Electronics and Communications in Japan最新文献

Many tactile displays have been developed to present the feeling of touch by means of vibrations. However, the vibration generated at the fingertip when touching an object varies nonlinearly with the contact pressure and tracing velocity. Currently, no signal generation model has been reported to deal with the non-linearity in response to touch. In this study, we have proposed and developed the first tactile logger that can acquire vibration distributions for various contact pressures and tracing velocities with a spatial resolution of 1 mm.

In this paper, a method to design an inverse LQR with a retarded state predictor for systems with time-delay in state and input is proposed. A feedback law is constructed by using the predictor which has a same state time-delay as the one in the systems. It is shown that the resulting closed-loop system is asymptotically stable and the proposed feedback law is an optimal control that minimizes a quadratic cost functional. Furthermore, we show that the constructed regulator has good robustness as same as an ordinary finite-dimensional LQR. Finally, numerical examples are given to evaluate the effectivity of the proposed method.

Atherosclerosis is a key factor in lifestyle-related diseases, characterized by near-irreversible arterial thickening and hardening. Early detection is crucial for effective intervention, however current wearable technology lacks noninvasive arterial stiffness assessment capabilities. This study explores the feasibility of using Photoplethysmogram (PPG) at the radial artery for arterial stiffness evaluation, focusing on green-light PPG. PPG signals were collected from 18 healthy young participants (9 males: 23.3 ± 3.7 years; 9 females: 24.7 ± 7.3 years) at the fingertip and wrist. The second derivative PPG (SDPPG) obtained from fingertip with green and near-infrared light and that from radial artery with green light was analyzed. Preliminary results showed that SDPPG aging indices obtained from fingertip with green and near-infrared light were highly correlated in 4 participants, suggesting its feasibility for vascular age estimation. However, at the radial artery, individualized vascular age estimation models may be required. Further studies are needed to validate this approach and establish standardized evaluation criteria.

In this paper, we have proposed a pitch-converting mechanism to realize a tactile display with both spatial resolution and vibration stimulation, aiming to present fine texture to human fingertips. To optimize the design of the proposed tactile display, we proposed a theoretical model of the relationship between design parameters and vibration amplitude. Based on the results, we designed and fabricated the seven elements pitch conversion tactile display. In the prototype display, 15-µm displacement was obtained at a voltage of 25 V, and independent drives of each diaphragm were demonstrated, respectively.

The purpose of this study was to evaluate the precision of various heart rate variability (HRV) analysis parameters during postural changes between sitting and upright postures, with a particular focus on Tone–Entropy analysis, and to verify the absolute evaluability and high reproducibility of Tone–Entropy analysis. Fifteen healthy young men (age 20.7 ± 1.5 years) from two different groups participated in the study, and their heart rates (HRs) were recorded during sitting and upright postures. The postural changes were repeated twice, and each posture was maintained for 2 min. Precision was evaluated by defining the error rate for each HRV index. As a result, Entropy showed almost the same precision as HR. On the other hand, standard frequency domain indices such as low frequency (LF), high frequency (HF), and LF/HF ratio showed consistently low precision. Furthermore, our results support the usefulness of Tone–Entropy analysis to date, as it can allow absolute evaluation in Tone–Entropy space even for different groups of subjects and experimental conditions, and the reproducibility of Entropy is also high. In conclusion, it is suggested that Tone–Entropy analysis has high reliability and reproducibility and that frequency power spectrum analysis lacks sufficient precision to be applied to long-term monitoring analyses in young male subjects.

Cannabinoids found in cannabis plants include substances designated as narcotics as well as those used in health and cosmetic products, creating a strong demand for the development of technologies to easily distinguish and detect them. However, these compounds have similar chemical structures, making it challenging to differentiate them with simple analytical methods. We have developed a paper-based microfluidic device capable of distinguishing and detecting tetrahydrocannabinol (THC) and tetrahydrocannabinolic acid (THCA), which are designated as narcotics, as well as cannabidiol (CBD) and cannabinol (CBN), which are used in health and cosmetic products. By reacting each of these cannabinoids with a diazo-coupling reagent, capturing the resulting colorimetric products with a digital camera, and analyzing the images, this device can successfully distinguish and detect the four cannabinoids.

In recent years, food adulteration—the mixing of one brand of meat with another brand of meat—is a significant issue. One approach to detecting such fraud is to monitor the relationship between livestock weight and the weight of its edible parts through a food traceability system. However, conventional methods often fail when fraudsters carefully adjust the weight transferred from one brand to another so that both brands remain within normal ranges. In this study, we propose two fraud detection methods that focus on distributional changes in both livestock weight and edible-part weight. Specifically, one uses a likelihood ratio to detect shifts caused by continuous adulteration, and the other uses correlation to detect a change from very weak correlation to a strong negative correlation caused by brand-to-brand meat transfers. Evaluation experiments show that when the frequency of adulteration exceeded 17.2%, our method achieved the target true positive rate. These results show the effectiveness of our proposed approach.

In this paper, we propose a hierarchical control method for the motion of transportation robots with the aim of solving problems related to the transportation of cargo in the logistics/transportation industry by introducing transportation robots. Specifically, multiple robots simultaneously achieve transportation of cargo to a target position, avoidance of collisions with obstacles, and coverage of the area in a two-dimensional region with obstacles. At first, the administrator specifies a transportation or coverage task for each robot as a global control. Then, one robot that is assigned a transportation task carries out the transportation of cargo while avoiding collisions with obstacles by local tangent bug-based motion control. On the other hand, the remaining robots without the transportation task continue to cover the region. Finally, the effectiveness of the proposed control method is verified by numerical simulations assuming a train station and the other for a shopping mall.

This study presents an automatic method for rally scene detection and score estimation in a broadcast table tennis video. Prematch analysis typically requires extensive manual recording of player actions, shot trajectories, and scores from videos. This time-intensive process impacts preparation efficiency. The proposed methodology integrates YOLOv8 for player and table detection with the Segment Anything Model (SAM) for scoreboard area segmentation. Rally scenes are identified through pixel change rate analysis combined with mean square error calculations for frame similarity assessment. The research introduces a score recognition technique functioning independently of scoreboard design variations. Experimental evaluation demonstrates a 9 percentage point increase in precision compared to existing methods, with reduced false positives and missed detections. By incorporating score change timing data, the system overcomes challenges presented by variable camera angles and scene transitions. This work contributes to automated sports video analysis by demonstrating the feasibility of detection systems that enhance prematch preparation while reducing manual analytical workload in professional table tennis contexts.

In this study, we aimed to evaluate the relationship between the concentration of active compounds in medicinal plants and their plant bioelectric potential responses. A miniaturized measurement system was developed using a Raspberry Pi to monitor the plant bioelectric potential and cultivation environmental factors. Rosmarinic acid content in red perilla, the sample plant, was quantified using a spectrophotometer and compared with parameters calculated from the potential responses. The results indicated that there was a correlation between these parameters and the rosmarinic acid content.