As the aging of society continues to accelerate, the number of elderly patients is increasing, as is the demand for manpower to care for them. In particular, there is an urgent need for bedridden patient care. However, limitations in the supply of human resources have caused an increase in the burden for care. In particular, nursing personnel often experience inconvenience and difficulties owing to the great deal of effort required to transfer a patient from bed to wheelchair, or vice versa. The most difficult process during the patient transfer is inserting the sling under the patient. Aiming to solve this problem, a mechanical Growing Sling was devised. The proposed sling adapts a growing mechanism comprising a low-friction fabric and steel shafts, and the sling is inserted under the patient by towing the steel shafts with cables connected to a motor. For the comfort and safety of the sling insertion, the required towing force was analyzed to find the minimum diameter of the shaft. The results from experimental evaluations using the proposed sling verified that it can be inserted under the patient without moving the patient, and with an acceptable level of pressure being applied to the patient.

In this study, a new type of sling for assisting bedridden patients is developed using a pneumatic growing mechanism. Growing Sling focuses on minimizing the labor input of the caregivers by automating the sling insertion and retraction process while maintaining safety and comfort. Improvements over the typical growing mechanism were made by reinforcing the sling with shafts and filament tape for restricting the height of the sling to ensure its design purpose. Analysis of forces exerted on the structure was made to interpret the driving power of the automated insertion process and to ensure the structural integrity of components. Experiments on materials and prototype devices were conducted to determine the quantitative load that the sling needs to endure and what type of material is suitable for fabrication. Further, we propose a fabrication process for the Growing Sling, including its dimensions, and validate the performance of the fabricated prototype.

Hyper-redundant manipulators driven by cables are used in minimally invasive surgery because of their flexibility and small diameters. In particular, manipulators composed of many rigid links and joints have the advantages of high stiffness and payload. However, these manipulators have difficulty in estimating their positions and shapes using calculations based only on the kinematics model that assumes all joint angles are equal. In this paper, we present a method for estimating the position and shape of the rolling joint in hyper-redundant manipulators by minimizing the joint moments. This allows the determination the equilibrium position of all segments of the rolling joint, and therefore an estimation of its shape. We experimentally determine the position and shape of a prototype of the rolling joint and compare them to a simulation of our method. The maximum error between the simulation and the experimental results is 4.13 mm, which is a 77.22% improvement over the kinematic model that calculates the same joint angle. This verifies that our method accurately estimates the position and shape of the rolling joint.

We present a transformable catheter head structure for endoscopic catheter allowing the simultaneous use of a camera module and a large tool channel introduced through a small incision. At the site of interest, the head with a camera can be expanded from the initial straight configuration, which opens a window for advancing a tool that is located behind the camera. Two different designs were proposed and prototyped. One option has flexure joints directly fabricated at the distal end of a polymer catheter by laser micro-machining, while another design employs a hinged metal head assembled at the tip of the same type of catheter. The kinematic behavior of each head was evaluated during the head-up and tip steering motions, and compared with each other to draw a selection guideline between them. Experimental results prove the feasibility of the proposed head structure for smarter endoscopic catheters.

Design optimization and fabrication of concentric tube robots are time consuming because of the complexity of their workspaces and the characteristics of the superelastic materials used to make them. This paper presents a procedure for the expeditious design and fabrication of a concentric tube robot for applications that require rapid tube preparation but have less complex design constraints. This procedure reduces a 3D workspace optimization problem to a 2D problem. The continuum robot includes a heat-shrink tube to reduce fabrication time and to give it a small radius of curvature. Experimental results illustrate the feasibility of the proposed procedure.

Shape tracking using a fiber Bragg grating sensor is a promising tool due to its thin, flexible, and weightless nature. Conventional investigations attached optical fibers with a metal rod which limited the curvature due to its stiffness and increased distance between the center of the fiber and that of the sensor. We fabricated ultrathin flexible shape sensor with 110 mm length and 560 μm diameter. Its low Young's modulus and small diameter makes it suitable for application in minimally invasive surgical robot such as active cannula. The sensor causes only miniscule resistance when the cannula rotates or moves, and allows extra spaces for other surgical tools thanks to its small diameter. After the calibration, the sensor was integrated to the active cannula and overall position of the sensor was tracked. It showed an average error of 3.17 ± 1.21 % of the lengths of the measured nodes from the fixed starting point. The error was comparable to the outer diameter of the cannula, 2.8mm.

As a steerable needle or robotic manipulator, the concentric-tube robot shows good potential for use in minimally invasive medical procedures. However, the torsional deformation of the precurved tubes comes at the price of instability, which not only limits the workspace and tool path but also potentially creates danger of tissue rupture when external load is applied. In this paper, we propose anisotropic patterning of tubes to solve the instability problem. Hole-patterning can tune the mechanical properties of the tubes so that the ratio of the torsional rigidity to the bending rigidity becomes higher. This study investigates the effect of pattern design parameters by building a lumped analytical model and examining it with finite-element analysis. The pattern is engraved via laser machining and we experimentally verify that material anisotropy reduces instability.

The concentric-tube continuum robot generates distal end motions by translating and rotating the proximal ends of pre-curved tubes that overlap concentrically. This robot does not require additional actuators along the tubes because the overall curvature and distal end position are determined solely by interactions between the inner and outer tubes. However, under certain conditions, the rotation of the distal end is hindered as the actuation energy accumulates into torsional energy of the tubes. As the distal ends are rotated further, the accumulated energy from the twisting is suddenly released, which makes the tubes snap to a remote position. This is called the snapping problem, and it considerably limits the performance of the robot. In this paper, we propose a novel design for the concentric tubes to eliminate the snapping problem. The new design creates groove patterns on superelastic nitinol tubes to make the tubes more flexible to bending than twisting. Simulations and experiments were performed to verify that the tubes with our groove patterns had anisotropic structural characteristics, and video image analysis verified that this structural property can eliminate the snapping problem. A concentric-tube robot with this new tube design can have a larger workspace area because tubes with greater curvatures can be used without the snapping problem.