NASA engineers develop safe landing system for small UAS

By Patrick C. Miller | May 24, 2017

What happens when a drone making a delivery in an urban area suddenly needs to land because of a technical problem?

A team at the NASA Langley Research Center in Hampton, Virginia, has developed a technology called Safe2Ditch to address the problem. Its small size, light weight and low power requirements allow Safe2Ditch to be deployed on even small unmanned aircraft systems (UAS) and provides an added layer of safety for commercial operations.

“A lot of drones have limited reliability because they have to be low cost to be profitable,” said Lou Glaab, a mechanical engineer and assistant branch head at the center. “You can’t have million-dollar aircraft delivering packages for Amazon.”

Referring to the 2009 United Airways jetliner piloted by Chesley Sullenberger that successfully ditched with no loss of life in the Hudson Bay after taking off from a New York city airport, Glaab said what UAS need is “an electronic Captain Sullenberger.”

Toward that end, the husband-and-wife team of Lou and Trish Glaab—a software engineer and aerospace technologist—developed Safe2Ditch, a system combining the technical monitoring capabilities of small UAS with a database of safe landing zones along the drone’s flight path.

Unlike a manned aircraft, a drone has no pilot to make decisions in in an emergency situation, Lou Glaab said. Safe2Ditch is designed to work autonomously because there’s usually not enough time to engage a person in the decision-making process. It taps into the aircraft’s monitoring system, sensors and onboard autopilot to guide it to a safe landing.

As Trish Glaab explained, the database used for the technology must be flexible and conditional in determining the best spot for a landing.

“Where are people typically not going to be? Where can you not go? What hours do you have to avoid a schoolyard? Where are the wet or forested areas you prefer to avoid?” she asked. “It has to be intelligent enough to keep from hurting anyone.”

The software uses complex selection logic to understand how much time the drone has before it must land and takes its performance characteristics into consideration. It can even be programmed to know how much area is need for a fixed-wing UAS landing as opposed to a rotorcraft landing.

Because Safe2Ditch is designed for small, low-cost UAS, the Glaab’s goal is to make their system affordable to the average drone pilot. They’re designing it with inexpensive components and aiming for a maximum price point of $500.

In the future, the Glaabs see the potential for manned aircraft to be equipped with Safe2Ditch, enabling an airplane with a disabled pilot to be safely landed autonomously.