Darwish Alshaddadi; M.H. Arvan; A.R. Vali
Volume 9, Issue 2 , September 2012
Abstract
An accurate calibration of inertial measurement unit errors is increasingly important
as the inertial navigation system requirements become more stringent.
Developing calibration methods that use as less as possible of IMU signals has
...
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An accurate calibration of inertial measurement unit errors is increasingly important
as the inertial navigation system requirements become more stringent.
Developing calibration methods that use as less as possible of IMU signals has
6-DOF gimballed IMU in space-stabilized mode is presented. It is considered
as held stationary in the test location incorporating 15 different error sources,
including accelerometers bias, scale factor error, gyros drift, initial alignment
error, and IMU case installation error. Using kinematic relations between IMU
platform, IMU body, and IMU platform centered inertial reference frame, six
differential equations of the only system-level IMU velocity and gimbal angle
are derived. Then the extracted model is validated for error-free case using Sim-
Mechanics MATLAB SIMULINK tools to evaluate the introduced mathematical
model. Simulation results for 24 hours point out the correctness of the developed
model in error-free case. The IMU error analysis methodology incorporates
! andquot;# !
gimbal angle measurements taken during one and a half hour with 9 platform attitudes
test to estimate IMU error sources. Without the need to install IMU at rotating
table, different platform attitudes are achieved using consequent rotations
of gimbals. IMU error sources estimation is accomplished off-line. This paper
describes the design and test results of a new gimballed IMU calibration method
without using a rotating table, and error model development methodology formulated
to support the design and test of EKF algorithm and two optimal smoothers:
forward-backward and RTS. Results obtained from EKF implementation indicate
that the technique is comprehensive and accurate, and requires less specialized
test equipments. Also, results show that constant states are not smooth-able. Ad-
M. Manshadi; A. Sharafi; M.H. Soltani
Volume 9, Issue 2 , September 2012, Pages 15-24
Abstract
An extensive experimental investigation is conducted to study the effect of canard position relative to the fuselage reference line on the aerodynamic forces of a fighter type configuration model. Aerodynamic forces at different flight conditions are measured in a subsonic wind tunnel. The wing and the ...
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An extensive experimental investigation is conducted to study the effect of canard position relative to the fuselage reference line on the aerodynamic forces of a fighter type configuration model. Aerodynamic forces at different flight conditions are measured in a subsonic wind tunnel. The wing and the canard have triquetrous shapes. Experiments are conducted at Reynolds number of 342209 and at 0 to 40 degree angles of attack. The results show that canard increases the lift and drag forces while it decreases the static stability of the model. The canard at itandrsquo;s up position increases the aerodynamic forces and decreases the static stability i.e., superior maneuver capability. Furthermore, when the forward position of the canard is considered, both lift and drag are increased; however, the overall aerodynamic efficiency and also more static stability are improved. The canard at up and forward position respect to the wing-body is an appropriate selection for the best performance at moderate to high angles of attack among the various wing-canard-body configurations.
S.H. Jalali Naini
Volume 9, Issue 2 , September 2012
Abstract
In this paper, an approximate solution of sensitivity matrix of required velocity with final velocity constraint is derived using a piecewise linear gravity assumption. The total flight time is also fixed for the problem. Simulation results show the accuracy of the method. Increasing the midway points ...
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In this paper, an approximate solution of sensitivity matrix of required velocity with final velocity constraint is derived using a piecewise linear gravity assumption. The total flight time is also fixed for the problem. Simulation results show the accuracy of the method. Increasing the midway points for linearization, increases the accuracy of the solution, which this, in turn, depends on the total flight time.
Abolfazl Mokhtari; A.A. Nikkhah; Mahdi Sabze Parvar; A.R. Novinzadeh
Volume 9, Issue 2 , September 2012
Abstract
There is a growing interest in the modeling and control of model helicopters using nonlinear dynamic models and nonlinear control. Application of a new intelligent control approach called Brain Emotional Learning Based Intelligent Controller (BELBIC) to design autopilot for an autonomous helicopter is ...
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There is a growing interest in the modeling and control of model helicopters using nonlinear dynamic models and nonlinear control. Application of a new intelligent control approach called Brain Emotional Learning Based Intelligent Controller (BELBIC) to design autopilot for an autonomous helicopter is addressed in this paper. This controller is applied to a nonlinear model of a helicopter. This methodology has been previously proved to present robust characteristics against disturbances and uncertainties existing in the system. The simulation results of this controller has compared with a PID controller. The policies for PID and BELBIC controller are the same. The controller design goal is that the helicopter tracks a special maneuver to reach the commanded height and heading. The performance of the controllers is also evaluated for robustness against perturbations with inserting a high frequency disturbance. Simulation results show a desirable performance in both tracking and improved control signal by using BELBIC controller.
M. Mortazavi; A. Askari
Volume 9, Issue 2 , September 2012
Abstract
Improvement of the launch phase of a jet powered Unmanned Aerial Vehicle (UAV) with Jet Assisted Take Off (JATO), has been the subject of attention in the UAV industry. Use of flight simulation tools reduces the risk and required some amount of flight testing for complex aerospace systems. Full nonlinear ...
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Improvement of the launch phase of a jet powered Unmanned Aerial Vehicle (UAV) with Jet Assisted Take Off (JATO), has been the subject of attention in the UAV industry. Use of flight simulation tools reduces the risk and required some amount of flight testing for complex aerospace systems. Full nonlinear equations of motion are used to study and simulate this maneuver and three case studies of their application to UAV launch phase problems are presented. Attempt was made to explain some aspects that were not definite in the test by simulation. The result of the examination was satisfactory. The second and third examples involve the flight test of the UAV. These two applications are typical of launch phase problems. The second example demonstrated a good applicability of this technique to improve and increase the stability of the UAV during launch. In the third example, the UAV in the presence of headwind showed that simulation and real test had a good coincidence.
Ali Ghamarian; H.R. Zarei
Volume 9, Issue 2 , September 2012
Abstract
This paper investigates the parametric study of the empty and foam-filled end-capped tubes under quasi static and dynamic loadings. The numerical crash analysis of the empty and foam-filled tubes was performed using the explicit finite element code ABAQUS- explicit. Satisfactory agreements were generally ...
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This paper investigates the parametric study of the empty and foam-filled end-capped tubes under quasi static and dynamic loadings. The numerical crash analysis of the empty and foam-filled tubes was performed using the explicit finite element code ABAQUS- explicit. Satisfactory agreements were generally achieved between the numerical and experimental results. In order to determine the crash behavior of the empty and foam filled tubes under dynamic impact, the dynamic amplification factor which relates the quasi-static results to dynamic responses was determined. The influence of the various parameters on the dynamic responses is investigated and then compared with the quasi-static results.
M. saraf; M.R. Mosavi; K. Mohammadi
Volume 9, Issue 2 , September 2012
Abstract
In this study, two novel learning algorithms have been applied on Radial Basis Function Neural Network (RBFNN) to approximate the functions with high non-linear order. The Probabilistic Evolutionary (PE) and Gaussian Mixture Model (GMM) techniques are proposed to significantly minimize the error functions. ...
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In this study, two novel learning algorithms have been applied on Radial Basis Function Neural Network (RBFNN) to approximate the functions with high non-linear order. The Probabilistic Evolutionary (PE) and Gaussian Mixture Model (GMM) techniques are proposed to significantly minimize the error functions. The main idea is concerning the various strategies to optimize the procedure of Gradient Descent (GD) in terms of the input feature vectors. The probability density of all feature vectors can help to optimize the learning rates of RBFNN by applying GMM. Another possibility is to utilize the Evolutionary Algorithms (EAs) to find the optimum solution. However, EAs often behave randomly which canandrsquo;t be mathematically controlled. So, a combined RBFNN based on novel PE algorithm has been proposed which has a soft behavior through the learning of non-linear function. The PE algorithm defines the occurrence probability of local minima in the space of extracted features as a Gaussian distribution correspondence to each chromosome. Then, it estimates the entire probabilities of local minima in an iterative procedure. These techniques have been utilized in the application of robust satellites subset selection. Geometric Dilution of Precision (GDOP) is the main factor to estimate the strength of goodness of each satellites subset. Then, the subset with the lowest value has been selected for improving the positioning performance, but it is so non-linear and has computational burden to navigation systems. These techniques have been implemented and the results on measured GPS data demonstrate that it significantly track the non-linearity of GPS GDOP comparison with the other conventional approaches.
