Check out this awesome perching UAV, developed by Alexis Lussier Desbiens.
“A flock of small, unmanned air vehicles flies quietly into a city, maneuvering among the buildings. They communicate as they search for places to land, not on streets or flat rooftops but on the sides of buildings and under the eaves, where they can cling, bat or insect-like, in safety and obscurity. Upon identifying landing sites, each flier turns toward a wall, executes an intentional stall and, as it begins to fall, attaches itself using feet equipped with miniature spines that engage small asperities on the surface. Using its propeller in combination with its limbs, the flier can creep along the wall and reorient for a better view. With opposed pairs of spines, the flier clings tenaciously to resist gusts of wind and ride out inclement weather. The fliers stay attached for hours or days, consuming little power and emitting no sound as they monitor the area. When finished, they launch themselves with a jump and become airborne again, ready for their next mission.”
As you can see from the vid, the UAV uses little spines like Spinybot as opposed to a sticky material like Stickybot. At this point, spines are much more effective at adhering to rough surfaces, while the synthetic gecko toe material only really sticks to smooth surfaces (unlike geckos themselves). Despite the differences between the two sticking technologies, the challenges to stickiness are similar: you need pliable toes that can individually conform to a surface at a specific angle, and if you don’t get that, you lose sticking efficiency and (possibly) your robot.
Alexis and his partners will be presenting their paper on perching UAVs at ICRA next month.