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 systems design (spacecraft, satellites, space stations and their equipment)
Vahid Bohlouri; Hossein Haghighi; Soheil Seyedzamani
Volume 12, Issue 4 , December 2019, , Pages 57-67
Abstract
In this paper, damping mode of a satellite attitude control is designed and implemented using magnetic actuators in software /hardware-in-the-loop testbed. To this end, the equivalent of Earth’s magnetic field is designed using Helmholtz coil, frictionless is made by air-bearing, and algorithms ...
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In this paper, damping mode of a satellite attitude control is designed and implemented using magnetic actuators in software /hardware-in-the-loop testbed. To this end, the equivalent of Earth’s magnetic field is designed using Helmholtz coil, frictionless is made by air-bearing, and algorithms are developed on designed control board. By measuring the Earth’s magnetic field, actuator commands are generated by the damping algorithm then braking torque is produced. Some applied restrictions and special requirements such as non-simultaneous operation between magnetic sensor and magnetic actuators, air-bearing friction, initial angular velocity are considered. By identifying the air-bearing frictional model, the results are compared in software/hardware-in-the-loop. The compared results show that the ability of the designed system to perform damping mode.
Vahid Bohlouri; Hosein Haghighi; Samane Kaviri; Marzieh Taghinezhad; ehsan maani; Soheil Seyedzamani
Volume 12, Issue 2 , September 2019, , Pages 55-70
Abstract
In this paper, the design and implementation of hardware-in-the-loop (HIL) test-bed for spacecraft attitude control are presented with respect to the practical consideration. This test-bed includes an air bearing 3-DOF table, Helmholtz coil, sun simulator, orbit simulator, reaction wheels and torqrods ...
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In this paper, the design and implementation of hardware-in-the-loop (HIL) test-bed for spacecraft attitude control are presented with respect to the practical consideration. This test-bed includes an air bearing 3-DOF table, Helmholtz coil, sun simulator, orbit simulator, reaction wheels and torqrods as actuators, gyro, GPS, AHRS, magnetometer, and processing board. In addition, online monitoring of attitude and orbit position in LabVIEW and Celestia software, data telemetry, battery package and power distribution board are developed in this case. Using this test-bed, different operational modes are evaluated and verified for satellite attitude control. The experimental results of damping mode show that the capability of decreasing the angular velocity to the desired value (0.3 deg/s). Moreover, a torque simulator to apply the disturbances and test of propulsion scenarios, online telemetry with ground station, near-optimal design of Helmholtz coil are the advantages of this test-bed.
S.Hamid Jalali-Naini
Volume 11, Issue 1 , June 2018, , Pages 13-29
Abstract
In this study, the preferred regions of Pulse-Width Pulse-Frequency Modulator (PWPFM) are obtained analytically for the static analysis. For this purpose, a comprehensive parametric study is carried out based on the two performance indices of fuel consumption and the number of thruster firings. The preferred ...
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In this study, the preferred regions of Pulse-Width Pulse-Frequency Modulator (PWPFM) are obtained analytically for the static analysis. For this purpose, a comprehensive parametric study is carried out based on the two performance indices of fuel consumption and the number of thruster firings. The preferred regions are presented by normalized relations and curves. Moreover, the exact analytical solutions of the two performance indices are obtained for a class of modulators with the assumption of constant inputs. The advantages of the present study are non dimensional analysis and obtaining the preferred regions in terms of each others, resulting in more accurate regions as opposed to inequality relations using constant values for a specified input signal. In addition, in the case of specified minimum pulse width (having the update frequency and thruster time constant), determining the preferred regions becomes more limited. In this regard, useful relations and curves based on the maximum possible value for the number of the thruster firings are derived and presented.
Vahid Bohlouri; S.H Jalali-Naini
Volume 10, Issue 4 , March 2018, , Pages 55-66
Abstract
his paper suggests arobust optimization algorithm for the design of the satellite attitude control system in order to increase the robustness of the performance under uncertainties. A single-axis on-off attitude control with rigid dynamics is considered using Schmitt-Trigger and PID controller. The model ...
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his paper suggests arobust optimization algorithm for the design of the satellite attitude control system in order to increase the robustness of the performance under uncertainties. A single-axis on-off attitude control with rigid dynamics is considered using Schmitt-Trigger and PID controller. The model uncertainties include the moment of inertia, thrust level, thruster delay and theexternal disturbance amplitude.A weighted combination of expected value and standard deviation of pointing error is considered as an objective function for the robust optimization. The numerical solutions show that the robust optimization reduces the variations of the objective function, i.e. it increases the robustness of the system performance compared to the deterministic optimization.
Reza Mohsenipour; Mehrzad Nasirian; Abdol Reza Kashaninia; Mohsen Fathi
Volume 8, Issue 1 , April 2015, , Pages 61-71
Abstract
Increasing in dimensions of the satellites and using light movingstructures, causes flexibility and uncertainty in their models. Therefor to control the attitude of the satellites, should use those methods which resist against the plant’s model uncertainty and could reject the disturbance and the ...
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Increasing in dimensions of the satellites and using light movingstructures, causes flexibility and uncertainty in their models. Therefor to control the attitude of the satellites, should use those methods which resist against the plant’s model uncertainty and could reject the disturbance and the measurementnoise. One of these methods is the robust control. But due to the location of the poles in the dynamic equations of the satellite, the design of robust controllers faces some problems. In this paper, using aninternal feedback, the dynamic equations are changed so that the poles are located in a more proper place. And then,considering flexibility affects as uncertainty and also, uncertainty in inertia matrix of the satellite, a H∞ controller, and finally to improve the performance, a µ-controller will be designed for the new equations. But these two controllers will be analyzed and compared for the primary equations and not for the new equations.For comparison, a classical controller is also designed forthe primary system.
A.A Nikkhah; J. Tayebi; J. Roshanian
Volume 7, Issue 2 , July 2014, , Pages 1-9
Abstract
In this paper attitude control system of nanosatellite based on Single Gimbal Control Moment Gyroscope (SGCMG) is presented. A LQR/LQG method is developed for stability of satellite and a feedback quaternion strategy is used for maneuvering mode. In the stabilization mode LQR/LQG controllers ...
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In this paper attitude control system of nanosatellite based on Single Gimbal Control Moment Gyroscope (SGCMG) is presented. A LQR/LQG method is developed for stability of satellite and a feedback quaternion strategy is used for maneuvering mode. In the stabilization mode LQR/LQG controllers are designed with linearization of nonlinear dynamic equation of satellite and control moment gyroscope, so that in other reseach didn’t use this controller in the stabilization mode of this system. In the maneuvering mode a feedback quaternion controller applyed for nonlinear system. Numerical simulations are provided to show the efficiency of the proposed controller for a nanosatellite with four single gimbal control moment gyroscope pyramid cluster. Results of simulations shown that LQR/LQG method is more accurate in compared with feedback quaternion controller.
A.H. Taghavi; A. Soleymani; T. Shojaee
Volume 7, Issue 2 , July 2014, , Pages 63-74
Abstract
Recently, new actuators known as fluidic momentum controllers (FMC) have been proposed for satellite attitude control. This actuator has many advantages such as high applied torque to weight ratio, easiness in assembly, low transmitted vibration and so on respect to the other momentum exchange devices ...
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Recently, new actuators known as fluidic momentum controllers (FMC) have been proposed for satellite attitude control. This actuator has many advantages such as high applied torque to weight ratio, easiness in assembly, low transmitted vibration and so on respect to the other momentum exchange devices like momentum/reaction wheels or CMGs. However, one of the main problems in implementing such actuators is complexity in mathematic modeling of them. This issue makes many researchers to use a simplified model for control system designing without to consider uncertainty in this simplified model. In this paper for eliminating of this problem, an adaptive sliding mode control (SMC) has been used in this article. This control method is not also robust respect to uncertainties but also can estimate over threshold of them without necessity to use larger and heavier actuators to be sure of satellite stability. According to the results, we can observe that proposed control system is capable to reach satellite to the desire attitude in minimum time and without overshoot.
M M. Moghaddam; A Salimi
Volume 1, Issue 1 , September 2008, , Pages 37-45
Abstract
This Paper presents a dynamic model of a micro-satellite in Mesbah class. At this model aerodynamic torque and solar radiation pressure torques are considered as disturbance torques. Gravity gradient torque is assumed as stabilizing torque and acts as a passive controller. Magnetic torquers act as an ...
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This Paper presents a dynamic model of a micro-satellite in Mesbah class. At this model aerodynamic torque and solar radiation pressure torques are considered as disturbance torques. Gravity gradient torque is assumed as stabilizing torque and acts as a passive controller. Magnetic torquers act as an active controller. There are three methods of optimization of power consumption; first using LQR controller, secondly using the mapping function (which is suggested to ensure that the generated magnetic moment by the coils is perpendicular to the local magnetic field vector), and finally powering on control system over the earth stations only for the purpose of power saving.
