BatBot in flight (via Polytechnic University of Madrid)
As much as humans have come to dominate the sky, there is one variant to flight that we have not been able to replicate, and that is flight by flapping wings. This is the most common way of flight in nature and researchers at the Polytechnic University of Madrid have found that the bat is a perfect animal to learn this flight technique from. They have learned much from observation and now they plan to construct an agile robot they are calling Batbot.
The reason they chose the bat is because their skeleton is designed so that the wing changes shape as it is flapping, to increase lift in the down stroke and reduce drag on the upstroke, which makes bats very agile. The skeleton of the bat resembles that of a human arm and hand which provides a simple blueprint for Batbot.
(Left) Complete system overview (Right) Arm muscle biometrics (via Polytechnic University of Madrid)
The researchers decided to use NiTi shape memory alloys (SMA’s) to create a similar system to that of a bat’s biceps and triceps. Different currents can be sensed by the SMA’s and correspond to different shapes the wings will take at different stages of the flapping process. Experimentation with the SMA’s lead to very useful information about the structures inertial forces corresponding to the wings elastic membrane and aerodynamic loads and how the uncertainty of airflow impact will affect the SMA’s current-motion relationship.
The team concluded that an actuation speed of 2.5Hz was sufficient to deliver the lift forces necessary to allow Batbot to fly. The final robot has not yet been built, but they calculate I will fly at a cruising speed of 5 m/s. (I look forward to the video)
Cabe
