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To obtain data for investigating the criteria for avoiding bruising caused by blunt impact in human-robot interactions, a Marmarou-type impact tester is introduced into experiments involving porcine extremities. The mechanical input data, i.e., the total transferred energy per unit area, and the peak mean contact pressure with and without internal bleeding, are measured. In our previous study, experiments at lower mechanical inputs required for defining the criteria could not be performed; however, this problem is solved using the Marmarou-type impact tester in this study.

This paper discusses bandwidth enhancement of a folded monopole antenna using an iron tower (FMAIT). First, the impedance of the FMAIT with one wire is analyzed by electromagnetic (EM) and circuit simulations. It is shown that the bandwidth can be expanded by reducing the step-up ratio in an equivalent circuit of the FMAIT. Then, the FMAIT with three driven-wires is proposed to reduce the step-up ratio. It is verified by EM simulation that the bandwidth enhancement can be achieved by separating wires from each other.

The rooftop antenna of the leading car on the Tokaido Shinkansen, which is a high-speed railway line in Japan, has two functions; 1) detection of the overhead-line voltage in 60 Hz and 2) wireless communication in the VHF band. In this paper, we propose a miniaturized antenna configuration to reduce aerodynamic noise caused by the antenna. When the detection rod that detects the overhead-line voltage is shortened, the performance of overhead-line voltage detection deteriorates, but the deterioration is minimized by making the antenna substrate area as large as possible within the antenna radome. Moreover, in the VHF band, the wideband characteristic is attained and the antenna gain becomes higher than the conventional antenna by using a folded monopole structure and a parallel resonant circuit. The effectiveness of the proposed antenna is confirmed by simulations.

This paper proposes the pattern matching technique to the signal pattern of windowed B-scan data to classify the object cross-section shape. The technique applies the dynamic time wrapping to adaptively measure the similarity of the object under test and the reference object. As studied case, we consider a metallic object with three basic shapes: circle, square, and triangle. To check the generality and performance of the proposed technique, we conduct the simulations and experimental studies with an ultra-wideband impulse radar. According to the results, the proposed technique is feasible enough, and it is applicable over the wide possible environments.

Non-contact detection using a Doppler sensor has been studied for heartbeat measurement. However, Doppler sensors are affected by reflected waves from surrounding objects, making accurate acquisition of heartbeats difficult. To solve this problem, we have proposed the heartbeat sensor using of the small loop antenna with low radiation efficiency. When it is placed near subject’s heart, the antenna input impedance change according to surroundings. In this paper, we show an adaptive control algorithm of a variable matching circuit according to changes in the surroundings of the antenna. The effectiveness of the proposed method is verified by measurements for multiple persons.

Gaussian Mixture Models (GMM) are a representative method to realize clustering and are used in many applications such as probability density modeling and soft clustering. There are several methods for parameter estimation of the GMM, among which the Variational Bayesian Gaussian Mixture Model (VBGMM) is known that they are hard to overfitting. In the VBGMM, the logsumexp takes up most of the computation time. This is due to the heavy use of the exponential function, which is computationally intensive. In this paper, we explain a method to speed up logsumexp by using an approximate exponential function. As a result, logsumexp is accelerated 1.991 times faster, and VBGMM is accelerated 1.229 times faster.

Reducing the noise from the sound of train travel is an important issue in high-speed railways such as the Shinkansen. There has been no change in the shape of the antenna installed on the roof on the leading car of the Tokaido Shinkansen since the line started service, even though this is a source of the noise. Here, by changing (miniaturizing) the shape of this antenna from the standpoint of noise countermeasures, we developed an antenna that satisfied both the overhead line voltage detection performance and wireless detection performance, analyzed its performance by examination in factory and running tests, and confirmed that it can be provided for practical use. In this paper, we report a summary of the antenna, the results of the performance evaluation under environments of rain and accumulated snow, and the results of performance evaluation by running tests.

This paper presents a novel methodology for estimating the common mode (CM) current in isolated converters. We applied mode conversion theory as related to imbalance factor mismatch in transmission lines to an LLC resonant converter, and derived a theoretical equation representing the CM current by examining four operation modes of the converter. The CM current described by our proposed equation agreed closely with the results of a circuit simulation, indicating that mode conversion theory specific to transmission lines is also effective for the CM current estimation in switching converter circuits.

A novel quad-band branched monopole antenna with filters is proposed. The proposed antenna consists of a mast, two branch-elements for low-band, and two branch-elements for high-band. Lumped-element filters are loaded at the roots of the low-band elements to suppress higher-mode currents at the high-band. It is clarified by simulations that desirable VSWR characteristic can be achieved at all bands of interest if band-pass filters with an appropriate Q-factor are loaded.

Machine learning technology has been developed along with the performance improvement of CPUs and GPGPUs, and it has been used for analyses of big data. Clustering is one task of them. Gaussian Mixture Models are a representation method that realizes clustering, and widely used in many applications for probability density modeling and soft clustering. However, the parameters of a GMM need to be estimated from data. There are some methods for estimate parameters, Variational Bayesian Gaussian Mixture Models (VB-GMM) are one of them, and it is hardly to over-fitting than other methods. But, it is computationally demanding. In this paper, we explain a parallel implementation of VB-GMM by GPGPU, and its evaluation. As a result, its execution speed is 524 times faster than that of CPU implementation.

This paper presents an area- and power-efficient TX/RX-isolation switch implemented in a 3072-ch ultrasound transceiver IC. The proposed dynamic gate-source shunt topology, which utilizes a negative-HV-transmit-driven shunt switch, eliminates area- and power-hungry HV level shifters and ensures OFF during TX periods. In addition, source-driven HV-PMOS for ON/OFF control enables both gate charging and discharging using single HV-PMOS, thus contributing to area reduction. Moreover, by preparing an attenuation mode, a per-channel TX to RX self-loopback test can be performed. This function provides an on-wafer AC test without probing 3072 electrodes and can be applied to field diagnosis of assembled ultrasound probes.

To obtain information on the mechanical tolerance of soft tissue bruise injury caused by dynamic contact between human body parts and a robot, impact tests were conducted using anesthetized live pigs. A falling-weight impact tester was used to conduct tests on the chest and extremities by varying the mass and dropping height of the impactor. The subcutaneous tissues of the impacted parts were sampled, and internal bleeding, as a sign of bruising, was pathologically observed. The minimum value of transferred energy per unit area, categorized as a mechanical tolerance value for bruising, was found to be significantly smaller in the extremities as compared to the chest owing to structural differences between the two parts. These structural differences should be carefully considered for safe robot designs.