlab/Simulink software. Then control strategies have implemented in the simulator’s computer and attitude control testing is executed. Finally the experimental data are compared with simulation results. In order to avoiding of singularity condition, SR method is used in steering law of single control moment gyros system. Results shown that agility maneuver of simulator realized and numerical results are almost according to experimental tests.

In this paper, a robust attitude control algorithm is developed based on backstepping-sliding mode control for a satellite using four reaction wheels in a tetrahedron configuration. In this method, asymptotic stability of the proposed algorithm has been proven in the presence of reaction wheels dynamic model based on Lyapunov theory. Then, in order to evaluate the performance of the proposed algorithm, a low-cost real-time prossecor in the loop test bed is provided. The presented test bed is capable of real-time assessing the attitude backstepping-sliding mode control algorithm. In this test bed, real-time modeling of satellite dynamic, environmental disturbances and reaction wheels are achieved in a simulator computer and the proposed control algorithm performance is investigated by implementing it in an electronic control board of the prossecor in the loop test bed.

Automatic control of satellites and spacecrafts, has been extensively paid attention. Attitude determination is one of the most important procedures to control a spacecraft. Star trackers are widely used for attitude determining. A star tracker provides images from the around space and try to identify the stars in the images. Several algorithms are proposed to this end. However, most of these algorithms use the raw measurements to star identification and attitude determination. As the measurements are often affected by various types of noise, the performance of such algorithms is degraded. Here, we employ tracking algorithms to improve the performance of existing methods for attitude determining. The Kalman filter-based tracking algorithms are shown to have satisfactory results for object tracking. We use the JPDAF to build an algorithm for accurate tracking of stars locations in successive images and, consequently, determining the attitude of spacecraft. The presented algorithm is compared with the well-known algorithm for attitude determining called SNA.

In this paper, an adaptive controller based on decentralized minimal control synthesis is designed n order to control an attitude of specific remote sensing satellite. The main design purposes are performing spinning, three axis and large angle maneuver as well as achieving a stable system and tracking the reference attitude trajectory in the presence of uncertainties. In the design process, the effects of internal and external disturbances, nonlinearities in the satellite dynamic and the accurate model of actuators are regarded. Four reaction wheels with pyramidal structure are modeled as the actuators to accomplish an attitude maneuver. So the exact reaction wheels’ model with regarding the maximum voltage, current, allowable angular velocities and power of wheels is developed. The simulation results show an acceptable performance of controller in the presence of exacts actuators’ model, external and internal disturbances and uncertainties in the satellite parameters.

Because of vast applications of Liquid fuel engines in rockets and importance of their functional parameters such as trust, specific impulse and fuel consumption in engine performance, it is needed to be tested in different functional conditions before operation in actual missions. The analysis of test data used to improve the design, engine troubleshooting and to expand the production program for future rockets. Selecting the suitable injector(s) is the key parameter for improving combustion parameters. With respect to finding the effective ways to analyzing the engine hardware performance without neglecting from their main characteristics, one of the alternatives is doing the hot-fire tests by using a sub scaled engine instead of the full-scale engine. In this research, the design process and manufacturing details of a 300N trust (nominal) micro engine with single swirl Injector is presented. Initial firings using the actual fuel and oxide were not successful. Low fuel flow, low mixing area of the fuel and oxide, and contamination in the self-ignition fuel (TR-1) were considered to be the reasons. Overcoming to these problems resulted in successful firing of the subscale engine.