UC's new drone research comes with a catch

UC researchers have developed a semi-autonomous drone that is moored to the ground and can be operated more safely by virtually anyone. No piloting skills are required. Operators simply move the tether to move the drone.

Tethered drones are often used for stationary monitoring, relying on a source of electricity on the ground to provide longer flight times. UC helped the Ohio Department of Transportation implement some of these systems to monitor traffic or construction projects where an eye in the sky provides a valuable perspective.

“The battery is a big limitation for drone flight time,” said Manish Kumar, a professor of mechanical engineering in UC’s College of Engineering and Applied Science. “Once connected to an electric tether, the drone can operate much longer.”

A tether can be a thin electric cord, a fiber-optic cable or even something as simple as a kite string. However pulling on a tether can destabilize a typical drone, sending it crashing to the ground. UC engineers fixed that by developing a semi-autonomous navigation system that allows a drone to self-stabilize in the air.

The drone remains stable in the sky in gusting winds or when the user pulls the tether. The user can move the drone simply by walking the tether to a new location like a child carrying a balloon.

UC’s custom navigation system uses artificial intelligence based on fuzzy logic, a type of computer decision making that relies on degrees of truth rather than a binary true-false dichotomy. This makes it a more robust system because no precise inputs are required.

Kumar demonstrated the system in his lab using a four-rotor drone called a quadcopter attached to a wooden rod. When Kumar pushed or pulled the rod, the drone automatically tilted in the same direction, maintaining its stability and position in the air.

“The way we fly kites, we can fly drones,” UC doctoral student Shraddha Barawkar said.

Researchers said tethered drones can be manipulated more safely and easily from the ground. With a tether, the user can restrict a drone’s flight radius and elevation so it can be flown safely around people or in restricted air spaces like airports.

As part of UC’s new Digital Futures initiative, part of the university’s 10-year research plan, Kumar and his students are working in his Situational Awareness Lab to create new innovations for unmanned aerial systems.

Besides longer flight times, tethers offer other big advantages.

“Safety comes first. We want to increase safety,” doctoral student Barawkar said. “With traditional drones, you fly with a remote control or with semi-autonomous navigation. But there’s a risk of it crashing.”

Kumar said the applications are endless — from responding to an emergency to deploying on a battlefield so soldiers on the ground can view terrain from a high vantage point.

“Or even as a children’s toy. It’s inexpensive and it’s safer than an untethered drone,” Barawkar said.

Barawkar, Kumar and Kumar’s frequent research partner Kelly Cohen, interim head of UC’s Department of Aerospace Engineering and Engineering Mechanics, obtained a provisional patent for their tethered drone.

“Tethered drones are connected to the ground to supply the energy required to allow for omnipresent surveillance over a limited area,” Cohen said. “Moreover, the tether allows for secure communication and transfer of information such as a video feed from the air vehicle to a ground station, making it resilient to cybersecurity threats.

“There are many important commercial as well as homeland security applications where tethered drones present immense value and a huge advantage over free-flying drones,” Cohen said.

Featured image at top: UC engineering professor Manish Kumar is developing a tethered drone that makes automatic adjustments to remain stable in the sky. Photo/Ravenna Rutledge/UC Creative + Brand