Micro aerial vehicles (MAV) with multiple rotors, or multicopters, usually face a critical problem: the flight time of MAVs is limited due to the low aerodynamic efficiency and high energy consumption. One promising solution is to make them rest on desired objects using perching – an important capability in biological flyers – instead of hovering in mid-air.
Engineers at Colorado State University have developed a novel perching gripper exhibiting mechanical intelligence that allows passively perching without accurate control of the contact speed, thereby reducing computational intelligence requirements. The device is mounted on top of a third-party MAV. The tiny drone, equipped with a gripper, can stay in one spot by holding onto a nearby object, using less power, and producing much less noise.
It has a mechanical plunger in the middle, which is linked to two diagonally raised folding arms, one on either side. At the top end of each arm is an inward-facing gripper pad. The plunger pulls a string, which closes the gripper arms together. The arms have rubber tips to allow a stronger grip.
Thanks to the new drone grip design, they can latch onto objects of various sizes and stay connected until told to let go. A large pad has been added in between the arms so that when it flies into an object, the arms pull closed automatically. The arms can either grasp it on either side with their gripper pads or encircle it and meet together on top. In either case, the grasping action is entirely mechanical, requiring no electricity. A small amount of electricity is sent to the plunger to release the arms when it’s time to drop down and resume flight.
The developers have tested the performance of the design experimentally by integrating the gripper onto a palm-size quadcopter to enable a mechatronic system for perching and demonstrate successful perching with both clipping and encircling methods as well as aerial grasping. Although this bistable gripper is used with a palm-size quadcopter, the design strategy can also be applied to large-size MAVs for both energy-efficient perching and aerial grasping.