|
|
|
 |
Search published articles |
 |
|
Showing 5 results for Terminal Sliding Mode Control
Farhad Bayat, Mohammadmehdi Farkian,
Volume 4, Issue 1 (3-2018)
Abstract
In this paper, electric power production using airborne systems (kites) has been investigated. In the first step, an appropriate model is extracted to describe the behavior of airborne systems. Based on this model, a new path planning algorithm is proposed for the airborne system in the traction phase. Then, in order to achieve the proper operation, tracking the desired path and thus extracting optimal wind energy, a robust controller based on the sliding mode approach is designed in the presence of variations in atmospheric parameters and uncertainties in the system model. In the proposed method, the control strategy is obtained based on the speed vector angle of the airborne. In the proposed approach, six target points are used for the path designing of the kite motion in the traction phase, which increases the precision and flexibility of the designed path. Furthermore, the effect of adjusting the shape of the flight path of the airborne system during the traction phase on the system performance and extraction of the maximum wind force is also investigated.
Dr Hadi Delavari, Ms Seyede Zahra Rashidnejad Heydari,
Volume 5, Issue 2 (3-2019)
Abstract
In this paper, by combining fractional calculus and sliding mode control theory, a new fractional order adaptive terminal sliding mode controller is proposed for the maximum power point tracking in a solar cell. To find the maximum power point, the incremental conductance method has been used. First, a fractional order terminal sliding mode controller is designed in which the control law depends on knowing the upper bound of uncertainty in the system, but in practical application it is difficult or in some cases impossible to calculate this upper limit. In this paper, an adaptive law is given for online calculating of this parameter. The stability proof of the sliding surface, as well as the proof of finite time convergence of closed-loop system, are investigated using the Lyapunov theory. Finally, the performance of the proposed controller is evaluated both in normal and partial shading conditions. For a better comparison of the proposed controller, the performance of this controller is compared in the presence of load variations and the variations of system parameters with the conventional (integer order) terminal sliding mode control.
Javad Mowlaee, Akbar Sharghi, Reza Aghaei Togh,
Volume 8, Issue 2 (3-2022)
Abstract
In this paper, a control input based on terminal sliding mode control is provided for a mobile robot with four Mecanum wheels to move in a predetermined path and convergence into the path in a fixed-time. First, according to the robot structure, a dynamic model of the robot is presented. The dynamic model follows a nonlinear second-order equation. Based on terminal sliding mode control, a nonlinear sliding surface which is a function of position error vector is defined and then the control input is designed based on this sliding surface. Using the Lyapunov theorem, it has been proven that, using this control input, the robot converges to the predetermined path at a fixed time. The convergence time is a function of the constants defined in the control input. Finally, the simulation is presented based on the control input and the results are shown.
Ali Abooee,
Volume 9, Issue 1 (9-2022)
Abstract
In this paper, the finite-time path tracking problem for a typical fully-actuated unmanned marine vehicle subject to unknown physical constants, modelling uncertainties, and environmental disturbance forces (generated by sea waves) is studied and discussed. To deal and handle the mentioned tracking problem, a novel hybrid control structure (based on the finite-time adaptive-robust approach) is proposed. First, a comprehensive model is extracted and introduced to describe kinematic and dynamic behaviors of the unmanned marine vehicle. In this model, all physical constants of the unmanned marine vehicle are assumed to be unknown. Also, modelling uncertainties and unknown environmental disturbance forces are considered as a lumped vector term added to the right side of the comprehensive model. To overcome with parametric uncertainties, all terms of the left side of the comprehensive model, which include unknown physical constants, are converted to the parametric linear regression form. Second, by developing the terminal sliding mode control method, defining several types of innovative nonlinear sliding manifolds, and designing adaptation laws, a novel adaptive-robust nonlinear control structure is proposed to exactly steer the unmanned marine vehicle (in the existence of aforementioned unwanted factors) to the desired trajectory within an adjustable finite time. Time responses related to the estimation of unknown physical constants will precisely converge to the fixed values after the finite time which are not identical to the nominal values of physical constants. Third, by utilizing mathematical analysis (based on the Lyapunov stability theorem), it is proven that the proposed hybrid control approach is able to both accomplish the path tracking objective and guarantee the global finite-time stability for the closed-loop unmanned marine vehicle. Moreover, the stability analysis demonstrates that the convergence finite time is the summation of two smaller finite time (called reaching and settling times) and these times could be determined by two novel separate inequalities. Finally, by using MATLAB software, the introduced adaptive-robust nonlinear control approach is simulated onto the Cybership II and simulation results demonstrate that the finite-time path tracking aim is appropriately fulfilled and satisfied.
Dr Ali Abooee, Mr Sajad Moradi, Dr Vahid Abootalebi,
Volume 9, Issue 2 (3-2023)
Abstract
ABSTRACT: In this paper, three different finite-time nonlinear controllers are proposed to steer a robotic surgical needle in prostate tissue subject to parametric and modeling uncertainties. The torque generated by each type of these controllers is injected to the surgical needle’s closed-loop structure and, in consequence, the system’s state variable precisely converges to the desired path in prostate tissue within an adjustable finite time. The mentioned controllers are constructed based on the developed terminal sliding mode control method (as the main approach of robust-nonlinear control) incorporated with the adaptive control technique (for designing adaptation laws and estimation of unknown physical constants). It is worth noting that the basic difference between these controllers is in the definition of their nonlinear sliding manifolds. By utilizing the Lyapunov stability theory and several applicable lemmas, it is mathematically proven that all types of the introduced control approaches are able to accomplish the finite-time steering objective and guarantee the global finite-time stability for the needle-tissue dynamical system. Adaptation laws (existing in the proposed nonlinear controllers) continuously estimate the unknown physical constants and it is demonstrated that time responses of these estimations exactly reach the constants values over the finite time. Finally, by using MATLAB software, three types of the proposed controllers are separately simulated onto a second-order needle-tissue system to illustrate their proper performance.
|
|
