Adaptive control for differential drag-based rendezvous maneuvers with an unknown target

Abstract This paper presents a differential atmospheric drag-based control algorithm for rendezvous with a non-cooperative target in Low Earth Orbit. The challenge of using a differential input that requires knowledge of physical parameters of the involved spacecraft, is addressed by designing a Lyapunov-based adaptive controller that compensates for the uncertain ballistic coefficient of the target spacecraft as well as the time-varying atmospheric density and velocity of the spacecraft relative to the atmosphere. Numerical simulations using the Schweighart-Sedwick relative dynamics are presented to validate the controller design. Additionally, simulations more accurate dynamics for each spacecraft along with the NRLMSISE-00 model of atmospheric density are presented to evaluate the performance of the controller under nonlinearities and input saturation.