Finite-Time Formation Tracking for Multiple Fixed-Wing Aircraft With Leader's Unknown Inputs and System Disturbances

Finite-time time-varying formation tracking control problems for multiple fixed-wing aircraft are investigated, where formation maintenance is required under leader detour maneuvers and unknown system disturbances. Unlike existing asymptotic or ideal finite-time results, practical finite-time stability with guaranteed residual bounds is addressed. The leader performs online evasive maneuvering to bypass hazardous zones while followers track the maneuvering trajectory using only local information. An adaptive double-arc trajectory planning algorithm is proposed for the leader considering geometric constraints of hazardous zones and normal acceleration limitations, together with a robust finite-time tracking guidance law based on hyperbolic tangent functions. For followers, a distributed adaptive finite-time controller based on an integral-type sliding mode is designed, incorporating dead-zone adaptive mechanisms to suppress chattering. Sufficient conditions for achieving practical finite-time formation tracking are derived via finite-time input-to-state stability theory, with explicit expressions of the convergent residual sets obtained. It is proven that when the time-varying formation feasibility condition holds, the proposed hierarchical protocol guarantees formation tracking errors converge to an arbitrarily small residual set in finite time despite unknown leader inputs and disturbances.