Adaptive NN Tracking Control For Uncertain Nonlinear Systems

Adaptive backstepping technique has been taken an important position in the control synthesis of nonlinear systems. For strict feedback nonlinear systems with parameter uncertainties, adaptive backstepping method can effectively solve the stabilization and tracing problem of such systems. However, most uncertainties in practical systems are very complex; parameter uncertainties just represent a small part of them. Traditional adaptive backstepping technique cannot be used when the system contain completely unknown uncertainties. Adaptive neural network(NN) control technique, as a NN algorithm-based design method, not only inherits the quintessence of traditional method, but also makes up the shortcomings of traditional adaptive backstepping technique. In modern intelligence algorithm, NN has shown its powerful ability in approximating nonlinear functions. Therefore, adaptive NN backstepping design method can effectively address the control problems of nonlinear systems with completely unknown uncertainties.Based on adaptive NN control technique, the tracking control problems of three types of uncertain nonlinear systems with completely unknown uncertainties are considered in this paper. First, the bounded tracking problems of a class of switched nonstrict-feedback nonlinear systems are investigated by combing the common Lyapunov function method with adaptive NN technique, and the target signal can be bounded tracked by the system output under the designed state feedback controller. Then, the tracking control problems of a class of high order nonlinear systems are solved by using adding a power integrator and adaptive NN control design method. Finally, the control problems of switched stochastic nonlinear systems with actuator dead-zone are taken into consideration by using adaptive NN technique and some theories and methods about stochastic systems include the differential operator and the bounded stability definition of stochastic systems. The designed controller guarantees that the target signal can almost surely be bounded tracked.