Kyu-Jin Cho

Origami has been a rich source for the design of soft deployable mechanisms capable of safe human‐robot interaction. However, the relatively weak structural stiffness of the folding crease lines gives rise to kinematic instability during shape transition, constraining practical robotic applications. Here, a 3D printed origami robotic actuator capable of load‐bearing deformation at the meter scale is proposed, enabled by programming the creaseline stiffness through modular assembly. During origami unfolding, the joint modules assembled onto the origami facets are stretched and subsequently provide antagonistic passive shape retention force to maintain kinematic stability. The integration of roll‐to‐roll (r2r) 3D printing further facilitates scalable fabrication of origami actuators with programmable robotic performance. The effectiveness of our framework is highlighted by a 1.3 m‐long collaborative robotic arm with variable workspace and an origami tent frame capable of automatic deployment and folding.

Crouch gait, characterized by excessive flexion of the lower-limb joints, is a common gait disorder among children with cerebral palsy (CP) that compromises mobility and increases energy expenditure. Although surgical and orthotic interventions can improve alignment, maintaining these benefits requires continued postural support and gait practice. While powered exoskeletons have been developed to support upright and coordinated movement, they are often too heavy and complex for practical use. To address this, we developed a lightweight passive exoskeleton that assists the hip, knee, and ankle simultaneously using a single elastic band. The device is designed to provide self-adjusting torque dependent on posture without the need for sensors or active control. It also features user-centric design components to ensure wearability and lightness through a garment-like waist belt and carbon-fiber knee-ankle exoskeleton. We evaluated the biomechanical effects of the exoskeleton in four children with crouch gait (GMFCS levels I-III) by comparing baseline and exoskeleton conditions during overground walking. The preliminary results showed that the exoskeleton tended to increase the mean hip and knee extension angles during the stance phase by 3.5◦ and 3.3◦, respectively, and increased ankle plantarflexion by 1.4◦, indicating the mechanical feasibility of assisting a more extended gait posture. Furthermore, the range of motion of the joints increased by 1.7◦ in the hip, 4.2◦ in the knee, and 8.5◦ in the ankle, suggesting that the passive assistance does not restrict motion and may allow for dynamic joint movement. These preliminary findings suggest the feasibility of passive, multi-joint assistance strategies to facilitate more upright gait patterns in children with crouch gait.

Patients with respiratory weaknesses due to neurological disorders or aging often face usability challenges with conventional mechanical ventilators, which

This study presents a vertically deployable rotor-sail structure utilizing multi-layer Sarrus linkages. The structure fully extends during sailing to maximize Magnus lift and compresses to less than half its length for docking. An analytical beam model integrates link thickness, mid part spacing, and centrifugal loading to predict deflection and mass. Parametric comparisons of two-layer, six-layer, and twelve-layer configurations reveal that the twelve-layer design reduces structural mass by 90% while meeting an L/1000 deflection limit. Dynamic simulations using RecurDyn confirm that mid part segmentation decreases damping time and reduces peak stress, thus enhancing deployability and mechanical reliability. The findings offer quantitative design guidance for high-speed rotating deployable structures.

Extendable structures often use rollable designs, with long, flexible materials that can be wound onto a hub for storage without the need for joints. However, achieving high stiffness and strength in the extended state while keeping the hub compact is challenging, given that stiff structures are difficult to bend and typically require larger hubs for storage. Here, we introduce a corrugated sheet–shaped foldable design that enables Z-folding by connecting multiple strips in parallel. The unfolded, corrugated form structure offers a high load-bearing capacity, and the folded, stacked form structure can be smoothly rolled onto a hub, enabling fold-and-roll storage. The key innovation is the formation of an interlaced origami structure by connecting strips through a ribbon-weaving technique. This interlacing design enables both localized flexibility and mutual constraints between strips: The localized flexibility accommodates perimeter differences between stacked strips during rolling, and the densely repeated mutual constraints make the corrugation resist excessive deformation under external forces. Using these structures, we made two deployable mobile robots: one with a 1.6-meter deployable arm for shelving tasks and another with a tetrahedral deployable frame that supported a meter-scale 3D-printing system. Our results showcase the potential of this interlaced, corrugated approach for deployable robotic systems requiring both compactness and strength.