Mitigation of inflight icing on unmanned aerial vehicles

Tor Arne Johansen
Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim, Norway
Center for Autonomous Marine Operations and Systems

In order to release the business potential in urban air mobility and other challenging cases, UAVs must be integrated into shared airspace to be able to operate safely beyond-visual-line-of-sight (BVLOS) and above populated areas. It is therefore necessary to ensure that UAVs are airworthy according to emerging industry standards and regulatory frameworks.  Detection and mitigation of icing on UAVs is one critical challenge for safety and airworthiness.  Yet, the research on the topic is rather limited and commercially available solutions are just emerging.

The presentation will provide an overview of the challenges and solutions. The process of icing and its effect on the UAV flight performance will be surveyed. Reduced lift, increased drag, reduced propulsion and control efficiency, increased power consumption, reduced stall margins, changes in flight dynamics and increased mass are all factors that reduce safety. Small UAVs typically operate with lower speed and altitudes than larger aircraft, and the consequences of this on icing will be highlighted.

Autonomous systems are needed to mitigate icing. This includes sensors and estimation methods for detection of icing conditions and actual icing. There are several strategies for inflight anti-icing and de-icing that are effective for larger aircraft, but they are not readily implementable on smaller UAVs. The presentation will focus on electro-thermal solutions that seems to be most promising. They supply heat to exposed surfaces and thereby prevent or remove icing at the cost of electric energy, which is a scarce resource on small UAVs. The control and optimization strategies needed to operate electro-thermal icing protection systems are therefore important in order to minimize energy consumption. This also includes mission planning that can exploit weather forecasts to plan safe and efficient missions in icing conditions. The presentation will use examples from our research on UAV icing since 2013, including simulations, icing wind tunnel tests and flight testing.

Biography: Tor Arne Johansen received the M. Sc. degree in 1989 and the Ph. D. degree in 1994, both in electrical and computer engineering, from the Norwegian University of Science and Technology, Trondheim, Norway. From 1995 to 1997, he worked at SINTEF as a researcher before he was appointed Associated Professor at the Norwegian University of Science and Technology in Trondheim in 1997 and  Professor in 2001. He has published several hundred articles in the areas of control, estimation and optimization with applications in the marine, aerospace, automotive, biomedical and process industries. In 2002 Johansen co-founded the company Marine Cybernetics AS where he was Vice President until 2008. Prof. Johansen received the 2006 Arch T. Colwell Merit Award of the SAE, and is currently a principal researcher within the Center of Excellence on Autonomous Marine Operations and Systems (NTNU-AMOS) and director of the Unmanned Aerial Vehicle Laboratory at NTNU and the SmallSat Laboratory at NTNU. He recently co-founded the spin-off companies Scout Drone Inspection, UBIQ Aerospace and Zeabuz.