Space subsystems design: (navigation, control, structure and…)
Abdolmajid khoshnood; Ali Aminzadeh; Peyman Nikpey
Volume 15, Issue 1 , March 2022, , Pages 63-71
Abstract
This paper is dedicated to modeling of fuel sloshing dynamics and its effect on the stability and control of the space vehicle. Sloshing due to the liquid movement in the fuel tank of a space vehicle's propulsion system can be effective on the vehicle’s control and stability. Force and moment interaction ...
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This paper is dedicated to modeling of fuel sloshing dynamics and its effect on the stability and control of the space vehicle. Sloshing due to the liquid movement in the fuel tank of a space vehicle's propulsion system can be effective on the vehicle’s control and stability. Force and moment interaction between fuel sloshing and space vehicle’s control system will be appeared as a feedback in the control system. With respect to simplicity of analyzing of a rigid body's equations of motion in comparison with a fluid dynamics equations and as a result reducing computational efforts, it is possible to apply a mechanical model instead. So in this paper fuel sloshing is modelled as a linear mechanical system to investigate its effect on the stability and control of the vehicle. For this purpose, two mechanical models, mass-spring and pendulum systems, are applied to model dynamics of a space vehicle with fuel sloshing and each system’s parameters are evaluated for simulat
Space subsystems design: (navigation, control, structure and…)
Nourbakhsh Fouladi; Neda sadat Seddighi renani
Volume 15, Issue 1 , March 2022, , Pages 73-87
Abstract
In this article, a universal algorithm and engineering software is presented for the conceptual design of cryogenic rocket propulsion system. The algorithm consisting five engine working cycles: pressure fed, gas generator, staged combustion, closed and opened expansion cycles. For validation, the Vulcain ...
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In this article, a universal algorithm and engineering software is presented for the conceptual design of cryogenic rocket propulsion system. The algorithm consisting five engine working cycles: pressure fed, gas generator, staged combustion, closed and opened expansion cycles. For validation, the Vulcain and HM7Bengines were redesigned, the obtained results certifies that the main design parameters have less than 5% errors and the other less than 20%. One of the advantages of this software is the presence of abut150 parameters in the output and 14 diagrams related to the flow behavior in the thrust chamber and cooling vest, which allows the parametric study of the effect of input changes on the outputs.The modeling of mathematical functions and the combustion has been done, by using the MATLAB and CEAsoftware. Finally, by merging in Visual studio programming environment and with the help of C# programming language, a software with GUI is presented.
Space subsystems design: (navigation, control, structure and…)
Reza Sheikhbahaei; Saeed Khankalantary
Volume 14, Issue 4 , December 2021, , Pages 51-59
Abstract
In this study, on the basis of proportional navigation strategy, design of explicit optimal guidance law for missiles tracking maneuvering targets in three-dimensional space using model predictive control is addressed. The model predictive control employs a model to predict the future process behavior ...
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In this study, on the basis of proportional navigation strategy, design of explicit optimal guidance law for missiles tracking maneuvering targets in three-dimensional space using model predictive control is addressed. The model predictive control employs a model to predict the future process behavior and calculates an optimal control input at each time step through the optimization of an objective function. Generalized model predictive control approach, employed in this study, solves the optimization problem offline to obtain the closed form optimal control law. In this paper, firstly, the equations describing the missile-target relative motion kinematics are formulated. Then, the optimal control law, as an explicit function of the state vector is obtained. The evaluation of the proposed scheme is studied by the comparison of the simulation results with the augmented proportional navigation system. Simulation studies, in three different scenarios, demonstrates appropriate performance for the proposed guidance system specially against maneuvering targets.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; P. Zarei
Volume 14, Issue 4 , December 2021, , Pages 77-83
Abstract
The use of four reaction wheels to control the three-axis attitude of the spacecraft, considering its mechanical performance and the possibility of its failure, is a practical solution in the face of a defect in one of the wheels. In this article, the optimal control of the spacecraft, which has four ...
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The use of four reaction wheels to control the three-axis attitude of the spacecraft, considering its mechanical performance and the possibility of its failure, is a practical solution in the face of a defect in one of the wheels. In this article, the optimal control of the spacecraft, which has four reaction wheels, is investigated. Controlling the attitude of a spacecraft with just two reaction wheels is a significant issue that conventional controllers are not able to do. Therefore, the use of nonlinear model-based predictive controller is used to control the attitude of this spacecraft and compared with optimal nonlinear control in a discrete-time comparison, which satisfies the acceptable results.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; Ahmad Ebrahimi
Volume 14, Issue 3 , September 2021, , Pages 15-22
Abstract
Turbulence in the spacecraft tanks has undesirable effects during maneuvers. Therefore, considering the importance of the correct orbit maneuver to reach the target orbit, it is necessary to model and select a proper method to control it before performing the orbital maneuvers. In this paper, by using ...
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Turbulence in the spacecraft tanks has undesirable effects during maneuvers. Therefore, considering the importance of the correct orbit maneuver to reach the target orbit, it is necessary to model and select a proper method to control it before performing the orbital maneuvers. In this paper, by using a new method for modeling turbulence in reservoirs and for the first time, spacecraft attitude control and turbulence control are simulated using this model. Fuel turbulence is modeled using a moving pulsed ball model, and the whole system's dynamic equations are derived using Krishehoff equations. The maneuver of the spacecraft and the motion of the moving pulsed ball is considered in the plane; therefore, the spacecraft and pulsed ball system will have four degrees of freedom. simulation results show successful modeling and simultaneous control of turbulence and situation
Space subsystems design: (navigation, control, structure and…)
Milad َAzimi; Samad Moradi
Volume 14, Issue 3 , September 2021, , Pages 51-63
Abstract
The free and forced vibration analysis of a rotating large flexible structure with a single crack is investigated using the Homotopy Perturbation Method (HPM). The crack is modeled with a torsional spring element on a structure that follows the Euler-Bernoulli theory. The nonlinear equations of motion ...
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The free and forced vibration analysis of a rotating large flexible structure with a single crack is investigated using the Homotopy Perturbation Method (HPM). The crack is modeled with a torsional spring element on a structure that follows the Euler-Bernoulli theory. The nonlinear equations of motion of the co-rotational system considering centrifugal forces are derived using the calculus of variation and the Assumed Mode Method (AMM). Applying the Galerkin method, the spatial domain is extracted and the time domain is transformed into a second-order nonlinear differential equation. The results of time response, phase plane, and bifurcation diagrams for different functional parameters variations such as base angular velocity, crack position and stiffness have been analyzed. Moreover, it is shown that as the base angular velocity increases, a tensile force appears along the cracked structure axis, stiff it, and shifts the backbone to the right, this can highly affect the nonlinear features of the system.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; Nazanin Safaei Hashekvaei
Volume 14, Issue 2 , June 2021, , Pages 77-88
Abstract
Adaptive control technique is taken into consideration because of overcoming the problem of existence of uncertainties in the space missions. In this paper, a novel optimal direct adaptive control technique which is based on Markov parameters is presented. In this technique, the system's performance ...
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Adaptive control technique is taken into consideration because of overcoming the problem of existence of uncertainties in the space missions. In this paper, a novel optimal direct adaptive control technique which is based on Markov parameters is presented. In this technique, the system's performance is expressed based on rotation matrices, and this method doesn't have a singularity problem. The problem of satellite attitude control using this method and nonlinear thruster actuator in existence of uncertainty in moment of inertia is analyzed. The novel adaptive controller using on-off thrusters is robust to inertia changes. In this paper, a mamdani fuzzy logic is used to schedule the gains of PD control method, and the satellite attitude control problem using a fuzzy controller is simulated. With considering the settling and rise times, it's shown that the fuzzy controller is better than the presented adaptive controller. Also, the problem of satellite attitude control using the novel adaptive controller in presence of a constant disturbance is analyzed, and simulation results illustrate that the new adaptive control is robust to a constant disturbance.
Space subsystems design: (navigation, control, structure and…)
Mahdi Jafari Nadoushan; Kosar Aramkhah
Volume 14, Issue 1 , March 2021, , Pages 1-13
Abstract
In this paper, the dumbbell model is used for gravity field of asteroid 216 Kleopatra. Utilizing the model results in governing equations of motion of a spacecraft around an asteroid similar to those of motion of a spacecraft in the restricted circular three-body problem. The equilibrium points and Jacobi ...
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In this paper, the dumbbell model is used for gravity field of asteroid 216 Kleopatra. Utilizing the model results in governing equations of motion of a spacecraft around an asteroid similar to those of motion of a spacecraft in the restricted circular three-body problem. The equilibrium points and Jacobi regions are calculated and symmetric periodic orbits are computed utilizing grid search and shooting methods. The xz-plane is considered as the symmetry plane. Stability of the periodic orbits is evaluated by Floquet theory that shows all the computed orbits are unstable. By adding the solar radiation pressure term to the governing equations of motion, the symmetric periodic orbits are recomputed and index of stability are examined. The results show that the solar radiation pressure, though change the values of the index of stability, does not affect the stability of computed periodic orbits. Therefore, stabilizing a spacecraft on the unstable periodic orbits requires controlling spacecraft.
Space subsystems design: (navigation, control, structure and…)
Ehsan Maani; Peyman Nikpey; Ehsan Zabihian
Volume 14, Issue 1 , March 2021, , Pages 23-33
Abstract
n GEO communicational satellites, thrusts are being used for many missions such as station keeping, longitude change maneuver and actuators desaturation. These types of actuators need fuel and its estimation requires many complicated calculations. In this paper, a novel method based on availed data for ...
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n GEO communicational satellites, thrusts are being used for many missions such as station keeping, longitude change maneuver and actuators desaturation. These types of actuators need fuel and its estimation requires many complicated calculations. In this paper, a novel method based on availed data for previous satellites is proposed for estimation of satellite fuel mass and it does not need mathematical modeling of satellite dynamics. Two methods, least square method and artificial intelligence, are used to this aim and two mathematical model are proposed for satellite fuel mass estimation. By applying the models to several previous satellites, it is shown that the models have lower than 5% average error. The proposed method in this paper is quick and accurate and can be utilized for GEO satellites feasibility study and conceptual design
Space subsystems design: (navigation, control, structure and…)
S. Hamid Jalali-Naini; omid Omidi Hemmat
Volume 14, Issue 1 , March 2021, , Pages 55-64
Abstract
This paper presents a modification to a type of Pulse-width Pulse-Frequency (PWPF) Modulator utilized an integrator block. In this modulator that called here as "Integral Pulse-Width Pulse-Frequency (IPWPF)," an integrator is used instead of the first-order low-pass filter. To improve the performance ...
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This paper presents a modification to a type of Pulse-width Pulse-Frequency (PWPF) Modulator utilized an integrator block. In this modulator that called here as "Integral Pulse-Width Pulse-Frequency (IPWPF)," an integrator is used instead of the first-order low-pass filter. To improve the performance of the control system, the modulator is modified by using a logical circuit in order to reset the output of the integrator. In this logical circuit, if the error signal becomes less than a specified small value, the integrator will be reset, that is, "Small Error-Reset Integrator (SE-RI)." The modification is applied to the stabilization and pointing modes. In stabilization mode, the control gain is obtained analytically such that the angular rate of the satellite becomes zero or less than a specific percentage of its initial value by a single pulse. Simulation results show that the performance of the modified IPWPF is comparable with that of PWPF in pointing mode.
Space subsystems design: (navigation, control, structure and…)
Mohammad Chiniforoushan; Mahdi Mortazavi; kamran raissi
Volume 14, Issue 1 , March 2021, , Pages 77-92
Abstract
The problem of jointly controlling relative attitude and position of spacecraft in the presence of actuator fault is investigated in this paper. Following a description about drawbacks and limitations of the existing models and the control approaches based on them, a new formulation of the spacecraft ...
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The problem of jointly controlling relative attitude and position of spacecraft in the presence of actuator fault is investigated in this paper. Following a description about drawbacks and limitations of the existing models and the control approaches based on them, a new formulation of the spacecraft relative motion is provided. Subsequently, the subspace predictive control framework, which is a powerful model-free approach, is extended in several dimensions, that is, adaptive nonlinear control, tolerance against abrupt faults and control allocation. Based on this generalized framework, three distinct data-driven fault-tolerant controllers for coupled, nonlinear and time-variant plants are developed. From the viewpoint of fault diagnosis, the only requirement of the control structure is to detect the occurrence time of faults. Furthermore, an internal data-driven fault diagnosis capability is introduced, which makes the control structure completely self-sufficient. The three controllers are then designed to solve the aforementioned problem, and their efficiency are verified via a multidimensional simulation scenario.
Space subsystems design: (navigation, control, structure and…)
S. Hamid Jalali Naini; Ali Arabian Arani
Volume 13, Issue 4 , December 2020, , Pages 1-13
Abstract
In this paper, a modified proportional navigation (PN) with weighted combination of linear acceleration and line-of-sight (LOS) acceleration feedback is suggested. For this purpose, a comprehensive miss distance analysis is carried out for PN with linear acceletation feedback and PN with LOS acceleration ...
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In this paper, a modified proportional navigation (PN) with weighted combination of linear acceleration and line-of-sight (LOS) acceleration feedback is suggested. For this purpose, a comprehensive miss distance analysis is carried out for PN with linear acceletation feedback and PN with LOS acceleration feedback using a fifth-order binomial guidance and control system. The miss distance (MD) due to initial heading error, target acceleration, and seeker noise is separately analysed. As a special case, a modified PN with acceleration feedback using variable gains is suggested based on MD analysis for infra red seekers. The comparison of PN strategies is carried out using an equivalent effective navigation ratio, defined by using LOS rate profile solution. In addition, the first-order optimal guidance law is converted into PN with PD block with variable gains.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; Nazanin Safaei
Volume 13, Issue 4 , December 2020, , Pages 25-35
Abstract
Several novel control techniques have been created as a result of the diversity of researches which are conducted about the problem of satellite attitude control. There are always uncertainties in the problem of satellite attitude control in the space missions. Therefore, Adaptive control is a method ...
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Several novel control techniques have been created as a result of the diversity of researches which are conducted about the problem of satellite attitude control. There are always uncertainties in the problem of satellite attitude control in the space missions. Therefore, Adaptive control is a method which is taken into consideration. High computational volume is one of the problems of adaptive control technique. In this paper, a control technique which is based on optimization concepts is introduced for the problem of satellite angular velocity and attitude control. Also, it's developed based on the three-dimensional special orthogonal group, and it's not faced by a singularity problem. For comparison, the linear quadratic regulator (LQR) control technique is simulated. Finally, the results of the simulations show that the performance of the presented adaptive control technique is optimal, and this method is robust to inertia changes.
Space subsystems design: (navigation, control, structure and…)
Niki Sajjad; Mehran Mirshams; Shahrokh Jaliian
Volume 13, Issue 3 , September 2020, , Pages 51-62
Abstract
This paper presents design, analysis and performance verification test of student microsatellite Attitude Determination and Control Subsystem (ADCS) . ADCS design and implementation procedure contains several various steps. There are four main test levels during simulation called “Model-in-the-Loop”, ...
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This paper presents design, analysis and performance verification test of student microsatellite Attitude Determination and Control Subsystem (ADCS) . ADCS design and implementation procedure contains several various steps. There are four main test levels during simulation called “Model-in-the-Loop”, “Software-in-the-Loop”, “Processor-in-the-Loop” and “Hardware-in-the-Loop”. This paper is a result of scientific and practical research during two years, on the student microsatellite, which is an eight-nation collaboration project among Asia-Pacific universities. In what follows, “Model-in-the-Loop” and “Processor-in-the-Loop” test and simulation will be discussed. The aim of this paper is to illustrate the result of these two tests and validate the ADCS design. In the end, it is demonstrated that designed control algorithms are precise enough to meet the student microsatellite ADCS requirements and they can be used in the next level of microsatellite development.
Space subsystems design: (navigation, control, structure and…)
S. Hamid Jalali-Naini; Ali Arabian Arani
Volume 13, Issue 2 , June 2020, , Pages 1-12
Abstract
In the present work, the performance of True Proportional Navigation (TPN) with different profiles for effective navigation ratio in terms of the relative velocity angle with respect to line-of-sight is investigated due to initial heading errors and target maneuvers. Since an appropriate profile of effective ...
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In the present work, the performance of True Proportional Navigation (TPN) with different profiles for effective navigation ratio in terms of the relative velocity angle with respect to line-of-sight is investigated due to initial heading errors and target maneuvers. Since an appropriate profile of effective navigation ratio for heading error is almost in contrary with the appropriate profile for maneuvering targets, a variable effective navigation ratio in terms of the relative velocity angle and its rate is introduced. In this way, the miss distance (MD) for the first two peaks of the normalized MD graph versus normalized final time, for example under an effective navigation ratio of 4, is reduced together. The analysis is carried out using normalized equations in polar coordinates for perfect and binomial fifth-order control systems without acceleration limit. Due to practical consideration, the effective navigation ratio is tuned and limited between 3 and 5.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; H. Ghanbari
Volume 13, Issue 2 , June 2020, , Pages 79-86
Abstract
In this paper, attitude control of spacecraft in the presence of uncertainties and disturbances has been simulated. Access to rapid maneuver in spacecraft decreased accuracy. Therefore, to enhance the accuracy of spacecraft rapid maneuver and to resist uncertainties the adaptive control L1 is suggested. ...
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In this paper, attitude control of spacecraft in the presence of uncertainties and disturbances has been simulated. Access to rapid maneuver in spacecraft decreased accuracy. Therefore, to enhance the accuracy of spacecraft rapid maneuver and to resist uncertainties the adaptive control L1 is suggested. The controller is able to control the attitude of the spacecraft due to rapid adaptation and robustness against uncertainties simultaneously. In this paper, an adaptive control of L1 is compared with reference model. The dynamics of the multi-input-multi-output system. Simulation results show the desired performance of the L1 controller.
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.