(2001-) In 1995 Active Cord Mechanism - Revision 1 (ACM-R1), that is wireless controlled snake like robot, was developed. During about a half hour, this robot can promote with serpentine locomotion controlled of the velocity, the head-direction, and the swing of the wave. It is not only becomes twice faster than old type, but also higher mobility with serpentine locomotion at gently sloping. Then, development of the machine model progressed, which has three-dimensional mobility and realizes various functions by new DOFs adding of a pitch axis. In 2000 three-dimensional type ACM, "ACM-R2" was developed (Photo.1). Furthermore, miniaturized and weight reduced model was developed as "ACM-R3" with the symmetry which was more suitable for 3-dimensional movement (photo.2).

The whole consists perpendicularly connected as a straight chain by the unit that has batteries, a control board, and actuator of 1 DOF, shell structure had lightweight and high rigidity (Figure.1). Then we can easily reconfigure the number of units for each research purposes. Moreover, high torque was realized by decelerating a servomotor moderately, with a moderate move speed at serpentine locomotion secured. The most characteristic part is a large-sized passivity wheel which can be easily detached and attached, and which covers the whole body. As it is easy to understand the front view (Figure.2), it can have the same grounding conditions in all the directions with any passive wheel. For this reason, it becomes possible to be able to perform smooth grounding and contact that is not in the former to the external environments, and to perform glide promotion to all position.

The conventional serpentine locomotion was of cause realized. It was real proved that the lateral rolling operation on a free curve was possible, therefore the lateral rolling locomotion (Figure.3) can also perform parallel translation by adding its operation during the serpentine locomotion was realized. When a snake winds and progresses, it floats and oscillates both ends in the air, because they work as frictional resistance. This motion called "Sinus-Lifting" is not only realized with ACM-R3 (Figure.4), but also explored to combine with lateral rolling. The other various promotion methods, such as lift rolling locomotion (Figure.5) that performs sinus-lifting with upside down posture, and pedal wave promotion which propels forward by movement wave like snail, are realized.