Snake-like robots Tutorial

I (Hirose) started the biomechanical study using actual snakes and the design of snake-like robots in 1971. There were two reasons for the interest in this snake research: one is the scientific interest in the mechanism of the snake's motion and another is the engineering interest in the future applications of snake-like robots. There were already several studies on the motion of the snake; however, these were not satisfactory. The analytical method was not always consistent, and the analysis was done in somewhat artificial conditions, such as the motion of the snake in a maze with multiple pegs. So, I decided to perform a more precise analysis on standard serpentine motion. I was especially interested in the simplicity of its shape and the versatility of its function, because of its expected future applications. The simple cord-like body of the snake becomes a leg when it moves among rocks, a body when it moves from branch to branch, and a hand when it coils around a prey. From these features of the snake, I could imagine multiple applications in future. Figure 1 shows the expected applications I dreamed in those days. I used them in the oral defense of my doctor's degree dissertation in 1976. Figure 1(a) shows a downsized snake-like robot that can be utilized as an active endoscope to go into intestines. Figure 1(b) shows an active rope for a crane that automatically wraps around an object. Figure 1(c) is a polar exploration vehicle. It will glide on ice using ski blades, and the long body will enable it to cross over a crevasse. Figure 1(d) is an active hose that will approach a fire automatically using hydraulically actuated joints driven by the high-pressure water inside the hose. Figure 1(e) was drawn later for a children's book, which shows a snake-like robot that does amphibious work.