The CRAM (Compressible Robot with Articulated Mechanisms) is a robot with a somewhat creepy biomimicry pedigree, namely, the cockroach.
(CRAM [Compressible Robot with Articulated Mechanisms] video)
Using a combination of postural adjustment from leg reorientation and body compression, cockroaches traversed and locomoted in vertically confined spaces. With this inspiration, we designed a robot that uses the above two principles to passively adjust its sprawl angle by reducing its vertical height and thus conforms to the confined space.
The key to robot performance is a flexible back spine (along the longitudinal axis) and a deformable shell made of overlapping plates similar to the exoskeletal plates of a cockroach abdomen. The design of the robot is realized using the smart composite microstructures (SCM) manufacturing technique.
The rigid elements of the robot are made of a poster board (4-ply Railroad Board; Peacock, Inc.) composite laminate with 0.001 in polyester sheet (Dura-lar; Grafix, Inc.) serving as the flexure layer. To construct the low-friction, deformable shell, we used 0.005-inch polyester sheet (Dura-lar; Grafix) as the stiffer material. The legs of the robot are L-shaped to allow good ground contact in the standing and maximally sprawled configurations and is 3D printed (ProJet3500; 3DSystems, Inc.).
The drive mechanism comprises two miniature DC motors (MK-07; Didel, Inc.) with custom 3D printed gearing operating independently to control the left and right side of the robot. We used commercially available electronics (Dashboard; Dash Robotics Inc.) to control the robot dynamics in open loop over Bluetooth 4.0.
The resulting robot prototype is small [18 cm long, 75 mm high (unrestricted)], lightweight (46 g, with onboard control electronics and battery), and capable of crawling in vertical confinements as small as 35 mm in height.
Science fiction fans have had at least a decade to absorb the idea of a robot able to squeeze under barriers to entry - the strangely beautiful spider robots from Steven Spielberg's 2002 film Minority Report. Watch them crawl under the door at about 1"00' in to the video, like the CRAM devices.