Masashi Konyo

Tomoya Takahashi, Masahiro Watanabe, Kenjiro Tadakuma et al.

Soft robots have attracted much attention in recent years owing to their high adaptability. Long articulated soft robots enable diverse operations, and tip-extending robots that navigate their environment through growth are highly effective in robotic search applications. Because the robot membrane extends from the tip, these robots can lengthen without friction from the environment. However, the flexibility of the membrane inhibits tip retraction. Two methods have been proposed to resolve this issue; increasing the pressure of the internal fluid to reinforce rigidity, and mounting an actuator at the tip. The disadvantage of the former is that the increase is limited by the membrane pressure resistance, while the second method adds to the robot complexity. In this paper, we present a tip-retraction mechanism without bending motion that takes advantage of the friction from the external environment. Water is used as the internal fluid to increase ground pressure with the environment. We explore the failure pattern of the retraction motion and propose plausible solutions by using hydrostatic skeleton robot. Additionally, we develop a prototype robot that successfully retracts by using the proposed methodology. Our solution can contribute to the advancement of mechanical design in the soft robotics field with applications to soft snakes and manipulators.

Tori Shimizu, Kenjiro Tadakuma, Masahiro Watanabe et al.

To detach a permanent magnet with a controlled force much smaller than its original attractive force, the Internally-Balanced Magnetic Unit (IB Magnet) was invented and has been applied to magnetic devices such as wall-climbing robots, ceil-dangling drones, and modular swarm robots. In contrast to its drastic reduction rate on the control force, the IB Magnet has two major problems on its nonlinear spring which cancels out the internal force on the magnet: complicated design procedure and trade-off relationship between balancing precision and mechanism volume. This paper proposes a principle of a new balancing method for the IB Magnet which uses a like-pole pair of magnets as a magnetic spring, whose repulsive force ideally equals the attractive force of an unlike-pole pair exactly. To verify the proposed principle, the authors realized a prototype model of the IB Magnet using magnetic spring and verified through experiments its reduction rate is comparable to those of conventional IB Magnets. Moreover, the authors discussed and realized a robotic clamp as an application example containing proposed IB Magnets as its internal mechanism.

Rio Mukaide, Kenjiro Tadakuma, Masahiro Watanabe et al.

Grippers can be attached to objects in a rigid mode, and they are therefore used in various applications, for example granular jamming gripper. This paper introduces a cutting-edge radial layer jamming mechanism with is tunable stiffness, which is critical for the development of grippers. The layer jamming mechanism generates friction between the layers of multi cylindrical walls by pulling wire. This paper describes the principles of three types of proposed tendon-driven jamming mechanism, in addition to their prototypes of string configuration and the experiments conducted on the holding torques of their joints. Due to the string configuration, the surface and three-dimensional (3D) shape. This mechanism can be implemented in various applications.

Kenjiro Tadakuma, Tori Shimizu, Sosuke Hayashi et al.

To attach and detach permanent magnets with an operation force smaller than their attractive force, Internally-Balanced Magnetic Unit (IB Magnet) has been developed. The unit utilizes a nonlinear spring with an inverse characteristic of magnetic attraction to produce a balancing force for canceling the internal force applied on the magnet. This paper extends the concept of shifting the equilibrium point of a system with a small operation force to linear systems such as conventional springs. Aligning a linear system and its inverse characteristic spring in series enables a mechanism to convert displacement into force generated by a spring with theoretically zero operation force. To verify the proposed principle, the authors realized a prototype model of inverse characteristic linear spring with an uncircular pulley. Experiments showed that the generating force of a linear spring can be controlled by a small and steady operation force.