Liquid phase change pouch actuators (liquid pouch motors) hold great promise for a wide range of robotic applications, from artificial organs to pneumatic manipulators for dexterous manipulation. However, the usability of liquid pouch motors remains challenging due to the nonlinear intrinsic properties of liquids and their highly dynamic implications for liquid-gas phase changes, which complicate state modeling and estimation. To address these issues, we propose a reservoir computing-based method for modeling the inflation states of a customized liquid pouch motor, which serves as an actuator, featuring four Peltier heating junctions. We use a motion capture system to track the landmark movements on the pouch as a proxy for its volumetric profile. These movements represent the internal liquid-gas phase changes of the pouch at stable room temperature, atmospheric pressure, and in the presence of electrical noise. The motion coordinates are thus learned by our reservoir computing framework, PhysRes, to model the states based on prior observations. Through training, our model achieves excellent results on the test set, with a normalized root mean squared error of 0.0041 in estimating the states and a corresponding volumetric error of 0.0160%. To further demonstrate how such actuators could be implemented in the future, we also design a dual-pouch actuator-based robotic gripper to control the grasping of soft objects. Our design and source code are available at: https://github.com/tatung/liquidpouch_reservoir.

In this paper, we propose an occlusion-resilient Ultra-Wideband (UWB) localization system by rethinking anchor placement. Typically, anchors are installed near the ceiling for broader line-of-sight (LOS) coverage. However, in crowded environments, practical ceiling heights often fail to maintain stable LOS. By placing anchors near the floor and leveraging ceiling reflections, we create a virtual anchor that extends LOS coverage. Experiments show our approach outperforms ceiling-mounted solutions in accuracy and resilience, opening new possibilities for practical UWB localization.

Figure 1: Overview of picoRing mouse, enabling 30-500 uW-class ultra-low-power wireless ring mouse for ubiquitous finger input.The ring can potentially operate over a month on a single charge of a 27 mAh battery (https://youtu.be/7RazVNMx0Ms).

High-accuracy indoor positioning systems provide various location-aware applications, enhancing our daily experiences. The Global Navigation Satellite System is difficult to use indoors, leading to the development of various indoor positioning methods. Among these, acoustic fingerprint-based positioning, which utilizes widely available speakers and microphones, provides robust performance in Non-Line-of-Sight (NLOS) environments that are common due to structural obstacles and furniture. These approaches typically use Received Signal Strength Indicator or Power Spectral Density as location fingerprints but face challenges in achieving high positioning accuracy. In this paper, we propose Geometric Sound Profile (GSP), a temporal feature of complex reflection waves, enabling high-accuracy localization with a single speaker. GSP, defined as the envelope of cross-correlation between the transmitted and received signals, starting from the transmission time, serves as a highly informative feature encapsulating the multipath-Time-of-Flight. Additionally, we implement a Convolutional Neural Network for the estimation of the user’s position using GSP. We generated a high-resolution pre-trained model in the simulation and fine-tuned it with measurement data, allowing accurate positioning with minimal measured training data. Our experiments demonstrated that the median positioning error was 0.14 m and the 90th percentile error was 1.23 m in the Line-of-Sight environment, and the median positioning error was 0.09 m and the 90th percentile error was 1.14 m in the NLOS environment.

We present a visible light positioning (VLP) method that allows indoor positioning using a smartphone camera with a narrow field of view (FoV). Our method employs omni-directional LEDs, each modulated at a unique frequency, mounted on the ceiling. The system calculates the 2-D position and azimuth of the smartphone by analyzing the brightness of ceiling reflection captured by the user’s smartphone front camera. This approach does not necessitate a direct line-of-sight to the LEDs, effectively overcomes the FoV limitations, and enables positioning over a wider space. We model the ceiling reflection as a transmission path between the LEDs and the ceiling, improving coverage and accuracy of estimation for the user’s position and azimuth compared to previous work. In experiments with two LEDs placed 2.6 m apart, our method covered a space over ten times larger than traditional methods, achieving coverage of $50 \mathbf{m}^{2}$ with a mean absolute error (MAE) in the positioning of 0.46 m and an MAE in azimuth estimation of 13.0°.

Low-cost and accurate indoor location information can add spatiotemporal context to information systems, enabling new location-aware applications. Time-of-Flight (ToF)-based acoustic localization using speakers and microphones allows for localization accuracy within a few tens of centimeters, outperforming RF-based techniques. However, ToF-based localization requires synchronization between the speaker and microphone, i.e., the time offset between them must be known. Previous time offset estimation methods required custom hardware for speakers, limiting their practical use. Estimating the time offset using a single, unmodified speaker is essential for leveraging widely deployed speakers and enhancing coverage. This paper presents the first method for time offset estimation using a single speaker and a microphone, enabled by two key factors: (i) a time offset computation method that utilizes higher-order floor-ceiling reflections as multiple geometrically-constrained virtual speakers, and (ii) a signal processing pipeline that isolates these critical reflections from numerous others by leveraging the speaker's frequency-dependent radiation pattern. Experiments show that the proposed technique can achieve time offset estimation with a 90th percentile error of 259 μs at a 5 m distance. Furthermore, we implemented a ToF localization system based on SyncEcho, demonstrating a 11.0 cm localization accuracy with a 90th percentile error.

Single-sided deafness (SSD) significantly restricts social participation in hearing/speaking cultures due to the person’s difficulty hearing conversations on their deaf side. Although hearing aids for SSD are effective in social situations, the acceptance rate remains low at 4%. To address this problem, we designed and developed a bone conduction-based device to be worn with eyeglasses, involving 53 individuals with SSD including two authors. We conducted a four-week diary study comparing our proposed device with traditional Contralateral Routing of Signals (CROS) hearing aids and explored the factors that might affect the acceptance rate of assistive devices for SSD. The findings indicated that our design was more acceptable for users with SSD due to its effectiveness, social acceptability, and the ability for wearers to use other devices simultaneously, such as earbuds. Based on our results, we discuss implications for designing wearable assistive devices to promote greater acceptance among the target population.

This paper investigates a novel millimeter wave (mmWave) radar-based inclination estimation to enhance the landing capabilities of unmanned aerial vehicles (UAVs) in poor visibility conditions. Unlike SAR based approaches, this method facilitates one-shot estimation by using known reflector patterns on landing surfaces. As a first step, we evaluate the performance of the estimation with obtained distance information, assuming that the coordinates of the UAV and port are known. The experimental results demonstrate that mmWave radar with centimeter-ordered resolution can estimate the inclination of less than 5° errors.

Prediction of the Received Signal Strength Indicator (RSSI) distribution is a very important task. However, most of the current research is on methods that complement the RSSI distribution for beacons that actually collect data. The most common method for fully online simulation without beacons is based on physical Ray-Tracing. However, the Ray-Tracing model requires the determination of the attenuation rate of the wall. This makes it difficult for ordinary people to perform the simulation. Also, without measuring the actual RSSI, it is impossible to know whether the simulation results are appropriate for the actual environment or not. To address these issues, we propose a data-driven RSSI simulation method. RSSI can be collected by various devices, and it is easy for the general public to obtain RSSI for each location. The simulation is based on the actual RSSI data, so that the simulation can be performed in a realistic environment. In this paper, we have realized a data-driven simulation that matches the environment by learning the attenuation of RSSI derived from the environment and actual data using Generative Adversarial Network(GAN). In order to conduct experiments in a real environment, the simulation model is trained in an office environment, and its accuracy is evaluated using actual RSSI values. As a result, the average absolute error of RSSI values was improved by 8% and the average positioning error of indoor localization was improved by 19% compared with the simulation using the radio propagation formula.

Soft robots made of flexible materials are highly adaptive, easy to fabricate, and safer to interact with. One of the ways for soft robots to interact with the surrounding environment is through their deformable bodily characteristics including internal body stiffness and external body friction. Though the flexibility of soft-bodied robots has been rigorously studied, the frictional skin of such soft-bodied robots, acting as a mechanical interface between the robot and the environment, remains unexplored. Being able to design the frictional skin will make soft-bodied robots more versatile in environmental navigation, more dexterous in manipulation tasks, and more flexible in haptic feedback. In this paper, we propose a robotic skin that can be programmed dynamically to change the mode of friction. The robotic skin is based on bistable bellow structures that can be switched between two folding states to change the contact points between the robotic skin and the ground. Our robotic skin can dynamically change its anisotropic frictional behavior to add another dimension to the designing space of soft robotics.

This paper presents MilliSign, a guidance system based on a batteryless tag to support unmanned aerial vehicles in all-weather conditions. Conventional batteryless guidance systems using visual signs fail to work in inclement weather due to poor visibility. The need for all-weather operation with long-range readability encourages the use of millimeter wave (mmWave) radar, which poses challenges in providing a wide 3-D read range and low-cost operation. To address these challenges, we introduce a corner reflector (CR) array-based chipless RFID tag and a one-shot slant range reading procedure with COTS mmWave radar. We establish a novel design method for the shape and alignment of CR units to decrease the tag's size and expand the 3-D read range. Additionally, we develop a signal-processing pipeline based on Root-MUSIC to achieve accurate power and spatial estimation, which facilitate automatic tag detection. Our evaluation demonstrates that the tag, measuring 292 mm × 600 mm × 19 mm and storing 8 bits, can be read by mmWave radar from a distance of more than 10 m with a viewing angle of more than 30° in elevation and azimuth. Moreover, its performance remains stable in poor visibility conditions and multipath-rich environments.

Robust indoor positioning systems provide stable location-aware applications, enhancing our daily experiences. Fingerprint-based positioning techniques enable estimation of a user's position in complex indoor environments. While previous studies have used the received signal strength indicator or power spectral density as fingerprints, they typically achieved only submeter accuracy. This paper presents Geometric Sound Profile (GSP) as a novel location fingerprint to elevate the performance ceiling of fingerprint-based positioning. GSP is derived from the cross-correlation of transmitted and received signals based on transmission time, and a user's position is computed using weighted k-nearest neighbors. Our experiments demonstrate a median error of 0.66 m, marking a significant advancement over previous fingerprinting techniques.

We propose Inkjet 4D Print, a self-folding fabrication method of 3D origami tessellations by printing 2D patterns on both sides of a heat-shrinkable base sheet, using a commercialized inkjet ultraviolet (UV) printer. Compared to the previous folding-based 4D printing approach using fused deposition modeling (FDM) 3D printers [An et al. 2018], our method has merits in (1) more than 1200 times higher resolution in terms of the number of self-foldable facets, (2) 2.8 times faster printing speed, and (3) optional full-color decoration. This paper describes the material selection, the folding mechanism, the heating condition, and the printing patterns to self-fold both known and freeform tessellations. We also evaluated the self-folding resolution, the printing and transformation speed, and the shape accuracy of our method. Finally, we demonstrated applications enabled by our self-foldable tessellated objects.

Wearable devices for life-logging and healthcare have been studied, but the need for frequent charging imposes inconvenience for long-term use. Integrating textile-based wireless chargers (i.e., coil) into clothing enables sustainable wearable computing by charging the on-body devices in use. However, the electromagnetic field generated by conventional coil chargers strongly interferes with human body, and the high resistance of conductive threads leads to inefficient power delivery. This paper presents Meander Coil++, enabling safe, energy-efficient, and body-scale wireless power delivery. Meander Coil++ uses a wiring pattern that suppresses electromagnetic exposure to the human body without compromising power delivery performance and a liquid-metal-based low-loss conductive cord. With these advancements, Meander Coil++ transmits a few watts of power to on-body devices at 25% DC-to-DC efficiency while complying with international safety guidelines regarding electromagnetic exposure. We envision Meander Coil++ can maintain multiple devices on body for weeks beyond the confines of their small battery capacity.

Origami/kirigami robotics are opening a path that leads to lightweight, compact, and expandable robots. However, it is generally challenging to design agile motions for origami/kirigami robots due to their size and the intrinsic limitation of the materials. In this paper, we propose to use the bistability of the waterbomb base structure to generate the swift motion of the robots. We evaluate the bistability of the waterbomb-based structure and build origami jumpers with different configurations of the body to help analyze the behavior of the waterbomb base bistable structure. The jumper is actuated by a phase change liquid pouch actuator. Our jumper is lightweight (0.3 g), flattenable, and able to jump to more than 12 times of its diameter and 112 times of its height.

Users and operators of shared spaces must ensure safety in such areas to prevent the spread of COVID-19. Although each organization has operated a variety of safety-related systems, including contact tracing, congestion monitoring, and check-in services, it is unclear what elements, such as privacy protection level, benefits, and permission procedures, have promoted the usage of these systems. In this study, we created MOCHA, a platform for sharing and tracking room-level locations. This platform automatically detects visited places by scanning Bluetooth beacons in each room using smartphones and shares location data according to predefined user settings. The collected data is used for room-level contact tracing, congestion monitoring, and reservation services. According to >6,500 users' usage data for a year in a university, outlining the advantages of utilizing the app encouraged people to install the app, and reinforced connections in small private groups are encouraged to use the app continuously.

When customers wait their turn to place an order at a street vendor, they often form a spontaneous queue. Due to the presence of passers-by and people standing outside the queue, it is more difficult than one might think to distinguish between those in the queue and those not in the queue. In this paper, we consider a method that uses acoustic ranging to autonomously detect who is in line and in which order, under the condition that all customers have smartphones. The proposed method is unique in that it can distinguish whether a newly arrived user has joined the end of the queue or not by taking cues from the geometric properties of the queue. Our preparatory queueing simulations confirm that 92.5% of the queuers are estimated correctly.

Indoor localization technology is one of the most important topics in the fields of Internet of Things (IoT) and ubiquitous computing, and it has attracted much attention in recent years due to its ability to enable a variety of services. Localization methods using Bluetooth or Wi-Fi signal strength can introduce a low-cost location estimation system. However, due to the instability of the received signal strength and signals leaking from adjacent rooms, a simple method based on signal strength alone frequently results in misjudgment, depending on the signal propagation characteristics. In this paper, we propose a method to suppress misjudgment by considering the characteristics of stay time in different rooms. Our proposed method estimates the user state by fitting the distribution of time spent in each room to a Weibull distribution and applying survival analysis. The experimental results suggest that the method will provide more accurate information about the rooms in which users stay.

The advancement of semiconductor and battery technologies popularized tiny acoustic wearable devices such as bone conduction wireless headsets. However, this small form factor poses inconvenience when controlling these devices, as they cannot equip large footprint intuitive interfaces such as volume sliders and touch screens. This paper presents a technique using acoustic responses measured by a bone conduction speaker and a microphone to utilize the ear as a touch input interface. We discovered that a finger placed on different parts of the ear affects the acoustic radiation characteristic of the ear, modulating the leaked sound, and by leveraging this effect, the touch position can be estimated. Experimental results show that five distinct frequency responses with five different finger positions can be obtained, which indicates that our method could allow bone conduction headsets to capture continuous finger positions without additional hardware.

Field-aligned parametrization is a method that maps a scalar function onto a surface, such that the gradient vector of the scalar function matches the input vector field. Using this idea, one can produce a stripe pattern that is convenient for various purposes such as remeshing, texture synthesis, and computational fabrication. In the final outcome, the positions of singularities (i.e., bifurcations of the stripe pattern) are essential for functionalities, manufacturability, or aesthetics. In this paper, we propose an algorithm to allow users to interactively edit the singularity positions of field-aligned stripe patterns. The algorithm computes a stripe pattern from a prescribed set of singularities, without generating any unwanted singularities. The solution of the algorithm is formulated as the global minima of a constrained quadratic optimization, whose computation speed is dominated by solving only two sparse linear systems. Furthermore, once the two matrices in the two linear systems are factorized, any update on singularity positions operates in linear time. We showcase several applications feasible with our fast yet simple algorithm.

Due to its natural warmth, wood is frequently used to produce touchable objects such as furniture and signboards. Laser cutting machines are becoming common in personal wood processing to cut and engrave wood. In this paper, we propose a method and workflow for producing various sensors and electrical circuits for interactive devices by partially carbonizing the wood surface with a laser cutting machine. Similar to wiring on a conventional printed circuit board (PCB), the carbonized part functions as a conductive electrical path. A method for creating electronic circuits and sensors made of carbon graphene on botanical materials has been proposed. This technique makes use of a raster-scanning femtosecond (fs) laser, which is less common for personal fabrication than a constant-wave (CW) laser. Moreover, raster-scanning requires a substantial amount of time to create a circuit that is mainly made of conductive lines. This paper extends the method with a defocused vector-scanning CW laser beam and reduces the time and cost required for fabrication. The proposed method uses an affordable CW laser cutter to fabricate an electrical circuit, including touch sensors, damage sensors, and load sensors on wood boards. The circuit can be easily connected to traditional PCBs and electric parts such as one-board microcomputers using metal screws and nails typically used in DIY woodworking. We develop ease of use software design tool that supports the creation and fabrication of carbon paths. In addition, we report on a series of investigations, including optimizing wood materials and laser parameters to establish design guidelines.

In this pictorial, we propose an approach to integrate electronics into a paper-woven craft. A paper-woven structure is formed by alternately and orthogonally weaving paper strips. The key idea is to add conductive layers to these strips by printing or transferring conductive materials. Our approach enables us to form the skeleton of an object and its wiring and sensor arrangement simultaneously. We explore the creative space of this approach, i.e., integrating functions such as sensing, display, and sound amplification into objects, for leveraging the paper-woven structure. We also outline the workflow of the approach, introduce a design support tool, and discuss example applications that combine the electronic-enabled functionality and woven structure.

This pictorial presents Circuit Assemblies, a design system for beginners to create 3D-printed interactive objects with embedded electronics. Circuit Assemblies are modules used to create objects that light up, move, or spin using basic electronic components like LEDs, batteries, and motors. To support beginners incorporating Circuit Assemblies into 3D designs, a set of virtual components were added to Tinkercad, a popular browser-based 3D CAD application with over 10 million users. In this paper, we begin with a set of design considerations gathered from interviews with three K-12 educators that teach electronics. We then present four different Circuit Assembly modules designed with these considerations in mind, highlighting the unique challenges that arise from combining electronics and 3D design for beginners, both in CAD software and physical assembly. We then present four different Circuit Assembly modules designed with these considerations in mind, highlighting the unique challenges that arise from combining electronics and 3D design for beginners, both in CAD software and physical assembly.

This paper presents PlushPal, a web-based design tool for children to make plush toys interactive with machine learning (ML). With PlushPal, children attach micro:bit hardware to stuffed animals, design custom gestures for their toy, and build gesture-recognition ML models to trigger their own sounds. We describe how, in the context of storytelling, PlushPal introduces core concepts in ML including data sampling and model evaluation. We conducted online workshops and in-person play sessions with 11 children between 8-14 years old building interactive stuffed animals with PlushPal. In these play sessions, we observed how children imagined bringing their toys to life using ML, as well as how children’s data literacy changed as a result of experimenting with sensors, data sampling, and building their own ML models. Our work contributes a novel design space for children to express their ideas using gesture, as well as a description of observed debugging practices, building on efforts to support children using ML to enhance creative play.

We present LightTouch, a 3D-printed passive gadget to enhance touch interactions on unmodified capacitive touchscreens. The LightTouch gadgets simulate finger operations such as tapping, swiping, and multi-touch gestures by means of conductive materials and light-dependent resistors (LDR) embedded in the object. The touchscreen emits visible light and the LDR senses the level of this light, which changes its resistance value. By controlling the screen brightness, it intentionally connects or disconnects the path between the GND and the touchscreen, thus allowing the touch inputs to be controlled. In contrast to conventional physical extensions for touchscreens, our technique requires neither continuous finger contact on the conductive part nor the use of batteries. As such, it opens up new possibilities for touchscreen interactions beyond the simple automation of touch inputs, such as establishing a communication channel between devices, enhancing the trackability of tangibles, and inter-application operations.

Flower jellies, a delicate dessert in which a flower-shaped jelly floats inside another clear jelly, fascinate people with both their beauty and elaborate construction. In efforts to simplify the challenging fabrication and enrich the design space of this dessert, we present Flower Jelly Printer: a printing device and design software for digitally fabricating flower jellies. Our design software lets users play with parameters and preview the resulting forms until achieving their desired shapes. We also developed slit injection printing that directly injects colored jelly into a base jelly, and shared several design examples to show the breadth of design possibilities. Finally, the user study with novice and experienced users demonstrates that our system benefits creators of all experience levels by iterative design and precise fabrication. We hope to enable more people to design and create their own flower jellies while expanding access and the design space for digitally fabricated foods.

With the pandemic of COVID-19, indoor crowd density monitoring has become one of the most critical responsibilities of public space managers. Beacon placement optimization has been tackled as fundamental research work as the performance of crowd density monitoring highly depends on how BLE beacons are allocated. In this research, we propose a novel beacon placement optimization approach to incrementally place the beacon on the updated detection status adaptively in favor of Bayesian optimization, which can help to provide the optimal beacon placement. Our proposed method can optimize the beacon placement effectively to improve the signal coverage quality in the given environment and minimize human workload.

We propose a method for controlling a device that draws letters and illustrations on large, flat surfaces. Similarly to conventional inkjet printers, the device ejects a volume of water from its nozzle, with the water droplets then forming dots on surfaces such as soil, concrete, and sand. Both the direction of the nozzle and the water pressure can be controlled to enable the device to draw arbitrary two-dimensional patterns within a semicircular region with a radius of six meters. The device can draw letters and illustrations. We have investigated the pressure, the shape of the nozzle, and droplet size in order to avoid further division of the droplets into even smaller droplets while traversing the air. In this paper, we introduce the mechanism of this device and demonstrate how a user can take advantage of this new drawing tool.

Kirigami Haptic Swatches demonstrate how kirigami and origami based structures enable sophisticated haptic feedback through simple cut-and-fold fabrication techniques. We leverage four types of geometric patterns: rotational erection system (RES), split-fold waterbomb (SFWB), the overlaid structure of SFWB and RES (SFWB+RES), and cylindrical origami, to render different sets of haptic feedback (i.e. linear, bistable, bouncing snap-through, and rotational force behaviors, respectively). In each structure, not only the form factor but also the force feedback properties can be tuned through geometric parameters. We experimentally analyzed and modeled the structures, and implemented software to automatically generate 2D patterns for desired haptic properties. We also demonstrate five example applications including an assistive custom keyboard, rotational switch, multi-sensory toy, task checklist, and phone accessories. We believe the Kirigami Haptic Swatches helps tinkerers, designers, and even researchers to create interactions that enrich our haptic experience.

Personal identification numbers (PINs) and grid patterns have been used for user authentication, such as for unlocking smartphones. However, they carry the risk that attackers will learn the PINs and patterns by shoulder surfing. We propose a secure authentication method called SheetKey that requires complicated and quick touch inputs that can only be accomplished with a sheet that has a pattern printed with conductive ink. Using SheetKey, users can input a complicated combination of touch events within 0.3 s by just swiping the pad of their finger on the sheet. We investigated the requirements for producing SheetKeys, e.g., the optimal disc diameter for generating touch events. In a user study, 13 participants passed through authentication by using SheetKeys at success rates of 78-87%, while attackers using manual inputs had success rates of 0-27%. We also discuss the degree of complexity based on entropy and further improvements, e.g., entering passwords on alphabetical keyboards.

Although picking up objects a few centimeters in size is a common task, achieving such ability in a robot manipulator remains challenging. We take a step toward solving this problem by focusing on the task of picking a 1.0-cm screw from a bulk bin using only tactile information to achieve the task. Inspired by how humans pick up small objects from a bin, we propose a "grasp-separate" strategy for robotic picking, which involves grasping many objects first and then separating a single object through manipulation in the fingers, for robotic picking. Based on this strategy, we developed a tactile-based screw bin-picking system. We trained a convolution neural network to estimate the number of screws in the fingers first and built a controller that generates manipulation behaviors to separate a screw using reinforcement learning. To compensate for the low resolution of off-the-shelf tactile sensor arrays, we adopted active sensing, which uses observations obtained during a predefined simple movement. We show that this approach enhances the estimation accuracy and manipulation performance. Furthermore, to enable flexible finger motion, such as between the thumb and the index finger in a human hand, we propose a soft robot finger structure that leverages compliant materials. A soft actor-critic algorithm successfully found dexterous screw separation behaviors in compliant soft robotic fingers. In the evaluation, the system obtained an average success rate of 80%, which was difficult to achieve without the grasp-separate manipulation technique.

We present the first demonstration of a battery-free untethered wirelessly powered sub-gram jumping robot on an insect-scale. In order to operate the insect-sized robot autonomously, the limitation in battery use emphasizes the need for a wireless power transmission system as an onboard power solution. We designed a wireless power transmission system based on inductive coupling to power the Shape Memory Alloy (SMA), which serves as an elastic energy storage element and actuator for the jumping robot. The assembled mechanical structures, onboard power and electronics yield a 2 mm (high) × 24 mm (long) × 12 mm (wide) robot with ~a weight of 216 mg. The experiments show that our jumping robot wirelessly lift-off up to 5.75 times its body length and repeats the jump around 7 times per minute. To date, out of the several untethered sub-gram insect-scale jumping robots with onboard power, this is the first wirelessly powered robot with the highest jumping performance. The novelty in this work, which addresses the engineering challenges in insect-scale jumping robots, is an untethered wirelessly powered design that achieves dynamic jumping maneuvers, and has self-righting ability.

The exploration of spatially limited terrestrial or aquatic environments requires miniature and lightweight robots. Soft-bodied robot research is paving ways for a new class of small-scale robots that can navigate a variety of environments with minimum influence on the environment itself. However, it is generally challenging to design miniature soft-bodied robots that efficiently adapt to the change between viscous environments. A small-scale soft-bodied robot, which could slowly move on dry land, will need rapid motions to be able to swim in a wet environment. Although using snap-through buckling of a deformable body could help to create swift motions of the robot, merely applying the snap-through buckling does not improve the swimming speed of the robot so much. Here we propose a design of a stringy soft-bodied robot that can crawl on dry surfaces and swim in liquid environments. Besides taking advantage of the snap-through buckling using coil shape memory alloys (SMAs), we design the body of the robot with a geometrical overlapping of the active body segments and control the frequency of the undulation movement, which is crucial for the swimming locomotion. We evaluate the performance of the robot in different density and viscosity liquids such as cooking oil and Glycerin solution. We found that the robot needs to drastically change its undulation from low to high frequency when it moves from high to low viscosity environments. Our robot can swim at a speed of 3. 37 body-lengths per minute (BL/min) and crawl at a speed of 1. 74 BL/min. We anticipate our findings will help shed light on the design of soft-bodied robots that adapt to the changing environments efficiently.

ExpandFab is a fabrication method for creating expanding objects using foam materials. The printed objects change their shape and volume, which is advantageous for reducing the printing time and transportation costs. For the fabrication of expanding objects, we investigated a basic principle of the expansion rate and developed materials by mixing a foam powder and elastic adhesive. Furthermore, we developed a fabrication method using the foam materials. A user can design expanded objects using our design software and sets the expansion areas on the surface. The software simulates and exports the 3d model into a three-dimensional (3D) printer. The 3D printer prints the expandable object by curing with ultraviolet light. Finally, the user heats the printed objects, and the objects expand to maximum approximately 2.7 times of their original size. ExpandFab allows users to prototype products that expand and morph into various shapes, such as objects changing from one shape to various shapes, and functional prototype with electronic components. In this paper, we describe the basic principle of this technique, implementation of the software and hardware, application examples, limitations and discussions, and future works.

Despite the recent growth in popularity of personal mobility devices (e.g., e-scooters and e-skateboards), they still suffer from limited safety and narrow design form factors, due to their rigid structures. On the other hand, inflatable interfaces studied in human-computer interaction can achieve large volume change by simple inflation/deflation. Inflatable structure also offers soft and safe interaction owing to material compliance and diverse fabrication methods that lead to a wide range of forms and aesthetics. In this paper, we propose poimo, a new family of POrtable and Inflatable MObility devices, which consists of inflatable frames, inflatable wheels, and inflatable steering mechanisms made of a mass-manufacturable material called drop-stitch fabric. First, we defined the basic material properties of a drop-stitch inflatable structure that is sufficiently strong to carry a person while simultaneously allowing soft deformation and deflation for storage and portability. We then implemented an interactive design system that can scan the user's desired riding posture to generate a customized personal mobility device and can add the user's shape and color preferences. To demonstrate the custom-design capability and mobility, we designed several 3D models using our system and built physical samples for two basic templates: a motorcycle and a wheelchair. Finally, we conducted an online user study to examine the usability of the design system and share lessons learned for further improvements in the design and fabrication of poimo.

Despite recent advancements in 3D printing technology, which allows users to rapidly produce 3D objects, printing tall and/or large objects still consumes more time and large amount of support material. In order to address these problems, we propose Pop-up Print, a method to 3D print an object in a compact "folded" state and then unfold it after printing to achieve the final artifact. Using this method, we can reduce the object's print height and volume, which directly affects the printing time and support material consumption. In addition, thanks to the reversibility of folding/unfolding, we can reversibly minimize the printed object's volume when unused for storage or transportation, and expand it only in use. To achieve Pop-up Print, we first conducted an experiment using selected printed sample objects with several parameters, in order to determine suitable crease patterns that make both the unfolded and folded state mechanically stable. Based on this result, we developed an interactive design tool to convert 3D models - such as a Stanford Bunny or a Huffman's cone - to the folded shape. Our design tool allows users to decide non-intuitive parameters that may affect the form's mechanical stability, while maintaining both functional crease patterns and the object's original form factor. Finally, we demonstrate the feasibility of our method through several examples of folded objects.

TelemetRing is a batteryless and wireless ring-shaped keyboard that supports command and text entry in daily lives by detecting finger typing on various surfaces. The proposed inductive telemetry approach eliminates bulky batteries or capacitors from the ring part. Each ring consists of a sensor coil (the ring part itself), 1-DoF piezoelectric accelerometer, and varactor diode; moreover, it has different resonant frequencies. Typing shocks slightly shift the resonant frequency, and these are detected by a wrist-mounted readout coil. 5-bit chord keyboard is realized by attaching five sensor rings on five fingers. Our evaluation shows that the prototype achieved the tiny (6 g, 3.5 cm^3) ring sensor and 89.7% of typing detection ratio.

We propose a 3D-printed interface, CAPath, in which conductive contact points are in a grid layout. This structure allows not only specific inputs (e.g., scrolling or pinching) but also general 2D inputs and gestures that fully leverage the "touch surface." We provide the requirements to fabricate the interface and implement a designing system to generate 3D objects in the conductive grid structure. The CAPath interface can be utilized in the uniquely shaped interfaces and opens up further application fields that cannot currently be accessed with existing passive touch extensions. Our contributions also include an evaluation for the recognition accuracy of the touch operations with the implemented interfaces. The results show that our technique is promising to fabricate customizable touch-sensitive interactive objects.

We introduce MorphIO, entirely soft sensing and actuation modules for programming by demonstration of soft robots and shape-changing interfaces.MorphIO's hardware consists of a soft pneumatic actuator containing a conductive sponge sensor.This allows both input and output of three-dimensional deformation of a soft material.Leveraging this capability, MorphIO enables a user to record and later playback physical motion of programmable shape-changing materials.In addition, the modular design of MorphIO's unit allows the user to construct various shapes and topologies through magnetic connection.We demonstrate several application scenarios, including tangible character animation, locomotion experiment of a soft robot, and prototyping tools for animated soft objects.Our user study with six participants confirms the benefits of MorphIO, as compared to the existing programming paradigm.

We present FoldTronics, a 2D-cutting based fabrication technique to integrate electronics into 3D folded objects. The key idea is to cut and perforate a 2D sheet to make it foldable into a honeycomb structure using a cutting plotter; before folding the sheet into a 3D structure, users place the electronic components and circuitry onto the sheet. The fabrication process only takes a few minutes allowing to rapidly prototype functional interactive devices. The resulting objects are lightweight and rigid, thus allowing for weight-sensitive and force-sensitive applications. Finally, due to the nature of the honeycomb structure, the objects can be folded flat along one axis and thus can be efficiently transported in this compact form factor. We describe the structure of the foldable sheet, and present a design tool that enables users to quickly prototype the desired objects. We showcase a range of examples made with our design tool, including objects with integrated sensors and display elements.

Soft-bodied robots are getting attention from researchers as their potential in designing compliant and adaptive robots. However, soft-bodied robots also pose many challenges not only in non-linear controlling but also in design and fabrication. Especially, the non-compatibility between soft materials and rigid sensors/actuators makes it more difficult to design a fully compliant soft-bodied robot. In this paper, we propose an all-printed sensor and actuator for designing soft-bodied robots by printing silver nano-particle ink on top of a flexible plastic film. We can print bending sensors and thermal based actuators instantly with home-commodity inkjet printers without any pre/post-processing. We exemplify the application of this fabrication method with an all-printed paper caterpillar robots which can inch forward and sense its body bending angle.

Living things in nature have long been utilizing the ability to "heal" their wounds on the soft bodies to survive in the outer environment. In order to impart this self-healing property to our daily life interface, we propose Self-healing UI, a soft-bodied interface that can intrinsically self-heal damages without external stimuli or glue. The key material to achieving Self-healing UI is MWCNTs-PBS, a composite material of a self-healing polymer polyborosiloxane (PBS) and a filler material multi-walled carbon nanotubes (MWCNTs), which retains mechanical and electrical self-healability. We developed a hybrid model that combines PBS, MWCNTs-PBS, and other common soft materials including fabric and silicone to build interface devices with self-healing, sensing, and actuation capability. These devices were implemented by layer-by-layer stacking fabrication without glue or any post-processing, by leveraging the materials' inherent self-healing property between two layers. We then demonstrated sensing primitives and interactive applications that extend the design space of shape-changing interfaces with their ability to transform, conform, reconfigure, heal, and fuse, which we believe can enrich the toolbox of human-computer interaction (HCI).

Sharing systems for personal mobility devices (PMDs) with batteries are gaining popularity because of their advantages in terms of maneuverability and low environmental burdens. However, PMDs suffer from a small battery capacity, a lack of charging stations, and the inconvenience of plugging in for charging. To solve these problems, we propose retrofitting city spaces into wireless power transfer (WPT) stations/pads by placing sheet-like transmitters in available open spaces. Many studies have considered WPT for electrical vehicles; however, little attention has been given to WPT for PMDs, although they have many unique characteristics to consider (e.g., light weight, form factor, sharing ecosystems, and random running routes). In this study, we investigated a form of WPT via magnetic resonant coupling for PMDs through coil design, analysis, and measurements based on two scenarios: (1) charging PMDs at charging stations and (2) charging in-motion PMDs from chargers placed on the road. Based on these considerations, we confirmed that around 90 % transfer efficiency can be obtained in laboratory setups, whereas practical setups achieved around 70% efficiency.

Magnetic resonant coupling wireless power transfer (MRC- WPT) using transmitter arrays is expected to be applied to power electric vehicles and electronic devices. Transmitter arrays can maintain power transfer efficiency despite lateral misalignment between the transmitter and receiver. However, methods of using transmitter arrays while reducing magnetic field leakage have not been studied. A new method of using transmitter arrays is necessary for electromagnetic compatibility and user safety. In this study, we optimized the input currents at transmitter arrays and the load at the receiver to reduce magnetic field leakage and maintain power transfer efficiency even with lateral misalignment between the transmitter arrays and the receiver. Simulations showed that the proposed method can reduce magnetic field leakage by more than 10 dB and 38 dB, with and without ferrite plates, respectively, compared to the existing method of maximizing power transfer efficiency.

We present PEP (Printed Electronic Papercrafts), a set of design and fabrication techniques to integrate electronic based interactivities into printed papercrafts via 3D sculpting. We explore the design space of PEP, integrating four functions into 3D paper products: actuation, sensing, display, and communication, leveraging the expressive and technical opportunities enabled by paper-like functional layers with a stack of paper. We outline a seven-step workflow, introduce a design tool we developed as an add-on to an existing CAD environment, and demonstrate example applications that combine the electronic enabled functionality, the capability of 3D sculpting, and the unique creative affordances by the materiality of paper.

Soft-bodied and continuum robots have shown great adaptability to the environment thanks to its flexibility of the body. They have great potential in environment exploring or rescuing mission. One of those robots is snake-like soft-bodied robots. A snake robot is often made by attaching passive wheels along a long body to achieve frictional anisotropy. This anisotropic structure helps to propel the body with serpentine locomotion and prevents it from sliding laterally. However, with a snake-like soft-bodied robot, attaching wheels is not only clumsy but also adding weight to the robot. In this paper, being inspired by the scales on the skin of a snake, we propose a designing scheme to achieve an all-printed wriggle soft-bodied robot by patterning high and low friction material to the ventral side of the robot. Compared to a totally flat ventral, we are able to speed-up the serpentine locomotion 2.8 times. Besides, by changing the configuration of high/low friction material, our wriggle soft-bodied robot can easily move forward or backward just by switching the controlling signal. The fabrication time is just less than 1 hour and the robot can achieve the speed of 26 mm/s.

This paper presents a methodology to design mechanosensor feedback to oscillator-based controller for worm-like soft-bodied robots. A reinforcement learning technique, i.e., PEPG, is employed to embed appropriate mechanosensor feedback to harness global entrainment among the controller, the body dynamics, and the environment without explicitly designing the interaction between the oscillators. Another reinforcement learning, actor-critic, was applied to train the controller for the simulation models to analyze the effectiveness of PEPG in the system. Furthermore, the gait controller was trained under different body dynamics, i.e., the physical model of a caterpillar and an earthworm. We found that PEPG is suitable for the system probably because it does not add exploration noise to actions and it conducts episode based parameter updates. The simulation results show the proposed method can acquire distinct behavior, i.e., caterpillars' crawling, inching and earthworms' crawling, under different body dynamics. The outcome implies, that by utilizing appropriate learning method, desired functionality can be achieved in soft-bodied robots without explicitly designing their behavior.

Shape changing robot is an approach towards locomotion on uncertain terrain due to its omni-directional features. However, the current locomotion method for such robots rely on discontinuous rolling. We propose a free form locomotion: an omni directional continuous crawling for deformable robots. This method introduce continuous shifting of contact surface similar to amoeba movement. A Mochibot that has thirty two telescopic legs is developed to verify the proposed locomotion method. Through the experiments, we have confirmed that the robot can track smooth paths: straight, smooth, and hand written curves. We also evaluate errors between desired and measured trajectories of the robot.

Recently, small and inexpensive portable projectors are commonly being used for presentations. For convenience, it is desired to perform a direct pointing operation on the screen without requiring to grip or mount any device and control the pointer intuitively. Therefore, this study proposes a new touch-operated large-screen projection system using acoustic vibration sensing and a projector-camera system. We apply a continuous signal in the inaudible range of an actuator to a surface and acquire its elastic compliance change as a resonance of sounds. We perform touch detection, position estimation, and pressure estimation by using machine learning techniques. Our actuator and sensor units are small and easy to install on a surface. Furthermore, our system can detect "true" touch without requiring any devices such as pens or pointers. We demonstrate a series of novel interactions for a large-screen projection system with our proposed technology through three applications.

This paper introduces Dynamic 3D Printing, a fast and reconstructable shape formation system. Dynamic 3D Printing can assemble an arbitrary three-dimensional shape from a large number of small physical elements. Also, it can disassemble the shape back to elements and reconstruct a new shape. Dynamic 3D Printing combines the capabilities of 3D printers and shape displays: Like conventional 3D printing, it can generate arbitrary and graspable three-dimensional shapes, while allowing shapes to be rapidly formed and reformed as in a shape display. To demonstrate the idea, we describe the design and implementation of Dynablock, a working prototype of a dynamic 3D printer. Dynablock can form a three-dimensional shape in seconds by assembling 3,000 9 mm blocks, leveraging a 24 x 16 pin-based shape display as a parallel assembler. Dynamic 3D printing is a step toward achieving our long-term vision in which 3D printing becomes an interactive medium, rather than the means for fabrication that it is today. In this paper, we explore possibilities for this vision by illustrating application scenarios that are difficult to achieve with conventional 3D printing or shape display systems.

The integrated fabrication of body structures, actuators, sensors, and electronic circuits into one robot system is an open problem in robotics. Simple and rapid construction of electric actuators in the body through existing approaches is difficult. We take advantage of the liquid-to-gas phase change, and propose an electric phase-change actuator comprising a printable fluidic actuator controlled by an inkjet printed electric heater. The actuator can easily be integrated with origami robots. We theoretically analyze the dynamics of electro-fluidic conversion in the actuator and compare it with actual measurement data. The proposed actuator is verified in real examples of a shape-shifting origami structure and a robot gripper with a printed touch sensor.

In this paper, we propose a passive and contactless epidermal pressure sensor patch printed on a paper substrate with silver nano-particle ink. This disposable patch can be used to measure the pressure between the clothes and the human body. Different from the conventional pressure sensors, the pressure can be measured wirelessly without disturbing the motion of the users. The sensor circuit pattern is printed by a conductive inkjet printer and the sensor's pressure value is detected by a reader coil through the change of the capacitance of an LC resonant circuit. We propose a sensor design method that minimizes the effect of the human body. We demonstrate our sensor patch by measuring the pressure exerted by compression garments whose pressure distribution is important for the wearer's health.

This paper proposes selective compressed sensing, an extension of the conventional compressed sensing that effectively compresses the frequency band(s) of interest while maintaining a backward compatibility with the compressed sensing. We exploit the fact that several sensing applications are interested in analyzing specific frequency bands only. In contrast to most conventional researches that use a random matrix as a measurement matrix, we present an optimized measurement matrix using the Walsh-Hadamard matrix and demonstrate that our selective compressed sensing method can reduce the amount of sensing data required to be transmitted. Compressed sensing can reconstruct all frequencies evenly from the raw data; the accuracy of the reconstructed data is primarily determined by the sparsity of the measurement signal. However, the compression process in the proposed selective compressed sensing method bypasses the calculation of unnecessary Fourier frequency band signals during the measurement. To reduce computational instructions and enable real-time compression by the resource-constrained microprocessors, we introduce two new techniques: the measurement matrix separations and the fast Walsh-Hadamard transform (FWHT) sorted by sequency. We demonstrate that this compression algorithm can reduce the number of instructions to approximately 1/512 of that of the compressed sensing to extract 40% of the whole spectrum from the raw data, when the data chunk size is 4096 bytes.

Recent advances in materials science have resulted in a range of commercially viable and easy-to-use conductive inks which novices, hobbyists, educators, students and researchers are now using to design and build interactive circuits quickly. Despite the ease with which practitioners can construct working circuits, one of the major limitations of designing circuits on-the-fly is the difficulty of detecting and understanding errors in prototype circuits. As well as short- and open-circuits, which often prevent a circuit from working at all, more subtle issues like high resistance traces can result in poor performance. Many users can't readily work out how to successfully modify their circuits, and they often don't have the tools or expertise to measure the relevant circuit parameters. In this paper we present ConductAR, a tool which can recognize and analyze hand-drawn, printed and hybrid conductive ink patterns. An on-screen augmented reality style interaction helps users to understand and enhance circuit operation. A key element of ConductAR is its ability to calculate the resistance of a circuit using a camera attached to an off-the-shelf PC or tablet. Our sparse coding technique is fast enough to support rapid iterative prototyping on real circuits using a conductive ink marker and/or eraser as shown in Figure 1. The system thereby enhances the feasibility of circuit prototyping with conductive ink.

Instant Inkjet Circuits by silver nano-particle ink realized home-brew electric circuit fabrication. However, current method can support only single-layered patterns, and conventional inter-layer connection methods are not suitable. In this paper, we will evaluate various easy-to-use inter-layer connection methods by making via holes, especially the ones made by different drilling mechanisms. We show that the felting needle is the best candidate as it can establish good conductivity immediately after nano-particle ink is printed into the hole, without using any curing process.

Full-duplex wireless information and power transfer allows the implementation of wireless sensor networks without batteries. In a full-duplex wireless network, an access point and sensor nodes transmit information and power signals simultaneously. However, this simultaneous transmission leads to a collision problem. To solve this collision problem, we propose a media access control (MAC) protocol, namely the Full-Duplex Simultaneous Wireless Information and Power Transfer Medium Access Control (FD-SWIPT MAC) protocol, for full-duplex wireless information and power transfer. The evaluation results show that the proposed FD-SWIPT MAC protocol outperforms other MAC protocols.

According to the statistics, people upgrade smartphones at every two years, which means tremendous number of phones will be left unused. In this paper, we propose a method to use Android-based smartphones as wireless sensors for environmental monitoring. Although the idea of using smartphones as a wireless sensor sounds naive, the previous approaches were un-practical because of its limited battery life. In this paper, we exploit the Linux kernel boot mode on Android devices to extend the battery life drastically. Unlike normal mode, power consumption in the kernel mode is minimum but still it is possible to access to all the sensors in principle. In this paper, we measure the power consumption of Nexus5 while booting, running and shutting down Android OS / Linux kernel and estimate the battery life assuming a duty cycle. The results show that utilizing the Linux kernel can extend the battery life up to 10.9 times when the sensing interval is 3 minutes.

Combining wireless transmission of data and power signals enables us to use wireless devices without charging batteries. To improve the utilization of wireless resources, a sender could simultaneously transmit data and power signals in the same frequency channel. A disadvantage of simultaneous transmission is that it induces interference between data and power signals. To minimize the effect of interference, we propose a new frequency-sharing system. The proposed system makes two contributions. The first contribution is interference cancellation of the power signal to receive data from the collided signal using a combination of digital and analog interference cancellation techniques. The second contribution is a media access control protocol to receive the transmitted power effectively by varying the sleep time. To evaluate the performance of the proposed system, we built an experimental apparatus using software-defined radio. Evaluations show that it is feasible to transmit data and power simultaneously using the proposed system.

We present a multimodal on-surface and near-surface sensing technique for planar, curved and flexible surfaces. Our technique leverages temporal multiplexing of signals coming from a universal interdigitated electrode design, which is printed as a single conductive layer on a flexible substrate. It supports sensing of touch and proximity input, and moreover is capable of capturing several levels of pressure and flexing. We leverage recent developments in conductive inkjet printing as a way to prototype electrode patterns, and combine this with our hardware module for supporting the full range of sensing methods. As the technique is low-cost and easy to implement, it is particularly well-suited for prototyping touch- and hover-based user interfaces, including curved and deformable ones.

We present a novel approach to the construction of electronic prototypes which can support a variety of interactive devices. Our technique, which we call circuit stickers, involves adhering physical interface elements such as LEDs, sounders, buttons and sensors onto a cheap and easy-to-make substrate which provides electrical connectivity. This assembly may include control electronics and a battery for standalone operation, or it can be interfaced to a microcontroller or PC. In this paper we illustrate different points in the design space and demonstrate the technical feasibility of our approach. We have found circuit stickers to be versatile and low-cost, supporting quick and easy construction of physically flexible interactive prototypes. Building extra copies of a device is straightforward. We believe this technology has potential for design exploration, research proto-typing, education and for hobbyist projects.

Wireless LAN multicast is a suitable mechanism for multimedia streaming because of its bandwidth efficiency. However, wireless multicast has several problems in terms of power efficiency. In this study, we analyze the power efficiency of multicast in IEEE 802.11 networks and show that multicast increases the power consumption of clients significantly irrespective of whether the clients join multicast groups or not. The main reason is that IP multicast packets are transferred as broadcast frames in IEEE 802.11 networks. To improve power efficiency, we propose a new multicast streaming mechanism. Our work is strongly motivated by Flexible Multicast Service (FMS), which is a new IEEE 802.11 standard. FMS permits access points (APs) to transmit multicast frames in more than one delivery traffic indication message (DTIM) interval, which allows clients to wake up at alternate DTIM intervals, rather than every DTIM. However, our analysis proved that FMS is not an optimal mechanism in terms of power efficiency. We propose a new mechanism that provides more power-efficient multicast multimedia streaming, without delay or throughput penalty. Our method focuses on how to reduce the number of unnecessary frames received by clients. The key idea is to stagger the transmission timing to let clients avoid receiving unnecessary frames. We evaluate the mechanism by comprehensive analysis and simulations. The results show that the mechanism achieves significant power savings in wireless LAN multicast networks.

Pedestrians have difficulty noticing hybrid vehicles (HVs) and electrical vehicles (EVs) quietly approaching from behind. We propose a vehicle detection scheme using a smartphone carried by a pedestrian. A notification of a vehicle approaching can be delivered to wearable devices such as Google Glass. We exploit the high-frequency switching noise generated by the motor unit in HVs and EVs. Although people are less sensitive to these high-frequency ranges, these sounds are prominent even on a busy street, and it is possible for a smartphone to detect these signals. The ambient sound captured at 48 kHz is converted to a feature vector in the frequency domain. A J48 classifier implemented on a smartphone can determine whether an EV or HV is approaching. We have collected a large amount of vehicle data at various locations. The false-positive and false-negative rates of our detection scheme are 1.2% and 4.95%, respectively. The first alarm was detected as early as 11.6 s before the vehicle approached the observer. The scheme can also determine the vehicle speed and vehicle type.

This paper presents a methodology and validation of print-and-self-fold electric devices. For printing functional structures for robotic use, we realize electric circuitry based on metallic polyester film (MPF). By exploiting the unique material properties of MPF, we developed fundamental electric devices, namely a resistor, capacitor, and inductor. The developed polyvinyl chloride laminated MPF sheet shows reliable self-folding processes under a heat application, and it configures 3D electric devices. Due to the pre-resolved kinematic design, these devices feature elasticity, making them suitable as sensors and actuators in soft circuits. Here we testify to a self-assembled variable resistor and capacitive strain sensor. An actuation mechanism consisting of a folded contractible coil is also considered and shown. Finally, an RLC circuit obtained from the integration of all the developed devices is demonstrated, in which the coil based actuator is controlled by reading a variable capacitive strain sensor.

In this paper, we considered the possibility of using electricity harvested from the microwave field leaked from commercial microwave ovens. Our experimental results showed that the leakage received by a dipole antenna was about 0 dBm (1 mW) at a point 5 cm in front of the door. A rectenna consisting of a dipole antenna and charge pump can convert the leaked microwave energy into a DC current. When a microwave oven is operated for 2 min, 9.98 mJ of energy was harvested. We demonstrated that this energy is sufficient for powering a digital cooking timer to count down for 3 min and beep for 2.5 s. The operation of other kitchen devices was also demonstrated.

This paper introduces a low cost, fast and accessible technology to support the rapid prototyping of functional electronic devices. Central to this approach of 'instant inkjet circuits' is the ability to print highly conductive traces and patterns onto flexible substrates such as paper and plastic films cheaply and quickly. In addition to providing an alternative to breadboarding and conventional printed circuits, we demonstrate how this technique readily supports large area sensors and high frequency applications such as antennas. Unlike existing methods for printing conductive patterns, conductivity emerges within a few seconds without the need for special equipment. We demonstrate that this technique is feasible using commodity inkjet printers and commercially available ink, for an initial investment of around US$300. Having presented this exciting new technology, we explain the tools and techniques we have found useful for the first time. Our main research contribution is to characterize the performance of instant inkjet circuits and illustrate a range of possibilities that are enabled by way of several example applications which we have built. We believe that this technology will be of immediate appeal to researchers in the ubiquitous computing domain, since it supports the fabrication of a variety of functional electronic device prototypes.

In this poster, we propose an authentication system, especially registration procedure, that can be used before and after a disaster. Using a two-tier HIDE, distributed authentications are done within each disrupted network segment without changing any user interface. To share the encrypted data among the users of this application at (8) of II-C, other types of encryption schemes are required. Attribute Base Encryption is one of these candidates and can be used as a smooth extension of the procedure described in this poster[7]. An actual implementation must be produced using an appropriate toolkit such as CCNx to evaluate the performance. This will be performed in future research. The work for this paper was performed in the context of the FP7/NICT EU-JAPAN GreenICN project.

Large scale content distribution schemes that use named data networking (NDN) experience a copyright protection problem because of the nature of P2P-based, consumer-generated media (CGM) distribution. It is difficult to manage copyright violations by content uploaded in the network. To overcome this problem, NDN provides a content firewall that permits and rejects packets depending on its routing policy. In untrusted networks, however, the content firewall of each NDN router may not be updated as expected. In this paper, we present a PKI-based two-way content management scheme where a content owner or a system supervisor can delete illegal content from the network. First, a content owner sends a target content deletion request to a supervisor. After the supervisor's acknowledgment, the deletion request is distributed throughout the whole network. An extension of this content management system based on a secret sharing scheme was investigated to determine its security loopholes and scalability.

Wireless LAN multicast can provide high quality location-aware content service. However, our research revealed that multicast might cause a significant increase in the power consumption. Flexible Multicast Service (FMS) which is defined in the IEEE 802.11v enables power efficient multicast service. In this paper, we prove that the FMS strategy is not optimal and a little extension on FMS will achieve great improvement in power efficiency without throughput or delay penalties.

During a disaster, it is important to exchange information such as the magnitude of the disaster and safety confirmation. However, the communication infrastructure, such as a mobile phone network, may not be available after a large-scale disaster because current communication infrastructures have centralized control structures. Thus, it is important to design a network that can maintain a normal service using the remaining network resources, such as base stations and user terminals, even if the central servers are no longer available because of disconnections among servers. In this study, we developed a distributed SNS service, or autonomous distributed network, based on named data networking (NDN) with two-tier hierarchical ID-based encryption (HIDE) for authentication. We conducted a simulation of a residential area in the suburbs of Tokyo to demonstrate the performance of this SNS application, where it was used to disseminate safety confirmation. We present the average message delivery time with different decision intervals, the synchronization intervals, and the ratios of moving people.

In emergent situations such as an earthquake, huge traffic from multiple services pours into IP Multimedia Subsystem (IMS) network and leads to a severe congestion problem. To protect IMS network, telecom companies usually take a measure of originator regulation on voice calls. However existing solutions are unable to maximize the service throughput for handling multiple services. This paper proposes an automatic originator regulation of IMS multiple traffic by stateless signal prioritization based on the types, message order and retransmissions of SIP messages within each call session. The best prioritization is to give a higher priority to a message type appearing at a later stage in each session and a lower priority to a retransmitted message. We also show the optimum queue length. For the effective confirmation of the safety at a disaster, an ideal communication system should pass more light-weight messages like instant messaging (IM) than those generated by voice calls. The simulation result shows the maximum throughput for each multimedia service is kept as in this ideal model even in an extremely congested situation with the 60 times larger offered load than usual which was observed in the 2011 earthquake off the Pacific coast of Tohoku.

In this paper we show a low cost and environmentally friendly fabrication for an agricultural sensing application. An antenna, a soil moisture sensor, and a leaf wetness sensor are inkjet-printed on paper substrate. A microprocessor attached to the paper substrate is capable of detecting the capacitance change on the surface of the sensor, and report the data over the wireless communication interface. This sensing system is useful to optimize irrigation systems.

Human activity recognition through the wearable sensor will enable a next-generation human-oriented ubiquitous computing. However, most of research on human activity recognition so far is based on small number of subjects, and non-public data. To overcome the situation, we have gathered 4897 accelerometer data with 116 subjects and compose them as HASC2011corpus. In the field of pattern recognition, it is very important to evaluate and to improve the recognition methods by using the same dataset as a common ground. We make the HASC2011corpus into public for the research community to use it as a common ground of the Human Activity Recognition. We also show several facts and results of obtained from the corpus.

Almost all recent mobile phones are equipped with multiple sensors, such as cameras, GPS, and accelerometers. By exploiting the sensing features, we capture many different events and share them over the mobile network. One of the most important challenges for such a participatory sensing system is the reduction of the battery consumption of the mobile device because the sensing task usually runs as a secondary task and should not disrupt the primary tasks of the mobile phone, such as phone calls. We overcome this problem by compressing the sensed data and sending a minimum amount of data over the wireless link. The compressed sensing (CS) technique is used for this compression with simple matrix operations at the mobile side, and the CPU-intensive reconstruction is performed on the resource-rich machine on the network side. In this paper, we validate this idea by implementing it on the iPhone/iPod platform. Since CS is a lossy compression technique, the reconstructed signal contains errors depending on the degree of sparseness of the original signal. We show that our system can reduce power consumption by approximately 16% compared with ZIP compression, and evaluate the reconstruction error using real sensing data of 86 test subjects.

Accelerometer data on a user's mobile phone contains abundant information that can be employed for user activity recognition. However, the existing schemes cannot provide accurate inference results under moving environments (e.g. on a train). This is because raw sensor data changes with the motion of the environment as well as the user. In this paper, we propose an enhanced collaborative recognition scheme that exploits neighborhood sensor data shared over a wireless network. Our preliminary experiment showed that the acceleration data of two different subjects on the same train was highly correlated. Further, it was possible to detect whether two subjects were on the same train with an accuracy of 69%. This result indicates that raw sensor data shared by spatially neighboring users can be used to detect transportation modes and enrich social networking applications.

Energy harvesting technology is one of the key technologies for the long-term operation of wireless sensor networks. However, power supply from such energy harvesting sources is not as stable as batteries. In order to compensate for the spatial and temporal variations of the energy harvesting sources, an energy storage device is used. Rechargeable batteries are commonly used in wireless sensor nodes. However, batteries can be charged and discharged for only a limited number of cycles. When the harvested energy is small, capacitors are better suited for energy storage because they can be charged and discharged quickly and efficiently. Moreover, the charge-discharge capability of capacitors does not degrade. The only critical problem of capacitors is that their energy leakage is too large to ignore. In this paper, we propose a capacitor leakage aware duty cycle control for energy harvesting wireless sensor networks. Our proposed method focuses on capacitor leakage reduction, which must be considered in a capacitor driven system but has not been considered to date. Our method maximizes the energy usage without degrading system availability by applying optimal control using multiple evaluations of the energy neutral operation and capacitor leakage.

This paper presents a simple but resilient method to suppress copyright violations among the content uploaded onto peer-to-peer (P2P) video sharing services, and is especially designed for consumer generated media (CGM). Encryption is a good way to block the circulation of illegal content. However, if the encryption key is caught by a malicious node in the P2P network, the ''denial of deletion'' ability offered by this key may make it difficult to stop the circulation of the content. To solve this problem, we propose a method to divide the encryption key into partial keys using the secret sharing scheme, and allowing them to be distributed into different nodes. Different from existing commercial P2P content distribution systems, this system is more scalable because the keys are managed in a distributed fashion. Regardless of the size of the P2P network, the probability of the encryption key being illegally used after the deletion operation for the target content is less than 0.1 even when more than 10% of the nodes are malicious.

This paper proposes a communication system using Wi-Fi (IEEE802.11g) to link between the Internet and high speed rail systems traveling at around 300km/h. In order to adapt Wi-Fi for high speed mobile communication, we optimized its coverage on a rail track with a developed directional antenna, which has a communication range of around 500m by 10mW. With the antenna, however, a mobile entity had to switch over antennae (a layer 2 handover (L2HO)) every 6 to 7 seconds. Furthermore Mobile IP handovers (a layer 3 handover (L3HO)) had to be appropriately controlled to avoid a simultaneous handover of Layer 2 and 3, which results in a fatal communication disruption. Therefore the designed system in this paper separated a L3HO from a L2HO. As a result, a maximum of 25Mbps with an average of 16Mbps for the UDP throughput and an average L2HO time of 110ms were realized while travelling at 270km/h.

In this demonstration we present an ubiquitous health monitoring system based on the NGN/IMS (next generation network/IP multimedia subsystem). It enables us to be taken care of by medical professionals anytime, anywhere using portable medical sensors and mobile networks. To provide seamless health monitoring services, an open, secure and functional platform is required. Such a platform should support multiple functions such as real-time transfer, event notification, and continuous data accumulation. The NGN/IMS is a potential platform to fulfill these requirements, because it is a standard- based open platform, which provides AAA (authentication, authorization and accounting), QoS (quality of service) support, event notification and a data management server. We present a system design and a prototype implementation on a NGN/IMS testbed.

The home networking becomes more interesting if users can share high quality contents with friends and colleagues living away from the user. DLNA certified devices allow users to share or access digital media contents on the same home network. However, the sharing of the content is only limited inside local area networks. In this paper, we propose a global content sharing home gateway named DAS (DLNA Agent for SNS). Different from exiting approaches using VPN, DAS enables to share specified contents to selected users with support of access control functionality provided by Social Network web services. As DAS behaves as a DLNA certified server, there is no need to modify commercial DLNA CE devices.

SUMMARY: G-compass is designed for efficient comparative genome analysis between human and other vertebrate genomes. The current version of G-compass allows us to browse two corresponding genomic regions between human and another species in parallel. One-to-one evolutionarily conserved regions (i.e. orthologous regions) between species are highlighted along the genomes. Information such as locations of duplicated regions, copy number variations and mammalian ultra-conserved elements is also provided. These features of G-compass enable us to easily determine patterns of genomic rearrangements and changes in gene orders through evolutionary time. Since G-compass is a satellite database of H-InvDB, which is a comprehensive annotation resource for human genes and transcripts, users can easily refer to manually curated functional annotations and other abundant biological information for each human transcript. G-compass is expected to be a valuable tool for comparing human and model organisms and promoting the exchange of functional information. AVAILABILITY: G-compass is freely available at http://www.h-invitational.jp/g-compass/. CONTACT: [email protected]

This paper shows a methodology of estimating a user's everyday energy expenditure using a 3-axis accelerometer of a mobile phone handset. We first infer the user's posture based on the acceleration sensor reading and calculate METS value, which is considered as a measure for estimating calorie consumption for daily activities. The experimental result shows that our application is as accurate as a reference device.

Tiny networked sensor devices will be disseminated over our physical life space, and take a significant role in realizing a ubiquitous computing environment. As sensor network technologies and its applications are still at its early stages, the architecture of the sensor network heavily relies on the applications. We believe it quite essential to come up with various kinds of applications, and obtain sufficient knowledge of sensor network architecture and its peripheral technologies through demonstrations. In this paper, we introduce our sensor network applications and present the way sensor network is used in them.

Ubiquitous computing as the integration of sensors, middleware, and networking technologies to form a "smart space" environment relies on the development of both software and hardware solutions. For over 3 years, our group has been developing a smart-space environment, involving the exploration of core technologies and attractive applications. We introduce the challenges faced and lessons learned in designing and developing a smart-space environment, including device control services, locating systems, wireless sensor nodes, and middleware services.