Aerospace Science and Technology
Benyamin Ebrahimi; Jafar Roshanian; Ali Asghar Bataleblu
Abstract
Significant attention has been given to the field of multi-agent systems in recent years due to its potential to solve complex problems that cannot be addressed by a single agent. One such problem is the cooperative search and coverage application, which requires multiple agents to efficiently search ...
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Significant attention has been given to the field of multi-agent systems in recent years due to its potential to solve complex problems that cannot be addressed by a single agent. One such problem is the cooperative search and coverage application, which requires multiple agents to efficiently search and cover a given area. However, the effectiveness of such systems is dependent on various factors, including mission definition parameters and the approach used to achieve mission performance optimality. In this paper, an optimal strategy for segregating multi-agent missions for search and coverage applications is proposed. The proposed strategy involves dividing a single mission into several simultaneous missions based on the optimal division of the environment that ensures system performance optimality while achieving a common goal. The mission area is divided into sub-areas, and each sub-area is assigned to specific agents to improve overall system performance. The effectiveness of the proposed strategy is demonstrated through simulations and relevant comparisons.
Aerospace Science and Technology
Fahimeh Barzamini; Jafar Roshanian; Mahdi Jafari-Nadoushan
Abstract
This paper aimed to utilize a Deep Neural Network (DNN) to achieve optimal path planning for a spacecraft during a landing mission on an asteroid. A minimum energy-consumption mission is evaluated in which a DNN is utilized to predict the optimal path in case of any failures or unforeseen alterations. ...
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This paper aimed to utilize a Deep Neural Network (DNN) to achieve optimal path planning for a spacecraft during a landing mission on an asteroid. A minimum energy-consumption mission is evaluated in which a DNN is utilized to predict the optimal path in case of any failures or unforeseen alterations. The paper uses a DNN and employs a polyhedral model, which is renowned as the most precise method for modelling the irregular shapes of asteroids. The DNN, is utilized for path planning and incorporates data calculated by the network into a spacecraft dynamics equations where an intelligent supporter model has been developed to handle the high computation load of the gravitational field of polyhedral models. Moreover, this study indicates that the prediction errors of final locations are less than 1 kilometer, as the training errors of networks are deemed entirely satisfactory. Eventually, the feasibility of the proposed approach is demonstrated through corresponding simulations
Aerospace Science and Technology
Mahsa Azadmanesh; Jafar Roshanian; Mostafa Hassanalian
Abstract
This paper employs the fast terminal sliding mode control with the sign and the saturation function to track the landing trajectory of a probe on an asteroid and to further improve the dynamic tracking performance. Then the controller is enhanced by adding the fuzzy control to both fast terminals. To ...
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This paper employs the fast terminal sliding mode control with the sign and the saturation function to track the landing trajectory of a probe on an asteroid and to further improve the dynamic tracking performance. Then the controller is enhanced by adding the fuzzy control to both fast terminals. To make fair judgments on the performance of the suggested method, the proportional derivative sliding mode control with both the sign function and the saturation function is simulated as well. The two-point barycentric gravitational model is used to describe the weak gravity around the asteroid. The proposed fuzzy fast terminal method raises the convergence speed, improves the desired trajectory tracking accuracy and ensures that the system modes are placed on the sliding surface in a short, limited time. The absolute errors for the proportional derivative sliding mode controller, fast terminal sliding mode controller and improved fast terminal sliding mode controller are about 244, 139 and 113. The trajectories along all three coordinate axes in the proportional derivative sliding mode controller, fast terminal sliding mode controller and improved fast terminal sliding mode controller were tracked in 8 seconds, 5 seconds and 4 seconds. The results show how the fuzzy-fast terminal sliding mode control with the saturation function is the better choice of controller and how the fuzzy system is able to adapt to the momentary fluctuations and cover them successfully.
Aerospace Science and Technology
Mahsa Azadmanesh; Jafar Roshanian; Mostafa Hassanalian
Abstract
This study aims to control a space robot's soft-landing trajectory on the asteroid EROS433 considering a weak, yet effective gravitational field. As the research innovation, the study employs a fast terminal sliding mode control (FTSMC) to manage the landing trajectory and enhance the dynamic tracking ...
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This study aims to control a space robot's soft-landing trajectory on the asteroid EROS433 considering a weak, yet effective gravitational field. As the research innovation, the study employs a fast terminal sliding mode control (FTSMC) to manage the landing trajectory and enhance the dynamic tracking performance for the soft landing of the space robot on the asteroid. This controller can ensure that the system modes are positioned on the sliding surface within a limited time. As an advantage over the PD sliding mode controller, the proposed controller raises the speed and improves the accuracy of tracking the desired trajectory and enhances the robustness of the control system. The study further compares the results of simulations performed in MATLAB to evaluate the proposed controller design. The results show that the absolute error value for FTSMC is significantly lower than the PD sliding mode controller, and when the sign function is replaced by a hyperbolic tangent, it makes the system behavior smoother and reduces the oscillations.
Aerospace Science and Technology
Mahdi Amani Estalkhkuhi; Jafar Roshanian
Abstract
In this paper, a multi-input/multi-output sliding controller is proposed and analyzed for a quad tilt-wing unmanned aerial vehicle (QTW-UAV). The vehicle is equipped to do take-off and landing in vertical flight mode and is capable of flight over long distances in horizontal flight mode. The full dynamic ...
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In this paper, a multi-input/multi-output sliding controller is proposed and analyzed for a quad tilt-wing unmanned aerial vehicle (QTW-UAV). The vehicle is equipped to do take-off and landing in vertical flight mode and is capable of flight over long distances in horizontal flight mode. The full dynamic model of the vehicle is originated from the Newton-Euler formulation. For developing the controller, a set of integral type sliding surfaces is selected and it is necessary to mention that in this approach, there isn't any linearization during controller design. Simulation has been conducted for a nonlinear, multivariable model that includes uncertain parameters and in the presence of pitch angle measurement noise and pitch moment disturbance. For verification, the proposed controller is compared with linear based controller design simulation. Results exhibit that the proposed controller is robust in the face of uncertainties, noise and disturbance and meets performance demands with control inputs of low amplitude.
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
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.
Ali Moosavi; Masoud Mirzaei; Jafar Dr. Roshanian
Volume 7, Issue 1 , March 2010, , Pages 1-8
Abstract
The purpose of this paper is to examine the multidisciplinary design optimization (MDO) of a reentry vehicle. In this paper, optimization of a RV based on, minimization of heat flux integral and minimization of axial force coefficient integral and maximization of static margin integral along reentry ...
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The purpose of this paper is to examine the multidisciplinary design optimization (MDO) of a reentry vehicle. In this paper, optimization of a RV based on, minimization of heat flux integral and minimization of axial force coefficient integral and maximization of static margin integral along reentry trajectory is carried out. The classic optimization methods are not applicable here due to the complexity of the equations, therefore in this research, the genetic algorithm technique is utilized for optimization of the RV. In addition, the results of the genetic algorithm, are validated with those of two other methods, Pareto genetic algorithm and response surface method. In the present paper, in order to decrease the computational time, parallel processing strategy is employed
M.A. Sharbafi; A. Mohammadinejad Mohammadinejad; Jafar Dr. Roshanian; Seddigh Khaki
Volume 6, Issue 2 , June 2009, , Pages 71-78
Abstract
Gain scheduling is one of the most popular nonlinear control design approaches which has been widely and successfully applied in fields ranging from aerospace to process control. Despite the wide application of gain scheduling controllers, there is a notable lack of analysis on the stability of these ...
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Gain scheduling is one of the most popular nonlinear control design approaches which has been widely and successfully applied in fields ranging from aerospace to process control. Despite the wide application of gain scheduling controllers, there is a notable lack of analysis on the stability of these controllers. The most common application of these kinds of controllers is in the field of flight control and autopilots. The main goal of this paper is to apply a methodology to prove stability of a gain scheduled controller used in directing Skid-to-Turn missiles. One of the most widespread applications of gain scheduling controller is the main problem of this paper. To design the controller we use pole placement in state feedback controllers and a kind of innovative interpolation to reduce jumping in gains related to changing the flight conditions. Finally we utilize root locus and Kharitonov’s Theorem to prove stability of the linearized plant. The presented approach for stability analysis is distinctive in the literature.
A.L. Mehrabian; Jafar Dr. Roshanian
Volume 4, Issue 2 , June 2007, , Pages 1-12
