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Showing 2 results for Subject: Hybrid Control Systems
Hamidreza Koofigar, Maedeh Malek,
Volume 7, Issue 2 (3-2021)
Abstract
In this paper, the problem of robust stabilization of uncertain and perturbed switched nonlinear systems has been investigated. It’s well-known that the solution of H∞ control problem may not exist for switched systems with a common storage function for all subsystems. On the other hand, by adopting multiple storage functions, different Hamilton-Jacobin inequalities need to be solved. Hence, the robust control problem is addressed here based on passivity, in two cases. First, it is assumed that there is at least one passive subsystem in the whole state space, and the problem is solved based on the average dwell time approach. In this case, by defining the concept of system passivity rate, the admissible range of average dwell time is obtained. In the second case, none of subsystems is passive and the H∞ control problem is solved by using the feedback passification. In addition to theoretical analysis of the design algorithms, the performance of the theorems for uncertain switched nonlinear systems has been investigated by providing two simulation examples and numerical analysis.
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.
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| نشریه سامانههای غیرخطی در مهندسی برق در خصوص اصول اخلاقی انتشار مقاله، از توصیههای «کمیته بینالمللی اخلاق نشر» موسوم به COPE و «منشور و موازین اخلاق پژوهش» مصوب معاونت پژوهش و فناوری وزارت علوم، تحقیقات و فناوری تبعیت میکند. |
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