Soft robots have the potential to solve problems that cannot be addressed using hard rigid robots such as harsh sounds from mechanical structures, structure weight, inefficient structures, and potential risks due to human-robot interactions. Soft sensors play an essential role in developing soft robots. Examples include strain, bending, and touch sensors. Soft strain sensors consist of elastomer and stretchable electrodes. Recently, many innovative solutions have been promoted to fabricate stretchable electrodes, including pad-printing, Langmuir-Schaefer (LS), supersonic cluster beam (SCB), and manual direct brushing method of carbon powder. Herein we fabricate stretchable electrodes simply, reliably, and economically using an automatic brushing machine (ABM). Our technique requires threeaxis machine tools to perform automatic brushing. An ABM can realize stretchable electrodes with a reliable quality. Moreover, the quality of the stretchable electrodes is controllable by selecting the appropriate type of elastomer. The ABM is suitable for future mass production of stretchable electrodes.

View full abstract

This research investigated the influence of chemical composition on the CH4 production capability, or Biochemical Methane Potential (BMP), of eleven different field grass samples that have the capability to produce methane (CH4)-rich biogas. These grasses were fast growing, has high yield and high digestible organic content (atratum, creeping signal, hamata stylo, mombasa guinea, pangola, para-, purple guinea, rhodes, ruzi, and napier grasses, plus napier grass silage). Anaerobic sludge from a cassava starch wastewater treatment plant was used as an inoculum seed. The BMP was significant statistical differences due to variations in the chemical composition, which was related to the C:N ratio and lignin content in the field grasses. The experimental results showed that the Carbon:Nitrogen (C:N) ratios were in the range of 17.2:1 to 89.6:1 and the BMPs were in the range between 121.5–251.9 Nm3/t VSadded with the maximum CH4 production rate of 3.60–11.46 mL/day. Outstanding BMP levels were found in the para grass, ruzi grass, and pangola grass, with suitable C:N ratio (20:1 to 30:1) and low lignin content. Para grass provided the highest BMP of 251.9 Nm3/t VSadded (4,799 Nm3 CH4/ha). The CH4 yield per hectare of the grasses depends on both its dry matter yield per hectare and its specific methane yield. Therefore, pangola grass had the highest potential as an energy crop with 7,915 Nm3 CH4/ha due to its high CH4 yield (230.9 Nm3/t VSadded) and high harvesting yield (37.5 t/ha).

View full abstract

The membrane formation mechanism of silica membranes prepared by chemical vapor deposition method for gas separation was investigated. The initial diffusion of carrier gases was measured to estimate the deposition rate of the silica. The effects of the organic substituent of the silica precursors on the pore sizes of the deposited membranes were investigated by using this in-situ analysis. The effects of the organic group of the silica precursors were discussed. The TMOS (tetramethoxysilane) deposited membrane showed high H2 permselectivity. TMOS consists of 4 alkoxy groups without organic groups. Both Ar (0.34 nm) and SF6 (0.55 nm) diffusion through the membrane during the deposition decreased with increasing deposition time. On the other hand, Ar diffusion decreased through the MTMOS (methyltrimethoxysilane) membrane after increasing the diffusion of SF6. The methyl group of MTMOS must be decomposed during the deposition of MTMOS. The pore size of the MTMOS deposited membrane was estimated to be approximately 0.39 nm, which is larger than that of the TMOS membrane. Smaller pores were obtained from the silica precursors with the smaller substituent, while the silica precursor with larger substituent do not diffuse into the deposited pores. As a results, Ar diffusion during the deposition for the silica precursor with larger substituent increased with increasing the deposition periods.

View full abstract

Thin pure-silica CHA-type zeolite (Si-CHA) membranes have been synthesized via secondary growth method on a porous silica support, to the best of our knowledge, for the first time The synthesis temperature was varied from 150 to 180℃ and the synthesis time was varied from 4 to 16 h. The obtained membranes were investigated for CO2 permeance and ideal and real CO2/CH4 selectivity. Higher synthesis temperatures have shown an increase in crystallization speed, whereas higher synthesis times had a positive effect in the separation layer’s crystallinity. However, although the increase of both variables resulted in a more selective and thicker zeolite layer, it was observed that, for membranes synthesized for over 4 h at temperatures of 160℃ and above, the silica from the substrate was considerably dissolved and separation layers could not be obtained. All membranes synthesized at 150℃ for 8 to 16 h have displayed a CO2/CH4 ideal selectivity of over 90. In a mixed gas permeance test with a CO2/CH4 mixture, the membrane synthesized at 150℃ for 16 h has shown a CO2 permeance rate of 4.2 × 10–7 mol m-2 s-1 Pa-1 and a real selectivity of 52. By fitting the experimental data to the Arrhenius equation, it was observed that the obtained membranes have shown not only molecular sieving as a permeation mechanism, but also surface diffusion of CO2. Since it is a novel technique for CHA zeolite membrane synthesis, these new results are satisfactory, although there is still much room for improvement.

View full abstract

For an automated driving system, accuracy in detecting and recognizing the objects in the surrounding environment is essential to ensure the safe driving. In recent years, Light Detection And Ranging (LiDAR) have been used as an external recognition sensor, which plays a vital role in mapping, location, and recognition. However, although LiDAR's 3D pointcloud information is accurate, the scanned data are sparse in the long distance. This paper proposes a sensor-fusion method that using the optical flow method to obtain the range information of feature points from straight line moving objects and fuse them with pointcloud data. The results show that our method effectively improved the density of the 3D LiDAR pointcloud.

View full abstract

Recently, Japan has witnessed a declining birth rate and an aging and declining population. Robots are expected to play an active role as a complement to the working population. In the Japanese robotic industrial market, the service field is expected to grow from 370 billion yen in 2015 to 4.9 trillion yen in 2035. Additionally, physical exercise is a preventive measure for the elderly. Therefore, in this study, we developed a system that enables humanoid robots to act as physical exercise instructors. An instructor performs physical exercise and acquires the joint position of a human from image data; moreover, the instructor makes the humanoid robot conduct the same movement through the Internet using the Robot Service Network Protocol, which is a common robot communication protocol. As an elderly human imitates the humanoid robot performing a particular movement, the instructor and elderly human can practice the physical exercise despite being physically apart. Additionally, the shortage of instructors can be addressed because one instructor can move several humanoid robots. In this experiment, two joints of the upper body of a humanoid robot were moved using a simulation from two-dimensional skeletal coordinates. Subsequently, three joints of the upper body of the actual humanoid robot were moved from three-dimensional skeletal coordinates. Consequently, we could send movement commands to humanoid robot NAO remotely. We confirmed that NAO moves in accordance with human movements in the simulation and actual robot. In future, we will also develop the lower body to increase the number of movements NAO can perform and a system where humanoid robots advise the elderly.

View full abstract

With the development, densification and demographic change within cities, existing evacuation areas in some places no longer meets the needs of evacuees. Especially, additional evacuation areas need to be designated in locations with elderly people who are not able to walk fast or for long distances. This study aims to verify the security of an Urban Redevelopment Area, which could potentially be used as an alternative evacuation area, using the Hamada theory to determine whether it meets the safety requirements. The number of people that can be accommodated in the area are also calculated. In this study, the East Redevelopment Area of Hikifune station in Sumida ward was selected as the study area. Employing the Hamada theory, this study calculates the usable safe area for evacuation, given different scenarios of fire occurrence in the surroundings of the redevelopment areas with consideration to the building structure and building density and therefore the firespread characteristics of the area. The calculation results show that the study area can achieve sufficient safety levels under different conditions and could be used as an evacuation area for surrounding residents. Also, this study examines the beneficial effects of reducing building density and increasing fireproof structures for preventing the fire spread.

View full abstract