Continuum robots(CRs) are featured with high compliance and adaptability. However, existing CRs commonly face issues of insufficient stiffness and actuation redundancy. This paper proposes a novel design of multi-layer jamming spherical joint (MLJSJ) and develops a pneumatically actuated variable-stiffness continuum robot. A segmented spherical expansion actuator airbag, resembling Tanghulu, is fabricated via the lost-wax method to meet the positive-pressure actuation requirements. The proposed robot consists of four serially connected continuum segments, each containing four spherical joints for smooth bending motion. By leveraging multi-layer frictional interactions within jamming structures, the robot achieves rapid and wide-range stiffness modulation under relatively low air pressure. Each continuum segment can be locked via a dedicated actuation airbag, with its pressure regulated by a proportional valve to enable rapid switching between rigid and flexible states. By switching the lock-unlock states of segments, the variable-stiffness mechanism decouples multi-segment motions into single-segment bending, enabling sequential actuation of all segments by using only four embedded alloy rods. A dedicated experimental setup was developed to characterize performance, demonstrating that a single segment reaches a maximum stiffness of 1403.03 N/m, with a stiffness modulation ratio of 35.85 and switching times ranging from 0.07 s to 0.43 s. Furthermore, by controlling the stiffness states and bending motions of different segments, the single segment of robot demonstrates a maximum payload capacity of 2 kg and versatile motion flexibility verified through obstacle avoidance and grasping tasks.

Rigid robots can achieve precise motions but expose shortcomings in system complexity, fabrication cost, and humanrobot interaction, which motivates researchers to develop various soft robots to fill these gaps. Electro-hydraulic actuators (EHAs) have received widespread attention and been used in many soft robots due to impressive high-strain, fast-speed and rapidresponse characteristics. However, existing EHAs face challenges in achieving large-deformation, high-robustness, and low-weight simultaneously. This limits the application of EHAs in robotic systems that are weight-sensitive or require fail-safe and faulttolerant behavior. Here, we present a lightweight (0.98 g) electropneumatic actuator (EPA) filled with air and only 0.1-mL liquid dielectric, which achieves high-speed bending from 11° to 93.5° in 60 ms, large-angle bending from 11° to 104° in 2 s (the largest in current EHAs), and high-frequency swing at 20 Hz. The EPA is ultrarobust and can operate properly after being punctured by four needles or crushed twice by a 1500-kg vehicle. Furthermore, to validate the above features of EPAs, three applications are demonstrated at a voltage of 6 kV, including four-finger grippers, fast-crawling robots, and water-walking robots. This work pushes the boundaries of robustness and lightweight for EHAs, providing a foundation for the application of electro-pneumatic actuation in soft robotics.

Multidirectional jumping is commonly found in living creatures and desirable to be integrated into mobile robots for enhanced agility. Existing jumping robots mostly employ complex or cumbersome structures and modular designs to achieve multidirectional jumping. There is a lack of a simple, lightweight, and compact actuator design for multidirectional jumping robots. Here, we present a multidirectional jumping soft robot (MDJSR) driven by a biaxial electrohydraulic actuator (BEHA). The BEHA has a simple structure, i.e., a thin plastic frame-guided film pouch with four pairs of distributed electrodes and enclosed with a dielectric liquid. Inspired by gall midge larvae, the MDJSR exhibits two switchable locomotion strategies, including continuous non-energy-storing jumping to move fast and energy-storing jumping to cross obstacles. Its multidirectional jumping capability was demonstrated in the navigation through a labyrinth with two ways of obstaclecrossing and obstacle-circumventing in different terrain environments. In addition, the robot can be deployed to detect unknown space and collect environmental factors. This work provides an enabling solution to miniature and lightweight multimodal jumping soft robots for various robotic tasks

Soft wall-climbing robots have been limited in their ability to perform complex locomotion in diverse environments due to their structure and weight. Thus far, soft wall-climbing robots with integrated functions that can locomote in complex 3-D environments are yet to be developed. This article addresses this challenge by presenting a lightweight (2.57 g) soft wall-climbing robot with integrated linear, turning, and transitioning motion capabilities. The soft robot employs three pneumatic bending actuators and two adaptive electroadhesion pads, which enable it to flip forward, transition between two walls, turn in two directions, and adhere to various surfaces. Different motion and control strategies are proposed based on a theoretical model. The experimental results demonstrate that the robot can move at an average speed of 3.85 mm/s (0.08 body length/s) on horizontal, vertical, and inverted walls and make transitions between walls with different pinch angles within 180°. Additionally, the soft robot can carry a miniature camera on vertical walls to perform detection and surveillance tasks. This article provides a reliable structure and control strategy to enhance the multifunctionality of soft wall-climbing robots and enable their applications in unstructured environments.

Owing to high compliance, adaptiveness, and easy controllability, soft actuators are widely adopted in soft grippers to grasp irregularly shaped or fragile objects. The specific motions can be preprogrammed into the flexible and constrained structures of the actuator, which provides an inexpensive and convenient method for desired motions. However, most preprogrammed structures cannot change the constraints on the actuator to achieve different kinds of deformations, which limits the motion diversities of actuators. This article proposes a scaffold reinforcement mechanism, where rotatable scaffolds distribute on the surface of the soft structure. The orientation adjustments of the scaffolds can change the deformation constraint of the actuator, which results in different kinds of motions. Based on the scaffold reinforcement mechanism, a scaffold-reinforced actuator is proposed, which can achieve bending motion and complex helical motion in the 3-D space by properly adjusting the orientation of the scaffolds. In addition, both the kinematic and mechanical models are proposed to forecast the behavior of the actuator when driven by cable displacement or tension force. Experimental results verify the validity of the theoretical model, and the actuator can achieve an independent control of bending and helical motion, which can be adopted in applications where both high dexterity and flexibility are required.