PFC design method for SAC based on the stability theorem of the descriptor system and frequency response fitting

Abstract

Simple adaptive control (SAC) is a control method that maintains control performance despite perturbations of a plant. However, there is a problem in that the vibratory output occurs in the transient response when SAC is applied to a vibration system which includes anti-resonance modes. The occurrence of the output depends on the structure of SAC and the output is caused by the vibratory input corresponding to the anti-resonance frequency. In order to overcome the problem, a method using an appropriate parallel feedforward compensator (PFC) is proposed. In the proposed method, an effective PFC is designed such that the gain of an augmented system is matched to that of a desired model under the ASPR condition of the augmented system. A design problem is described by LMI/BMI conditions. The problem using LMI/BMI conditions is solved by an iterative procedure. However, the leading coefficient of the PFC must be given a priori in order to guarantee the ASPR property, which provides some restrictions for applications of the proposed method. In the present paper, an improved method to overcome the abovementioned restrictions is proposed using the stability theorem of the descriptor system. The effectiveness of the proposed method is verified through numerical simulations and experiments.

Keywords

• simple adaptive control
• parallel feedforward compensator
• frequency response fitting
• descriptor system
• lmi
• vibration system