Vahid Johari Majd
@modares.ac.ir
Electrical Engineering
Tarbiat Modares University
Vahid J. Majd received his B.Sc. degree in 1989 from the electrical engineering department of the University of Tehran, Iran. He then received his M.Sc. and Ph.D. degrees in the area of Control Theory from the electrical engineering department of the University of Pittsburgh, PA, U.S.A. in 1991 and 1995, respectively. He is currently an associate professor in the control system department of Tarbiat Modares University, Tehran, Iran, and is the director of intelligent control systems laboratory. His areas of interest include: Intelligent identification and control, reinforcement learning, deep learning, ingestible capsule robots, soft robots, neuro-fuzzy control, multi-agent learning, cooperative control, formation control.
EDUCATION
Ph.D., Electrical Engineering, University of Pittsburgh, Pittsburgh, PA, USA, 1995.
RESEARCH INTERESTS
Intelligent identification and control, reinforcement learning, deep learning, ingestible capsule robots, soft robots, neuro-fuzzy control, multi-agent learning, cooperative control, formation control.
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Hossein Zamani, Khosro Khandani, and Vahid Johari Majd
Elsevier BV
Hossein Zamani, Vahid Johari Majd, and Khosro Khandani
SAGE Publications
In this article, the fixed-time formation problem in fractional-order multi-agent systems is addressed. By using the Reimann–Liouville fractional derivative, the memory effects are considered in the dynamics of agents. The goal is to design distributed controllers for such agents of fractional order to achieve formation with a fixed-time convergence rate. To solve this problem, a fractional-order control protocol with a neighborhood-based error variable is proposed. By using the fixed-time Lyapunov stability theorem, it has been theoretically shown that the fixed-time formation tracking can be achieved within a certain settling time, and the upper bound of the settling time has been obtained explicitly. The proposed upper bound does not depend on the initial conditions. Finally, several simulations are worked out to verify the theoretical results. The superiority of the proposed method over finite-time protocols has been illustrated.
Hamidreza MahmoodZadeh, Vahid Johari Majd, and Abbas Ehsani-Seresht
IEEE
Capsule endoscopy robots have been used to detect digestive diseases in recent years. This paper explores the design and implementation of capsule robot localization and control systems using magnetic waves. The built system includes five external electromagnetic coils, and a permanent magnet added to the inactive capsule robot, which is available on the market. The instantaneous position of the robot is calculated through image processing. Moreover, The speed of the robot and the coil's current is measured using the rate of the position and the current sensor. A sliding mode controller is designed for 3D motion of the robot in the digestive system test environment in the lab. Our results show the suitable performance of the robot in tracking the desired position.
Yousef Farid, Vahid Johari Majd, and Abbas Ehsani-Seresht
SAGE Publications
In this article, a robust adaptive intelligent fault-tolerant controller with prescribed performance is proposed for an uncertain quadruped robot with actuator fault. The control system comprised of three terms: (1) a full-state feedback controller which includes the prescribed performance function, (2) an adaptive intelligent wavelet-based Takagi-Sugeno fuzzy network (TSFN), and (3) a robust control term. The proposed controller does not utilize the robot dynamic model. A wavelet-based TSFN is utilized to approximate adaptively the lumped nonlinear terms, parameter uncertainties, and defective torque signal. The wavelet block acts as a feature extractor, reduces the number of fuzzy rules, and also acts as a normalization function. The parameters of TSFN are tuned online by an adaptive law based on Lyapunov stability theory. The proposed controller guarantees the desired specification such as minimum speed of convergence, maximum steady-state error, overshoot concerning the position tracking error, and also bounded closed-loop signals. Numerical simulations on MATLAB/SimMechanics environment demonstrate the stable walking of the quadruped robot in the presence of the actuator faults and parameter uncertainties.
Majid Parvizian, Khosro Khandani, and Vahid Johari Majd
Wiley
In this paper the problem of non‐fragile adaptive sliding mode observer design is addressed for a class of nonlinear fractional‐order time‐delay systems with uncertainties, external disturbance, exogenous noise, and input nonlinearity. An H∞ observer‐based adaptive sliding mode control considering the non‐fragility of the observer is proposed for this system. The sufficient asymptotic stability conditions are derived in the form of linear matrix inequalities. It is proven that the sliding surface is reachable in finite time. An illustrative example is provided which corroborates the effectiveness of the theoretical results.
Majid Ramedani and Vahid J. Majd
IEEE
In recent years, three-dimensional measurement techniques have been widely used in medical sciences, and thus, depth detection in an image plays an important role in computer vision applications. In this paper, we discuss the estimation of the distance between the head of an endoscope and the small intestine septum and its problems. The main objective is to detect the depth of the small intestine to estimate distance. Images were collected through video sampling, and then the data are preprocessed. Morphological reconstruction, bounding box, Convex Hull, and Euclidean distance are employed to update the mentioned distance. At the end of this process, the outputs are simulated, and we are given the output distance in centimeters. This method will assist the endoscope to move inside the small intestine without injuries.
Navid Dini and Vahid Johari Majd
Springer Science and Business Media LLC
Mahdi Siavash and Vahid Johari Majd
IEEE
This study discusses a robust distributed finite-time formation control of the stochastic Lipchitz multi-agent systems within the actuator fault. Furthermore, the orientation of formation is often adjusted in step with the leader's orientation. The agents are modeled as stochastic nonlinear systems either thanks to their intrinsic behavior or working in a very random vibrating environment. Additionally, biased and effectiveness faults are considered. To cater to these, employing a distributed sliding-mode approach and the infinitesimal operation, a robust finite-time fault-tolerant controller is presented in mean-square sense. Finally, a multi-aircraft model under stochastic wind is used to validate the effectiveness of the offered control law.
Alamdar Hafezi, Khosro Khandani, and Vahid Johari Majd
Informa UK Limited
ABSTRACT This paper addresses the design of a non-fragile exponential polynomial observer for a class of fractional-order nonlinear systems. Existence of the observer is proven and a sufficient condition for the stability of the state estimation error dynamics with a predetermined exponential convergence rate is derived employing the Lyapunov stability theorem. The exponential stability criterion is proposed in the form of linear matrix inequalities (LMIs). Moreover, some numerical examples have been provided to illustrate the effectiveness of the proposed approach. The synchronisation of fractional-order Lorenz systems has been investigated using the proposed method. Then, the proposed method has been applied to the chaotic communication problem of fractional-order chaotic systems with four scroll attractors.
Mahdi Siavash, Vahid Johari Majd, and Mahdie Tahmasebi
SAGE Publications
In this paper, the fault-tolerant formation control of nonlinear stochastic multi-agent systems in the presence of actuator faults, disturbances, and time-varying weighted topology is considered. While most traditional fault-tolerant control methods in the literature use fixed weights on the topology edges, in this study these weights are considered time-varying using a pre-designed function, which allows formulating the system more realistically. Moreover, in contrast with previous works on fault-tolerant multi-agent systems, in this study, the model of the agents is considered to be stochastic in general. Furthermore, the actuators of the agents are considered to have a time-varying fault of additive and multiplicative types. A passive and an active fault-tolerant controllers are designed based on the back-stepping sliding-mode approach. In the passive method, a constant robust controller is proposed using an upper bound of the faults while, in the active controller, the additive and multiplicative faults are estimated using adaptive laws. The active and passive fault-tolerant controllers guarantee that the formation errors converge to a bounded region near the origin in a mean-square sense and all of the existing signals in the closed-loop system remain bounded in probability. The results of the formation control are extended to consensus control as well. Finally, a stochastic multi-aircraft model and an RLC circuit with stochastic part are used as two case studies to illustrate the effectiveness of the proposed design method.
Majid Parvizian, Khosro Khandani, and Vahid Johari Majd
SAGE Publications
In this paper, state estimation and adaptive sliding mode control (SMC) of uncertain fractional-order Markovian jump systems (FO-MJSs) with time delay and input nonlinearity are considered. A non-fragile observer is proposed to estimate the system states, and an observer-based adaptive sliding mode controller is synthesized to ensure the reachability of the sliding surfaces in the state-estimation space in finite time. The sufficient condition for stochastic stability of the error system and sliding mode dynamics is derived in the form of linear matrix inequalities (LMIs). Finally, some numerical examples are presented to illustrate the effectiveness of the proposed method.
Navid Dini and Vahid Johari Majd
Elsevier BV
M. J. Koopaee and V. J. Majd
This paper extends the idea of switching T-S fuzzy systems with linear consequent parts to nonlinear ones. Each nonlinear subsystem is exactly represented by a T-S fuzzy system with Lure’ type consequent parts, which allows to model and control wider classes of switching systems and also reduce the computation burden of control synthesis. With the use of a switching fuzzy Lyapunov function, the LMI conditions for asymptotic stability of the system with maximum decay-rate and disturbance attenuation properties under arbitrary switching law are derived. Moreover, several numerical examples are provided to demonstrate the effectiveness of the proposed approaches to reduce the computational burden of control synthesis and improving the closed-loop performance of the system.
Mahdi Siavash, Vahid Johari Majd, and Mahdie Tahmasebi
Informa UK Limited
ABSTRACT This paper addresses a practical finite-time leader-following formation controller design for the second-order stochastic Lipchitz nonlinear systems under uncertain communication environments and external disturbances. It is desired that the orientation of the formation change according to the variations in the leader’s orientation. The time-varying weighted topology matrix is modelled as a linear combination of a finite number of constant Laplacian matrices with time-varying coefficients. The proposed back-stepping sliding-mode controller guarantees that all the signals in the closed-loop system remain bounded in probability and the norm of sliding trajectories converge almost surely in finite-time to an arbitrary small neighbourhood of origin, which can be called almost-surely practical finite-time formation. The results are then modified for solving the consensus problem as well. In the simulation section, a stochastic multi-aircraft model, as well as a numerical example, are used to illustrate the effectiveness of the proposed design methods.
B. Shahriari, V. J. Majd, and H. Moradi Shahrebabaki
Springer Science and Business Media LLC
Mazda Moattari and Vahid Johari Majd
Springer Science and Business Media LLC
Mehran Attar, Vahid Johari Majd, and Navid Dini
Springer Science and Business Media LLC
Yousef Farid, Vahid Johari Majd, and Abbas Ehsani-Seresht
Wiley
This paper deals with the robust adaptive tracking control problem for an uncertain quadruped robot subject to the time‐varying actuator faults. First, the desired interaction forces of the robot legs with the ground are calculated using a pseudo‐inverse method. The proposed scheme includes a sliding‐mode angular velocity observer, an adaptive fault estimator, and an adaptive sliding‐mode force‐position controller. The amplitude of the actuator faults and the upper bounds of the lumped uncertainties are adaptively estimated, and appropriate modifications are provided to the joint torque control signal. The tracking errors of the overall closed‐loop system, as well as the fault estimation error, are guaranteed to converge to the neighborhood of the origin using the Lyapunov stability theorem. Finally, numerical simulations are exhibited to demonstrate the performance of the developed method.
Mazda Moattari and Vahid Johari Majd
Elsevier BV
Yousef Farid, Vahid Johari Majd, and Abbas Ehsani-Seresht
Elsevier BV
Mehrasa Ayatollahi, Vahid Johari Majd, and Mohammad Mehdi Nasrabadi
Hindawi Limited
The problem of cooperative optimal control of multiagent systems with linear periodic continuous-time dynamics is considered. The state consensus problem is formulated as an optimal control problem in which the consensus requirement is reflected in the cost. The cost optimization of each subsystem is considered over finite horizon while the states of the agents converge to a common value, with a control signal that depends on the interactions of the neighboring subsystems. The proposed control law consists of a local and regional terms to capture local measurements and measurements due to interactions with the neighboring agents, respectively. These two terms are obtained by solving a Hamilton-Jacobi-Bellman partial differential equation. A numerical example is presented to demonstrate the effectiveness of the proposed method.
Khosro Khandani, Vahid Johari Majd, Mahdy Rezaei Darestani, and Hassan Talebi
IEEE
This paper addresses the stochastic sliding mode control problem of an aircraft model given in the literature which is perturbed by Gaussian noise. The objective is to stabilize the decoupled longitudinal dynamics of motion. An integral sliding surface is proposed and the sufficient conditions for stochastic stability of the closed-loop dynamics on the proposed sliding surface are given in terms of linear matrix inequalities (LMIs). The proposed method guarantees the reachability of the sliding surface, then the tracking error tends to zero in finite time.
Khosro Khandani, Vahid Johari Majd, and Mahdieh Tahmasebi
Institute of Electrical and Electronics Engineers (IEEE)
In this paper, stochastic systems with fractional Gaussian noise (fGn) are stochastically stabilized using a new robust sliding mode control scheme. The system is assumed to have state time delay and the system matrices have uncertainties. The proposed sliding hyper-surface is a fractional Ito process which is proven to be attainable almost surely in finite time by applying the fractional Ito formula. The trajectories of the system will be kept within a time-varying region around the sliding hyper-surface. The stochastic asymptotic stability of the closed-loop dynamics at sliding mode is guaranteed by the feasibility of some linear matrix inequalities (LMIs). The usefulness of the theoretical findings is demonstrated by providing a case study on the problem of stream water quality standards regulation. In addition, to show the effectiveness and superiority of the method a numerical example is presented.
Yousef Farid, Vahid Johari Majd, and Abbas Ehsani-Seresht
IEEE
Due to the complex and high nonlinear structure of the quadruped robots, the dynamic control of quadruped robots has long been a big challenge for the researchers. In this paper, a guaranteed performance adaptive control algorithm is proposed for tracking control of a quadruped robot with parameter uncertainties. The controller is designed based on the sliding mode theory, and incorporates a transformed error, which includes the performance indices. Parameter uncertainties are estimated by a linear network. By choosing a proper Lyapunov function, the prescribed performance with the proposed controller is proven in the scenes of the parameter uncertainties and the environment constraint. Numerical simulations demonstrate the effectiveness and superiority of the proposed controller.
Mehran Attar, Vahid Johari Majd, Navid Dini, and Farid Edrisi
IEEE
In this paper, an estimation of the dynamics of a 2 degrees of freedom robot manipulator with uncertainties, is derived, using an extended state observer. Decentralizing approach in multivariable systems, is an methodolgy used in an increasing number of practical systems to simplify the controller design. On the other hand, these systems usually contain uncertainties, and also parts of the system's dynamics are unknown. Due to the robust characteristics of extended state observers, these observers would be able to estimate these unknown dynamics, which has been discussed in the literature thoroughly. In this paper, a special class of extended state observers, namely the time varying extended state observer, will be discussed to estimate the dynamics and the disturbances related to the couplings in a manipulator with 2 degrees of freedom. The proposed observer significantly reduces the estimation error's peaking phenomenon, using time variant gains. Thus, it has a better performance compared to similar observers in the literature. This specific class, has time varying parameters, which makes its design simpler and presents a better performance, compared to other linear or nonlinear observers available. As shown in the simulations, the estimation error pick phenomena reduces drastically.