From small unicellular organisms to large mammals, swallowing is an important way for them to interact with their external environment. The majority of these animals swallow their targets for the purpose of hunting, and some fish and amphibians protect their cubs from external injury by swallowing them. Thus, swallowing can produce an efficient capture, keep the integrity of targets, and provide effective protection for swallowed objects. Inspired by this, we propose a novel soft swallowing robot (SSR) capable of swallowing various objects that have different shapes and stiffnesses, protecting objects from squeeze and collision, and withstanding high temperature, which are enabled by a compliant guiding structure consisting of a double thin-walled capsule filled with fluid and a linearly movable traction body. In this article, we study the SSR supported by air and water, respectively; furthermore, we experimentally conclude that the working medium has a great influence on the inherent characteristics of the SSR. Our study helps lay the foundation for the research of soft robotic systems with swallowing characteristics, and the SSR is expected to enter the practical application field from the laboratory.

Web structure is a flexible structure widely used in animal predation behavior and human hunting work, which exhibits an excellent capability of gripping objects stably and securely. Inspired by the predation behavior of spiders, in this article, we present a bioinspired cobweb soft gripper, named WebGripper, which takes on a form like a spider web before grasping an object and presents an entangling state like a snake after grasping the object. These characteristics result in broad adaptability to various objects and enhanced grasping stability. The design concept, grasping principle, and fabrication process of the WebGripper are presented in this work, and the influences of cable layout and soft finger installation angle are analyzed to provide a reference for the design of the WebGripper. To evaluate the performance of the WebGripper, we carried out experiments on grasping objects with different shapes and sizes. Experimental results illustrated the universal adaptable grasping ability of the WebGripper, which exhibits excellent application prospects in many fields, such as goods sorting, fruit picking, and underwater fishing. This work is expected to promote the development of a high-performance soft gripper that may be used in a number of applications based on the understanding of the bionic web structure.

In the deployable mechanism for a conventional truss antenna, the nodes cannot be adjusted to be uniform in attitude. To solve this problem, a method of adding constraint chains is proposed based on the reciprocal screw theory. By performing type synthesis of the deployable mechanisms for the truss antenna, a novel deployable mechanism is developed that not only enables complete folding and unfolding but also allows the attitude of the nodes to be made uniform. First, according to the unit division of the antenna reflection surface and the characteristic motions of the nodes, constraint chains that can be added between two adjacent nodes are synthesized based on the reciprocal screw theory. Second, to improve the overall rigidity of the mechanism, a series of basic developable unit mechanisms is obtained by adding virtual constraint chains, again based on the reciprocal screw theory. Next, a method of dividing the minimum combination unit of the curved-surface antenna mechanism is proposed. The design of the minimum combination unit mechanism is optimized, such that the attitude of all nodes in the final folded state can be made consistent. Finally, the feasibility of the optimized minimum combination unit mechanism is verified by simulation analysis. The proposed method for type synthesis provides a new approach to the design of deployable mechanisms for truss antennas, and novel deployable mechanisms for the curved-surface truss antenna with better performance are obtained.

Dyskinesia of the upper limbs caused by stroke, sports injury, or traffic accidents limits the ability to perform the activities of daily living. Besides the necessary medical treatment, correct and scientific rehabilitation training for the injured joint is an important auxiliary means during the treatment of the effected upper limb. Conventional upper-limb rehabilitation robots have some disadvantages, such as a complex structure, poor compliance, high cost, and poor portability. In this study, a novel soft wearable upper limb rehabilitation robot (SWULRR) with reinforced soft pneumatic actuators (RSPAs) that can withstand high pressure and featuring excellent loading characteristics was developed. Driven by RSPAs, this portable SWULRR can perform rehabilitation training of the wrist and elbow joints. In this study, the kinematics of an SWULRR were analyzed, and the force and motion characteristics of RSPA were studied experimentally. The results provide a reference for the development and application of wearable upper limb rehabilitation robots. An experimental study on the rotation angle of the wrist and the pressure of the RSPA was conducted to test the effect of the rehabilitation training and verify the rationality of the theoretical model. The process of wrist rehabilitation training was tested and evaluated, indicating that SWULRR with RSPAs will enhance the flexibility, comfort, and safety of rehabilitation training. This work is expected to promote the development of wearable upper-limb rehabilitation robots based on modular reinforced soft pneumatic actuators.

Recently, the truss antennas with deployable tetrahedron unit mechanisms have been successfully applied in orbit, owing to the advantages of large calibers, high accuracy, and large folding ratios. As multiloop coupled mechanisms, deployable tetrahedral mechanisms have multiple different output links, whose supporting limbs connecting output links and the base are mutually coupled. These mechanisms are also called the passive-input overconstrained mechanisms because their passive torsion springs are used as drivers and because the number of the drivers contained is more than the degrees of freedom (DOFs). In this work, a method based on the equivalent concept of first link-removing and then restoring is proposed for the DOF analysis of the multiloop coupled deployable tetrahedral mechanisms. With one coupled chain removed, the equivalent serial chains between the coupled components and the base are established in the remainder of the mechanisms. Then, the coupled chain removed is restored and the equivalent of the multiloop coupled mechanisms is obtained. The Lagrange method is used to establish the dynamic equation of the passive-input overconstrained mechanisms; the influence of the stiffness and number of torsion springs on the unfolding motion is examined.