Design Engineering

This tiny drone can haul 40 times its weight

Devin Jones   

Automation General Machine Building unmanned aerial vehicle

Classified as a micro air vehicle, the FlyCroTug weighs 100 grams and features a winch and cable system.


All photos courtesy of ©EPFL / Laboratory of Intelligent Systems.

Engineers at Stanford University and École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have created a micro air vehicle (MRV) called the “FlyCroTug,” that is capable of pulling 40 times its weight. While the FlyCroTug looks like a standard quad-copter drone, its base is equipped with 32 microspines that can attach to rough surfaces, a dry adhesive that replicates a gecko’s foot pads for smooth surfaces, and a winch-and-cable system that provides its aforementioned pulling ability.  Once the 100-gram MAV is flown to a remote location while spooling out its winch line, it anchors itself to a rough or smooth surface and can activate its winch—via remote control—tugging whatever object it’s attached to.

“MAVs are great, for the mobility they offer is relatively straightforward,” says Matthew Estrada, a graduate student at Stanford and lead author on the paper. “However, all of these aerial vehicles are limited in the amount of payload they can carry due to the amount of thrust they can produce. Typically, a payload will be around the weight of the MAV and not much more. This multimodal strategy, using aerial locomotion for mobility and adhesive interaction forces for strong tugging, resulted in a platform that had the unique characteristic of being micro, mobile, and mighty,” he says.

Estrada says the dry, gecko-inspired adhesive is composed of tapered silicone stalks that can grip any smooth surface. “When pulled along a surface in a specific direction, these stalks lay down along the surface making such intimate contact that they generate Van der Waals forces that hold them into the surface,” he says. The drone’s operator is able to release the drone by piloting it in the opposite direction; the stalks pop back up and the material easily releases from the surface.


“Creating a system with so many different capabilities, all within a weight budget of 100 grams, was this biggest challenge we faced,” Estrada says. “It came down to scouring the market for the smallest actuators that were commercially available. It was enough of a challenge to integrate the system that we didn’t have the resources to develop components from scratch. Ultimately, this dictated the final size of the system—what we could find commercially available.”

Estrada envisions the FlyCroTug as useful in search and rescue operations. One of the experiments his team put the FlyCroTug through tasked two of the tiny drones to work in tandem to open a door. One drone slipped a spring-loaded hook under the door and attached itself to the carpet. Meanwhile, a second FlyCroTug hooked onto the door handle in flight and then landed and attached its gecko-inspired adhesive to the glass door. It then pulled the door handle down with 20 N of force and MAV2 pulled the door open with 40 N horizontally.

Since the FlyCroTug is manually operated via a FrySky Taranis 2.4 GHz radio controller (communication with a mini receiver) Estrada and the team are working on a way to implement perception and autonomy to the vehicle. This would allow the FlyCroTug to operate with minimal human interaction.



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