Adaptive NN Control of a Class of Nonlinear Systems with Unknown Control Direction

In this paper, adaptive neural-network (NN) control which is combined with the technique of variable structure control (VSC) is presented for a class of nonlinear system with unknown control directions. In the course of design, the procedure of the adaptive NN controller design is firstly applied via backstepping approach; then, the control directions were rectified by defining the shifting conditions of the VSC. All the signals in the closed loop are guaranteed to be semiglobally uniformly ultimately bounded and the output of the system is proven to converge to a small neighborhood of the desired trajectory. Simulation results demonstrated the effectiveness of the approach.