In this paper, a three-dimensional (3-D) path-following control design for an underactuated stratospheric airship is proposed based on the parameterized path description. The desired attitude, velocity, and the path parameter updating law are obtained by employing the guidance-based path-following principle. The resultant system possesses a cascaded structure, which consists of a guidance loop, an attitude stabilization loop, and a velocity tracking loop. The stability analysis shows that the path-following error and all states of the closed-loop system are ultimately uniformly bounded. Simulation results demonstrate the effectiveness of the proposed controller.

Effective energy management systems are critical for long endurance stratospheric airships. This article presents a hybrid energy system consisting of one renewable (photovoltaic) and two energy storage (lithium battery/regenerative fuel cell) systems. After examining different models of energy harvesting, balancing, and storage, we present the details of a rule-based energy management strategy. We further validate it by presenting the various power curves and state of charge (SOC) measurements. The results indicate that the strategy is effective for energy management planning.