Space systems design (spacecraft, satellites, space stations and their equipment)
Hojat Taei; Pourya Shokrolahi
Volume 13, Issue 2 , June 2020, , Pages 87-96
Abstract
The final phase of orbital rendezvous and docking has been studied in this article. The main objective is to control the position of a chaser that can reach the target in the minimum time, or in other words, bypassing the optimal path. Another important objective of this paper is the minimum energy consumption. ...
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The final phase of orbital rendezvous and docking has been studied in this article. The main objective is to control the position of a chaser that can reach the target in the minimum time, or in other words, bypassing the optimal path. Another important objective of this paper is the minimum energy consumption. In the dynamic simulation, the equations of the linear form of Clohessy-Wiltshire (CWH) equations have been utilized. In linear CWH equations, the change in either direction of X or Y will result in the change in another direction and will affect the orbital docking operation. In order to achieve the objectives of this paper, the design variables should be optimized; To optimize the design variables, two methods, i.e. genetic algorithm (GA) and particle swarm optimization (PSO), have been used. Finally, to evaluate the real conditions, the results will be investigated by applying uncertainty in the outputs of thrusters.
Space subsystems design: (navigation, control, structure and…)
Maziar Shefaee Roshan; Mahdi Ghobadi; Mahdi jafari Nadoushan
Volume 13, Issue 1 , March 2020, , Pages 71-82
Abstract
Using linear programming method in control allocation for attitude control subsystem of spacecraft with redundant thrusters is studied in this paper. The simplex algorithm is utilized as a solver and the Direction Preserving and Bodson’s Reduced size Direction preserving approaches are used as ...
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Using linear programming method in control allocation for attitude control subsystem of spacecraft with redundant thrusters is studied in this paper. The simplex algorithm is utilized as a solver and the Direction Preserving and Bodson’s Reduced size Direction preserving approaches are used as optimal approaches to deal with non admissible solutions. Also, proper functioning of these approaches against thrusters fault phenomenon is evaluated. The results show that the Direction Preserving approache has less computational time and less fuel consuming. However, the Bodson’s Reduced size Direction preserving approache has more computational time and more fuel consuming but less tri-axis tracking error. It should be noted that the PD controller has been used as a spacecraft control rule, and simulations have been made for the number and configuration of the specific thrusters.
Alireza Fathi; Mahdy Ahangar
Volume 12, Issue 2 , September 2019, , Pages 1-10
Abstract
corona discharge which had been considered undesired before, has become popular for different uses in the past decades; including space thrusters. The basic corona discharge has a simple setup including two electrodes with unequal cross-sections; one of which connected to a high voltage and the other ...
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corona discharge which had been considered undesired before, has become popular for different uses in the past decades; including space thrusters. The basic corona discharge has a simple setup including two electrodes with unequal cross-sections; one of which connected to a high voltage and the other connected to ground or opposite voltage. By changing the number of electrodes, the efficiency of corona discharge can be improved. In this paper, number of electrodes have been changed from 2 to 3 in order to study an electrohydrodynamic thruster. Flow characteristics have been studied by solving the electrostatics and Navier-Stokes equations by finite element method (FEM). The results show that with increasing the number of cathodes the thrust, electric current and thrust efficiency will also increase. In similar condition and geometry, maximum produced velocity resulted by applying any electric potential to anode, increases by about 30% in comparison with one-cathode setup.
ehsan maani; Hossein Nejat Pishkenari; Amir Reza Kosari
Volume 11, Issue 3 , December 2018, , Pages 63-71
Abstract
In this paper, the combination of reaction wheels and thrusters is applied to attitude control of a satellite. First, governing equations of satellite attitude dynamics are given using quaternion and PID controller is designed based on the satellite quaternion to determine the applied control torque. ...
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In this paper, the combination of reaction wheels and thrusters is applied to attitude control of a satellite. First, governing equations of satellite attitude dynamics are given using quaternion and PID controller is designed based on the satellite quaternion to determine the applied control torque. By applying the reaction wheels physical constraints such as its maximum torque, its maximum momentum and maximum power on the desired torque, reaction wheels angular momentums and torques are found. The obtained results show that the unsaturated reaction wheels capabilities in attitude control. Results also show that the wheels saturation leads to error in control and increases the Euler angles and quaternions. Satellite thrusters are utilized to reaction wheels de-saturation and attitude control simultaneously.Three different strategies are proposed in this paper for wheels de-saturation using thrusters. Two well known methods, pulse width modulator (PWM) and pulse width pulse frequency (PWPF) modulator are used to attitude control using thrusters. All methods are compared together and the optimal method is proposed for the satellite attitude control. This paper results can be useful in design and control of different class of satellites.
H. Fazeli; H. Naseh; M. Mirshams; A.B. Novinzadeh
Volume 7, Issue 3 , October 2014, , Pages 9-21
Abstract
Designing space propulsion systems as one of the important subsystems of the spacecrafts and upper stage space launch systems needs to bypass different and complicated steps. In this article the comprehensive process of designing liquid fuel low-thrust space propulsion systems was illustrated. In the ...
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Designing space propulsion systems as one of the important subsystems of the spacecrafts and upper stage space launch systems needs to bypass different and complicated steps. In this article the comprehensive process of designing liquid fuel low-thrust space propulsion systems was illustrated. In the presented pattern, first of all according to the requirements and mission constraints, the main characteristics of the system were determined and then other characteristics were extracted. Finally, for the evaluation of the presented pattern, a low-thrust space propulsion system was designed based on a special mission and the results were compared with a real model. Comparison between the designed space propulsion system and the real one showed an appropriate accuracy of the presented pattern
