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external-disturbances
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Enhancing the roll dynamics of an AUV by contra-rotating-propellers
, Article Ships and Offshore Structures ; Volume 16, Issue 7 , 2021 , Pages 787-796 ; 17445302 (ISSN) ; Kamali, A ; Abbaspour, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
Roll control of the Autonomous Underwater Vehicles (AUVs) is a significant issue in the current field of research for many researchers in the subject of AUV control system designation. Especially at higher speeds, the roll angle generated by a single rotating propeller or other external disturbances can considerably influence the whole dynamics and therefore the operation of the vehicle. In this paper, the utilisation of a system of contra-rotating-propellers (CRP) to enhance the roll dynamics of an AUV is evaluated by developing a six-degrees-of-freedom (6DOF) dynamics and control systems’ simulator. The results show that: 1. The single propeller system can cause roll angle deflections...
Simultaneous trajectory tracking and aerial manipulation using a multi-stage model predictive control
, Article Aerospace Science and Technology ; Volume 112 , 2021 ; 12709638 (ISSN) ; Banazadeh, A ; Sharif University of Technology
Elsevier Masson s.r.l
2021
Abstract
With the exception of a few works, the current approaches to aerial manipulation control do not typically consider the system constraints in the control design process. Also, the issue of closed-loop stability in the presence of system constraints is not thoroughly analyzed. In this paper, a novel multi-stage model predictive control (MPC)-based approach for aerial manipulation is proposed to ensure the closed-loop stability in the presence of model uncertainties and external disturbances, while satisfying the operational constraints. The detailed nonlinear model of a general aerial manipulator, consisting of a quadrotor equipped with a 3 degrees of freedom manipulator, is first developed...
Dynamics and control of a novel microrobot with high maneuverability
, Article Robotica ; Volume 39, Issue 10 , 2021 , Pages 1729-1738 ; 02635747 (ISSN) ; Nejat Pishkenari, H ; Meghdari, A ; Sharif University of Technology
Cambridge University Press
2021
Abstract
In this study, we introduce a novel three-dimensional micro-scale robot capable of swimming in low Reynolds number. The proposed robot consists of three rotating disks linked via three perpendicular adjustable rods, actuated by three rotary and three linear motors, respectively. The robot mechanism has an important property which makes it superior to the previously designed micro swimmers. In fact, our goal is designing a micro swimmer which its controllability matrix has full rank and hence it will be capable to perform any desired maneuver in space. After introducing the mechanism and derivation of the dynamical equations of motion, we propose a control method to steer the robot to the...
Applied flight dynamics modeling and stability analysis of a nonlinear time-periodic mono-wing aerial vehicle
, Article Aerospace Science and Technology ; Volume 108 , 2021 ; 12709638 (ISSN) ; Banazadeh, A ; Sharif University of Technology
Elsevier Masson s.r.l
2021
Abstract
This paper presents fly-ability, trim-ability, stability, and control ability of a mono-wing aerial vehicle as an under-actuated multi-body system. A nonlinear mathematical model of this vehicle with translational and rotational movements is developed. Based on early simulations, a conceptual prototype of the mono-wing is initially designed and constructed. A comprehensive nonlinear simulation is then performed by modeling aerodynamic forces and moments using the Blade Element Momentum (BEM) theory. Modeling and simulation are validated against experimental data to satisfy research needs. Twenty-three efficient dynamic parameters of the mono-wing are studied in ninety-seven simulation...
Control of an anaerobic bioreactor using a fuzzy supervisory controller
, Article Journal of Process Control ; Volume 103 , 2021 , Pages 87-99 ; 09591524 (ISSN) ; Vafa, E ; Shahrokhi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In the present work, a fuzzy supervisory control approach combined with an adaptive model predictive controller (AMPC), has been proposed to maximize the productivity of an anaerobic digestion (AD) process, while keeping the operation stable. In the proposed hierarchal control strategy, the set-point of the inner loop is provided by a supervisory controller. In the inner loop an AMPC has been applied to achieve the desired methane production rate by manipulating the feed flow rate. The AMPC is designed based on the auto-regressive moving average (ARMA) model whose parameters are updated at each sampling time to make the controller more robust against uncertainties and external loads. In the...
A new fast finite time fractional order adaptive sliding-mode control for a quadrotor
, Article 7th International Conference on Control, Instrumentation and Automation, ICCIA 2021, 23 February 2021 through 24 February 2021 ; 2021 ; 9780738124056 (ISBN) ; Vedadi Moghaddam, T ; Emamifard, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Fast finite time adaptive sliding mode control of a quadrotor in the presence of uncertainties and unbounded external disturbances is dealt in this paper. To this end, a fractional order sliding surface is first defined and then, an adaptive sliding mode controller is designed to guarantee finite time stability with fast convergence of quadrotor states to the desired trajectory. In this controller, it is assumed that the upper bound of the model uncertainties and external disturbances is a nonlinear function with unknown coefficients. These coefficients are estimated via stable adaptive laws. Finite time stability of the closed-loop system is analyzed using Lyapunov theorem. Simulation...
Dual-mode global stabilization of high-order saturated integrator chains: LMI-based MPC combined with a nested saturated feedback
, Article Nonlinear Dynamics ; Volume 102, Issue 1 , 2020 , Pages 211-222 ; Ahi, B ; Haeri, M ; Sharif University of Technology
Springer Science and Business Media B.V
2020
Abstract
This paper considers the problem of high-performance global stabilization of an integrator chain via a bounded control at the presence of input disturbance. While nested saturated feedback (NSF) is known as the most inspiring existing solution in the literature, we shall highlight the inherent shortcomings of this approach which cause a poor performance in terms of convergence rate. Then, a novel dual-mode control scheme combining an improved NSF law with a linear matrix inequality (LMI)-based model predictive controller (MPC) is developed to overcome the weaknesses of pure NSF. By offline calculations, a set of nested robust invariant attraction regions and their attributed feedback gains...
Enhancing the roll dynamics of an AUV by contra-rotating-propellers
, Article Ships and Offshore Structures ; 2020 ; Kamali, A ; Abbaspour, M ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Roll control of the Autonomous Underwater Vehicles (AUVs) is a significant issue in the current field of research for many researchers in the subject of AUV control system designation. Especially at higher speeds, the roll angle generated by a single rotating propeller or other external disturbances can considerably influence the whole dynamics and therefore the operation of the vehicle. In this paper, the utilisation of a system of contra-rotating-propellers (CRP) to enhance the roll dynamics of an AUV is evaluated by developing a six-degrees-of-freedom (6DOF) dynamics and control systems’ simulator. The results show that: 1. The single propeller system can cause roll angle deflections...
Fault-tolerant predictive trajectory tracking of an air vehicle based on acceleration control
, Article IET Control Theory and Applications ; Volume 14, Issue 5 , 2020 , Pages 750-762 ; Banazadeh, A ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
A novel fault-tolerant model predictive control (MPC)-based trajectory tracking approach for an aerial vehicle is presented in this study. A generalised online sequential extreme learning machine is introduced first to identify the corresponding coefficients of actuator faults. Subsequently, a robust trajectory tracking control is developed based on MPC, where the system constraints can be effectively considered in the designed control scheme. Trajectory tracking control is achieved by controlling only the acceleration of the aerial robot in the MPC structure. This leads to less computational burden and faster closed-loop dynamics. In addition, an effective disturbance observer is employed,...
Adaptive synchronization of two different uncertain chaotic systems with unknown dead-zone input nonlinearities
, Article JVC/Journal of Vibration and Control ; Volume 26, Issue 21-22 , 2020 , Pages 1956-1968 ; Shahmoradi, S ; Shahrokhi, M ; Sharif University of Technology
SAGE Publications Inc
2020
Abstract
The present work addresses chaos synchronization between two different general chaotic systems with parametric and structural uncertainties, subject to external disturbances and input dead-zone nonlinearities. In this regard, a novel robust controller has been designed that guarantees asymptotic stability of synchronization errors and boundedness of all closed-loop signals. One advantage of the proposed controller over the existing control algorithms is using only one update law for estimating the structural uncertainties, external disturbances, and unknown characteristics of the dead-zone nonlinearities, which reduces the computational burden considerably. The designed controller is...
Sensitivity to cumulative perturbations for a class of piecewise constant hybrid systems
, Article IEEE Transactions on Automatic Control ; Volume 65, Issue 3 , 2020 , Pages 1057-1072 ; Tsitsiklis, J. N ; Jamaloddin Golestani, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
We consider a class of continuous-Time hybrid dynamical systems that correspond to subgradient flows of a piecewise linear and convex potential function with finitely many pieces, and which includes the fluid-level dynamics of the Max-Weight scheduling policy as a special case. We study the effect of an external disturbance/perturbation on the state trajectory, and establish that the magnitude of this effect can be bounded by a constant multiple of the integral of the perturbation. © 1963-2012 IEEE
Adaptive synchronization of uncertain fractional-order chaotic systems using sliding mode control techniques
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 234, Issue 1 , 2020 , Pages 3-9 ; Siahi Shadbad, A ; Safavi, K ; Salarieh, H ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
In this article, an adaptive nonlinear controller is designed to synchronize two uncertain fractional-order chaotic systems using fractional-order sliding mode control. The controller structure and adaptation laws are chosen such that asymptotic stability of the closed-loop control system is guaranteed. The adaptation laws are being calculated from a proper sliding surface using the Lyapunov stability theory. This method guarantees the closed-loop control system robustness against the system uncertainties and external disturbances. Eventually, the presented method is used to synchronize two fractional-order gyro and Duffing systems, and the numerical simulation results demonstrate the...
Energy and exergy evaluation of a new bi-evaporator electricity/cooling cogeneration system fueled by biogas
, Article Journal of Cleaner Production ; Volume 233 , 2019 , Pages 1494-1509 ; 09596526 (ISSN) ; Vajdi, M ; Rostamzadeh, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Bi-evaporator electricity/cooling cogeneration systems can be a favorable addition to the integrated power plants since the generated cooling load should be addressed for different demands. More consequentially, taking advantage of such an integral set-up operated with highly reliable heat source such as biogas can be appreciable for nowadays industries. Regarding this demand, an innovative bi-evaporator electricity/cooling cogeneration system is introduced at first. Next, the suggested system is integrated with a gas turbine cycle fueled by biogas. In the subsequent part, the plausibility of the introduced integrated power plant is examined from first and second laws of thermodynamics (as...
Distributed Observer Type Protocol for Flocking of Linear Second-Order Multi-Agent Systems Subject to External Disturbance
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 141, Issue 6 , 2019 ; 00220434 (ISSN) ; Haeri, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
This paper studies the leader-follower flocking of multi-agent systems for the linear second-order dynamics, subject to the external disturbance problem. It is assumed that the dynamic of the leader is Lipschitz-type. Also, the velocity is the output of the system, and full-state information is not available for feedback. A distributed full-order observer is employed to estimate every agent's states and external disturbance. A control protocol for each agent is designed based on the measurement of its output/velocity and relative velocity of its neighbors. Under the proposed protocol, the velocity convergence of whole agents to the velocity of the virtual leader is guaranteed as well as the...
Control of high order integrator chain systems subjected to disturbance and saturated control: A new adaptive scheme
, Article Automatica ; Volume 100 , 2019 , Pages 108-113 ; 00051098 (ISSN) ; Ahi, B ; Haeri, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This paper is concerned with the global stabilization of multiple integrator systems subjected to input saturation. Among the existing works, nested saturation method has been demonstrated to be an effective tool. In the present contribution, an adaptive nested saturation feedback law is proposed which takes the advantages of time varying parameters in the saturation functions along with employing the well-known extended state observer. The global stability of the proposed approach for a desired order of integrators’ chain is demonstrated. The performance of the proposed control law is compared with the existing methods in the case of a triple integrator chain. It is shown that the proposed...
Adaptive fuzzy nonlinear sliding-mode controller for a car-like robot
, Article 5th IEEE Conference on Knowledge Based Engineering and Innovation, KBEI 2019, 28 February 2019 through 1 March 2019 ; 2019 , Pages 686-691 ; 9781728108728 (ISBN) ; Shojaeefard, M. H ; Amirkhani, A ; Behroozi, H ; Intelligent Systems Scientific Society of Japan; Iran Computer and Video Games Foundation; Islamic World Science Citation Center (ISC) ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, a nonlinear controller, which can be updated online by means of fuzzy logic, has been proposed for tracking the trajectory of a car-like robot. The advantage of this control scheme is that it eliminates the effects of model disturbances and uncertainties, which cannot be avoided; and especially when we consider the difficult task of determining the exact kinematic and dynamic models of car-like robots. The proposed approach comprises a robust nonlinear section that uses the sliding mode control and a fuzzy section that can update, online, parameters of the nonlinear controller. The stability and the error convergence of the closed-loop system are verified through the Lyapunov...
Hardware implementation of an ADRC controller on a gimbal mechanism
, Article IEEE Transactions on Control Systems Technology ; Volume 26, Issue 6 , 2018 , Pages 2268-2275 ; 10636536 (ISSN) ; Nobakhti, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Active disturbance rejection control (ADRC) is applied to a one-axis gimbal mechanism. The dynamic model of the system is derived and validated from mathematical modeling and practical experiments. Disturbances acting on the complete model of the gimbal mechanism are introduced via base lateral acceleration and angular motion. The ADRC is designed by utilizing an extended state observer for observing and suppressing the effects of external disturbances and internal parameter uncertainties. A PID controller is used to form a basis of comparison for set-point tracking and disturbance rejection performance. The effects of identification errors and observer bandwidth are experimentally...
Decentralized robust model predictive control for multi-input linear systems
, Article UKACC 12th International Conference on Control, CONTROL 2018, 5 September 2018 through 7 September 2018 ; 2018 , Pages 13-18 ; 9781538628645 (ISBN) ; Haeri, M ; Pannocchia, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, a decentralized model predictive control approach is proposed for discrete linear systems with a high number of inputs and states. The system is decomposed into several interacting subsystems. The interaction among subsystems is modeled as external disturbances. Then, using the concept of robust positively invariant ellipsoids, a robust model predictive control law is obtained for each subsystem solving several linear matrix inequalities. Maintaining the recursive feasibility while considering the attenuation of mutual coupling at each time step and the stability of the overall system are investigated. Moreover, an illustrative simulation example is provided to demonstrate the...
Adaptive model predictive control-based attitude and trajectory tracking of a VTOL aircraft
, Article IET Control Theory and Applications ; Volume 12, Issue 15 , 2018 , Pages 2031-2042 ; 17518644 (ISSN) ; Rezaeizadeh, A ; Sharif University of Technology
Institution of Engineering and Technology
2018
Abstract
A novel adaptive model-based predictive controller for attitude and trajectory tracking of a vertical take-off and landing(VTOL) aircraft in the simultaneous presence of model uncertainties and external disturbances is introduced in this study. Animportant challenge of designing the model-based controllers is developing an accurate model, especially in the presence ofmodel uncertainties. In this study, first, the nominal model of a ducted-fan air vehicle, which is a multi-input multi-outputnonlinear system with non-minimum phase behaviour, is given as the test case of this research. After that, two modified robustand adaptive model predictive controllers are proposed for tracking a...
Hierarchical decentralized control of a five-link biped robot
, Article Scientia Iranica ; Volume 25, Issue 5B , 2018 , Pages 2675-2692 ; 10263098 (ISSN) ; Salarieh, H ; Foumani, M. S ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
Most of the biped robots are controlled using pre-computed trajectory methods or methods based on multi-body dynamics models. The pre-computed trajectory-based methods are simple; however, a system becomes highly vulnerable to the external disturbances. In contrast, dynamic methods make a system act faster, yet extensive knowledge is required about the kinematics and dynamics of the system. This fact gave rise to the main purpose of this study, i.e., developing a controller for a biped robot to take advantage of the simplicity and computational efficiency of trajectory-based methods and the robustness of the dynamic-based approach. To do so, this paper presents a two-layer hierarchical...