Apr 3, 2016 | By Alec
Why are virtually all 3D printed drones powered by propellers? Sure, it’s a relatively easy way for us humans to achieve flight, but the world is full of very energy-efficient flying creatures that, over several million years, perfected very different forms of flight. Various robotics experiments have already shown that we can learn a thing or two from animal movement, so it’s good to see that a team of researchers from the University of Illinois and Brown University have been remarkably successful in replicating bat flight using 3D printing. Their robotic bats are so successful, that they believe they could be valuable surveillance robots, for instance on construction sites.
It’s a remarkable project that actually grew out of a casual conversation on robotics, but grew into a project backed by a $1.5 million grant from National Science Foundation (NSF) to build mechanical bats for construction sites. The project is being led by Professor Seth Hutchinson from the University of Illinois’s Department of Electrical and Computer Engineering, and also includes Assistant Professor Soon-Jo Chung, Aerospace Associate Professor Timothy Bretl, and Assistant Professor Mani Golparvar-Fard. “Building construction projects are complicated, and rarely do they happen the way they are intended to happen,” Hutchinson said. “Keeping track of whether the building is being put together the right way at the right time is not trivial. So the bats would fly around, pay attention, and compare the building information model to the actual building that’s being constructed.”
Of course they’re not the only researchers seeking to replicate wing-powered flight, like the Shanghai-based researchers who have developed a 3D printed flying Dragonfly and other animals. But they chose bats as their inspiration, they reveal, for their unrivaled agility and maneuverability.
This project has been ongoing since 2014, and has already been remarkably successful. Hutchinson focuses on the robot planning and control algorithms (for flight trajectories, for instance), while Chung has been working on flight control and dynamics, Bretl on motion planning, and Golparvar-Fard on the various applications this robot can have on a building construction site. They have also brought in bat flight experts and Brown professors Kenneth Breuer and Sharon Swartz, who were given their own grant of $700,000. “Professors Breuer and Swartz are going to provide us with actual data on wing kinematics (study of objects’ motion) and how bats are able to do upside-down perching on ceilings,” Chung said back in 2014.
And that knowledge could really add a lot the a drone’s flying capacity, as bats are notoriously efficient flyers. “When a bat flaps its wings, it’s like a rubber sheet,” Hutchinson said. “It fills up with air and deforms. And then when the wing gets to the end of its motion, that rubber wing pushes the air out when it springs back into place. So you get this big amplification of power that comes just from the fact you are using flexible membranes inside the wing itself.”
The idea is that bat flight patterns can contribute to a more efficient use of energy and longer battery life, than can currently be seen on rotorcraft robots. “We think we can build a dynamic structure that takes advantage of the flapping wing flight in a clever way to make it low-power,” Hutchinson said. “Also, you can imagine bats locking their wings and gliding. In principle, you can put one up in the air and have it circle around for a long time without spending much power at all. A quad rotor always has to be burning energy to stay in the air.”
What’s more, robotic bats could even be safer than quadcopters, as their blades can pose a threat to people in the surrounding area. A chance collision with a 3D printed bat won’t do as much damage. The team is therefore optimistic that these bats can really change the concept of aerial robotics –used for surveillance, but also delivery and other applications. “We think we can bring many benefits to robotics by using this biologically inspired architecture,” Hutchinson said. “We mean to make a robot that can have the same advantages in terms of performance, agility, and lifetime of flight as the biological thing.”
And so far, progress has been excellent. Below two clips can be found, one from January 2016 and one from last week, showing exactly to what extent bat flight can be mimicked. TO do so, the partially 3D printed bat features a microprocessor-based onboard computer a 6 DOF IMU sensor package, five DC motors with encoder feedback for flapping and wing articulation, power/comm electronics, a carbon-fiber frame and silicone membrane wings. Weighing just 92 grams, they can already achieve flight with asymmetric wing folding and leg/tail control. Could we be looking at the future of 3D printed flying robots?
Posted in 3D Printing Application
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