Adaptive Sliding Mode Control of the Furuta Pendulum

To deal with the control problems of the three-phase PWM rectifier under the unbalanced grid voltage conditions, this paper proposes a modified direct power control strategy using adaptive sliding mode control algorithm with model of the PWM rectifier in stationary αβ frame. The active and reactive power dynamics of the PWM rectifier are linearized and decoupled based on the inverse system algorithm. Then a sliding mode control scheme is designed to improve the robustness and reduce the influences caused by the system parameters variations and load disturbances. In order to satisfy the state requirements, an adaptive law is introduced to the control strategy to reduce the sliding mode control gain on the premise that the system is stable. Simulation results confirm the feasibility of the proposed control strategy.

A new adaptive fuzzy sliding-mode control (FSMC) scheme was proposed, which incorporated the fuzzy logic into sliding-mode control using fuzzy logic to approximate the equivalent control and the upper bound of uncertainty which involved the disturbance and approximation error, thus the influence of modeling error was reduced and the gain of sliding-mode control part was more fitting, such that the chattering effects could be alleviated . Besides, inspired by the thought of fully tuned RBF neural networks, a fully tuned fuzzy logic was proposed which enhanced the approximating ability of fuzzy logic system. Lyapunov stability theorem was used to prove the stability of the system and the adaptive laws were deduced. Finally, simulation results of some BTT missile were included to illustrate the effectiveness of the adaptive fuzzy sliding-mode control scheme.

This study aims to resolve the problems of low precision, poor flexibility and unstable operation in the control performance of loading robots with long telescopic booms and heavy loads. Firstly, the kinematics and dynamics of long-arm heavy-duty robots are analyzed, and the dynamics model of a long-arm heavy-duty robot is established using the Lagrange method. A new power-hybrid sliding-mode approach law is proposed, and a hybrid force/position control strategy is used to control long-arm heavy-duty robots. The position control of long-arm heavy-duty robots uses a new sliding-mode adaptive control to improve the position accuracy of important joints, and PD control is used to force control the other joints. The two-stage telescopic arm is flexible and the long-arm heavy-load robot is simulated. The simulation results show that the long-arm heavy-load robot obtained using the improved sliding-mode adaptive control algorithm has good track-tracking and jitter-suppression effects. The new power-hybrid sliding-mode controller designed in this paper reduces the jitter amplitude of the end-effector of long-arm heavy-duty robots by 28.75%, 10.92% and 16.22%, respectively, compared with the existing new approach law sliding-mode controller. The simulation results show that the proposed power-hybrid reaching law sliding-mode controller can effectively reduce the amplitude difference of the end-effector. Finally, the force/position control strategy is combined with force-based impedance control, and the design process of impedance controller parameters is introduced, which provides a reference for the trajectory-tracking and vibration-suppression of end-effectors of long-arm heavy-duty robots.

This paper deals with the trajectory tracking of differential driven wheeled mobile robots (WMRs). It is widely known that parameter uncertainty and unknown external disturbances could bring adverse effects to WMRs. To achieve high-performance tracking, a control scheme is proposed in this paper, which integrates a kinematics controller and a dynamics controller. The kinematics controller is designed by the backstepping control and the dynamics controller is derived via adaptive sliding mode control. Moreover, dual radial basis function neural networks (RBFNNs) with adaptive adjust algorithms are adopted to approximate parameter alterations of system dynamics as well as external disturbances. To solve the uncertainty of wheel rolling radius, an adaptive control law is applied. In addition, a PI-type sliding mode control strategy with an exponential reaching law is designed to compensate for the approximation errors of the RBFNNs. Furthermore, the stability and global asymptotic convergence of the control system are proved by the Lyapunov stability theorem. Finally, simulations are provided to verify the effectiveness of the proposed control strategy. The results indicate that the proposed control law is effective in response to parameter uncertainty and external disturbances.

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.

This study develops the application of adaptive sliding mode control to earthquake-excited uncertain structures. Adaptive sliding mode control is useful as it only requires the boundness feature of uncertainties and disturbances to determine control gain (and not the amplitude of bounds). Moreover, the amplitude of chattering effect, the main drawback of sliding mode control, attenuates while stability and robustness are preserved. For this purpose, two adaptive-gain control algorithms are considered. In addition, a time-varying boundary layer is considered to increase the accuracy. In order to examine the feasibility of the applied method, a three-story benchmark structure is considered. Furthermore, performance indexes are used to evaluate the effectiveness of adaptive sliding mode control in comparison to sliding mode control and fuzzy sliding mode control. Comparison of the simulation results in accordance to performance indexes demonstrates that adaptive sliding mode control not only attenuates the amplitude of control effort (i.e. chattering amplitude) but also makes the control of the maximum response of the structure applying adaptive sliding mode control more convenient. It is shown that displacement and drift performance indexes of adaptive sliding mode control are equal to or less than ones of sliding mode control, while root mean square of the control effort of adaptive sliding mode control is attenuated around 50%.

Disturbance observer based adaptive sliding mode control for power tracking of PWRs

A new adaptive sliding-mode control (SMC) scheme was proposed, which incorporated Full Adaptive RBF NN into sliding-mode control using Full Adaptive RBF NN to approximate the equivalent control and the upper bound of uncertainty which involved the disturbance and approximation error, thus the influence of modeling error was reduced and the gain of sliding-mode control part was more fitting, such that the chattering effects could be alleviated . Lyapunov stability theorem was used to prove the stability of the system and the adaptive laws were deduced. Finally, simulation results of some BTT missile were included to illustrate the effectiveness of the adaptive sliding-mode control scheme.KeywordsRBFadaptiveSMCmissile

A nonlinear adaptive sliding mode control strategy for modular high-temperature gas-cooled reactors

In this article, an adaptive sliding mode control (SMC) strategy is designed for the attitude control of aircraft under the influence of dynamic disturbances. A radial basis function neural network (RBFNN) is integrated with the SMC framework, effectively handling the nonlinear aerodynamic forces and moments. This network adapts through the variation in weights and provides a real-time function approximation in order to improve the robustness of the controller against uncertainites. A sigmoid function is incorporated for smoother control input to reduce the chattering effect which is found commonly in SMC. The control strategy has been formulated using only partial information from the aerodynamic model based on available physical parameters of the plant. Its effectiveness is verified through the use of a quadratic Lyapunov function which helps confirm that closed loop system remains stable and the states stay within bounded limits. The simulations show that the control method works well, as it follows the desired attitude commands closely and keeps performing reliably even when different disturbances are introduced.

In this paper, we propose a Takagi-Sugeno-Kang (TSK) fuzzy model for a four-Mecanum-wheel omni-directional mobile free-base (4MW-ODMFB) with system uncertainties and external disturbances based on the model given in [12], [13], and then design an adaptive sliding-mode control (ASMC) system for trajectory tracking of 4MW-ODMFB, which combines the techniques of adaptive control and sliding-mode control. By using Lyapunov method we prove that the ASMC system is global asymptotic stable. We also conduct simulation experiments in MATLAB environment to test our TSK fuzzy model and the ASMC method. All the simulation results demonstrate the effectiveness of the proposed TSK fuzzy model and the stability and robustness of ASMC system.

Adaptive sliding mode control in a novel class of chaotic systems

Integral backstepping sliding mode control for quadrotor helicopter under external uncertain disturbances

This paper presents a non-linear Sliding Mode Control (SMC) strategy based on continuous switching law for large-power (10MW) Permanent Magnet Synchronous Generator (PMSG) based Wind-Energy Conversion System (WECS). The WECS model consists of a wind turbine, PMSG, rectifier fed boost converter, PWM inverter and the filter. The controller is used to maintain the DC-link voltage constant and to generate controlled active and reactive power for grid. For verification of validity of proposed control scheme and model, the proposed system's dynamic model is simulated in MATLAB/Simulink. SMC has the promising features of: fast switching, insensitivity to parameter uncertainty, disturbance rejection quality, and more robustness than the conventional linear controllers. The proposed continuous control compelled the states trajectories of the system onto the surface in error space (sliding surface) for the system behavior to obtain design specifications. Simulation results demonstrate that the proposed SMC is effective and gives superior performance than conventionally tuned PI controller.

We propose a novel data‐driven model‐free adaptive terminal sliding mode control (SMC) for a class of discrete nonlinear systems with perturbations in which tracking error constraints are taken into account in improving tracking accuracy. The goal of this design is that the tracking error trajectory is maintained within the prescribed convergence region which is defined by the performance function, while the disturbances exist. In explaining the advantage of this proposed control scheme, at first, by theoretical calculation, it is proved theoretically that the quasi‐sliding mode can be achieved in a limited time under the specified tracking performance. Furthermore, comparative investigation results are given to validate the effectiveness of the proposed control scheme. Simulation results show that the proposed strategy is superior to model‐free adaptive control, model‐free adaptive terminal SMC, and data‐driven adaptive SMC with prescribed performance control algorithms in terms of tracking accuracy and response speed, which demonstrates the efficiency of the proposed scheme.