GPS and navigation GPS)، GLONASS، GALILEO
Reza Ghasrizadeh; Amir Ali Nikkhah
Volume 16, Issue 3 , September 2023, , Pages 37-49
Abstract
This paper presents a solution for detecting and recovery for the spoof error of GPS receiver signals, in order to increase the accuracy of the navigation system integrating inertial systems with GPS signals. integrated inertial navigation and GPS data has many advantages. However, due to the weakness ...
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This paper presents a solution for detecting and recovery for the spoof error of GPS receiver signals, in order to increase the accuracy of the navigation system integrating inertial systems with GPS signals. integrated inertial navigation and GPS data has many advantages. However, due to the weakness of satellite signals against jamming and spoof attacks of providing analytical solutions, they have a special place in improving Kalman filter estimation compared to hardware solutions. In this paper, a new method for loosely coupled of INS/GPS is presented, in which the steady state of Kalman gain parameters is used during deception detection and recovery. With the gain parameters of the Kalman filter tending to constant values, with the aim of correcting and predicting the error of state variables, it can be used to detection GPS spoofed data. It can be detected by spoof in the GPS receiver signal when couple with inertial waves through the amount of Kalman gain fluctuations. In the case of closed loop, the Kalman gain matrix denominators tend to a constant value, and in case of deception, this function is associated with many fluctuations. By using dynamic weighting, the effect of errors caused by these attacks is recovered.
space sciences and exploration
Farshad Somayehee; Amir Ali Nikkhah; Jafar Roshanian
Volume 14, Issue 2 , June 2021, , Pages 103-110
Abstract
In this paper, a new algorithm for determining the density of scattered data at the surface of the sphere is presented and then the proposed algorithm along with Geodesic Weighted K-Means clustering and Deluany triangulation are used to make uniform star catalogs. Comparison of the results with the results ...
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In this paper, a new algorithm for determining the density of scattered data at the surface of the sphere is presented and then the proposed algorithm along with Geodesic Weighted K-Means clustering and Deluany triangulation are used to make uniform star catalogs. Comparison of the results with the results of other related articles shows that the proposed algorithm resulted in a significant decrease in the probability of observing a large number of stars in all simulated star sensor fields of view. This improvement is due to the uniformity of the star catalog, especially in the celestial sphere poles due to the proposed density determination algorithm. On the other hand, the use of a proper data density algorithm has increased the likelihood of observing a few stars (such as 3 or 5) in all fields of view used in the Monte Carlo simulation.
GPS and navigation GPS)، GLONASS، GALILEO
Reza Ghasrizadeh; Amirali Nikkhah
Volume 13, Issue 4 , December 2020, , Pages 81-90
Abstract
This paper presents a new approach to eliminating noise and disturbances in the corse alignment process for inertial navigation systemsBecause of extreme fluctuations and quasi-static environments, the corse alignment process often involves a lot of errors and noise. Initially, the coarse alignment process ...
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This paper presents a new approach to eliminating noise and disturbances in the corse alignment process for inertial navigation systemsBecause of extreme fluctuations and quasi-static environments, the corse alignment process often involves a lot of errors and noise. Initially, the coarse alignment process for inertial navigation systems is described exhaustively and then, with the assumption of disturbances and noise, we attempt to nudify to improve and initialize the initialization accuracy. Subsequently, introducing the filtering characteristics of the digital filter for the mutation , Due to the deletion of some of the sensor's main data, identifies the missing parameters and estimates the state variables using the Kalman filter matrix based on the variance of the data error. Identifying the missing parameters of the transformation matrix in the coordinate system using the Kalman filter Matrix is the innovation of this paper, which leads to improved note coarse alignment will be inertial navigation systems.
Amie ali Nikkhah; farsahd somayehee; Jafar Roshanian
Volume 11, Issue 3 , December 2018, , Pages 21-32
Abstract
In this paper, the aim is to simulate night-sky images for use in star-sensor designing software. For this purpose, a comprehensive and precise algorithm was developed to simulate night sky images based on the ideal pinhole method and the use of Gaussian distribution functions. Then, in order to create ...
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In this paper, the aim is to simulate night-sky images for use in star-sensor designing software. For this purpose, a comprehensive and precise algorithm was developed to simulate night sky images based on the ideal pinhole method and the use of Gaussian distribution functions. Then, in order to create more realism, sources of random and systematic errors, the elongated images due to the high dynamics of the platform, as well as the asymmetric back-lighting of the moon, the sun, and the planets of the solar system have been simulated. Finally, considering the importance of realism in the problem-solving simulation approach, the use of precision ray tracking method as an alternative to the ideal pinhole method is suggested.
Mojtaba Alavi pour; Amir Ali Nikkhah; Jafar Roshanian
Volume 9, Issue 4 , April 2017, , Pages 13-25
Abstract
In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch ...
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In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch function for obtaining the switching times, which complicates the numerical solution of the optimal control problem, the presented algorithm uses a simple and optimal process to find the burn and coast times. To solve the tow point boundary value problem, an improved indirect shooting method with high performance is used which in addition to having higher precision, converges very fast to the desired condition.
S. M. SalehiAmiri; A. A. Nikkhah; H. Nobahari
Volume 7, Issue 3 , October 2014, , Pages 1-8
Abstract
This paper presents a method for calculation the non observable states in alignment and calibration process in gimballed inertial navigation system, using estimation method in static linear system and heuristic optimization algorithms. The non observable constant states in alignment process are horizontal ...
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This paper presents a method for calculation the non observable states in alignment and calibration process in gimballed inertial navigation system, using estimation method in static linear system and heuristic optimization algorithms. The non observable constant states in alignment process are horizontal accelerometers biases and azimuth gyroscope drift. In order to use the estimation method in static system, the observations are recorded in necessary time duration to convert the dynamic alignment process to static process. Simulation results show appropriate accuracy of purposed method for calculation the non observable states. Although the case study is the alignment process for gimballed inertial navigation system, the purposed method can be used for calibration and alignment of any inertial navigation systems.In purposed method the genetic heuristic optimization algorithm is used.
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.
R. Zardashti; A. A. Nikkhah
Volume 2, Issue 3 , December 2009, , Pages 13-17
Abstract
In this paper, Design of flight trajectory in unpowered phase namely “Coast Phase” which is important in energy reduction in transition orbit of spacecrafts and launch vehicles is considered. To this aim, the velocity impulse at both sides of the transition phase (between initial and final ...
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In this paper, Design of flight trajectory in unpowered phase namely “Coast Phase” which is important in energy reduction in transition orbit of spacecrafts and launch vehicles is considered. To this aim, the velocity impulse at both sides of the transition phase (between initial and final orbits) is described as a parametric function of the geometry of the path. Then the optimal coasting trajectory is proposed using simple minimization techniques like Fibonacci Search Method and a Velocity-Required Based Steering technique simultaneously. A numerical study is performed using a three stage launch vehicle with a coast phase between second and third stages to show that the proposed technique is capable to produce optimum transition trajectory and since it is accompanied by guidance technique could be used as an online technique.
S. H. Miri Roknabadi; S. M. Mirshams; A. A. Nikkhah
Volume 2, Issue 3 , December 2009, , Pages 35-42
Abstract
This paper presents an optimal attitude maneuver by means of Reaction Wheels to achieve desired attitude for a Satellite. At first, Dynamic Equations of motion for a satellite with three Reaction Wheels as its active actuators has been educed, and then State Equations of this system has been obtained. ...
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This paper presents an optimal attitude maneuver by means of Reaction Wheels to achieve desired attitude for a Satellite. At first, Dynamic Equations of motion for a satellite with three Reaction Wheels as its active actuators has been educed, and then State Equations of this system has been obtained. In derivation of equations, coupling of Reaction Wheel electrical equations with dynamic equations of satellite motion, and Reaction wheel saturation avoidance approaches are considered. Then an optimal attitude control with the LQR method has exerted for a distinct satellite by its Reaction Wheels. As a result of simulation has presented an optimal effort by calculated Gain matrix to achieve desired attitude for chosen Satellite. It shows that satellite becomes stable in desired attitude with a low energy and time consumption.
S.H. Miri Roknabadi; M. Mirshams; A. A. Nikkhah
Volume 2, Issue 2 , July 2009, , Pages 61-68
Abstract
This paper presents a technical note of mathematic model, design and manufacturing steps of a Reaction Wheel, one of the most important active actuators of satellite. After that Reaction Wheels are tested for the satellite simulator of K.N.Toosi University of Technology, Iran. There were some requirements ...
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This paper presents a technical note of mathematic model, design and manufacturing steps of a Reaction Wheel, one of the most important active actuators of satellite. After that Reaction Wheels are tested for the satellite simulator of K.N.Toosi University of Technology, Iran. There were some requirements and restrictions such as needed maximum torque and control accuracy for attitude maneuver, receivable power, voltage and current. Accordingly fundamental components of Reaction Wheel have been designed and selected. Wheel, motor, bearings and retentive are the significant components. At the rest of the paper, the substantial parameters of the Reaction Wheels are confirmed by a new test set. The results of test guarantee a satisfactory stabilization and accurate maneuver.
