Multimodal Limbless Crawling Soft Robot with a Kirigami Skin

Limbless creatures can crawl on flat surfaces by deforming their bodies and interacting with asperities on the ground, offering a biological blueprint for designing efficient limbless robots. Inspired by this natural locomotion, we present a soft robot capable of navigating complex terrains using a combination of rectilinear motion and asymmetric steering gaits. The robot is made of a pair of antagonistic inflatable soft actuators covered with a flexible kirigami skin with asymmetric frictional properties. The robot's rectilinear locomotion is achieved through cyclic inflation of internal chambers with precise phase shifts, enabling forward progression. Steering is accomplished using an asymmetric gait, allowing for both in-place rotation and wide turns. To validate its mobility in obstacle-rich environments, we tested the robot in an arena with coarse substrates and multiple obstacles. Real-time feedback from onboard proximity sensors, integrated with a human-machine interface (HMI), allowed adaptive control to avoid collisions. This study highlights the potential of bioinspired soft robots for applications in confined or unstructured environments, such as search-and-rescue operations, environmental monitoring, and industrial inspections.

Inflatable Kirigami Crawlers

Kirigami offers unique opportunities for guided morphing by leveraging the geometry of the cuts. This work presents inflatable kirigami crawlers created by introducing cut patterns into heat-sealable textiles to achieve locomotion upon cyclic pneumatic actuation. Inflating traditional air pouches results in symmetric bulging and contraction. In inflated kirigami actuators, the accumulated compressive forces uniformly break the symmetry, enhance contraction compared to simple air pouches by two folds, and trigger local rotation of the sealed edges that overlap and self-assemble into an architected surface with emerging scale-like features. As a result, the inflatable kirigami actuators exhibit a uniform, controlled contraction with asymmetric localized out-of-plane deformations. This process allows us to harness the geometric and material nonlinearities to imbue inflatable textile-based kirigami actuators with predictable locomotive functionalities. We thoroughly characterized the programmed deformations of these actuators and their impact on friction. We found that the kirigami actuators exhibit directional anisotropic friction properties when inflated, having higher friction coefficients against the direction of the movement, enabling them to move across surfaces with varying roughness. We further enhanced the functionality of inflatable kirigami actuators by introducing multiple channels and segments to create functional soft robotic prototypes with versatile locomotion capabilities.

Weld n'Cut: Automated fabrication of inflatable fabric actuators

Lightweight, durable textile-based inflatable soft actuators are widely used in soft robotics, particularly for wearable robots in rehabilitation and in enhancing human performance in demanding jobs. Fabricating these actuators typically involves multiple steps: heat-sealable fabrics are fused with a heat press, and non-stick masking layers define internal chambers. These layers must be carefully removed post-fabrication, often making the process labor-intensive and prone to errors. To address these challenges and improve the accuracy and performance of inflatable actuators, we introduce the Weld n'Cut platform-an open-source, automated manufacturing process that combines ultrasonic welding for fusing textile layers with an oscillating knife for precise cuts, enabling the creation of complex inflatable structures. We demonstrate the machine's performance across various materials and designs with arbitrarily complex geometries.