Arctic UAS research challenges boundaries of autonomous flight

By Ann Bailey | September 10, 2015

Engineers on a German research icebreaker have programmed a multicopter to measure ice drift direction and speed in the Arctic Ocean.

Engineers on board the Polarstern, the Alfred Wegener Institute’s icebreaker, have programmed a multicopter which can navigate despite the deviation produced by the Earth’s magnetic field near the North Pole. The researchers, who are part of the Alfred Wegener Institute’s deep sea team, recently had success with an autonomous site, landing the multi-copter on an ice floe.

Autonomous navigation is challenging at high latitudes, said Sascha Lehmenhecker, a researcher at the Alfred Wegener-Institute Center for Polar and Marine Research.  Near the poles, the lines of the Earth’s magnetic field are nearly perpendicular to the ground which makes precise navigation difficult, Lehmenhecker said.

 That means that commercial multicopter control systems are not well-suited for navigation systems, which typically use magnetic sensors, he said. Lehmenhecker and two University of Wurzburg PhD candidates refined the multi-copters’ control systems. The systems are designed to land on ice floors and fly back to the ship autonomously after several hours.

Lehmenhecker and his crew built a new frame for the multicopter. Most of the components of the multi-copter frame are made from polyactic acid (PLA), a compostable material, and were printed on a 3-D printer, Lehmenhecker said.

The challenge that faces the multicopter operators is that the ship must continue on its scheduled course to conduct other research and, meanwhile, ice floes are drifting from the wind, waves and currents. The task of the multicopter is to determine the direction and speed at which the floes drift.

To accomplish that, the multicopter stays in constant contact with the receiving station which uses the vehicle’s data to calculate the discrepancies.

To conduct its first test, the research team and multicopter were left on an ice floe in the Arctic Fram Strait where they were clear of the magnetic interference produced by the ship’s electric motors. The team manually flew the copter about two miles to the edge of visual range and then activated the autonomous return program. The aerial vehicle successfully flew to the pre-set coordinates and landed safely on its own.

Lehmenhecker and his co-workers in the AWI Deep Sea Research Group conceived the idea in connection with the use of sensitive devices under the ice. For example, the group has an autonomous underwater vehicle called “Paul” which explores the ocean beneath the sea ice. To optimally plan the UAV’s dives, it is important to have precise information on the sea ice, Lehmenhecker said, and that typically was achieved by deploying ice trackers on floes with the help of a Zodiac boat or helicopter.

That method not only was difficult and time consuming, water temperatures that hover at the freezing point, jagged ice floes drifting about and polar bears pose safety risks to researchers and they try to avoid leaving the Polarstem whenever possible.