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Aiming at the accurate speed tracking control of electric vehicles (EV) driven by permanent magnet synchronous motors (PMSM) under external load torque disturbances, this paper proposes an approach for prescribed performance back-stepping control based on a disturbance observer. Firstly, a controller was designed using the back-stepping technique, and a second-order sliding mode differentiator was introduced to approximate the derivative of the virtual control law, which can solve the "differential explosion" problem in traditional back-stepping control techniques. Secondly, in order to reduce the influence of motor load disturbances in the driving process of EV, a novel disturbance observer was proposed, bolstering the anti-interference capability of system. In addition, to achieve the preset high transient and steady-state speed tracking performance, a prescribed performance control strategy was incorporated to guarantee tracking errors within predefined boundaries. Finally, the Lyapunov function was utilized to verify the system stability. The simulation results showed that, compared with traditional PI control, the designed controller significantly increased motor speed tracking precision by more than 5 times, demonstrating a superior speed tracking performance and enhanced anti-interference capability.

This paper investigates the trajectory tracking control problem of a four-wheel independently driven skid-steering mobile robot (FWID-SSMR) while considering friction resistance, parameter variation and external disturbances. Unlike previous studies that only achieved stable tracking control of FWID-SSMR, this paper accomplishes prescribed steady-state and transient performance. Based on the dynamic model of FWID-SSMR, an integer-order prescribed-time controller (IOPTC) is developed first, which can make the tracking errors converge to a predetermined residual set with a preset convergence rate in a prescribed time. Motivated by it, a fractional-order prescribed-time controller (FOPTC) is developed by exploiting the genetic attenuation properties of fractional calculus (FC) for improving the control performance. The feasibility and effectiveness of the developed controller are verified by Lyapunov theoretical analysis and numerical simulation studies. The simulation results show that both the IOPTC and FOPTC outperform the feedback controller (FBC). Moreover, the influence of the performance function on control performance is also tested, which can serve as a reference for selecting the appropriate performance function to use in future applications. [ABSTRACT FROM AUTHOR]

In this study, we investigate a terminal sliding mode control (TSMC) system combined with predefined-time and prescribed-performance control methods for an unmanned planing hull (UPH) system in the presence of a control input delay at the heading axis and a porpoising motion due to pitching-moment disturbance. A second-order TSMC system is adopted to bypass the unstable heading-angle response of the conventional first-order TSMC system caused by the control input delay of the hydraulic rudder actuator system. Next, predefined-time and prescribed-performance control methods are proposed to enhance the disturbance rejection performance of an uncertain UPH. The results of sequential comparative simulations show that the disturbance rejection performance of the proposed hybrid disturbance rejector using both the predefined-time and prescribed-performance control methods for a porpoising motion is superior to those of conventional controller systems without introducing disturbance observers. [ABSTRACT FROM AUTHOR]

This paper investigates the prescribed-time leader-following output-feedback consensus problem for second order multiagent systems without velocity measurement. Firstly, by introducing a time-scaling function, novel prescribed-time state observers are designed to estimate the second-order states of the agents. Then, a distributed output-feedback scheme is proposed to achieve leader-following consensus, where the transient performance, including the convergence rate and the overshoot, can be offline pre-assigned. It should be noted that the singularity-like problem is solved for the system under measurement errors by adopting a form of piecewise functions. Moreover, the control strategy is modified by introducing an auxiliary system when taking the common saturation problem into account. Finally, the efficiency of the proposed schemes is illustrated by numerical simulation examples. • A novel kind of prescribed-time performance functions is designed. • A form of sine functions is introduced to deal with the singularity-like problem. • The prescribed-time stability of the system is guaranteed by the proposed scheme. [ABSTRACT FROM AUTHOR]

In this study, we investigate a terminal sliding mode control (TSMC) system combined with predefined-time and prescribed-performance control methods for an unmanned planing hull (UPH) system in the presence of a control input delay at the heading axis and a porpoising motion due to pitching-moment disturbance. A second-order TSMC system is adopted to bypass the unstable heading-angle response of the conventional first-order TSMC system caused by the control input delay of the hydraulic rudder actuator system. Next, predefined-time and prescribed-performance control methods are proposed to enhance the disturbance rejection performance of an uncertain UPH. The results of sequential comparative simulations show that the disturbance rejection performance of the proposed hybrid disturbance rejector using both the predefined-time and prescribed-performance control methods for a porpoising motion is superior to those of conventional controller systems without introducing disturbance observers.

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]