A Novel Robust Adaptive Second-order Sliding Mode Tracking Control Technique for Uncertain Dynamical Systems with Matched and Unmatched Disturbances

Saleh Mobayen,Fairouz Tchier 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.3

This paper investigates a robust adaptive second-order sliding mode control method for tracking problemof a class of uncertain linear systems with matched and unmatched disturbances. The fundamental idea of thesuggested control method is that the discontinuous sign function is used for the time-derivative of the controlsignal and hence the smooth control input achieved after an integration process is continuous and removes thechattering problem. Using a PID sliding surface, the finite-time convergence of output tracking errors is obtained. The adaptive gain-tuning control law removes the necessity of gaining information about the upper bounds of theexternal disturbances. The control system is in the sliding mode and then, tracking errors converge to the origin ina finite time under the presence of the external disturbances. Simulation results on an uncertain numerical systemand a turntable servo-system are presented to indicate the effectiveness and feasibility of the proposed scheme.

Adaptive Global Terminal Sliding Mode Control Scheme with Improved Dynamic Surface for Uncertain Nonlinear Systems

Saleh Mobayen 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

This paper proposes an adaptive global terminal sliding mode control scheme for tracking control of uncertain nonlinear systems. Using the proposed global sliding surface, the reaching period is omitted and the robust performance of the whole system is improved. The discontinuous sign function is involved in the controller derivative and then, the control signal achieved after integration is continuous and attenuates the chattering problem. Two adaptation laws are employed to cope with the uncertainties and disturbances whose upper bounds are not required to be known, where the proposed technique is more flexible in the real implementations. This method guarantees robustness against uncertainties, disturbances and nonlinearities of the system. Moreover, the proposed scheme removes the chattering phenomenon using the adaptive-tuning parameters and hyperbolic tangent function in the reaching control law. Numerical simulations display the success and applicability of the proposed scheme in comparison with the results of the other method.

Adaptive Nonsingular Integral-type Second Order Terminal Sliding Mode Tracking Controller for Uncertain Nonlinear Systems

Saleh Mobayen,Hamede Karami,Afef Fekih 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.4

Achieving accurate and reliable tracking control for nonlinear systems with uncertainties and disturbances is one of the most challenging problems in nonlinear control. In this paper, we propose an adaptive nonsingular integral-type second order terminal sliding mode tracking control for nonlinear systems with uncertainties. First an integral type sliding manifold is defined to ensure finite time tracking convergence. Then an adaptation mechanism is proposed to estimate the unknown uncertainty upper bound. Finally, the adaptive nonsingular integral-type second order terminal sliding mode controller is synthesized without any assumptions about the uncertainties. System stability is proven using the Lyapunov stability theorem. Its performance is assessed using a thruster system and an inverted pendulum. Chattering attenuation, finite time convergence and disturbance mitigation are among the positive features of the proposed approach. Additionally, eliminating the need for the upper bound knowledge resulted in a design that can practically be implemented to a wide range of applications.

Chattering-free Fault-tolerant Attitude Control with Fast Fixed-time Convergence for Flexible Spacecraft

Seyed Majid Esmaeilzadeh,Mehdi Golestani,Saleh Mobayen 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2

This paper is mainly dedicated to the challenging issue of fixed-time attitude control for a flexible spacecraft in the presence of actuator faults, external disturbances and coupling effect of flexible modes. The attitude controller is developed by employing a fixed-time nonsingular terminal sliding mode under which the convergence time is bounded and independent of the initial states. This robust attitude controller is able to provide superior properties such as fast fixed-time attitude manoeuvring with high pointing accuracy, singularity avoidance and chattering free. More specifically, a new reaching law is employed to provide convergence rate improvement as well as chattering alleviating simultaneously. The actuator fault problem is also considered and the attitude control is achieved even when the actuators experience severe faults. The proposed controller ensures that the closed-loop attitude system is stable in the sense of fixed-time stability concept. Furthermore, since the upper bound of external disturbances and flexible vibrations acting on the spacecraft is not available, an adaptation mechanism is presented. Numerical simulations demonstrate that the proposed controller is able to successfully accomplish attitude control with high attitude pointing accuracy and stability in spite of the actuator faults, flexible structures vibrations and external disturbances.

Optimal Control of a MIMO Bioreactor System Using Direct Approach

Abolfazl Simorgh,Abolhassan Razminia,Saleh Mobayen,Dumitru Baleanu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.3

In this paper, the optimal control of a continuous type bioreactor with multi-input-multi-output signals is presented for the two active phases: growth and stationary. The underlying criterion to be minimized generalizes the classic quadratic forms to address some crucial objectives in controlling the bioreactor. In particular, the protection of actuators against fast switching in the controller output is considered by including a weighting term of the control signal derivatives. The direct optimal control approach is used to carry out the optimization in the presenceof various limiting constraints. Direct methods are based on transcribing the infinite-dimensional problem to a finite-dimensional one. In this manuscript, direct single shooting and trapezoidal collocation methods are used for transcription, and the successive quadratic programming method is employed to solve the resulting nonlinear programming problem. It is shown that the trapezoidal method is an effective method for controlling the bioreactor in all the active phases, whereas the single shooting fails in dealing with the unstable one (i.e., growth). To analyzesolutions in a more accurate manner, an auxiliary criterion is defined, and then the cheap control analysis is studied. The convergence to the lowest value of the auxiliary cost function and the effects on the optimal state and control trajectories are then examined by varying cheap parameters. Several numerical simulations support the presented theoretical formulation.

Vibration characteristics of microplates with GNPs-reinforced epoxy core bonded to piezoelectric-reinforced CNTs patches

Forsat, Masoud,Musharavati, Farayi,Eltai, Elsadig,Zain, Azlan Mohd,Mobayen, Saleh,Mohamed, Abdeliazim Mustafa Techno-Press 2021 Advances in nano research Vol.11 No.2

In the current study, vibration characteristics of a three-layered rectangular microplate with Graphene nanoplatelets (GNPs)-reinforced Epoxy core which is fully bonded to piezoelectric-reinforced single-walled Carbon nanotubes (SWCNTs) patches are provided. The face sheets are subjected to the electric field and the microplate is assumed to be in a thermal environment and also, is located on the visco-Pasternak model of the elastic substrate. The GNPs and SWCNTs are dispersed through the core's and face's thickness according to the given functions. To account the shear deformation effect, tangential shear deformation theory (TGSDT) as a higher-order theory is employed and the modified strain gradient theory (MSGT) with tree independent length-scale parameters is selected to capture the size effect. Using the extended form of Hamilton's principle and variational formulation, the governing motion equations are derived and solved mathematically via Navier's scheme for simply supported edges microplate. By ensuring the validity of the results after comparing them in a simpler state with previously published ones, the effects of the most prominent parameters on the results are investigated. It is seen GNPs and CNTs dispersion patterns play an important role in the microplate vibrational behavior, as well as temperature variations. Since the under consideration microstructure can be accounted as smart structures, therefore, the outcomes of this study may help to design and create more efficient engineering structures, such as sensors and actuators and also micro/nano electromechanical systems.

Constrained Robust Control by a Novel Dynamic Sliding Mode Surface

Kazem Zare,Mokhtar Shasadeghi,Taher Niknam,Mohammad Hassan Asemani,Saleh Mobayen 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3

In this paper, a sliding mode control (SMC) using a novel dynamic sliding surface is proposed for multi-input multi-output (MIMO) nonlinear systems. The proposed control design provides a robust approach with additional degrees of freedom to satisfy the control input constraint. By decomposing the original system into subsystems, the coupling dynamic terms are modelled in the form of system uncertainties. The dynamic sliding surface is established from inspiring state-space representation of an LTI system with error as input, internal states, and the surface as output. Moreover, the adaptive law is designed to estimate the upper bounds of uncertainties. The performance of the proposed controller is evaluated through a benchmark quadruple-tank process (QTP).