Nonsingular terminal sliding-mode funnel control for prescribed performance of motor servo systems with unknown input saturation

A nonsingular terminal sliding-mode funnel control (NTSMFC) scheme is proposed for tracking the prescribed performance of motor servo systems with unknown input saturation. Based on the mean-value theorem, the nonsmooth saturation is transformed into a smooth affine function, and then is approximated and compensated by using a simple sigmoid neural network. Rather than constructing the complex barrier Lyapunov function or inversely transformed function, we employed a new constraint variable to force the tracking error to fall into prescribe boundaries. Then, a nonsingular terminal sliding-mode funnel control is developed for tracking the prescribed performance of the motor servo system. With the proposed scheme, no prior knowledge is required on the bound of input saturation, and the convergence of the position tracking error is guaranteed via the Lyapunov synthesis. Comparison simulation examples are given to illustrate the effectiveness of the proposed method. ©, 2015, South China University of Technology. All right reserved.