Approximation-Free Control for Nonaffine Nonlinear Systems with Prescribed Performance

This paper addresses the tracking control problem for nonaffine nonlinear systems with unknown dynamics. An approximation free control method based on the prescribed performance control is developed to increase the tracking precision. First, a Levant's differentiator is utilized to reconstruct the immeasurable states of the derived affine system, after the nonaffine system is converted into the affine form via a combination of the first-order filter and the coordinate transformation. Second, an approxiamtion free control method with a simple proportionallike structure, is developed without function approximations. The computational burden and complexity are significantly reduced, while the control error is remained in a predefined boundary. Finally, comparative simulation results validate the performance of the presented algorithm.