Rbfn-based Backstepping Control And Applications On Bilateral Teleoperations

In recent years,with the continuous development of industrial technologies,the demand for better control methods in engineerings have gradually increased.Uncertainties,non-smooth characteristics,and time-delay characteristics often exist in practical systems,which makes it difficult for traditional control schemes to meet the needs of actual control tasks.The backstepping control method based on radial basis function neural networks can handle the uncertainty of the system,attracting broad interest of researchers in the field of control of nonlinear systems.This method has been applied in a variety of engineering control scenarios.Based on the existing research results in the literature,this paper further explores the theoretical research of the backstepping control method based on the radial basis function neural network,and applies it to the control task of the manipulator system and the bilateral teleoperation system.The research work of this dissertation mainly includes the following aspects:(1)The tracking control problem of a class of high-order nonlinear systems in the pure-feedback form is studied.On the premise that the nonlinear function of the system is a continuous,the median value theorem is used to decouple the high-order nonlinear system with pure feedback structure into a strict feedback form,and on this basis,the backstepping control method is used to control the system Design.Under the framework of the backstepping control method,the RBF neural network is used to approximate the unknown items in the system,and the uncertain nonlinear problem of the system is transformed into the parameter update problem of the RBF neural network.Taking the finite time stability theory as the performance index of the controller design of the system,a control scheme that can make the controlled system stable in a finite time is proposed.Under the action of this control scheme,the controlled system can quickly reach a stable state,and the output signal of the system can track the reference signal with ideal accuracy.In addition,due to the consideration of the impact of the input dead zone phenomenon on the system performance,this control scheme can better meet the needs of actual control tasks than the traditional control scheme.(2)For the manipulator system,an adaptive funnel control method is proposed.The manipulator system is one of the most common control systems in the engineerings.Although the related control problems of the robotic arm system have been extensively studied,there are still many problems.Because of the requirements for work efficiency,the manipulator system often needs to work under high-speed motion,and it is prone to large overshoot under high-speed motion,which will damage the accuracy of the controlled system.Considering the working requirements of the high-speed operation of the robotic arm system,a control method with limited output is proposed for it,so that it can avoid high overshoot under the condition of high-speed operation.Specifically,under the design framework of the back-step recursive method,the principle of funnel control is introduced to limit the tracking error of the system to a funnel-shaped boundary curve.As the terminal equipment of the teleoperation system,the research of its control scheme has a strong practical engineering application prospect,and it is also the basis of the research of the control method of the teleoperation system.(3)Aiming at the bilateral teleoperation system affected by the constant communication delay,a quantitative synchronization control scheme is proposed.Bilateral teleoperation system is not only a system with many uncertainties,but also an interrelated system composed of two terminal subsystems of the master and slave manipulators.The research on the control scheme of the teleoperation system is inseparable from the previous work content.Considering the possible influence of communication bandwidth on the control performance of the teleoperation system and the inevitable communication delay between the master and slave end,an input quantizer with hysteresis characteristics is applied to the control task of the bilateral teleoperation system.Through the hysteresis quantizer,the original intensive continuous control variable is quantified as a discrete control variable that changes with the change of control demand,which greatly reduces the bandwidth requirements of the communication system.(4)For a class of bilateral teleoperation system under time-varying delay communication conditions,a finite time synchronization control scheme is proposed.In the actual teleoperation system,the communication channel often passes through the public communication network,and the public communication network has a time-varying communication delay,which will have a serious impact on the control performance of the system.Considering the influence of time-varying delay on the system,the influence of the input dead zone on the control accuracy of the manipulator system is also considered in the controller design process.By constructing a suitable Lyapunov-Krasovskii function,using the backstepping recursion method and the finite-time stabilization method,a class of adaptive control schemes is proposed.Through simulation comparison,this control method has more stable control performance than other methods under the condition of input dead zone.Related experimental results are also given to verify the effectiveness of the proposed control scheme.