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Inflated ergo: Flexible robots more resilience, efficiency than their stiff competition

By Nicholas Gerbis
Published: Friday, April 28, 2023 - 3:41pm
Updated: Friday, April 28, 2023 - 5:58pm

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ASU's Wenlong Zhang and his team have developed a quadrotor drone with an inflatable frame to enable resilience to collisions and an innovative gripper that lets the device securely perch on a wide range of surfaces.

When you’re meant to operate independently and perform a variety of tasks — from exploration to monitoring to search-and-rescue — it pays to be flexible and resilient.

So ASU’s Wenlong Zhang and his team developed a drone that can change the stiffness of its woven-nylon frame on the fly.

“It is able to conform to the object that is colliding and generate longer contact time and allow the drone to basically react in a safer way and then facilitate recovery,” he said.

Thus, the pneumatic approach makes the soft robot better suited to tight, unpredictable environments than drones with rigid frames.

“Their collision resilience is very poor, and pretty much when you collide on something, the frame breaks and then the rotors are gone, and then the drone crashes,” said Zhang, who is an associate professor in ASU’s School of Manufacturing Systems and Networks.

The drone’s tests are reported in the journal Soft Robotics.

Five years ago, KJZZ’s Arizona Science Desk reported on another project from the Zhang lab: a flying drone with a flexible grasper for sampling and retrieving objects. At the time, Salt River Project was considering using the drone to sample and clean up canals and reservoirs.

The new iteration adds flexibility to the frame itself and exchanges the grasper for a claw made up of flexible bands. Like slap bracelets, they use the energy and momentum of landing to clasp a wide variety of perches. This mimics the passive tendon mechanism used by birds and bats, which takes no additional energy to remain locked around a perch.

The frame’s flexibility also helps the landing and perching process by slowing the impact and lengthening the contact time before bouncing off a surface.

“This is really inspired by biology,” said Zhang. “When you look at how a bird perches on a tree branch, the compliant body of the bird is playing a key role — the body is basically helping the claw of the bird to stay in contact with a branch for longer.”

The team hopes to add AI to the drone to increase it autonomy and to include onboard sensors to let it navigate environments that are more cluttered, such as forests or collapsed tunnels.