Dynamics and Control Study of Titan Aerobot from a Systems Design Perspective

Abstract

*† ‡ § , # ** †† Robotic lighter-than-air vehicles, or aerobots, provide a strategic platform for the exploration of planets and moons with an atmosphere, such as Venus, Mars, Titan and the gas giants. Aerobots have modest power requirements, extended mission durations, and long traverse capabilities. They can execute regional surveys, transport and deploy scientific instruments and in-situ laboratory facilities over vast distances, and also provide wide-area surface sampling. With the arrival of the Huygens probe at Saturn’s moon Titan in January 2005, there is considerable interest in a follow-on mission that would use a substantially autonomous aerobot to explore Titan's surface. In this paper, we discuss results to date of a dynamics and control study for a Titan aerobot. A new nonlinear robotic airship (aerobot) model is used to evaluate system design and control interactions. Presently, the airship model has been configured as a Titan aerobot to investigate the effects of mass placement and sudden net-buoyancy changes on the aerobot's behavior and controllability in a Titan atmosphere. Our initial results highlight that payload placements determine critical moment arms, that in turn dictate demands on actuators during typical maneuvers. Ultimately, this relation limits the size of disturbance a closed-loop control system can accommodate. However, our results indicate that designers have a wide range of acceptable choices for payload placement. In addition, the airship is generally robust to net-buoyancy disturbances in the Titan atmosphere in both open and closed loop. a v = Acceleration of the airship w.r.t. inertial frame [m/s 2 ] z