In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators...In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators with the existence of unknown bounded complex uncertainties and external disturbances.The proposed approach is a hybrid scheme of the online non-negative adaptive mechanism,tracking differentiator,and nonsingular fast terminal sliding mode control(NFTSMC).Based on the online non-negative adaptive mechanism,the proposed control can remove the assumption that the uncertainties and disturbances must be bounded for the NFTSMC controllers.The proposed controller has several advantages such as simple structure,easy implementation,rapid response,chattering-free,high precision,robustness,singularity avoidance,and finite-time convergence.Since all control parameters are online updated via tracking differentiator and non-negative adaptive law,the tracking control performance at high-speed motions can be better in real-time requirement and disturbance rejection ability.Finally,simulation results validate the effectiveness of the proposed method.展开更多
An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper.It can significantly accelerate the convergence rate of the state error which is initially far from the...An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper.It can significantly accelerate the convergence rate of the state error which is initially far from the origin and achieve the fixed-time convergence.In addition,conventional double power term based reaching law is improved to ensure the convergence of sliding state in the presence of disturbances.The proposed approach is applied to the hovering control of an unmanned underwater vehicle.The controller exhibits both fast convergence and strong robustness to model uncertainty and external disturbances.展开更多
We studied carrier landing robust control based on longitudinal decoupling.Firstly,due to the relative strong coupling between the tangential and the normal directions,the height and the velocity channels were decoupl...We studied carrier landing robust control based on longitudinal decoupling.Firstly,due to the relative strong coupling between the tangential and the normal directions,the height and the velocity channels were decoupled by using the exact linearization method,so that controllers for the two channels could be designed seperately.In the height control,recursive dynamic surface was used to accelerate the convergence of the height control and eliminate″the explosion of complexity″.The radial basis function(RBF)neural network was designed by using the minimum learning parameter method to compensate the uncertainty.A kind of surface with nonsingular fast terminal sliding mode and its reaching law were developed to ensure finite time convergence and to avoid singularity.The controller for the velocity was designed by using super-twisting second-order sliding mode control.The stability of the proposed system was validated by Lyapunov method.The results showed that the Levant′s robust differential observer was improved and used for the observation of the required higher order differential of signals in the controller.The response of aircraft carrier landing under the complex disturbance is simulated and the results verified the approach.展开更多
基金the Vietnam National Foundation for Science and Technology Development(NAFOSTED)Vietnam under Grant No.(107.01-2019.311).
文摘In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators with the existence of unknown bounded complex uncertainties and external disturbances.The proposed approach is a hybrid scheme of the online non-negative adaptive mechanism,tracking differentiator,and nonsingular fast terminal sliding mode control(NFTSMC).Based on the online non-negative adaptive mechanism,the proposed control can remove the assumption that the uncertainties and disturbances must be bounded for the NFTSMC controllers.The proposed controller has several advantages such as simple structure,easy implementation,rapid response,chattering-free,high precision,robustness,singularity avoidance,and finite-time convergence.Since all control parameters are online updated via tracking differentiator and non-negative adaptive law,the tracking control performance at high-speed motions can be better in real-time requirement and disturbance rejection ability.Finally,simulation results validate the effectiveness of the proposed method.
文摘An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper.It can significantly accelerate the convergence rate of the state error which is initially far from the origin and achieve the fixed-time convergence.In addition,conventional double power term based reaching law is improved to ensure the convergence of sliding state in the presence of disturbances.The proposed approach is applied to the hovering control of an unmanned underwater vehicle.The controller exhibits both fast convergence and strong robustness to model uncertainty and external disturbances.
基金supported in part by the National Natural Science Foundation of China(No.51505491)
文摘We studied carrier landing robust control based on longitudinal decoupling.Firstly,due to the relative strong coupling between the tangential and the normal directions,the height and the velocity channels were decoupled by using the exact linearization method,so that controllers for the two channels could be designed seperately.In the height control,recursive dynamic surface was used to accelerate the convergence of the height control and eliminate″the explosion of complexity″.The radial basis function(RBF)neural network was designed by using the minimum learning parameter method to compensate the uncertainty.A kind of surface with nonsingular fast terminal sliding mode and its reaching law were developed to ensure finite time convergence and to avoid singularity.The controller for the velocity was designed by using super-twisting second-order sliding mode control.The stability of the proposed system was validated by Lyapunov method.The results showed that the Levant′s robust differential observer was improved and used for the observation of the required higher order differential of signals in the controller.The response of aircraft carrier landing under the complex disturbance is simulated and the results verified the approach.
