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This paper is devoted to the control design for uncertain pure-feedback nonlinear systems. Remarkably, the systems under investigation allow t he completely nonaffine appearance of the virtual/actual controls and can be subjected to serious nonparametric uncertainties and unknown control directions, which are arguably the most severe uncertainties. Even so, a prescribedperformance control design scheme is proposed for the systems, w here the system states are ensured to evolve within prescribed funnels. By suitably choosing the prescribed funnels, the controller designed can not only accomplish the basic steady performance on stabiliz ation/tracking but also achieve other prescribed performance to guarantee the efficiency and reliability of the systems. Particularly, based on the scheme with suitably choosing the prescribed funnels, global stabilization with prescribed convergence rate and global/semiglobal practical tracking with prescribed transient performance (arrival time/maximum overshoot) are achieved for the uncertain pure-feedback systems. [ABSTRACT FROM AUTHOR]

• The uncertain parts of the system are considered in the process of system dynamics modeling. • The derivative of the virtual control law is approximated by the SOSMD in finite-time. • The PPC is introduced to guarantee the tracking error within a given prescribed boundary. • The finite-time stability of the proposed method is proved based on Lyapunov stability theory. This paper investigates the problem of smoothing power control for photovoltaic (PV) inverter in islanded systems. In order to optimize the power control performance of an islanded PV inverter, a novel finite-time adaptive fuzzy control method with prescribed-performance control (PPC) is presented. Therein, the unmodeled parts in the dynamic model of a PV inverter is considered and approximate them by fuzzy logic systems, which reduce the dependence of the control effect on model accuracy. Moreover, adaptive control solves the problem of uncertainty of the model parameters and further increases the accuracy of the proposed controller. In addition, PPC is introduced to ensure the DC voltage tracking error converges within a limited bound, while the addition of a second-order sliding mode differentiator solves the differential expansion problem of backstepping method, and compensates the filtering error introduced by the compensation signal. Finally, the finite-time stability of the proposed method is proved based on Lyapunov stability theory, guaranteeing the convergence of the tracking error in finite-time. The effectiveness of the proposed control method is compared in the simulation. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of accurate speed tracking control of electric vehicles powered by permanent magnet synchronous motor (PMSM) under external load torque disturbance. Firstly, the dynamic model of PMSM is given, and the controller is designed based on backstepping control. Secondly, a second-order sliding mode differentiator is used to approximate the derivative of virtual control law and solve the problem of explosion of complexity. Considering the load disturbance of PMSM in the actual operation due to road roughness, a novel disturbance observer is proposed to the estimate the load disturbance. In addition, in order to achieve prescribed tracking error performance, the prescribed-performance control is proposed to guarantee the tracking error within a given prescribed boundary. Finally, the finite-time stability of the system is proved, the simulation and real-time implementation results verify the effectiveness of the designed controller. • The fuzzy logic systems are used to approximate the nonlinear function of the system. • The PPC is proposed to guarantee the tracking error within a prescribed boundary. • The novel DO is introduced to estimate the load disturbance in the actual operation. • The SOSMD is used to approximate the derivative of the virtual control law. [ABSTRACT FROM AUTHOR]