This paper presents a fabric actuator consisting of ordinary polymer fibers, conductive fibers, and twisted and coiled soft actuators (TCAs). Previous studies have developed a Spandex TCA (STCA) that is driven at a lower temperature than the conventional Nylon TCA and exhibits greater actuation strain. However, no method to drive STCAs via electrical joule-heating has been developed yet. The fabric actuator presented in this paper offers a solution to this problem by employing an STCA multiple fabrication method, a continuous fabrication method, bundling technology, and weaving technology. Two types of samples (cylindrical and planar) are fabricated and their performances are evaluated experimentally. From the actuation test according to the loads, the maximum contraction strain of 34.3% is measured. The repeatability is also verified through 200 cycles of actuation. Using a linearized model, the dynamic performance of the fabric actuator is predicted and compared with experimental results. An actual human arm size mannequin is driven by applying the fabric actuator, and angle control can be achieved with an encoder mounted on the joint. In addition, fabric actuator is weaved to sweater showing the possibility of wearable assistive robot.

From being soft, flexible and producing movement by contracting, soft linear actuators are said to have muscle-like properties. Due to these similarities, they are often called “artificial muscle actuator.” However, the strain produced by these actuators is generally insufficient to be utilized in a large range of applications. Some solutions have been developed, but they sacrifice force to increase the displacement. Meanwhile, the force produced by skeletal muscles increases as it contracts due to its working principle, which is based on the “sliding filament mechanism.” The limitations of soft linear actuators could be overcome by mimicking the contraction process of skeletal muscles. Two types of muscle-inspired robotic joint mechanisms based on the sliding filament mechanism principle are proposed in this work. The mechanisms can be operated using any type of soft linear actuators as well as traditional actuators or motors, and this work realizes the implementation using shape memory alloy wires and 3D printed mechanical parts. The feasibility of both proposed mechanisms, and their capabilities were experimentally verified.

This paper presents a hexapod crawling robot which has bioinspired design and locomotion posture from the insects. The robot, called S-Hex II, is an upgraded version of the different printable monolithic hexapod robot which is named as S-Hex I. The S-Hex II is studied for the project of developing mesoscale walking robots actuated by the soft dielectric elastomer actuators. In comparison with the S-Hex I, the S-Hex II owns smaller dimension, lighter weight, and significantly faster walking speed. We improve and increase the total number of degree-of-freedom (DOF) of the soft dielectric elastomer actuators (DEAs) from three, used in the S-Hex I, up to five, employed in the S-Hex II, and that provides the promising versatile locomotion ability to the S-Hex II robot. This robot has successfully demonstrated the back and forth ambulation on flat surfaces using the alternating tripod gait with the walking speed of 52 mm/s (approximately 0.35 body-lengths per second) at 7 Hz of actuation frequency.

This paper demonstrates a new haptic display based on soft actuator and soft sensor. The device consists of an array rigid coupling actuator and an array tactile sensor which configured sensor located on the top of actuator. The actuator includes a frame with rigid coupling made by silicone and a dielectric elastomer actuator(DEA). The movement of the DEA is transferred to touch pad via rigid coupling. Thus, it provides a soft, comport touch feeling and eliminates the danger of applying high voltage to the human skin. The actuator can work at a wide range frequency of 0–150 Hz and produce sufficient force of 50 mN over the human hand threshold. The tactile sensor can measure the pressure, locate the objects and send the feedback signals to control the actuator. In this work, a 8×12 haptic tactile display is made with high resolution. In addition, the high voltage signal processing also developed to generate variable 0–3.5 kV, and can control individual cell by using the dynamic scanning actuation algorithm. Then, it can display any shape such as a circle, a smile/sad face, a star, etc. In the future, we will build the “emotion touch pad” system which can transfer a person's emotion to another one via internet.

Aiming to apply soft actuators in driving a walking robot, the design, fabrication and locomotion of a bio-inspired printable hexapod robot are studied. The robot mimics the insect's design and walking posture by driving six legs with alternating tripod gait which provides its locomotive adaptability on flat terrains. The versatile movements of the robot's leg are achieved by using soft and multiple degree-of-freedom actuators. The actuators are made by dielectric elastomers with a simple mechanism based on antagonistic configuration. By using 3D printing method, the actuator can be embedded into the frame of the robot and a control system is developed. Finally, the robot's locomotion is successfully demonstrated with variable speeds and stride lengths.