Sea snakes live in water, and eventerrestrial snakes sometimes show swimming abilities on the water’s surface. The structure of ACM-R5 enables it to mimic quite successfully this amphibious movement thanks to its joints, which consist of auniversal joint and flexible bellow (which can be seen in black in the image); it was developed on the basis of the previous model HELIX, which was designed for research of spirochete-like helicalswimming.
A universal joint plays the role of bones, and bellows take the role of an integument. This joint structure gives ACM-R5 the ability to form a smooth shape, which is important for effectivelocomotion. To be precise, the universal joint has one passive twist joint at the intersection point of two bending axis, which help to prevent mechanical interference with the bellows.
One of the mainchallenges the researchers faced was creating a wavelike motion. In order to do so, they equipped the ACM-R5 with paddles and passive wheels around the body. To generate propulsive force by undulation,the robot needs resistance, since it glides freely in tangential directions but cannot in normal directions. Thanks to the paddles and passive wheels, ACM-R5 obtains that characteristic bothin water and on ground, as can be seen in this video.
ACM-R5 has an advanced control system. Each joint unit has a CPU, a battery, and motors so it can operate independently. Through communication lines...