filter by: Publication Year
(Descending) Articles
International Journal of Systems Science (00207721)
This research proposes a novel hybrid force/position control (RL-HC) approach for robotic systems, utilising reinforcement learning. The proposed controller demonstrates superior robustness and performance, particularly in tracking the end-effector's position and contact force, compared to the hybrid sliding mode force/position control (HSMC) method, even in the presence of structural and non-structural uncertainties. The RL-HC controller is designed around a fixed-time sliding mode model, integrating force and position control components. The stability of this controller is established using the Lyapunov theory. Additionally, the reward function within the reinforcement learning network is carefully crafted to align with key objectives, including minimising chattering, force error, position error, and control effort. A simulation performed using a 3-DOF Delta Robot illustrates the effectiveness of the RL-HC approach. Results indicate that RL-HC outperforms traditional methods, showcasing better performance and robustness when facing various external disturbances and uncertainties. Specifically, the findings highlight a significant reduction in position error, force error, total control effort, and chattering. The study also illustrates how different reward function designs impact the achievement of the desired objectives. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
Advances in Space Research (02731177) 75(7)pp. 5656-5668
This study focuses on the boundary control of flexible satellites equipped with honeycomb panels using Lyapunov's direct method. The panels are modeled as Euler–Bernoulli beams, and the govern ing dynamic equations are derived through Hamilton's principle. A novel Lyapunov function candidate is introduced, and asymptotic stability is rigorously established through the extended LaSalle's invariance principle. Control input laws are strategically developed to handle actuator failures while ensuring stability with minimal sensor utilization. Numerical simulations, performed using the assumed mode method, validate the theoretical findings. The results underscore key contributions, including guaranteed asymptotic stability, large-angle maneuvering capabilities, robustness to actuator failures, and the prevention of spillover instability phenomena. © 2025 COSPAR
Journal of Sound and Vibration (10958568) 617
The study thoroughly considers the Vibro Impact Nonlinear Energy Sink (VI-NES) system, highlighting its capacity to absorb and dissipate energy under various initial conditions. This system consists of a Linear Oscillator (LO) or a nonLinear Oscillator (nonLO), featuring a damper, spring, and a ball within a cavity. The analysis incorporates stochastic and deterministic optimization methods. Different initial velocities were applied to assess the system's efficiency. Designers can identify the optimal parameters, including the mass of the impact element, the coefficient of restitution, and the cavity length, that perform effectively over a wide spectrum of initial velocities. This article offers insights into uncovering logical relationships among the optimal values of these parameters, providing guidance for their efficient design. Optimization is employed when the system is excited by an initial velocity. However, when an external force is applied, defining an objective becomes challenging, and the system's behavior must be analyzed instead. Moreover, bifurcation analysis is utilized to explore the system's dynamic behavior in relation to cavity length and the restitution coefficient. The bifurcation diagrams reveal that chaotic strong modulated response (CSMR) occurs at specific values of cavity lengths and restitution coefficients. Additionally, a system with two degrees of freedom and vibro-impact nonlinearity is considered, with optimal parameters for vibro-impact designed to minimize the system's energy. These findings underscore the potential application of VI-NES in engineering contexts, particularly in the design of vibration reduction and energy dissipation mechanisms for complex dynamic systems like mechanical systems and structural engineering. © 2025 Elsevier Ltd
Arabian Journal for Science and Engineering (21914281) 49(2)pp. 1697-1712
In this paper, an optimal nonlinear attitude controller is designed and implemented as hardware in the loop for a spacecraft simulator under various failures of reaction wheels. The proposed controller is developed in the closed form based on predicting the nonlinear continuous responses of spacecraft simulator. The special case of the controller when all uncertainties are ignored leads to feedback linearization. However, the stability of the controller in the presence of parametric uncertainties and unmodeled dynamics of the platform is analyzed, and the effect of the prediction time on the boundedness of system responses is presented. A redundant reaction wheel is located in the platform to compensate for failures of three main reaction wheels. How to distribute torque between healthy wheels under different types of failure including stuck and oscillatory failures is addressed and experimentally implemented. The laboratory results that are consistent with computer simulations show the accuracy and validity of the designed controller. It is seen that the spacecraft attitude converges in a limited time in the presence of system uncertainties and actuator failures. © King Fahd University of Petroleum & Minerals 2023.
ISA Transactions (00190578) 138pp. 705-719
In this paper, the attitude of a spacecraft simulator is controlled in the presence of nonlinearities, uncertainties and constraints of the system. An optimization-based controller is developed in the closed form based on predicting the nonlinear responses of spacecraft system. For practical requirements of the spacecraft actuated by the reaction wheels (RWs), the control method considers the actuator limitation in the torques applied to RWs and the restriction in the angular momentum of the wheels due to the limited rotational speed of motors. In this way, the momentum constraint is equated with the torque constraint by a prediction-based transformation. Then, the constrained optimal control law is calculated by solving an equivalent optimization formulation. The constrained stability is analyzed by the Lyapunov second method and the bound of system response is obtained in terms of the prediction time. In the results, at first, the performance of the unconstrained version of the proposed controller, which leads to the feedback linearization like controller, is evaluated in the presence of uncertainties through computer simulations. Finally, the constrained version is simulated and experimentally implemented as hardware in the loop on the spacecraft simulator. The obtained comparative results indicate a good performance for the constrained controller in realistic conditions. © 2023 ISA
IET Control Theory and Applications (17518644) 17(8)pp. 953-967
This paper aims to discuss the approach of constrained modified feedback linearization model predictive control for the spacecraft simulator. By utilizing the high accuracy and constrained properties of model predictive control (MPC), an optimum MPC is designed for the spacecraft feedback linearized system. The composite controller has the ability to control both the attitude and angular velocity of the reaction wheels (i.e. steering the angular momentum to zero at the end of the maneuver). The simulation and experimental results demonstrate that the proposed hybrid controller has an insignificant calculative cost and facilitates the spacecraft to perform regulation maneuver with sufficient precision in the presence of external torques and actuator saturations. © 2023 The Authors. IET Control Theory & Applications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
Aerospace Science and Technology (12709638) 139
This brief proposes two novel double-loop fault-tolerant controllers to tackle the problems of stabilizing the attitude and nullifying appendages' vibration of flexible spacecraft by integrating the advantages of model predictive control (MPC) and sliding mode control (SMC). The structure of the first method is as follows: First in the external loop, by using terminal sliding mode (TSM), the attitude of the spacecraft is derived to its reference value, and the proper angular velocity of the interior part is generated. Then, by employing the preciseness and constrained attributes of MPC, an optimal fault-tolerant controller is suggested in the internal part. Constrained fault-tolerant MPC tracks the angular velocity to the set value while guaranteeing appendages' passive vibration suppression. In another method, as opposed to the first technique, in the inner loop fault-tolerant finite-time TSM, and in the outer loop MPC are designed. The unified double-layer nonlinear controller schemes guarantee good dynamics and robustness against external torques and actuator faults. The closed-loop system's stability of the controllers is precisely proved using the Lyapunov theorem in the presence of actuator faults and external disturbances and in the absence of the damping matrix to study the advantages of the proposed methods. The performance of the proposed methods has been compared with each other. Moreover, the simulation results substantiate that the proposed method outperforms faster fixed-time sliding model control significantly. © 2023 Elsevier Masson SAS
Asian Journal of Control (19346093) 25(1)pp. 262-270
A nonlinear disturbance observer based on a super twisting controller is designed and implemented on the uncertain spacecraft attitude control subsystem simulator. The reaction wheels' angular momentum and their rate saturation are concerned in the controller design. The super twisting algorithm (STA) is devised in a way to make the reaction wheels into rest at the end of the maneuver. A nonlinear-disturbance-observer (NDO) is applied in estimating the external disturbances, unmodeled inertia moment, the eccentricity of rotation and mass center of simulator, and the reaction wheel saturation constraint. The finite-time stability of the closed-loop system is established according to the Lyapunov theory. The simulation and experimental results of this newly designed controller-observer on the spacecraft attitude simulator are compared in uncertain conditions. © 2022 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd.
JVC/Journal of Vibration and Control (10775463) 29(1-2)pp. 346-361
This paper aims to design an attitude controller for a flexible spacecraft under external disturbance and uncertainty. The spacecraft’s attitude is controlled by a super twisting controller based on a disturbance observer. This paper’s spacecraft system is non-minimum phase since mode-shapes are included in the output; thus, the following four methods are designed to compensate for the constraint: (1) The output redefinition method, where outputs are redefined as a combination of mode-shapes and quaternions. (2) The flexible spacecraft is controlled without measuring the mode-shapes, and only the quaternion parameters are selected as the output. (3) An advanced sliding surface is proposed, in which the mode-shapes are considered in the sliding surface. (4) The difference between flexible and rigid spacecraft dynamics is considered as disturbance, and its effect on the system is compensated. The finite-time stability of the closed-loop system is proved by leveraging the Lyapunov theory. The numerical simulation illustrates the closed-loop system’s effectiveness in terms of robustness compared to the existing controller and the four mentioned methods. © The Author(s) 2021.
IEEE Transactions on Industrial Electronics (02780046) 70(3)pp. 2739-2747
In this article, two dual-loop control methods are proposed for attitude control and reaction wheels momentum management of the spacecraft simulator by assimilating the advantages of sliding mode and model predictive control (MPC). In the first method, by utilizing the high accuracy and constrained features of the MPC, an optimal controller is designed in the inner loop. MPC drives the angular velocity to the desired value while keeping the reaction wheel velocity to a small region near the origin, considering the constraints of the actuators. Furthermore, based on the fixed-time terminal sliding mode (TSM) the proper angular velocity is produced in the outer layer of this composite controller for the MPC part. In the second method, contrary to the first one, in the exterior loop MPC and in the interior loop finite-time TSM have been designed. The incorporated twofold nonlinear controllers' policy insures a good dynamic and robustness against external disturbances. The high yielding of the control algorithms has been analyzed by simulation and experimental validation utilizing MATLAB software with real-time connection based on LabVIEW. © 1982-2012 IEEE.
Journal of Sound and Vibration (10958568) 535
In this article, a novel multi-objective modified fractional-order nonsingular terminal sliding mode (MFONTSM) controller is designed for the flexible spacecraft attitude control and passive vibration suppression, assuming the control torque saturation in the system dynamics. Then, by considering the effects of flexible components on the appendages modal equation as an external disturbance, an active FONTSM controller is designed separately to suppress any residual vibrations using piezoelectric actuators. The practical fixed-time stability of the closed-loop system is analyzed and proved using the Lyapunov theorem. Finally, the proposed controllers’ performance has been tested in the presence of uncertainties, external disturbances, and the absence of the damping matrix to study the proposed method's effectiveness. It was observed that the proposed passive and active control strategies were able to achieve fast attitude stabilization while providing substantial vibration suppression under uncertainty and disturbance even in the absence of any damping terms in the system. © 2022 Elsevier Ltd
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 539-545
In this article, a super-twisting algorithm-based ADRC structure is proposed. This structure contains three parts, a super twisting sliding mode controller, an extended state estimator, and an optimal tracking differentiator. This proposed ADRC is employed to control the Delta parallel robot both numerically, in MATLAB, and experimentally. In numerical simulations, the robustness of the proposed ADRC is verified by applying various external disturbances. Both the numerical and experimental results show the ability of the proposed ADRC structure in controlling the Delta robot in the presence of disturbances and uncertainties. © 2022 IEEE.
ISA Transactions (00190578) 128pp. 162-173
In this study, a new adaptive fractional-order nonsingular terminal sliding mode (AFONTSM) controller is presented. A novel multi-purpose sliding surface is constructed, with the aim of bringing the reaction wheels in to rest after every attitude stabilization maneuver, utilizing the fractional-order difference of the quaternion error and the reaction wheels angular momentum error. The closed-loop system's practical fixed-time stability is investigated using the Lyapunov theorem under uncertainty and external disturbance. The AFONTSM controller's performance is compared with the existing nonsingular terminal sliding mode (NTSM), full-order NTSM, and fractional-order sliding mode controllers. Finally, the proposed AFONTSM controller's effectiveness is studied in close-to-reality situations through practical experiments on the spacecraft attitude control subsystem simulator under internal/external disturbance and uncertainty; then, the results are compared with previous studies. © 2021 ISA
This study aimed to improve the control scheme incorporated into the unknown system dynamics estimator (USDE) to deal with unknown dynamics and external disturbances. In comparison with the nonlinear disturbance observer (NDO) that requires calculating the inverse of the inertia matrix, USDE can be easily implemented, and their parameter tuning is more straightforward. We use the super twisting sliding mode algorithm (STA) to achieve a faster convergence rate and increase tracking performance. The closed-loop stability of the new composite controller is proved. Finally, the improvement of the new hybrid proposed controller is confirmed by using numerical simulation and experimental tests on a DELTA robot. Then the performance of the new controller is compared with the previous method. © 2022 IEEE.
The leader-following attitude consensus problem for multiple rigid spacecraft formation systems (MSF) with uncertainties, external disturbances, and actuator saturation is addressed in this paper. The first step to solve this problem is to assume that all parameters of the rigid spacecraft system and networks communication links are known. At first, the leader-following consensus problem is redefined to well defined error system by utilizing a nonlinear distributed observer for the leader spacecraft. Then by composing a high order disturbance observer (HODO) and adaptive super twisting algorithm (ASTA) the control problem is solved for each spacecraft. Finally, a simulation example is given with one leader and four followers. © 2021 IEEE.
Aerospace Science and Technology (12709638) 84pp. 361-374
In this paper, to control the six degree-of-freedom non-linear unmanned aerial vehicle, two strategies are implemented using adaptive super-twisting sliding mode control approach. The first one is a single-channel controller that is designed on the basis of decoupled equations of motion. The other one is a three-channel controller that is designed based on the coupling equations of motion along with an adaptive super-twisting observer. The stability of the closed loop system of the controller-observer is proven. The comparison between the single-channel controller and the three-channel could lead us to select between a little lower efficiency and less complexity versus efficiency and more complexity. To examine the performance and robustness of these two control loops, their performances are analyzed in the presence of combined uncertainties, including aerodynamics, mass, inertial moment, sensor, and actuator disturbances and parametric uncertainties in the stage separation phase. The explosive bolt separation mechanism is assumed to perform the stage separation, and its forces, moments and disturbances are modeled as needed. Finally, the responses are compared with the classic PID controller. © 2018 Elsevier Masson SAS
Control Engineering Practice (09670661) 84pp. 72-81
In this paper the attitude control of a spacecraft simulator using Reaction Wheels (RW) as the actuators is investigated. The main goal of the current study is to bring the RWs to the rest at the end of the maneuver without angular velocity measurement. A modified feedback linearization controller is applied by considering the Euler angles of the simulator as the output and the RWs angular momentums as the internal state variables. The stability of the proposed controller and the internal dynamics is analyzed using Lyapunov theory. Two modified sliding mode observers are designed to estimate the angular velocities of the spacecraft attitude control subsystem simulator. The proposed observers do not use the control input and the detailed knowledge of the model and thus it can be implemented easily. The global stability of the system is proved. The proposed controller and observers are finally evaluated numerically and experimentally on an attitude spacecraft simulator. © 2018 Elsevier Ltd
Journal of Sound and Vibration (10958568) 422pp. 300-317
The robust attitude and vibration control of a flexible spacecraft trying to perform accurate maneuvers in spite of various sources of uncertainty is addressed here. Difficulties for achieving precise and stable pointing arise from noisy onboard sensors, parameters indeterminacy, outer disturbances as well as un-modeled or hidden dynamics interactions. Based on high-order sliding-mode methods, the non-minimum phase nature of the problem is dealt with through output redefinition. An adaptive super-twisting algorithm (ASTA) is incorporated with its observer counterpart on the system under consideration to get reliable attitude and vibration control in the presence of sensor noise and momentum coupling. The closed-loop efficiency is verified through simulations under various indeterminate situations and got compared to other methods. © 2018 Elsevier Ltd
Journal of Marine Science and Technology (Taiwan) (10232796) 26(1)pp. 1-10
Due to the important role of hydrodynamic coefficients in the control and guidance of an autonomous underwater vehicle (AUV), sensitivity analysis is proposed here, as a preliminary step to motion control design. Taking the standard maneuvers, including turning circle and horizontal and vertical zigzag, the sensitivity of various hydrodynamic coefficients with respect to velocities and position is determined. Such analyses are then used to classify the model parameters into three categories, as non-sensitive coefficients, coefficients with low influence on the motion and more sensitive coefficients.
Advances in Space Research (02731177) 62(7)pp. 1813-1825
In this study, a rendezvous mission between two spacecraft is programmed. The system is modelled as a 6-DOF formation flying. It is expected that this system be robust against various uncertainties and disturbances while minimizing the energy consumption, considering thrusters and control torques limitations. For this purpose, three robust fractional-order PDD (FOPDD) controllers are designed. The first one is designed based on robust constraint on transfer function. In the second method, the controller gains are tuned by using Particle Swarm Optimization (PSO) algorithm. The third designed controller is implemented according to Model Reference Adaptive Controller with Fractional Order Adjustment Rules (FOAR-MRAC) which is a combination of FOPDD controller tuned by PSO algorithm and an adaptive time variable gain. The performance of these controllers are compared in—various uncertain conditions (disturbances, mass and inertia uncertainty and sensor noises) considering actuators limitations. © 2018 COSPAR
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering (09544100) 232(10)pp. 1944-1960
In this study, a hardware-in-the-loop implementation of attitude control algorithms based on high-order sliding mode theory is performed and then both compared in terms of performance and functionality. The spacecraft simulator consists of a free-floating platform hinged on a spherical air-bearing support. In order to compensate for the unreliable performance of the rate gyros, a super-twisting sliding mode observer is incorporated to estimate the angular velocities fed back to the controller unit. The proposed scheme makes full use of novel sliding mode methods to alleviate the chattering effects without increasing the control effort; both controllers and observer are tuned to deal with the saturation of reaction wheels with respect to momentum and its rate. The ab initio simulations compared well with the simulator responses, implying that involved instruments including actuators and sensors have been properly emulated. This also proved that the external disturbances were modeled in a reliable manner. The robustness and effectiveness of the proposed scheme have been validated experimentally under extreme circumstances of disturbances and levels of uncertainties. © IMechE 2017.
International Journal of Control, Automation and Systems (20054092) 16(2)pp. 896-903
In this article, a hardware-in-the-loop implementation of two robust controllers based on high-order sliding mode and μ-synthesis method are performed and compared in terms of performance and functionality. The spacecraft simulator consists of a free-floating platform hinged on a spherical air-bearing support. The proposed scheme makes full use of adaptive super twisting algorithm to alleviate the chattering effects without increasing the control effort; both controllers are adapted to deal with the saturation of reaction wheels with respect to momentum and its rate of change. The ab-initio simulations compared well with the simulator responses, implying that involved instruments including actuators and sensors have been properly emulated. This also proved that the external disturbances were modeled in a reliable manner. The robustness and effectiveness of the proposed scheme have been validated experimentally under extreme circumstances and uncertainties. © 2018, Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 101-106
In this paper the attitude control of a spacecraft simulator using Reaction Wheels (RW) as the actuators is investigated. The simulator attitude is controlled considering the saturation of RWs angular momentum and its angular rate. The main goal of the current study is to bring the RW s to the rest at the end of the maneuver without using extra actuators. A modified feedback linearization is applied to control the attitude of the system. To this end, the Euler angles of the simulator are considered as the output and the RWs angular momentums are assumed as the internal state variables. The internal dynamics stability is proved by rewriting the dynamics of the system in normal form. The stability of the proposed controller is analyzed using Lyapunov stability approach. The proposed algorithm is finally evaluated numerically and experimentally on an attitude spacecraft simulator. © 2017 IEEE.
International Journal of Engineering, Transactions A: Basics (17281431) 30(4)pp. 567-574
The spacecraft simulator robust control through H∞-based linear matrix inequality (LMI) and robust adaptive method is implemented. The spacecraft attitude control subsystem simulator consists of a platform, an air-bearing and a set of four reaction wheels. This set up provides a free real-time three degree of freedom rotation. Spacecraft simulators are applied in upgrading and checking the control algorithms' performance in the real space conditions. The LMI controller is designed, through linearized model. The robust adaptive controller is designed based on nonlinear dynamics in order to overcome a broader range of model uncertainties. The stability of robust adaptive controller is analysed through Lyapunov theorem. Based on these two methods, a series of the laboratory and computer simulation are made. The tests' results indicate the accuracy and validity of these designed controllers in the experimental tests. It is observed that, these controllers match the computer simulation results. The spacecraft attitude is converged in a limited time. The laboratory test results indicate the controller ability in composed uncertainty conditions (existence of disturbances, uncertainty and sensor noise). © 2017, Materials and Energy Research Center. All rights reserved.
IEEE Transactions on Aerospace and Electronic Systems (00189251) 53(5)pp. 2534-2543
In this paper, the robust control problem for spacecraft formation flying in virtual structure algorithm is addressed. The effects of external disturbances, model uncertainties, sensor noises, and actuator saturation are taken into account. A robust controller based on μ-synthesis is first designed to overcome the environmental disturbances. To obtain a control law with lower order, an H∞-based linear matrix inequality controller is designed, using the linearized model with uncertainties. Then, a robust adaptive controller, based on the Lyapunov stability theorem, is presented to overcome a broader range of model uncertainties, which also guarantees the stability. From a comparison viewpoint, the numerical results are also demonstrated to show the performance of the robust controllers in tracking the desired attitude and position. © 2017 IEEE.
Koofigar, H.R. ,
Malekzadeh, M. ,
Abolvafaie, M. ,
Abolvafaie, M. ,
Koofigar, H.R. ,
Malekzadeh, M. 2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 90-95
To improve the tracking control performance, in the presence of parametric uncertainties, for an autonomous underwater vehicle (AUV), the sensitive parameters are first identified, using the direct sensitivity analysis method. Then, an adaptive second order sliding mode controller is proposed to ensure the robust stability and performance, without any a priori knowledge on the upper bound of perturbations. To this end, a proportional integral derivative (PID) structure is adopted, as the sliding surface. The unknown sensitive parameters are estimated by some adaptive mechanisms. On the other hand, the second order sliding mode control (2-SMC) is developed to neutralize the effects of unstructured uncertainties and disturbances. The closed loop stability is shown, using the Lyapunov stability theorem, and verified by various numerical simulations. © 2016 IEEE.
This article describes the construction of a five spacecraft flight simulator based on an air bearing system, which was designed and instrumented in university of Isfahan laboratory to evaluate and to perform research in the field of Attitude Determination and Control Systems for spacecraft. This simulator is modeled in Autodesk-Inventor software package to design the simulator component precisely. The hardware and software components of the testbed are detailed in this article. the constraints for the construction and final realization of this attitude simulator testbed are depicted. It describes all modifications needed to reconfigure the simulator system testbed. © 2016 IEEE.
A robust Fractional Order PDD (FOPDD) controller is designed for a nonlinear spacecraft rendezvous subject to uncertain conditions considering actuator saturation. The controller is designed for the linear and decouples system. It is applied on nonlinear uncertain system in large maneuverings. In order to design the FOPDD controller, the specifications are calculated through the phase margins, sensibility function and robustness constraints. The controller parameters are obtained through Particle Swarm Optimization (PSO) due to high convergence speed, low computation, easy simulation and rapid response. The simulation results indicate the designed FOPDD controller can track the desired trajectory in the composite uncertain condition (considering constant, impulse and sinusoidal disturbance, parametric uncertainty and sensor noises). The FOPDD performance is compared with the classic PDD controller for nonlinear model. The simulation is based on the SPHERES project. © 2016 IEEE.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025
This paper deals with mobile robot navigation in an unknown environment. The proposed algorithm is inspired from artificial potential field (APF) and rotational force method. In the proposed algorithm, the robot's velocity vector is simply determined by relative position vector of robot with respect to target and obstacles. This algorithm is applicable to both stationary and dynamic environments with one or more obstacles and guarantees that the robot can safely track the moving target even in the conditions of local minima or goal not reachable with obstacle nearby. In order to make the simulation more practical, it is applied to wheeled mobile robot. Simulation results show the effectiveness of the proposed approach. © 2014 IEEE.
Koofigar, H.R. ,
Malekzadeh, M. ,
Abolvafaie, M. ,
Abolvafaie, M. ,
Koofigar, H.R. ,
Malekzadeh, M. 2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 432-437
Sensitivity analyses in the turning circle and zigzag maneuvers, as two main standard ones, are proposed here as a preliminary step to motion control design for an Autonomous Underwater Vehicle (AUV). The most effective parameters of the AUV are then adopted to be estimated by some adaptation mechanisms. Adaptive sliding mode control is developed to ensure the robust stability and performance, without a priori knowledge about the bound of perturbations. A simulation study is also presented to demonstrate the effectiveness of the method. © 2015 IEEE.
Moallem, P. ,
Malekzadeh, M. ,
Zadeh F.K. ,
Asiri, S. ,
Zadeh F.K. ,
Moallem, P. ,
Asiri, S. ,
Malekzadeh, M. 2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 890-895
This article presents the results of a study on a prototype of spherical rolling robot and proposed a linear quadratic regulator controller to stabilize the system. The dynamic model of this spherical rolling robot has been presented with 2-DOF pendulum located inside a spherical shell and considered as a plate-ball system. The motion of the system is generated with a servo motor for left and right direction and a DC motor for forward and backward motion. Dynamic equations of the system are derived based on Euler-Lagrange method. Controlling a spherical robot is a challenging problem till today due to its nature of kinematics and highly nonlinear dynamics. Accordingly, a mid loop linear quadratic regulator (LQR) has been designed using full-state feedback to control the spherical robot. Simulation and experimental test have been carried out to show the effectiveness of the proposed controller. © 2014 IEEE.
Archive of Applied Mechanics (14320681) 83(9)pp. 1257-1272
An analytical transfer matrix method is presented to determine the effect of intermediate flexible constraints on the dynamic behavior of a multi-span beam subject to a moving mass. By using the Timoshenko beam theory on separate beams and applying the compatibility requirements on each constraint point, the relationships between every two adjacent spans can be obtained. By using a transfer matrix method, eigensolutions of the entire system can be determined. The forced responses can then be calculated by the modal expansion theory using the determined eigenfunctions. Some numerical results are presented to show the effects of intermediate constraints and locations on the dynamic response of the multi-span beams. It will be seen that the general formulation developed here can cover a large array of problems such as cracked or intermediately constrained beams. © 2013 Springer-Verlag Berlin Heidelberg.
Asian Journal of Control (19346093) 14(2)pp. 553-563
In this paper, the problem of attitude control of a three dimension nonlinear flexible spacecraft is investigated. Two nonlinear controllers are presented. The first controller is based on dynamic inversion, while the second approach is composed of dynamic inversion and μ-synthesis schemes. It is assumed that only three torques in three directions on the hub are used. Actuator saturation is also considered in the design of controllers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environmental disturbance and nonlinearity in large maneuvers. Simulation results confirm the ability of the proposed controller in tracking the attitude trajectory while suppressing the panel vibration. It is also verified that the perturbations, environment disturbances and measurement errors have only slight effects on the tracking and suppression performances. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.
IEEE Transactions on Aerospace and Electronic Systems (00189251) 47(4)pp. 2423-2434
In this paper, the problem of attitude control of a 3D nonlinear flexible spacecraft is investigated. Two nonlinear controllers are presented. The first controller is based on dynamic inversion, while the second approach is composed of dynamic inversion and μ-synthesis schemes. The extension of dynamic inversion approach to flexible spacecraft is impeded by the nonminimum phase characteristics when the panel tip position is taken as the output of the system. To overcome this problem, the controllers are designed by utilizing the modified output redefinition approach. It is assumed that only three torques in three directions on the hub are used. Actuator saturation is also considered in the design of controllers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance, and nonlinearity in large maneuvers. Simulation results confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration. It is also verified that the perturbations, environment disturbances, and measurement errors have only slight effects on the tracking and damping performances. © 2011 IEEE.
JVC/Journal of Vibration and Control (10775463) 17(13)pp. 1938-1951
In this paper, the problem of attitude control of a flexible spacecraft is investigated. Three controllers are presented. The first controller is based on dynamic inversion, while the second is based on the μ-synthesis method and the third approach is composed of dynamic inversion and μ-synthesis schemes. It is assumed that only one torque on the hub is used. Actuator saturation is also considered in the design of controllers. To evaluate the performance of the proposed controllers, an extensive number of simulations on the model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, suppression of panel vibration, sensitivity to measurement noise, environment disturbance, and nonlinearity in large maneuvers. Simulation results confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration. It is also verified that the perturbations, environment disturbances, and measurement errors have only slight effects on the tracking and damping performances. It is notable that the composite method (dynamic inversion and μ-synthesis) is not new; however, this application is new. © The Author(s) 2010 Reprints and permissions.
Scientia Iranica (23453605) 17(2 A)pp. 81-88
Double Concave Friction Pendulum (DCFP) bearing is a new generation of friction isolator that contains two separate concave sliding surfaces with different properties. Accommodating enhanced performance, compared to the Friction Pendulum System (FPS), is one of the most important benefits of DCFP. Herein, the seismic behavior of structures isolated by DCFP bearings is compared with the response of the same buildings using the FPS bearing. Accordingly, a series of nonlinear dynamic analyses are carried out under ensembles of ground motions at three different hazard levels (SLE, DBE and MCE). Moreover, the adaptive behavior of DCFP and its advantages in protecting secondary systems is investigated. The probability of exceedance curves of peak roof acceleration, peak inter-story drift and peak isolator displacement is compared for two types of isolation system. The result supports the advantages of DCFP isolation systems. © Sharif University of Technology.
In this paper, the problem of automated attitude control of a 3D nonlinear flexible spacecraft is investigated. Two nonlinear controller designs are presented. These controllers are composed of feedback linearization and μ-synthesis controllers. The first controller is based on classic feedback linearization, while the second one is robust feedback linearization. The robust feedback linearization method gives a linearizing control law that transforms the nonlinear system into a linear system based on operating condition. It is assumed that only three torques in three directions on the hub are used. Actuator saturation is considered in the design of controllers. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. Simulation results show the ability of the proposed controller in tracking the attitude trajectory and damping panel vibration. It is also verified that the perturbations, environment disturbance and measurement errors have only slight effects on the tracking and damping performance. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Scientia Iranica (23453605) 17(3 B)pp. 217-228
In this paper, the problem of attitude control of a ID non-linear flexible spacecraft is investigated. Three controllers are presented. The first is a non-linear dynamic inversion, the second is a linear μ-synthesis and the third is a composition of dynamic inversion and a μ-synthesis controller. It is assumed only one reaction wheel is used. Actuator saturation is considered in the design of controllers. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panels, sensitivity to measurement noise, environment disturbance and non-linearity in large maneuvers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a non-linear model of the spacecraft are performed. Simulation results show the. ability of the. proposed controller in tracking the. attitude trajectory and damping panel vibration. It is also verified that the perturbations, environment disturbance and measurement errors have only slight effects on the tracking and damping responses. © Sharif University of Technology, June 2010.
In this paper, the problem of attitude control of a 3D nonlinear flexible spacecraft is investigated. Two nonlinear controllers are presented. The first controller is based on dynamic inversion, while the second approach is composed of dynamic inversion and μ-synthesis schemes. The extension of dynamic inversion approach to flexible spacecraft is impeded by the non-minimum phase characteristics when the panel tip position is taken as the output of the system. To overcome this problem, the controllers are designed by utilizing the modified output re-definition approach. It is assumed that only three torques in three directions on the hub are used. In particular, the assumption that all sate variables are measurable is not realistic; hence sliding mode observers is used to estimate states. Actuator saturation is also considered in the design of controllers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. Simulation results confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration. It is also verified that the perturbations, environment disturbances and measurement errors have only slight effects on the tracking and damping performances. © 2010 AACC.
In this paper, the problem of attitude control of a 1D nonlinear flexible spacecraft is investigated. Two nonlinear controllers are presented. The first controller is based on dynamic inversion, while the second one is composed of dynamic inversion and μ-synthesis controllers. The extension of dynamic inversion approach to flexible spacecraft is impeded by the non-minimum phase characteristics when the panel tip position is taken as the output of the system. To overcome this problem, the controllers are designed by utilizing the modified output re-definition approach. It is assumed that only one torque on the hub is used. Actuator saturation is considered in the design of controllers. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. Simulation results show the ability of the proposed controller in tracking the attitude trajectory and damping panel vibration. It is also verified that the perturbations, environment disturbance and measurement errors have only slight effects on the tracking and damping responses. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
