In industrial production, current pipe-climbing robots can replace humans in real-time monitoring, leak inspection, and other tasks. However, most pipe-climbing robots are designed for specific applications with complex structures; this limits the adaptability to various conditions. To solve this issue, this letter presents a one-piece 3D-printed pipe-climbing robot composed of sequenced novel soft bending mechanisms. The mechanisms use the small strains of soft materials to achieve large bending deformation. The proposed robot is highly adaptable to pipes with various diameters, radii of curvature, inclinations, and even outer/inner walls because of modular grippers and an inchworm inspired middle section. The good strength and flexibility of the robot are simultaneously achieved by reasonable structural design using one material. In this letter, the design concept and processing methods are introduced. The finite element method is adopted to predict the maximum bending angle of modules to aid design, and a torque test bench is built to acquire output torque and restoring torque. Then, the model of the entire robot is built to facilitate specialized design. Finally, several experiments are conducted to verify the good adaptability of the robot to pipes of various diameters (18–36 mm), inclinations (0–90°, even horizontal pipes), and radii of curvature (minimum to 19 mm). The static bearing ability of the robot reaches 1000g (without climbing at 7 bar, 22 mm diameter vertical pipes), which is almost 80 times its weight. In addition, the load-bearing ability of the robot while climbing on pipes in various states is obtained.

This paper presents an earthworm-inspired multimodal pneumatic continuous soft robot enhanced by wire-winding transmission. First, a derived overlapped continuous control law based on multiple peristaltic waves is introduced to effectively improve the motion performance of the robot. Second, by applying the wire-winding transmission method, the extension of one segment is simultaneously transformed into the contraction of other segments, achieving coordinated deformation and making it more similar to real earthworms. In addition, an autonomous obstacle-avoidance control strategy based on contact force sensing is developed to enhance the environmental adaptability of the robot. Based on these methods, an earthworm-inspired soft robot that can perform multimodal movements with autonomous obstacle-avoidance ability and enhanced motion efficiency is developed. A series of experiments including in- and cross-plane crawling, obstacle avoidance steering, and pipeline crawling are conducted to validate the robot’s multimodal motion capabilities. The robot can achieve a speed of 6.65 mm/s (36.0 × 10 ⁻³ bl/s) during in-plane crawling movement and 1.66 mm/s (8.97 × 10 ⁻³ bl/s) during pipeline crawling movement. In terms of the in-plane crawling speed, the robot surpasses other robots of the same type. In conclusion, the robot’s multimodal capabilities and enhanced motion efficiency demonstrate superior overall performance, and the robot has good potential for medical and industrial applications.

A vacuum-driven inclined hexagonal prism soft-rigid hybrid contraction actuator inspired by Kresling origami pattern and with low driving pressure, high contraction ratio, and fast response was proposed. The advantages of soft-rigid hybrid vacuum contraction actuators over conventional positive-type oscillators were investigated. Under 30 kPa vacuum pressure, the actuator can realize a torsional angle of 87°, contraction ratio of 59%, contracting response time of 0.2 s, and restoring response time of 0.42 s. The design and fabrication of the proposed actuator were discussed. A mathematical model treating all creases as a combination of linear and torsion springs, which is firstly considered compared with previously proposed models of Kresling origami-based actuators, was established to predict the output performance. The excellent output force prediction performance of the proposed method was validated experimentally. To investigate the application potential of the proposed modular actuator, six actuators were assembled on a pipe-crawling robot that can crawl in horizontal, vertical, elbow rigid pipes as well as flexible pipes with inner diameters ranging from 55 to 71 mm. The robot achieved a maximum crawling velocity of 34.8 mm s⁻¹ (0.226 body lengths per second) and maximum load of 1000 g (12.5 times its own weight) in tests. Thus, the excellent application potential of the proposed actuator was validated.

In wearable applications, traditional pneumatic artificial muscles (PAMs) cannot fully satisfy the requirements of safe and sufficient interaction with the human body. The requirements include high contraction ratio, self-contained sensing, reconfiguration, locking abilities, and avoidance of the squeezing force acting on the human tissue. In this letter, a reconfigurable self-sensing pneumatic artificial muscle (RSPAM) based on modular multi-chamber soft actuator with locking ability is developed, which provides an alternative that can satisfy all the requirements for the wearable applications. The contraction principle of the RSPAM, which includes transforming the expansion of the soft actuator into contraction by fabric winding, has an inherently high contraction ratio and completely avoids squeezing of human tissue. Self-sensing of contraction stroke based on liquid metal and locking ability based on positive pressure jamming are integrated. A driving force and contraction ratio of 70.14 N and of 71% were validated at 3 bar air pressure. Modular design of the actuator makes it possible to change the configuration by adjusting the actuator amount and the fabric length according to the application. In addition, the actuator unit can move on the fabric by itself, enabling a noteworthy self-adjustment ability for the muscle. The displacement self-sensing ability is verified through square-wave tracking experiments with closed-loop control. Finally, a preliminary test of assisting elbow movement verifies that the RSPAM can reduce 53.05% of the muscle fatigue.

This paper presents a novel flat modular pneumatic artificial muscle (FMPAM) consisting of thin-film cylinder modules, which have no expansion in the thickness direction when pressurized to generate transverse force, and transverse-to-longitudinal deformation translation structures around modules, which accumulate the distributional deformation and ultimately obtain large cumulative deformation and output force. The FMPAM is designed for contractile assistance in soft wearable robots to achieve no squeezing on users’ skin and better wearing comfort. This design combines the advantage of fast time response of positive-pressure pneumatic artificial muscles (PAMs) and the features of good flexibility of negative-pressure ones. Additionally, the design avoids the disadvantages of relatively large thickness or radical expansion of positive-pressure PAMs. In this paper, the design and processing methods of the FMPAM are introduced in detail. It is worth mentioning that the whole FMPAM is printed utilizing the same type of material at one time. Identification of the module model is carried out. Module net output force and restoring force test benches are built to acquire experimental data for assisting the modeling. The shape of the film and modular output force can be predicted during actuation. Experimental results show that low predictive error can be obtained. Finally, an output force test bench, various radius arches and an arm-like structure are built to verify the output characteristics of the FMPAM: good compliance to surfaces with different radiuses, long-lasting endurance (more than 10 000 reciprocating cycles), and high response speed (100 Hz), indicating that the proposed design can provide theoretical guidance and a good alternative for soft wearable robot actuators.