Tracking control method of dead-zone nonlinear time delay system

Abstract

The invention relates to a tracking control method for a dead-zone nonlinear time-delay system, which comprises the following steps of: firstly, approaching a time-delay item in the dead-zone nonlinear time-delay system by adopting a radial basis function neural network to form a new system expression; then, a backstepping control method is used for carrying out backstepping control on the new system expression, in the process of backstepping control, a nonlinear filter based on a timing variable integral function is introduced, a virtual control law of each step of the backstepping control method passes through the nonlinear filter, and backstepping control of the next step is designed through the obtained filtered virtual control law; controller design is carried out in the last step of backstepping control, and during controller design, online estimation is carried out on a dead zone interference term, a neural network error term and an unknown term of a nonlinear filter by using an adaptive law, so that a system tracking error is converged to zero, and thus controller design is completed. According to the method, the problem of differential explosion caused by a traditional backstepping design method can be effectively avoided, the calculation burden is reduced, and boundary layer errors can be eliminated.

Description

technical field [0001] The invention belongs to the technical field of nonlinear system control, and relates to a tracking control method for a dead zone nonlinear time-delay system. Background technique [0002] In recent years, adaptive control of nonlinear systems has received extensive attention. It is very important to ensure that the controller satisfies the steady-state performance and accurate tracking performance of the system. Dead zone and time lag phenomenon exist in most of the actual control systems, affecting the stability of the system. For the characteristics of the dead zone, the academic community mainly reduced the influence of the characteristics of the dead zone on the system by constructing the inverse of the dead zone. Document 1 (Adaptive control of plants with unknown dead-zones[J].IEEE Transactions on Automatic Control,1994,39(1):59-68) first proposed the dead zone inverse; Document 2 (Deadzone compensation in motion control systems using neural ...

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Problems solved by technology

Document 1 (Adaptive control of plants with unknown dead-zones[J].IEEE Transactions on Automatic Control,1994,39(1):59-68) first proposed the dead zone inverse; Document 2 (Deadzone compensation in motion control systems using neural networks [J].IEEE Transactions on Automatic Control,2000,45(4):602-13) through the construction of the dead zone inverse model, the design of an adaptive control scheme, to solve a class of nonlinear control problems with dead zone input, and then Some scholars have designed the controller based on the dead zone inverse model technology combined with the backstepping method, which can not only ensure the stability of the system, but also ensure the transient performance, but the backstepping method has the inherent problem of "differential explosion"; in order to solve this One problem, document 3 (Dynamic surface control for a class of nonlinear systems[J].IEEE transactions on automatic control, 2000,45(10):1893-9.) and document 4 (Dynamic surface control for a class of state-constrained non- linear systems with uncertain time delays[J].IETControl Theory&Applications,2012,6(12):1948-57.) proposed a dynamic surface control technology, because the structure of the dead zone inverse is very complicated, which is not conducive to the controller design; in the literature 5 (Robust adaptive control of a class of nonlinear systems with unknown dead-zone [J]. Automatica, 2004, 40(3): 407-13), the author simplifies the dead zone model into two parts: linear input and bounded disturbance Since then, the controller design based on the simplified dead zone model has achieved a lot of results; Literature 6 (Adaptive tracking controller design of nonlinear systems with time delays and unknown dead-zone input[J].IEEETransactions on Automatic Control,2 008,53(7):1753-9.) Considering the bounded time-delay when the parameters of the dead zone are unknown, a smooth adaptive state observer is designed, and the system can converge to an arbitrarily small neighborhood; currently for Dead zone nonlinear time-delay system, literature 7 (Adaptive fuzzy decentralized control for a class of interconnected nonlinear system with unmodeled dynamics and dead zones[J]. Neurocomputing, 2016, 214 (972-80.) Using fuzzy control technology to approximate unknown functions, The LyapunovKrasovskii functional was constructed to deal with the delay term, which can successfully solve the system tracking problem; Document 8 (Indirect adaptive neural network dynamic surface control for non-linear time-delay systems with prescribed performance and unknown dead-zone input[J].IET Control Theory&Applications, 2018,12(14):1895-906.) By using the radial basis neural network to deal with the delay term and dead zone characteristics, the system tracking error can converge to a predetermined range, but the system tracking error after processing by this method is still relatively large

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