Saturn’s moon Titan is of high interest for in situ study due to its many intriguing features. This moon has a dense atmosphere; rough, icy terrain; and low surface winds that make it the ideal place to send a controlled aerial robotic platform, such as a conceptual Aerobot Airship. An important feature of a self-propelled, lighter-than-air aerial vehicle is that it must be autonomously controlled to navigate and avoid obstacles because of a 2.6-hour communication delay between the Earth and Titan. Developing a dynamic model that can be tuned will enable robust and reliable control of the Aerobot Airship.

This work describes a linear parameterized analytical lateral dynamic model for the airship, completing the three-dimensional motion of an airship. The method used to develop this dynamic model does not use system identification as is typically used, but relies on the use of aircraft stability derivative methods with the basic geometric and aerodynamic properties of the airship. This method reduces time and cost while providing ease of implementation for tuning multiple operating points. Comparisons of simulations of the model with other stable airship dynamic models show similar behavior that validates the method.

Development of lateral linear dynamic airship models is expensive and requires extensive wind tunnel experiments and system identification work. Merging Airship Linear modeling theory with aircraft stability derivatives estimation techniques, it is possible to develop a linearized dynamic airship model from geometric and aerodynamic data, thus reducing the cost of the model development by minimizing flight testing. The merging of aircraft stability derivative estimation techniques with linear dynamic model methods for airships is an approach that was validated to be a mathematically correct method.

Completion of the dynamic modeling method facilitates the development of a good control system for the conceptual aerobots and other airships. The parameters in this modeling method can be easily tuned for use with multiple operating points; this capability will enhance the development of airship control system design.

This work was done by Eric A. Kulczycki, Alberto Elfes, David S. Bayard, and Marco B. Quadrelli of Caltech; and Sarah Koehler of Cornell University for NASA’s Jet Propulsion Laboratory. NPO-47858

Software Tech Briefs Magazine

This article first appeared in the September, 2014 issue of Software Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.