Design finite-time output feedback controller for nonlinear discrete-time systems with time-delay and exogenous disturbances

This paper considers the finite-time output feedback controller design for nonlinear discrete-time systems with time-delay and time-varying exogenous disturbances. The exogenous disturbances are unknown bounded signals. In this regard, a theorem is given and the sufficient conditions are extracted which guarantees the finite-time boundedness of the time-delay closed-loop system via selecting the appropriate Lyapunov-Krasovskii functional. Furthermore, the gain of output feedback is achieved through the feasibility testing of the derived linear matrix inequalities (LMIs). Finally, a numerical example is given to verify the effectiveness of the developed technique

Robust finite-time synchronization of uncertain chaotic systems: application on Duffing-Holmes system and chaos gyros

This paper considers the finite-time synchronization of chaotic systems in the presence of model uncertainties and/or external disturbances. The synchronization happens between the two nonlinear master and slave systems. Control law is designed in such a way that the state variables of the slave system follow the state variables of the master system in the presence of uncertainties and external disturbances. In order to design a robust finite-time controller, first, a novel terminal sliding surface is proposed and its finite-time convergence to zero is analytically proved. Then a terminal sliding mode controller is designed which can conquer the uncertainties and guarantees the finite-time stability of the sliding motion equations. In this regard, a theorem is proposed and according to the Lyapunov approach it is proved that the synchronization happenes in finite-time. Additionally, in order to show the applicability of the proposed controller, it is applied on two practical systems, the Duffing–Holmes system and chaotic gyroscope system. Computer simulations verify the theoretical results and also display the effective performance of the proposed controller

Robust control design for path tracking of non-affine UAV

Path tracking of Unmanned Aerial Vehicles (UAVs) with three degrees of freedom is studied in this paper with approach of dynamic sliding mode control. For this purpose, the equations of UAV are written. The difficulty and complexity of these equations is that they are non-affine with respect to control inputs. Moreover, they are not directly in the inertial coordinate system while the desired flight path is given in the inertial coordinate system. These two major problems add complexity to the design procedure. Therefore, it is necessary that equations be rewritten in the inertial coordinate system. By definition of virtual inputs; the equations convert to affine structure with respect to virtual inputs and the transformation between the real and virtual inputs has been obtained. After that, the Input/output (I-O) equations of the system are written and converted into controller canonical form. The dynamic sliding mode control law is then designed based on (I-O) equations. Optimal coefficients are also achieved numerically by considering an appropriate cost function. Finally, computer simulation is utilized to illustrate the performance of the designed controller

Robust output tracking of a class of non-affine systems

This paper considers the robust output tracking problem for a class of uncertain non-affine systems. The state-space equations of these systems have a non-affine quadratic polynomial structure. In order to design the output tracking controller, first the error dynamical equations are constructed. Then, a novel sliding mode controller is designed for robust stabilization of the error dynamical equations. For this purpose, a proper sliding manifold which is a function of error vector is suggested. According to upper and lower bounds of uncertainties, two quadratic polynomials are built and with respect to the location of the roots of the given polynomials, the new sliding mode control law is obtained. The proposed controller can conquer the uncertainties and guarantees the asymptotic convergence of the system output toward the wanted time-varying reference signal. Finally, in order to verify the theoretical results, the proposed method is applied to the magnetic ball levitation system. Computer simulations demonstrate the efficiency of the proposed method