Youngjin Moon

Accurate needle positioning in robot-assisted pain intervention requires kinematic accuracy, structural stiffness, and stable motion transmission under external loading. Our earlier needle insertion robot, based on a spherical five-bar remote-center-of-motion mechanism, exhibited structural deformation and rotational play during repeated bidirectional actuation. This study redesigned the rotational joint while preserving the architecture and degree-of-freedom configuration. Joint geometry was modified to enlarge the supporting contact area by approximately 4.2-fold, and a friction-based keyless shaft coupling was introduced to improve shaft fastening and suppress rotational clearance. An equivalent stiffness model related vertical needle guide loading to structural displacement and rotational joint compliance. Comparative experiments evaluated structural stiffness, rotational lost motion, and phantom insertion stability. The improved design exhibited smaller steady-state displacement under vertical loads of 0.5–2.0 N, reducing displacement to approximately 40–52% of the previous design; linear force–displacement analysis yielded stiffness values of 0.839 and 1.345 N/mm, an approximately 1.60-fold increase. Rotational lost-motion tests showed an increased mean output-to-input peak ratio, indicating improved transmission. Phantom insertion tests, performed under matched insertion-force conditions, showed significantly reduced peak lifting distance for the improved design across all tested insertion angles. Overall, the redesigned interface reduced structural compliance and improved needle guide stability without altering the fundamental robot architecture.

Background: Preterm neonates have a substantially higher risk of developing cerebral palsy than term neonates, and early identification of abnormal fidgety movement (FM) is clinically important for early risk screening. Methods: This pilot study investigated whether a combined metric-learning loss can improve FM/non-FM (nFM) representation learning in a neonatal multimodal dataset. Data were obtained from 11 preterm neonates at 3–5 months of corrected age and segmented into 1957 multimodal samples consisting of motion history image (MHI) features and inertial measurement unit (IMU) signals, with FM/nFM labels and segment metadata organized in a unified manifest. The proposed ImageBind-based framework was trained using MHI and IMU inputs, with FM/nFM labels used for supervised loss optimization, and final test-stage inference was likewise performed using only MHI and IMU data. To address the complementary limitations of triplet loss and tuned constellation loss, we designed a combined loss that jointly enforces local distance constraints and global embedding structure. Results: Within this predefined internal sample-level evaluation setting, the combined-loss model outperformed single-loss baselines, achieving an accuracy of 0.838, F1-score of 0.828, AUROC of 0.909, and AUPRC of 0.894 on the internal test partition. These findings suggest that the combined loss mitigated the failure modes of single-loss training and improved class-wise balance under the present pilot methodological setting. Conclusion: Overall, this study provides foundational evidence that multimodal metric learning can support FM/nFM representation learning in preterm neonates and motivates further validation in larger subject-held-out cohorts.

This study presents the development of a smart patient-care robot designed to assist healthcare workers by automating routine monitoring tasks and enhancing autonomous mobility in hospital wards. Unlike conventional systems that rely on multiple sensors, the proposed platform achieves reliable navigation using a single two-dimensional light detection and ranging sensor combined with an enhanced D* lite algorithm. A key contribution of this work is the introduction of virtual obstacle spaces in occupancy grid maps, which simplify path planning and significantly increase the success rate of passing through narrow doorways, one of the most collision-prone scenarios in ward environments. Experimental results show a navigation success improvement of over 30%, confirming enhanced safety and efficiency in mobility. This research establishes a practical foundation for deploying patient-care robots in real hospital settings, showcasing both technical advances in autonomous navigation and the potential to reduce healthcare staff workload while ensuring patient safety.

To advance the application of continuum robots in the medical field, this study proposes the integration of compliant bi‐stability in continuum robots to enable the ability to form custom shapes. The process includes designing a compliant bistable mechanism (CBM), deconstructing a ball‐joint‐based continuum robot segment, and then integrating the two. This allows the resultant continuum segment to become bistable. Two versions of this CBM‐integrated continuum segment arose from the design process: an “Extending” version that improves the effective length and reachability of the segments, and a “Locking” version that locks certain regions and enhances stiffness. When used together, these two segment types enable the CBM‐based continuum robot to demonstrate mechanical intelligence by achieving custom shapes in different configurations through passive mechanical design. The paper also presents an analytical model to characterize the CBM. Simulation and experimental results for the segments establish a 50% increase in workspace by using the extending segment. Using the locking segment results in an 80% to 100% increase in stiffness. A shape formation test for a liver biopsy procedure shows a decrease of 61% in the tip‐to‐target deviation, demonstrating a potential application for minimally invasive surgeries.

Traditional surgical interventions for frontal sinus fractures necessitate a cut on the forehead skin, and extant closed reduction techniques aimed at enhancing accessibility continue to grapple with secure tool fixation, stable bone elevation, and screw breakage risk. To address these challenges and augment surgical efficiency, this study introduces novel surgical devices. Design parameters for models with spiral or L‐shaped tips are established, considering practical medical requirements and constraints, and subsequently validated through finite element method numerical simulations using commercial software, Ansys. Four spiral‐type prototypes are constructed, and three scenarios for each prototype, varying in projection distance from the device handle to the bone‐device contact point, are examined via nonlinear simulation analyses. For the L‐shaped type, three prototypes are developed, and static analyses are conducted for four scenarios per prototype, differing in traction force locations, based on another simulation result concerning moments of inertia calculation with a force boundary condition unlike pressure. Maximum stress results under a specific force are analyzed, and the maximum permissible force is determined under the most unfavorable force application condition. Simulation outcomes indicate that the spiral type offers greater applicability with less force to lift multiple bones, while the L‐shaped type is more suitable under bone hardening conditions.

Wire actuation in tendon-driven continuum robots enables the transmission of force from a distance, but it is understood that tension control problems can arise when a pulley is used to actuate two cables in a push-pull mode. This paper analyzes the relationship between angle of rotation, pressure, as well as variables of a single continuum unit in a quasi-static equilibrium. The primary objective of the quasi-static analysis was to output pressure and the analysis, given the tensions applied. Static equilibrium condition was established, and the bisection method was carried out for the angle of rotation. The function for the bisection method considered pressure-induced forces, friction forces, and weight. {\theta} was 17.14{\deg}, and p was 405.6 Pa when Tl and Ts were given the values of 1 N and 2 N, respectively. The results seemed to be consistent with the preliminary design specification, calling for further simulations and experiments.