From New Scientist:
A drone with legs can perch just like a bird – or land and walk on flat surfaces. Bhargav Gajjar of Vishwa Robotics in Brighton, Massachusetts, designed the legs as an add-on for small US air force drones.
Small drones generally lack landing gear. Many rely on a controlled crash-landing, a somewhat crude approach compared with the elegant precision landing of a perching bird. Gajjar studied dozens of bird species and recorded their landings using a high-speed camera. His drone’s legs are based on those of the American kestrel.
The drone perches in an upright position with a powerful gripping action from an electric motor. Its claws are extremely sharp so that its grip is difficult to break.
A remote computer uses footage from a camera fitted to the drone to control flight and get the drone into the correct position for landing. Just like a real bird, the drone has to brake sharply just above its landing site and perform a controlled stall in order to touch down. Birds’ legs also act as shock absorbers, and the mechanical version mimics this.
Gajjar’s perching legs can waddle short distances, so the drone can explore indoor spaces.