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It has been agreed that a proper level of flexibility in moving appendages like a fin of swimming animals enhances their propulsive performance. However, a few efforts have been spent to characterize the criterion, as a simple guideline for designing a biomimetic propulsor, at which the beneficial effect of compliance is maximized. Recently, it was reported that a sinusoidally pitching panel produces the enhanced thrust when the passively bending angle of a trailing edge lags behind its pitching angle by around π / 2 due to its compliance. To understand its mechanism, we perform a series of particle image velocimetry measurements around a panel pitching in quiescent water, while varying its compliance, planform shape and pitching frequency. For all the planform shapes and frequencies considered, with a phase delay of about π / 2 , the region of high streamwise velocity with thrust-generating momentum is retained farther (in the streamwise direction) in the wake, caused by the large effective pitching angle during the accelerating stage of pitching rotation. When the panel is stiffer (or the phase delay is smaller than π / 2 ) than the optimal condition, however, a strong interaction between the trailing-edge vortices (TEVs) formed successively at each half strokes pushes the surrounding fluid into the transverse direction, thereby accelerating the decay of thrust-generating streamwise velocity. This interaction between TEVs is weak for the case of optimal compliance. On the other hand, in the case of over-compliance, the trailing edge of the panel rotates opposite to the pitching direction, which indicates that the inertial work required to rotate the panel during the stroke-reversal becomes excessive at the expense of rotational circulation which eventually weakens the thrust.

This article presents a new, modularized design concept based on a bottom-up approach to assembly. This concept enables the structures and motions of soft robots to be rapidly revised to create new designs that can accomplish different tasks. We designed three basic types of pneumatically actuated soft modules, called soft robotic blocks (SoBL), that implement a single motion each (translation, bending, or twisting), which, when assembled, create structures capable of various motions. We introduce three types of connection mechanisms-screw thread, push fitting, and bistable junction-that can be used with any of the modules and that are designed to make for easy assembly and disassembly. Units were fabricated by multimaterial threedimensional (3-D) printing or silicone molding.

Manufacturing paradigms have historically been shaped by social, economic, and technological aspect, including limitations and needs. Design for manufacturing (DFM) has been the main paradigm for last three decades since design is defined by the limitations of available manufacturing processes. Since reducing the time required for the development of new products has been one of the key issues for businesses, removing the gap between designers and manufacturers has been one of today’s main goals. Many methods were developed to reduce this gap including information and communication technologies (ICT). However, current issues have been shifting towards design-related issues such that researchers have been trying to make products desired by the customers rather than that which is cheaper to manufacture. In this article, hybrid manufacturing (HM) and the concept of smart factory are introduced as key technologies for the future paradigm of manufacturing: Manufacturing for Design (MFD). Issues related to the development of HM process and examples of HM process are explained, and the importance of smart factories for the implementation of MFD is shown. Finally, future trends of HM and smart factory are predicted at the end of this article.

This article presents Exo-Glove Poly (EGP) II, a soft wearable robot for the hand with a glove that is completely constructed of polymer materials and that operates through tendon-driven actuation for use in spinal cord injury (SCI). EGP II can restore the ability to pinch and grasp any object for people with SCI in daily life. The design of the glove allows it to be compact and extends the range of hand sizes that can fit. A passive thumb structure was developed to oppose the thumb for improved grasping. To increase the robustness of the glove, EGP II was designed to have a minimal number of components using a single material. A kinematic model of the system was used to optimize the design parameters of an antagonistic tendon routing system on a single actuator for various hand sizes and repeated actuations. Experiments were conducted on two subjects with SCI to verify the grasping performance of EGP II. EGP II has a compact glove and an actuation system that can be placed on a desk or wheelchair, with the weights of 104 g and 1.14 kg, respectively.

In this paper, we propose an omnidirectional jumper with expanded locomotion capabilities. The mechanisms for four functions—jumping, steering, self-righting and take-off angle adjustment—are designed using only two motors to maximize the jumping performance. Jumping uses the modified active triggering mechanism with one motor. Steering shares this motor and uses the wheel touching the ground. The take-off angle is adjusted by changing the angle between the body and the foot using another motor. Self-righting is possible by utilizing combinations of the movements that occur in the energy storing and angle adjustment processes. With these four functions, the robot is capable of jumping in all directions and can jump anywhere in between the maximum height and maximum distance. It can also jump multiple times by self-righting. The robot, with a mass of 64.4 g, jumps up to 113 cm in vertical height, and 170 cm in horizontal distance. This robot can be deployed to explore various environments. Moreover, the design method to implement more functions than the number of motors can be applied to design other small-scale robots.

Designing softness into robots holds great potential for augmenting robotic compliance in dynamic, unstructured environments. However, despite the body's softness, existing models mostly carry inherent hardness in their driving parts, such as pressure-regulating components and rigid circuit boards. This compliance gap can frequently interfere with the robot motion and makes soft robotic design dependent on rigid assembly of each robot component. We present a skin-like electronic system that enables a class of wirelessly activated fully soft robots whose driving part can be softly, compactly, and reversibly assembled. The proposed system consists of two-part electronic skins (e-skins) that are designed to perform wireless communication of the robot control signal, namely, "wireless inter-skin communication," for untethered, reversible assembly of driving capability. The physical design of each e-skin features minimized inherent hardness in terms of thickness (1 millimeter), weight (~0.8 gram), and fragmented circuit configuration. The developed e-skin pair can be softly integrated into separate soft body frames (robot and human), wirelessly interact with each other, and then activate and control the robot. The e-skin-integrated robotic design is highly compact and shows that the embedded e-skin can equally share the fine soft motions of the robot frame. Our results also highlight the effectiveness of the wireless inter-skin communication in providing universality for robotic actuation based on reversible assembly.

Microrobots that are light and agile yet require no artificial power input can be widely used in medical, military, and industrial applications. As an actuation system to drive such robots, here we report a biologically inspired bilayer structure that harnesses the environmental humidity energy, with ratchets to rectify the motion. We named this actuator-ratchet system the hygrobot. The actuator uses a hygroscopically responsive film consisting of aligned nanofibers produced by directional electrospinning, which quickly swells and shrinks in lengthwise direction in response to the change of humidity. The ratchets based on asymmetric friction coefficients rectify oscillatory bending motion in a directional locomotion. We mathematically analyzed the mechanical response of the hygrobot, which allowed not only prediction of its performance but also the optimal design to maximize the locomotion speed given geometric and environmental constraints. The hygrobot sterilized a trail across an agar plate without any artificial energy supply.

PURPOSE To investigate the technical feasibility of stent placement in the cartilaginous portion of the Eustachian tube (ET). MATERIALS AND METHODS Twelve ETs of 6 cadavers were used. Two different-sized stents were placed on either the right (2.5 mm in diameter) or left (3.5 mm in diameter) side of the ET. The procedural feasibility was assessed by subtraction Eustachian tubography, computed tomography before and after the procedure, and fluoroscopic and endoscopic images. The stent location, inner luminal diameter of the stented ET, radiation dose, procedural time, and fluoroscopy time were analyzed. RESULTS Stent placement was successful in 11 of 12 cadaveric specimens without procedure-related complications. In the 1 specimen, the balloon catheter with crimped stent was passed into the bony canal of the ET without any resistance. The distal end of the stent was located in the middle ear cavity. Stents were located within the cartilaginous portion of the ET (n = 1), the proximal tip bridging the nasopharyngeal orifice of the ET (n = 5), or the proximal end of the stent protruded from the tubal orifice (n = 5). The mean luminal diameter in the outer segment was significantly smaller than in the middle (P < .001) and inner (P < .001) segments. The mean procedure time was 128 ± 37 seconds. The mean radiation dose and fluoroscopy time of each cadaver were 3235.4 ± 864.8 cGy/cm2 and 139 ± 49 seconds, respectively. CONCLUSIONS Stent placement of the ET under endoscopic and fluoroscopic guidance is technically feasible in a human cadaver model.

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.

How to walk and jump on water Jumping on land requires the coordinated motion of a number of muscles and joints in order to overcome gravity. Walking on water requires specialized legs that are designed to avoid breaking the surface tension during motion. But how do insects, such as water striders and fishing spiders, manage to jump on water, where extra force is needed to generate lift? Koh et al. studied water striders to determine the structure of the legs needed to make jumping possible, as well as the limits on the range of motion that avoids breaking the surface tension (see the Perspective by Vella). They then built water-jumping robots to verify the key parameters of leg design and motion. Science , this issue p. 517 ; see also p. 472

In this study, the effect of the initial curvature of a tool plate on the snap-through load of square cross-ply bistable composites was analyzed. The snap-through load is a function of the cured curvature and residual moment. In the curing process, both these physical quantities are affected by the initial tool-plate curvature. As a result, the snap-through load can also be changed by adjusting the initial tool-plate curvature. Then, for evaluating its effect on the snap-through load, a snap-through process was simulated by minimizing the total potential energy of the bistable composites through the Rayleigh–Ritz approximation method. The simulation results show that the snap-through load changes linearly with the initial tool-plate curvature. The simulation results are compared with those obtained experimentally and by a finite element analysis (FEA) in order to verify the pre-identified effect of the initial tool-plate curvature.

To improve the multi-functionality of a structure, a foldable or deployable structure with variable stiffness is needed. This article presents dual-stiffness structures with two stiffness states: a stiff state and a flexible state for a multi-mission capability. This dual-stiffness structure is based on a hybrid structure that combines rigid and flexible segments; when the rigid segments are rearranged, the bending motion of the compliant material is constrained by the rigid segments, which varies the stiffness of the structure. Instead of continuously changing the stiffness, the dual-stiffness structure abruptly changes the stiffness state with a simple reconfiguring mechanism. We developed two reconfiguring mechanisms: a sliding mechanism and a folding mechanism. Using a layering process, the dual-stiffness structure with a two-dimensional multi-layer design was manufactured. To verify the behavior of the structure, a simplified structure with no sliding mechanism was designed and simulated using a finite element method. The ratio of the length of a rigid segment to the length of a compliant segment determined the stiffness of the structure. This dual-stiffness structure with the reconfiguring mechanism can be effective for applications that require a big change in stiffness, such as for a deployable solar panel, or flexible display.

Recently, there have been many researches about applications of origami to mechanical engineering, which realizes a 3D sturcture by folding a 2D plane material. With this simple manufacturing process, origami was even adopted by some roboticists as a way to build an entirely new robot with benefits in terms of cost, weight, and structural simplicity. In this paper, we propose a new type of a walking robot based on origami structure. Because all the components of the robot that generate gait motion are mechanically connected, it can actually walk forward with only a single actuator. We also showed the similarity of gait trajectories between a kinematic analysis and the actual gait motion measured by video tracking. This result proved the possibility of designing an origami-based robot with the identical gait trajectory as we plan.

The aim of this study was to evaluate the effectiveness of our technique on further collapse of the femoral head in Association Research Circulation Osseous (ARCO) stage II, patient’s functional improvements, and analyze the survival rate of the affected hip. Between June 2007 and March 2015, 24 hips diagnosed with osteonecrosis of the femoral head (ONFH) were treated with our muscle pedicle bone grafting (MPBG) technique using anterior one-third of gluteus medius attached to the greater trochanter. The group was consisted of 15 men and eight women, mean age of 36 years at the time of surgery. Mean follow-up was 6.2 years. Four hips showed regeneration, 11 hips showed no progression, and nine hips showed slight extent of the lesion. But during the follow-up, three hips underwent total hip arthroplasty at the mean follow-up of 5.8 years after the surgery. The survival rate at the last follow-up was approximately 87.5%. Excluding the three failed cases, the mean total Harris hip score was improved from 57.2 to 82.3 points (p

To evaluate the technical feasibility of direct Eustachian tube catheterisation and subtraction Eustachian tubography in a cadaver model. A total of 12 separate sessions were performed on both sides of the Eustachian tube (ET) in six human cadavers. Cadavers were positioned for the submentovertical view on a fluoroscopy table. Endoscopy-guided ET selection was used in the first three cadavers, whereas fluoroscopy-guided ET selection was used in the remaining three. Eustachian tubography was performed by injecting 2 ml of contrast media through a 5-Fr catheter. We recorded the success of ET selection, number of attempts, procedure time, and tubography quality using native and subtraction images (range, 0–3). Both endoscopy- and fluoroscopy-guided selections were successfully performed in five of six sessions (83.3%). There were no statistically significant differences between the endoscopy- and fluoroscopy-guided procedures in terms of the number of attempts, procedure time, rate of immediate contrast leak to the middle ear cavity, and quality of tubography (p > 0.05). An excellent quality of tubography was obtained in 83.3% (10 of 12 sessions) of subtraction images and in 33.3% (4 of 12 sessions) of native images. The tubography quality score was significantly higher for the subtraction images than for the native images (p = 0.04). Subtraction Eustachian tubography using direct catheterisation seems to be technically feasible. The entire ET can be well visualised; thus, this technique can be used as a simple tool for assessment of ET function and anatomy. • Direct catheterisation of the Eustachian tube is technically feasible. • The entire Eustachian tube could be well visualised by direct Eustachian tubography. • Subtraction Eustachian tubography images have better image quality than native images. • Subtraction Eustachian tubography can provide objective assessment of ET function and anatomy.

A foldable arm is one of the practical applications of folding. It can help mobile robots and unmanned aerial vehicles (UAVs) overcome access issues by allowing them to reach into confined spaces. The origami-inspired design enables a foldable structure to be lightweight, compact, and scalable while maintaining its kinematic behavior. However, the lack of structural stiffness has been a major limitation in the practical use of origami-inspired designs. Resolving this obstacle without losing the inherent advantages of origami is a challenge. We propose a solution by implementing a simple stiffening mechanism that uses an origami principle of perpendicular folding. The simplicity of the stiffening mechanism enables an actuation system to drive shape and stiffness changes with only a single electric motor. Our results show that this design was effective for a foldable arm and allowed a UAV to perform a variety of tasks in a confined space.

Pneumatic artificial muscles (PAMs) are frequently used actuators in soft robotics due to their structural flexibility. They are generally characterized by the tensile force due to the axial contraction and the radial force with volume expansion. To date, most applications of P AMs have utilized axial contractions. In contrast, we propose a novel way to control radial expansions of particular P AMs using anisotropic behaviors. P AMs generally consist of a cylindrical rubber bladder that expands with injection of air and multiple flexible but inextensible strings or mesh that surround the bladder to generate axial contraction force. We propose methods of generating radial expansion force in two ways. One is to control the spatial density of the strings that hold the bladder, and the other is to give asymmetric patterns directly to the bladder for geometrical anisotropy. To evaluate the performance of the actuators, soft sensors made of a hyperelastic material and a liquid conductor were attached to the P AMs for measuring local strains and pressures of the PAMs. We also suggest use of the proposed PAMs to a wearable therapeutic device for treating text neck symptoms as an application. The P AMs were used to exert a pressure to the back of the neck to recover the original spinal alignment from the deformed shape.

Field of soft robotics has been widely researched. Modularization of soft robots is one of the effort to expand the field. In this paper, we introduce a magnet connection for modularized soft units which were introduced in our previous research. The magnet connector was designed with off the shelf magnets. Thanks to the magnet connection, it was simpler and more intuitive than the connection method that we used in previous research. Connecting strength of the magnet connection and bending performance of a soft bending actuator assembled with the units were tested. Connecting strength and air leakage prevention of the connector was affordable in a range of actuating pneumatic pressure. We hope that this magnet connector enables modularized soft units being used as a daily item in the future.

Inspired by the relationship between leg compliance and jumping performance in the false stick insect, this paper describes how variations in leg compliance and jumping direction affect the performance of a flea-inspired jumping mechanism. The amount of energy lost during jumping was determined by examining the ratio of kinetic energy to input energy (also called conversion efficiency). Leg compliance is modeled based on the compliant mechanics to determine energy transfer during jumping and determined the optimum degree of leg compliance for maximizing performance. Jumping experiments are then performed using six different legs with progressively greater degrees of stiffness and three different jumping directions. The experiments show that conversion efficiency decreases by approximately 3-5% as leg stiffness increases, compared to the optimal case. In the most compliant legs (i.e. stiffness of 0.0338 Nm rad-1 or less), conversion efficiency rapidly drops to near 0% because the leg bends so much that it cannot support the thrusting force. The optimal conversion efficiency tends to increase when the mechanism jumps vertically owing to reduced slippage and increased ground reaction force. These investigations show that optimizing leg compliance can improve the performance of a jumping robot by up to 5% by enabling more of the initially stored energy in the leg to be used. This finding will likely prove helpful for choosing the leg stiffness for a small-scale jumping robot.

A CardBot is a crawler with a thin card-sized structure, which has a limit in crawling when turned upside down. A double-sided CardBot presented in this paper is a robot that can crawl even when it is turned upside down because it can crawl on both sides. By adding one more robot body on a single-sided CardBot and sharing a motor to drive both slider cranks, a low height double-sided robot can be made. This 19 mm high, 26.39 g robot can crawl at a speed of 0.25 m/s. Thanks to the low body height, the robot can explore narrow gaps. Experiments were conducted to compare the running performance between the single-sided CardBot and the double-sided CardBot. Compared with a single-sided CardBot, only little degradation of the performance occurs due to implementation of a double-sided driving. The design has been adapted to reduce the friction, but the weakness of the shared joint due to the interaction of both cranks remains an unsolved problem. The structure of the robot will be modified to provide better performance in the future.

We report on the design, optimization, and performance evaluation of a new wheel-leg hybrid robot. This robot utilizes a novel transformable wheel that combines the advantages of both circular and legged wheels. To minimize the complexity of the design, the transformation process of the wheel is passive, which eliminates the need for additional actuators. A new triggering mechanism is also employed to increase the transformation success rate. To maximize the climbing ability in legged-wheel mode, the design parameters for the transformable wheel and robot are tuned based on behavioral analyses. The performance of our new development is evaluated in terms of stability, energy efficiency, and the maximum height of an obstacle that the robot can climb over. With the new transformable wheel, the robot can climb over an obstacle 3.25 times as tall as its wheel radius, without compromising its driving ability at a speed of 2.4 body lengths/s with a specific resistance of 0.7 on a flat surface.

Fish generates thrust with a compliant fin which is known to increase the efficiency. In this paper, the performance of a robotic dolphin, the velocity and the stability, was improved using an optimal compliant caudal fin under certain oscillating frequency. Optimal compliance of the caudal fin exists that maximizes the thrust at a certain oscillating frequency. Four different compliant fins were used to find the optimal compliance of the caudal fin at a certain frequency using the half-pi phase delay condition. The swimming results show that the optimal compliant fin increases the velocity of the robotic fish. The compliance of the caudal fin was also shown to improve the stability of the robotic fish. A reactive motion at the head of the robotic dolphin causes fluctuation of the caudal fin. This phenomenon increases with the oscillating frequency. However, compliant fin reduced this fluctuation and increased the stability.

Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods. Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis. The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0±17.0 (2nd), 87.8±14.4 (3rd) in isokinetic, 80.9±11.0 (2nd), 81.6±12.4 (3rd) in isotonic contraction, F [1,8]=11.168; P =0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy.

This paper presents the complete development and analysis of a soft robotic platform that exhibits peristaltic locomotion. The design principle is based on the antagonistic arrangement of circular and longitudinal muscle groups of Oligochaetes. Sequential antagonistic motion is achieved in a flexible braided mesh-tube structure using a nickel titanium (NiTi) coil actuators wrapped in a spiral pattern around the circumference. An enhanced theoretical model of the NiTi coil spring describes the combination of martensite deformation and spring elasticity as a function of geometry. A numerical model of the mesh structures reveals how peristaltic actuation induces robust locomotion and details the deformation by the contraction of circumferential NiTi actuators. Several peristaltic locomotion modes are modeled, tested, and compared on the basis of speed. Utilizing additional NiTi coils placed longitudinally, steering capabilities are incorporated. Proprioceptive potentiometers sense segment contraction, which enables the development of closed-loop controllers. Several appropriate control algorithms are designed and experimentally compared based on locomotion speed and energy consumption. The entire mechanical structure is made of flexible mesh materials and can withstand significant external impact during operation. This approach allows a completely soft robotic platform by employing a flexible control unit and energy sources.

In this paper, the control algorithms for strength exercise using wearable robotic hand are reviewed and the experimental results are analyzed and discussed. The SNU Exo-Glove is a soft exoskeleton that actuates motor function in disabled hands. This new type of device comprises a jointless simple mechanical structure and is actuated with wires. The strength exercise algorithms include isotonic, isokinetic, and impedance control exercises. An electromyography (EMG) regulation algorithm is proposed to limit the maximum level of activation of the muscles to prevent injury of the muscles and joints. The tension of the wire and the sEMG signal are analyzed to validate the effectiveness of rehabilitation with SNU Exo-Glove.

Soft robotics, a concept contrary to conventional “hard” robotics, is a robot design methodology that uses soft materials inspired by nature. In contrast to a hard robot, a soft robot is composed of soft and flexible materials that blur the distinction between an actuator and a structure, which leads to unique characteristics that cannot be found in a conventional hard robot. This paper presents our approach to the issues that arise when the concept of soft robotics is applied to a wheeled robot. The compliance of the wheel diversifies its potential movement and allows for a high degree of adaptability to the environment. Although the wheel radius of the robot is 50 mm, it can pass through a 30 mm gap and climb a 45 mm step. While soft robotics displays properties whose performance can be challenging to implement, it also enables us to create complex forms of movement in a cheaper and simpler way. We expect that this kind of approach can provide a new design method for a deformable wheel.

This paper proposes three design concepts for developing a crawling robot inspired by an inchworm, called the Omegabot. First, for locomotion, the robot strides by bending its body into an omega shape; anisotropic friction pads enable the robot to move forward using this simple motion. Second, the robot body is made of a single part but has two four-bar mechanisms and one spherical six-bar mechanism; the mechanisms are 2-D patterned into a single piece of composite and folded to become a robot body that weighs less than 1 g and that can crawl and steer. This design does not require the assembly of various mechanisms of the body structure, thereby simplifying the fabrication process. Third, a new concept for using a shape-memory alloy (SMA) coil-spring actuator is proposed; the coil spring is designed to have a large spring index and to work over a large pitch-angle range. This large-index-and-pitch SMA spring actuator cools faster and requires less energy, without compromising the amount of force and displacement that it can produce. Therefore, the frequency and the efficiency of the actuator are improved. A prototype was used to demonstrate that the inchworm-inspired, novel, small-scale, lightweight robot manufactured on a single piece of composite can crawl and steer.

As one of the most important force production mechanisms of swimming and flying animals, the fluid dynamics of flapping has been intensively studied. However, these efforts have been mainly directed toward animals in forward motion or locomotive appendages undergoing linear translation. Here we seek to complement the existing knowledge of the flapping mechanism by studying angularly reciprocating flat plates without a free stream velocity, under a so-called ‘bollard pull’ condition. We visualize the flow field around the flat plate to find that two independent vortical structures are formed per half-cycle, resulting in the separation of two distinct vortex pairs at sharp edges rather than a single vortex loop which is typical of a starting–stopping vortex paradigm in flows with free streams. Based on our observations, we derive a scaling law to predict the thrust of the flapping plate; this is the first experimentally validated theoretical model for the thrust of angularly reciprocating plates without a prescribed background flow.

In order to operate a search and rescue robot in hazardous area, the robot requires high mobility and adaptable locomotion for moving in unpredictable environments. In this paper, we propose the deformable soft wheel robot that can produce three kinds of driving modes; caterpillar driving mode, normal wheel driving mode, legged-wheel driving mode. The robot changes its driving mode as it faces the various obstacles such as a small gap, stairs etc. Soft film and composite materials are used for fabrication of deformable wheel structure and Shape Memory Alloy (SMA) coil spring actuators are attached on the structure as an artificial muscle. Film lamination and an composite manufacturing process is introduced and the robot design is required to be modified and compromised to applying the manufacturing process. The prototype is developed and tested for verifying feasibility of the deformable wheel locomotion.

Legged locomotion has been widely researched due to its effectiveness in overcoming uneven terrains. Due to previous efforts there has been much progress in achieving dynamic gait stability and as the next step, mimicking the high speed and efficiency observed in animals has become a research interest. The main barrier in developing such a robotic platform is the limitation in the power efficiency of the actuator: the use of pneumatic actuators produce sufficient power but are heavy and big; electronic motors can be compact but are disadvantageous in producing sudden impact from stall which is required for high speed legged locomotion. As a new attempt in this paper we suggest a new leg design for a mobile robot which uses the slider-crank mechanism to convert the continuous motor rotation into piston motion which is used to impact the ground. We believe this new mechanism will have advantage over conventional leg mechanism designs using electronic motors since it uses the continuous motion of the motor instead of sudden rotation movements from stall state which is not ideal to draw out maximum working condition from an electronic motor. In order to control impact timing from the periodic motion of the piston a mechanical passive clutch trigger mechanism was developed. Dynamic analysis was performed to determine the optimal position for the mechanical switch position of the clutch trigger mechanism, and the results were verified through simulation and experiment. Development of a legged locomotion with two degrees of freedom, slider-crank mechanism for impact and additional actuation for swing motion, is proposed for future work.

`Multi-scale mass-deployable cooperative robots` is a next generation robotics paradigm where a large number of robots that vary in size cooperate in a hierarchical fashion to collect information in various environments. While this paradigm can exhibit the effective solution for exploration of the wide area consisting of various types of terrain, its technical maturity is still in its infant state and many technical hurdles should be resolved to realize this paradigm. In this paper, we propose to develop new design and manufacturing methodologies for the multi-scale mass-deployable cooperative robots. In doing so, we present various fundamental technologies in four different research fields. (1) Adaptable design methods consist of compliant mechanisms and hierarchical structures which provide robots with a unified way to overcome various and irregular terrains. (2) Soft composite materials realize the compliancy in these structures. (3) Multi-scale integrative manufacturing techniques are convergence of traditional methods for producing various sized robots assembled by such materials. Finally, (4) the control and communication techniques for the massive swarm robot systems enable multiple functionally simple robots to accomplish the complex job by effective job distribution.

Small mobile robots which use round wheels are suitable for driving on a flat surface, but it cannot climb the obstacle whose height is greater than the radius of wheels. As an alternative, legged-wheels have been proposed by many researchers due to its better climbing performance. However, driving and climbing performances have a trade-off relationship so that their driving performance should be sacrificed. In this study, in order to achieve both driving and climbing performances, a new transformable wheel was developed. The developed transformable wheel can have a round shape on a flat surface and change its shape into legged-wheel when it makes a contact with an obstacle. For design of the transformable wheel, the performance of legged-wheel was analyzed with respect to the number and curvature of the leg, and then the new transformable wheel was designed based on the analysis. Contrary to the existing transformable wheels that contain additional actuators for the transformation, the developed transformable wheel can be unfolded without any additional actuator. In this study, in order to validate the transformable wheel, a simple robot platform was fabricated. Consequently, it climbed the obstacle whose height is 2.6 times greater than the wheel radius.

This paper introduces SNUMAX, the grand winner of the RoboSoft Grand Challenge. SNUMAX was built to complete all the tasks of the challenge. Completing these tasks required robotic compliant components that could adapt to variable situations and environments and generate enough stiffness to maintain performance. SNUMAX has three key components: transformable origami wheels, a polymer-based variable stiffness manipulator, and an adaptive caging gripper. This paper describes the design of these components, and how they worked together to allow the robot to perform the contest’s navigation and manipulation tasks.

Exo-Glove is a soft wearable robotic hand to assist hand function of people who have paralysis of the hands. Exo-Glove is compactly structured with soft fabrics and adapts an under-actuation concept. Pinch performance is defined, and the variation of the pinching performance with Exo-Glove with respect to the tendon route design is shown through an experiment. A subject with spinal cord injury participated in the experiment. As shown by the experimental result, Exo-Glove provides adequate pinching performance, and the tendon routing of Exo-Glove severely affects its pinching performance.

This paper presents the design improvement of a polymer-based tendon-driven wearable robotic hand, Exo-Glove Poly. The wearability and adaptiveness are the key points to design the Exo-Glove Poly in considering the cases of practical use. Thus, magnets are embedded into the wearable part for easy donning and doffing. Also, the tendon length adjustment mechanism is designed to adapt different hand sizes by changing length of the tendons. Through these improvements, it is increased the change to practical use of the Exo-Glove Poly.

In this paper, we propose a self-deployable origami structure and its application to a gliding wing module for jump-gliding. Generally, origami structures are composed of flat rigid facets. By using curved compliant facets instead of flat rigid facets, we endowed the origami structure with the ability to self-deploy and self-lock. When the origami structure is folded, the curved facets gradually flatten, and potential energy is stored on the flattened facets. By using the stored energy, the structure can rapidly deploy without an actuator. The geometry of the curved facet generates a notably high joint stiffness in the deployed state, which can be used as a self-locking mechanism. In jump-gliding, the gliding wing should be foldable and lightweight for efficient jumping and capable of rapid deployment for efficient gliding. By applying the suggested origami structure as a basic frame, the deployable gliding wing module can satisfy these requirements. The wing span of the module is 44.7 cm, and it weighs 20.3 g including a battery and a servo motor. The module can be folded in 1/8.1 of the deployed area, and it deploys within 350 ms when it needs to glide.

In this paper, the force characteristics of the rolling contact joint are studied. Design parameters affecting performance of the rolling contact joint are considered, and the effects of tension and compression are shown by analysis. The rolling contact joint is compared to the pin joint by modeling, and it is shown that the force capability of the rolling contact joint is higher than that of the pin joint at a small scale. Finally, to explore the feasibility of using the rolling contact joint in prosthetics, a prototype hand prosthetic is developed using rolling contact joints.

This paper presents the development of a polymer-based tendon-driven wearable robotic hand, Exo-Glove Poly. Unlike the previously developed Exo-Glove, a fabric-based tendon-driven wearable robotic hand, Exo-Glove Poly was developed using silicone to allow for sanitization between users in multiple-user environments such as hospitals. Exo-Glove Poly was developed to use two motors, one for the thumb and the other for the index/middle finger, and an under-actuation mechanism to grasp various objects. In order to realize Exo-Glove Poly, design features and fabrication processes were developed to permit adjustment to different hand sizes, to protect users from injury, to enable ventilation, and to embed Teflon tubes for the wire paths. The mechanical properties of Exo-Glove Poly were verified with a healthy subject through a wrap grasp experiment using a mat-type pressure sensor and an under-actuation performance experiment with a specialized test set-up. Finally, performance of the Exo-Glove Poly for grasping various shapes of object was verified, including objects needing under-actuation.

In this paper, we propose a trajectory-adjustable integrated milli-scale jumping-crawling robot with improved ability to overcome obstacles compared to a robot that can only crawl. The robot employs a novel jumping module with enhanced energy storing-capacity and a height-adjustable active trigger. To increase the energy-storing capacity, latex rubber and knee-like joints are employed to utilize large displacement of the elastic material. The active trigger is based on a single DC motor and can release stored energy at any state, enabling the robot to control the take-off speed of jumping. The jumping module is integrated with the lightweight Dash crawler. The integrated jumping-crawling robot weighs 59.4 g and controls its moving trajectory by adjusting both its crawling speed and its jumping take-off speed.