Optimization of Grid-Connected Photovoltaic Power Generation Technology Based on Nonlinear Back-Stepping Controller

This paper presents an adaptive terminal sliding mode control method for anti-synchronization of uncertain chaotic systems. By fusion of the terminal sliding mode control and the adaptive control techniques, a robust controller is designed so that the states tracking error can reach the terminal sliding mode surface and converge to zero in a finite time. Finally, some simulation results are included to demonstrate the effectiveness and the feasibility of the proposed anti-synchronization scheme.

Vehicle platoon is one of the innovations in the automated highway systems, which has the potential to reduce fuel consumption, alleviate traffic congestion and lighten the driver’s burden. How to control the vehicle effectively to ensure the stability of the queue is a challenge. Aiming to overcome the shortcomings of the platoon control method based on traditional sliding mode control, a non-singular terminal sliding mode control method optimized by the extreme learning machine is proposed in this paper. Firstly, the vehicle longitudinal dynamics are derived from the analysis of the forces acting on the vehicle in the longitudinal direction. A constant time headway policy is taken as the spacing policy. The modified non-singular terminal sliding mode control method has outstanding performance, simulation results demonstrate that the following vehicles can rapidly track the trajectory of the leading vehicle in the platoon with less spacing error and guarantee string stability. In this study, several experiments are set up to consider the disturbance and other uncertain practical factors. The performance of the proposed method is superior to the traditional sliding mode control method. Experimental results show that the proposed method can significantly reduce chattering and has good robustness under the circumstances of the disturbance.

To eliminate the effect of the uncertain disturbances and improve the control accuracy of spacecraft Attitude Control System, a nonlinear control algorithm named nonsingular terminal sliding-mode feedback controller is proposed in this work, which is mainly made up of nonsingular terminal sliding-mode controller and sliding-mode feedback controller. In the first place, nonsingular terminal sliding-mode controller is designed, which guarantees global asymptotic convergence of the attitude in the presence of the uncertain perturbations from the space. Despite that, it is the influence of the uncertain disturbances that hinder the control accuracy. Then, in order to promote the control accuracy, the sliding-mode feedback controller based on the principle of minimum sliding-mode error is proposed, which is used to compensate the control errors of the nonsingular terminal sliding-mode controller caused by the uncertainties. Hence, the determination principle of the weighting matrix in sliding-mode feedback controller is discussed, and the algorithm structure of the sliding-mode feedback controller is also analyzed, which provides the theoretical basis for the sliding-mode feedback controller. By contrast, an adaptive fuzzy algorithm is designed and introduced into the nonsingular terminal sliding-mode controller to improve the control accuracy, which named the nonsingular terminal fuzzy sliding-mode controller. Last but not the least, several numerical examples are presented to demonstrate the efficacy of the proposed nonsingular terminal sliding-mode feedback controller. Simulation results confirm that the control accuracy of the nonsingular terminal sliding-mode feedback controller is higher than the nonsingular terminal sliding-mode controller and the same as nonsingular terminal fuzzy sliding-mode controller. Not only is the calculation of the nonsingular terminal fuzzy sliding-mode feedback controller smaller than nonsingular terminal fuzzy sliding-mode controller, the adjusted parameters are also fewer than nonsingular terminal fuzzy sliding-mode controller obviously. The numerical results clearly indicate that the proposed nonsingular terminal sliding-mode feedback controller based on the principle of minimum sliding-mode error can compensate control errors accurately and quickly; therefore, it can reduce the effect of the uncertainties from the space indirectly.

Head pursuit interception is useful in modern industries. Because it is difficult to intercept a high-speed target directly, the head pursuit is frequently used to intercept targets such as re-entry flight vehicle. This paper proposes an adaptive terminal sliding mode control method for intercepting a high-speed manoeuver target with impact angle considered. It introduces the mathematical model of relative motion between interceptor and target to design the sliding mode surface so as to meet the critical conditions of head pursuit interception. With the dynamic characteristics of both interceptor and target considered, it designs an adaptive terminal sliding mode guidance law to compensate for modelling errors and to improve the interception accuracy. It uses the Lyapunov method to analyse the theoretical stability. Finally it carried out numerical simulations to validate the robustness and effectiveness of the guidance law, thus obtaining good interception performances.

This paper aims to design an adaptive fault-like model-based sliding-mode control (SMC) law for a class of vehicle platoon systems, where the follower vehicles have quantized input, unknown actuator deadzone, and distance restrictions. Using adaptive terminal sliding mode control method and barrier Lyapunov function (BLF), an adaptive controller is designed to ensure the collision avoidance and communication connection keeping. In addition, the problem of the unknown actuator deadzone and input quantization is first transformed to a fault-like problem, which will simplify the control design procedure. Finally, the effectiveness of the proposed control strategy is verified by a numerical example.

Improved line-of-sight trajectory tracking control of under-actuated AUV subjects to ocean currents and input saturation

Chapter 1 - Modeling and Control of a New Narrow Vehicle

This paper presents a new terminal sliding mode actuator failure compensation control scheme for the nonlinear system of near-space vehicle. The proposed method can ensure that the tracking errors of near-space vehicles converge to zero in finite time after encountering unknown actuator failure. Different from other traditional terminal sliding mode control methods, this method makes the system avoid the singularity problem; Also, this method can ensure the stability of the system, and only needs to consider the sliding stage of the sliding mode control. Furthermore, on this basis, the system errors can still converge to zero in finite time with actuator failures. Finally, the terminal sliding mode control algorithm is used for the near-space vehicle with actuator failures, and the simulation results show the effectiveness of the algorithm.

The inherent characteristics of the DC-DC convertors, such as high nonlinearity and time-variation, often result in some difficulties in designing control approaches. Adaptive backstepping sliding mode control method and terminal sliding mode control method are combined in this paper to propose a new kind of adaptive backstepping based terminal sliding mode control for DC-DC convertor to improve control effect. The new method can not only make the system adapt the uncertainty factors, but also enable the system to reach the steady state within a limited time. Simulation results show the superiority of this combination approach.

This paper investigates the trajectory-tracking problem of an uncertain quadrotor in the presence of complex disturbances. A new fractional-order terminal sliding mode control method (FOTSMC) is designed for a quadrotor attitude, which can increase the control robustness against the external disturbances and modeling uncertainty, and decrease the chattering problem. A new fractional non-integer sliding mode control technique for a quadrotor position is designed to stabilize its state variables and attenuate wind disturbance and the effects of variation in the mass. The stability analysis is studied by the Lyapunov theory. Numerical simulation for complex flight trajectory under disturbances is given to illustrate the validity of the proposed methods.

In the declining stage of soft landing on asteroid, there are many problems in control system of probe such as low convergence speed, long convergence time and severe chattering. A terminal sliding mode control method based on double power reaching law is proposed in this paper. On the basis of conventional reaching law analysis, combined with nonlinear, weak gravitational field characteristics, control schemes in this paper proposes double power reaching law and adopts the terminal sliding mode control method. The controller can weaken the chattering, improve system stability and convergence rate, so that the system can make status tracking error converges fast to zero in the limited time. It has a fast speed either away from or approach to the sliding surface. Simulation results show that the proposed control method achieve fast convergence of the system state in a finite time and strong robustness to disturbances, and eliminates the presence of control chattering. Also, the proposed control law can ensure a smooth landing to the specified descent height, and ultimately secure a soft landing.

This paper deals with utilizing a recursive singularity-free fast terminal sliding mode control method for finite-time robust tracking control in a class of nonholonomic systems described by an extended chained form. To enhance the performance of the proposed method, the constrained parameters in the controller are exactly tuned using evolutionary algorithms such that the tracking error reaches zero in a short time and without chattering. A comparative study is also presented among the applied evolutionary algorithms namely differential evolution, bat optimization, cuckoo optimization and bacterial foraging optimization. Applying the proposed design method leads to a considerable reduction in convergence time of the states as well as the chattering phenomenon. It is shown that the method is robust against disturbance in the input of the system. Numerical simulations for a well-known nonholonomic system, i.e., wheeled mobile robot demonstrate effective improvement in the results compared with conventional terminal sliding mode control method. DOI: http://dx.doi.org/10.5755/j01.itc.47.1.15031

This paper investigates finite-time attitude tracking control strategies for hypersonic flight vehicles (HFVs) with parameter uncertainties, external disturbances, and actuator saturations by applying sliding model control, adaptive mechanism, and nonlinear disturbance observer techniques. A nonlinear dynamic model of HFV attitude system in reentry flight phase is established. Then, a basic attitude control method of the HFV system is designed based on a terminal sliding mode control (TSMC) scheme to accommodate the system-lumped disturbance torques and guarantee the finite-time stability. To relax the prior knowledge of bounded lumped disturbance of the TSMC-based HFV attitude system, an adaptive TSMC (ATSMC) scheme is proposed. In order to relax the limit of compound uncertainties and attenuate chattering phenomenon of the TSMC-based HFV attitude system, a nonlinear disturbance observer-based TSMC (DO-TSMC) scheme is presented, which enhances the disturbance attenuation and robust tracking performance. Finally, simulation results of a generic X-33 nonlinear model exhibit the effectiveness of the proposed TSMC, ATSMC, and DO-TSMC schemes.

In this paper, the attitude control of rigid-liquid-flexible multi-body coupling spacecraft with unknown external disturbances and uncertain inertia parameters is studied, and an attitude maneuver control method based on disturbance observer and fuzzy terminal sliding mode control is proposed. The sloshing of liquid fuel in the spacecraft is equivalent to a spherical pendulum model, and the flexible appendages are assumed to be an Euler-Bernoulli beam. The coupled dynamic equation of the liquid-filled flexible spacecraft is derived by using the Lagrange method. First of all, the interference from space, the parameter uncertainty of the moment of inertia of the spacecraft, the coupling interference caused by the liquid sloshing and the vibration of flexible accessories are summed up as lumped interference. Design disturbance observer to compensate and estimate the lumped disturbance of the system. Then, based on the designed disturbance observer, a fuzzy terminal sliding mode control law is presented, and it is proved that the state of the closed-loop system is finite-time stable under the control law, and converges to the specified terminal sliding mode surface. The fuzzy terminal sliding mode control law uses fuzzy control to improve the switching gain based on the traditional terminal sliding mode control to achieve the purpose of suppressing system jitter. This optimization method can not only reduce the complexity of terminal sliding mode control method, but also reduce the difficulty of debugging parameters because it does not introduce new functions. The numerical simulation results show that the designed fuzzy terminal sliding mode control law can not only achieve the finite-time stability of the closed-loop attitude control system of the liquid-filled flexible spacecraft, but also effectively suppress the liquid sloshing and the vibration of the flexible appendages. At the same time, it has good robustness to disturbances caused by external disturbances and parameter uncertainties, and has better control performance.

A novel fractional-order adaptive non-singular terminal sliding mode control (FONTSMC) method is investigated for the synchronization of two nonlinear fractional-order chaotic systems in the presence of external disturbance. The proposed controller consists of a fractional-order non-singular terminal sliding mode surface and an adaptive gain adjusted with sliding surface. Based on Lyapunov stability theory and stability theorem for fractional-order dynamic systems, the controlled system’s stable synchronization is guaranteed. A dual-channel secure communication system is presented to transmit useful signals based on the proposed synchronization controller. Finally, numerical simulations and comparison with fractional-order PID controller, fractional-order PD sliding mode controller and adaptive terminal sliding mode controller are given to demonstrate the effectiveness and the robustness of the proposed FONTSMC control. The application of the proposed synchronization method is studied in the dual-channel secure communication.