Limber legs (Image: Konrad Wothe/Minden Pictures/FLPA)

THE forelegs of the praying mantis are unique for more than just their pious appearance. Their versatility is remarkable – the mantis uses them for walking, capturing prey and hanging on to it during a meal. They have now inspired a robot.

Ramón Cardona of the InterAmerican University of Puerto Rico has built a prototype mechanical limb about 30 centimetres long that mimics the design of the mantis leg. Like its natural counterpart, it should give a robot the ability to walk, grab objects and manipulate them using the same limb.

The mantis’s forelegs have a spiky claw near each tip that aids in trapping and grasping its prey. The claw can be stowed to allow a rod-like attachment called a tarsus to extend, upon which the insect walks.


Cardona built a multi-jointed leg that worked similarly: walking, trapping objects, and even toying with them. A rotatable hip joint gives the device the dexterity to perform more than mere back-and-forth walking motions, while an ankle joint allows the limb to hold objects in place on the ground.

Cardona presented the work in May at the Florida Artificial Intelligence Research Society conference on Marco Island. He plans to perfect a gripper for the leg and then make a full praying-mantis-inspired robot.