In November 2011 Robert Shepherd, George Whitesides, and colleagues at Harvard published “Multigait soft robot” in the Proceedings of the National Academy of Sciences. The paper described a quadrupedal robot built entirely from soft elastomeric polymers, with no hard internal skeleton, inspired by animals such as squid, starfish, and worms that move without rigid bones.
The robot is actuated pneumatically. Channels embedded in the soft body inflate when air is pumped in, bending the limbs. Using only five actuators and a simple valving system operating at low pressures of under ten pounds per square inch, the robot achieved several distinct gaits, including a crawling motion and an undulating motion. Combining these gaits let it squeeze under a low obstacle that a rigid robot of similar size could not pass.
The work helped launch soft robotics as a field. Because soft bodies deform to fit their surroundings, they can be inherently safer around people and more robust to bumps and uneven contact than traditional rigid machines built from metal links and motors. The trade-off is that they are harder to control precisely.
For a general reader, this paper is a reminder that not all robots are stiff metal arms; a whole research direction treats compliance and softness as features, useful for safe interaction, delicate gripping, and squeezing through tight spaces.