The Georgia Institute of Technology and US defense researchers have teamed up to trial robotic legs on helicopters to help them land on uneven and moving ground.

Helicopters have been fitted with four articulated, jointed, automated legs which have force-sensitive contact sensors on their feet.

As the helicopter lands, the leg extends or contracts according to the terrain. The legs also fold up when the helicopter is in flight.

Defense Advanced Research Projects Agency (Darpa) has funded the project, conducted by the university, through its Mission Adaptive Rotor programme.

The hope is that military helicopters can land and take off from angled, irregular and moving surfaces on many military and national security missions, Darpa said.

The legs could mean helicopters can land on surfaces with a gradient of up to 20 degrees and on landing surfaces on violent seas, Darpa added.