Study of a 2-DOF joint for the small Active Cord Mechanism

The Active Cord Mechanism (ACM) such as a snake-like robot is suitable for tasks in a narrow environment because of its slender body, but mechanical models developed in prior research were somewhat large for practical usage. In this paper, we propose a new 2-dof joint mechanism for the small ACM. A usual joint mechanism has the same number of rotational axes as that of the actuators, but the proposed mechanism has 4 rotation axes against 2 actuators. This joint mechanism has relatively large range of motion and it can improve the capability of ACM in a narrow environment. We verified the specification of the proposed mechanism and the result showed that it is suitable for the small ACM. In addition, we developed the ACM with the proposed joint mechanism, and it realized a sidewinding motion, which is a kind of snakes´ locomotion style. We think this result shows that the proposed mechanism will contribute to the study of the small ACM.