An approach of inverse system to model following control for nonlinear mechanical systems without matching conditions

Extensions of the results of the model reference adaptive control (MRAC) to nonlinear systems have been attempted. In particular, design methods of MRAC for nonlinear mechanical systems have been studied with much interest. For this purpose, the authors propose a design method for model following control (MFC) as a first step toward MRAC for nonlinear mechanical systems affine in the control. First, they consider Hirschorn's algorithm concerning the invertibility of nonlinear control systems. However, it is difficult to apply the algorithm directly to the control objective due to the small number of input channels and no matching conditions. Secondly, they propose an alternative design method for MFC, based on a kind of nonlinear model matching techniques which make it possible to assign any damping characteristics. Thirdly, they consider an example of application to the inverted pendulum to demonstrate the feasibility and efficiency of the proposed control design strategy. Finally, they investigate two extentions of the present method to both the case of modeling error and of nonaffine type control.