Aerospace Science and Technology
Jafar Roshanian; Ehsan Rahimzade
Abstract
In this research, new adaptation law for updating parameters of the model reference adaptive control and the model reference adaptive control with feedback integrators for a specific class of nonlinear systems with additive parametric uncertainty are presented. The innovation presented in this paper ...
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In this research, new adaptation law for updating parameters of the model reference adaptive control and the model reference adaptive control with feedback integrators for a specific class of nonlinear systems with additive parametric uncertainty are presented. The innovation presented in this paper is the consideration of a new form for Lyapunov functions candidate to prove the stability of the closed-loop system. In general, Lyapunov functions candidate, which is used to prove stability and to derive rules for updating control parameters, include two sets of quadratic expressions. The first quadratic expression contains the trajectory tracking error and the second category includes the error of estimating the controller parameters. In this research, it is proved that by selecting quadratic expressions including the variable of trajectory tracking error in the form of power series, a new adaptation law is obtained that includes quadratic expressions in terms of the variable of tracking error in the form of power series. This type of adaptation law can be considered as an adaptation law derived from quadratic Lyapunov functions, except that the gain adaptation matrix parameters vary with time. It has been shown that by using an adaptive controller with a feedback integrator, the tracking error tends to zero faster and the flying object roll angle tracks the reference trajectory after a shorter time. In order to evaluate the control performance of the designed controllers, the system of one degree of freedom of the Wing Rock phenomenon has been used.
Aerospace Science and Technology
Ali Motamedi; Abolghasem Naghash
Abstract
The purpose of this paper is to present a Multi-Input Multi-Output (MIMO) linear controller based on the eigenstructure assignment method for a fixed-wing Unmanned Aerial Vehicle (UAV) in longitudinal and lateral-directional channels. To this end, a six degree-of-freedom model of the aerial vehicle is ...
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The purpose of this paper is to present a Multi-Input Multi-Output (MIMO) linear controller based on the eigenstructure assignment method for a fixed-wing Unmanned Aerial Vehicle (UAV) in longitudinal and lateral-directional channels. To this end, a six degree-of-freedom model of the aerial vehicle is considered, where dynamic modes of the system in each channel are analyzed, and the effect of each dynamic mode on state and output variables of the system is investigated. Then, the eigenvalue and eigenvector parameters of the designed controller are appropriately assigned for the system dynamic modes in each channel. In addition, the system requirements of each dynamic mode are satisfied with the proposed controller, and the adverse interaction between the system state variables is minimized. The capability and effectiveness of the designed controller in a desired maneuver are demonstrated with a nonlinear model simulation of a fixed-wing UAV. In this regard, the results in longitudinal and lateral-directional channels are presented.
Aerospace Science and Technology
Ehsan Abbasali; Amir reza Kosari; Majid Bakhteiari
Abstract
In this paper, the effect of perturbations of oblate primaries in the Circular Restricted Three-Body Problem is studied, and the equations of satellite orbital motion in the Circular Restricted Three-Body Problem are developed by employing Lagrangian mechanics. Since the equations have no closed-form ...
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In this paper, the effect of perturbations of oblate primaries in the Circular Restricted Three-Body Problem is studied, and the equations of satellite orbital motion in the Circular Restricted Three-Body Problem are developed by employing Lagrangian mechanics. Since the equations have no closed-form solution and numerical methods must be applied, the problem can have different periodic or quasi-periodic solutions depending on the equation's initial conditions of orbital state parameters. For this purpose, an algorithm named “orbital correction algorithm” is proposed to correct the initial conditions of orbital state parameters. The limited number of periodic orbits in the study environment indicates the algorithm’s need for suitable initial guesses as input. In the present paper, suitable initial guesses for orbital state parameters are selected from the third-order approximation of the Unperturbed Circular Restricted Three-Body Problem’s periodic solutions, increasing the chance of obtaining desired periodic solutions. The obtained perturbed and unperturbed periodic orbits are compared in order to understand the effect of perturbations. Adding the perturbations brings the study environment closer to the real environment and helps understand satellites' natural motion.
Aerospace Science and Technology
Amir reza Kosari; Masoud Mirzaei Tashenizi
Abstract
This article is aimed to investigate the interference elimination between multiple aircraft using game theory. A differential game is used to eliminate the interference if all the interfering aircraft cooperate to eliminate the interference or if each makes a rational decision based on their own interests. ...
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This article is aimed to investigate the interference elimination between multiple aircraft using game theory. A differential game is used to eliminate the interference if all the interfering aircraft cooperate to eliminate the interference or if each makes a rational decision based on their own interests. All interfering aircraft calculate the interference elimination route in cooperative mode by defining the flight priority. In the non-cooperative state, the problem of eliminating the interference is investigated using the Nash equilibrium, and then the new path is calculated. A point mass model has been used to implement this problem, which is converted into a linear model by changing the control variable. The above problem is solved using the quasi-spectral numerical solution method. In order to validate the presented method, the problem of eliminating the interference between several aircraft in two-dimensional space has been studied, and the results show the appropriate performance of the presented method.
Aerospace Science and Technology
M. Khoshnood; H. Ashoori
Abstract
In this paper, a neural network backstepping controller is designed for the control of a reentry vehicle. The backstepping control system is applied to the nonlinear six degree of freedom dynamics of the reentry vehicle for tracking the desired input. The neural network is used for estimation of ...
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In this paper, a neural network backstepping controller is designed for the control of a reentry vehicle. The backstepping control system is applied to the nonlinear six degree of freedom dynamics of the reentry vehicle for tracking the desired input. The neural network is used for estimation of nonlinear parts of backstepping controller during entry to atmosphere and to estimate the nonlinear terms as well as the external disturbances. Numerical simulations have been performed to verify the performance of the proposed control method.
Aerospace Science and Technology
Ehasan Zibaei; Mohammad-Ali Amiri Atashgah; Ahmad Kalhor
Volume 12, Issue 2 , October 2019, , Pages 19-33
Abstract
This paper presents a tuned behavior-based guidance algorithm for formation flight of quadrotors. The behavior-based approach provides the basis for the simultaneous realization of different behaviors such as leader following and obstacle avoidance for a group of agents; in our case they are quadcopters. ...
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This paper presents a tuned behavior-based guidance algorithm for formation flight of quadrotors. The behavior-based approach provides the basis for the simultaneous realization of different behaviors such as leader following and obstacle avoidance for a group of agents; in our case they are quadcopters. In this paper optimization techniques are utilized to tune the parameters of a behavior-based guidance algorithm; to compromise between safety, trajectory optimality, and control effort during the formation flight. The tuning is formulated as a constraint optimization problem where the penalty function method is used to secure the safe passage of quadrotors around an obstacle. The guidance subsystem is integrated with a consistent dynamic inversion controller to realize a smooth maneuver of the quadrotors along desired trajectories. For more, MATLAB/Simulink is used as the programming platform. The effectiveness of the tuning method is verified, based on the performance of the closed-loop system in the presence of an overall navigation system uncertainties and actuator lags.
Aerospace Science and Technology
Karim Dastgerdi; Farshad Pazooki; Jafar Roshanian
Volume 12, Issue 2 , October 2019, , Pages 61-70
Abstract
airplane in presence of asymmetric left-wing damaged. Variations of the aerodynamic parameters, mass and moments of inertia, and the center of gravity due to damage are all considered in the nonlinear mathematical modeling. The proposed discrete-time nonlinear MRAC algorithm ...
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airplane in presence of asymmetric left-wing damaged. Variations of the aerodynamic parameters, mass and moments of inertia, and the center of gravity due to damage are all considered in the nonlinear mathematical modeling. The proposed discrete-time nonlinear MRAC algorithm applies the recursive least square (RLS) algorithm as a parameter estimator as well as the error between the real damaged dynamics and a model of nominal undamaged aircraft to generate the desired control commands. The discrete-time adaptive control algorithm is augmented with a Nonlinear Dynamic Inversion (NDI) control strategy and is implemented on the NASA generic transport model (GTM) airplane while considering the effect of wing damage and un-modeled actuator dynamics. The stability of the proposed nonlinear adaptive controller is demonstrated through Popov’s hyperstability theory. Simulation results of the introduced controller are compared with the classical discrete-time adaptive control strategy. The results demonstrate the effective performance of the proposed algorithm in controlling the airplane in presence of abrupt asymmetric damage.
Aerospace Science and Technology
Hamidreza Jafari; Farid Shahmiri
Volume 12, Issue 1 , March 2019, , Pages 39-51
Abstract
In this paper, the particular solution technique for inverse simulation applied to the quadrotor maneuvering flight is investigated. The trust-region dogleg (DL) technique which is proposed alleviates the weakness of Newton’s method used for numerical differentiation of system states in the ...
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In this paper, the particular solution technique for inverse simulation applied to the quadrotor maneuvering flight is investigated. The trust-region dogleg (DL) technique which is proposed alleviates the weakness of Newton’s method used for numerical differentiation of system states in the solution process. The proposed technique emphasizes global convergence solution to the inverse simulation problem. This algorithm is evaluated by calculating the control inputs necessary to enable the quadrotor to follow a specified trajectory including climb-hover and cruise-hover maneuvers. The trajectory is generated by the direct simulation using a linear optimal control developed for the quadrotor. The model of rotors for the quadrotor is a nonlinear model developed based on blade element theory (BET), linear aerodynamics, and non uniform inflow over the rotor disc. The results show that the control inputs obtained from the inverse simulation are in good agreement with control inputs estimated by direct simulation. The results also confirm that the maximum difference between the prescribed trajectory and the trajectory generated by the direct simulation is less than 0.02%, and thus the potential application of the inverse simulation with the trust-region dogleg optimization is evident.
