Terrain Following Controller for Affine Parameter-Dependent Systems: An Application to Model-Scale Helicopters

Abstract

This paper presents a terrain following controller for model-scale helicopters that takes into account the terrain characteristics ahead of the vehicle as measured by a Laser Range Scanner. The methodology used to solve the terrain following control problem amounts to posing it as a discrete time path following control problem where a conveniently deflned error state space model of the plant is augmented with terrain preview data. A piecewise a‐ne parameter-dependent model representation is used to accurately describe the linearized error dynamics, for a pre-deflned set of operating regions. For each region, the synthesis problem is stated as a state feedback H2 control problem for a‐ne parameterdependent systems and solved using Linear Matrix Inequalities (LMIs). A sub-optimal technique to compute the feed-forward preview gain matrix is proposed that avoids solving LMIs involving a large number of unknowns. The resulting nonlinear controller is implemented under the scope of gain-scheduled control theory using the D-methodology. Simulation results obtained with the full nonlinear helicopter model are presented and discussed.