An Attitude Control of Underactuated Flying Objects with Initial Angular Momentum.

Abstract

Many researchers are working on nonholonomic systems modeled as driftless nonlinear state equations, such as vehicles and flying robots with zero initial angular momentum. Flying robots with nonzero initial angular momentum, however, are no longer modeled as driftless state equations and do not attract much attentions so far. Although they have drift terms, they are still tough systems for feedback control. In this paper, we will propose an attitude controller for flying robots with nonzero initial angular momentum. We will show that, by introducing time varying state coordinate transformation and feedback, the state equation of the flying robot can be transformed into a time invariant nonlinear state equation whose linear approximation is controllable. This state equation enables us to control the landing posture of the flying robot. An adaptive controller is also proposed to eliminate the posture error caused by parameter uncertainties.