LFT/H∞ varying sampling control for Autonomous Underwater Vehicles

This paper deals with the robust control of an Autonomous Underwater Vehicle (AUV) subject to communication constraints. The aim is the design of a gain-scheduled varying sampling controller using non periodic measurements from ultrasonic sensors.The contribution of this work lies in a new model formulation of varying sampling discrete-time systems using the Linear Fractional Transformation (LFT) representation.This allows to design, in the LFT context, an H∞ controller whose matrices are scheduled w.r.t the varying control interval. Moreover the proposed design ensures a performance adaptation when the sampling interval varies. This methodology is developed for AUV and emphasizes important improvements compared with an H∞ discrete-time control with fixed sampling.