Deformation-Driven Closed-Chain Soft Mobile Robot Aimed for Rolling and Climbing Locomotion

The inherent compliance of soft mobile robots makes them a safe option for interaction with humans and fragile environments. To expand their possibilities around our daily life, it is desirable for them to have enhanced traversal ability with safe structure and movement. To meet this requirement, we propose a new type of soft mobile robot that moves while selecting rotational, wave, and climbing locomotion. The proposed robot, named DECSO, forms a closed chain of modular segment actuators that individually generate contraction and bidirectional bending motion by applying negative pressure. In this paper, after presenting methods for generating the above three kinds of locomotion, the characteristics and modeling of the segment actuator are illustrated. Furthermore, the experimental results show that a 4-segment prototype achieved smooth rotational movement in the horizontal plane at a velocity of 75 mm/s, while a 6-segment prototype was able not only to move forward by travelling waves, but also to cross over the human body and obstacles of 62% of its own height by rotational movement. These findings suggest a new possibility for soft mobile robots that can safely touch and move around the human body.