Northrop Grumman’s Global Hawk are flying missions over Japan, providing information about the earthquake and tsunami destruction as well as the damaged nuclear reactors (see “UAVs Conquer The Skies” at www.electronicdesign.com). The Global Hawk is a large aircraft, but small UAVs like Draganfly Innovations’ Draganflyer X6 helicopter have been employed for a range of applications.
Aerial robots don’t have to look like aircraft or helicopters, though. AeroVironment’s Nano Hummingbird ornithoper and Festo’s SmartBird not only look like birds, they fly like them too.
AeroVironment’s Nano Hummingbird weighs in at only 19 g (Fig. 1). It can hover, pivot, and fly like a hummingbird. Its design wasn’t an accident either. Its appearance allows it to hide in plain sight—as long as hummingbirds aren’t unusual wherever they’re deployed.
The Nano Hummingbird has a 16-cm wingspan. It can fly as fast as 17 km/h, zipping up and around like a big hummingbird. It also can tolerate a 2-m/s breeze. It’s a bit larger than most hummingbirds but smaller than the largest hummingbird.
The body houses the battery, motors, a microcontroller, and a small video camera. It can stream video to a remote location, allowing a pilot to fly it. A four-point landing platform allows it to set down on level surfaces as well.
The Nano Hummingbird was part of a Defense Advanced Research Project Agency (DARPA) Nano Air Vehicles (NAV) program.
Inspired by the herring gull, Festo’s SmartBird is a bit larger than the Nano Hummingbird. Strip off the Festo logo and at a distance it can be hard to determine whether it’s real or a robot. Festo’s Bionic Learning Network developed it.
At 485 g, the SmartBird is definitely bigger than AreoVironment’s robot. A carbon fiber frame and extruded polyurethane foam lining minimize its weight. The SmartBird also uses a different approach to driving its 1.96-m wingspan.
A twisting active torsion drive flaps the wings using the same flight mechanism that real birds employ. Each two-part wing spar is linked to a trapezoidal joint and central axle in the body. A servo that twists the outer wing as the wing moves up and down handles active torsion, optimizing thrust.
The center part of the body is rigid, but most of the remaining structures move. The tail can provide lift in addition to adjusting the robot’s pitch and yaw rate like a real bird’s tail would. The robot doesn’t have feathers, but the results are similar.
The body houses the two 7.4-V, 450-mA batteries, two servos, and a brushless dc motor. The motor’s Hall Effect sensors track the wing’s position for the microcontroller.
A 50-MHz Texas Instruments LM3S811 Cortex-M3 microcontroller with 64 kbytes of flash and 8 kbytes of RAM controls the SmartBird. ZigBee is used for wireless communication.
The SmartBird’s efficient flight mimics a real bird. It alternately flaps its wings and glides, taking advantage of updrafts. It also moves its head. It’s equipped with a video camera for streaming information back to the pilot. And, the SmartBird can operate autonomously or by remote control.
Birds are elegant, and these robots try to replicate their grace and efficiency. The Nano Hummingbird and SmartBird are research platforms that may lead to more common deployment of aerial robots that may be harder to detect.