Adaptive Tracking Control for Underactuated Lunar Hopping Vehicles

Abstract

This paper develops two different adaptive control solutions for a propulsive exploration lunar hopping vehicle along with their performance characterization. Full six-degree-of-freedom error dynamics relative to an a priori defined reference trajectory are outlined for controller derivation. A certainty equivalence adaptive controller and a noncertainty equivalence adaptive controller are derived utilizing a baseline backstepping design to handle the lunar hopping vehicle’s inherent underactuated dynamics. The flight and landing requirements are evaluated for both controllers to compare and critically evaluate their relative performance features. The noncertainty equivalence adaptive estimate exhibits more desirable behavior than the certainty equivalence adaptive estimate at the cost of additional filtered states to compute. Overall, both controllers satisfy the flight and landing requirements, with the noncertainty equivalence controller achieving better landing criteria by nearly [Formula: see text] across all landing requirements and more desirable parameter estimation behavior.