This paper shows a new design and prototyping method for a bending pneumatic rubber actuator and its application to a soft-bodied manta swimming robot. The design is based on optimal design using non-linear finite element method, in which geometrical and material non-linearity are considered and fabrication process is based on a rapid and efficient prototyping system using a CAD/CAM based rubber molding process. In this paper, the characteristics of several possible actuators are analyzed and evaluated to lead to an optimal actuator design. The actuator works very well with smooth and soft motion. The manta swimming robot in which the developed actuators are embedded is also designed based on non-linear finite element method. The developed manta swimming robot is made only of rubber and it swims in water smoothly as if it was a living fish. The experimental results of the manta robot motion show that good agreement with those of analytical results.

A flexible microactuator (FMA) driven by an electropneumatic (or electrohydraulic) system has been developed. It has three degrees of freedom-pitch, yaw, and stretch-making it suitable for robotic mechanisms such as fingers, arms, or legs. It is made of fiber-reinforced rubber, and the mechanism is very simple, enabling miniature robots without conventional link mechanisms to be designed. Serially connected FMAs act as a miniature robot manipulator. The kinematics and control algorithm for this type of robot are presented. FMAs combined in parallel act as a multifingered robot hand, with each FMA representing a finger. An algorithm for the cooperative control for such FMAs, the stable region for holding, and its performance have been developed.

This article presents the development of modular soft robotic wrist joint mechanisms for delicate and precise manipulation in the harsh deep-sea environment. The wrist consists of a rotary module and bending module, which can be combined with other actuators as part of a complete manipulator system. These mechanisms are part of a suite of soft robotic actuators being developed for deep-sea manipulation via submersibles and remotely operated vehicles, and are designed to be powered hydraulically with seawater. The wrist joint mechanisms can also be activated with pneumatic pressure for terrestrial-based applications, such as automated assembly and robotic locomotion. Here we report the development and characterization of a suite of rotary and bending modules by varying fiber number and silicone hardness. Performance of the complete soft robotic wrist is demonstrated in normal atmospheric conditions using both pneumatic and hydraulic pressures for actuation and under high ambient hydrostatic pressures equivalent to those found at least 2300 m deep in the ocean. This rugged modular wrist holds the potential to be utilized at full ocean depths (>10,000 m) and is a step forward in the development of jointed underwater soft robotic arms.

This paper presents a redundant musculoskeletal robot using thin McKibben muscles that is based on human anatomy. The purpose of this robot is to achieve motions and characteristics that are very similar to a human body. We use a thin McKibben muscle, which is compliant and flexible, as the actuator of a musculoskeletal robot. Using a bundle of thin McKibben muscles, we develop a multifilament muscle that has characteristics similar to those of human muscles. In contrast, the actuators of conventional musculoskeletal robots are very heavy, not densely attached and have poor backdrivability. Because multifilament muscles are light and can be densely attached, we can attach them to the musculoskeletal robot as skeletal muscle and achieve a redundant system that is equivalent to a human drive mechanism. In this paper, we report a method for fabricating multifilament muscles that imitate various muscles, the development of a lower-limb muscle mechanism for the redundant musculoskeletal robot with thin McKibben muscles and experimental results showing that the proposed musculoskeletal robot achieves humanlike motions that have not yet been reported for other robots.