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Search Results: 1 - 10 of 513 matches for " Kojiro Matsushita "
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Virtual Reality Driving Simulation for Measuring Driver Behavior and Characteristics  [PDF]
Seyyed Meisam Taheri, Kojiro Matsushita, Minoru Sasaki
Journal of Transportation Technologies (JTTs) , 2017, DOI: 10.4236/jtts.2017.72009
Abstract: This article provides new insights regarding driver behavior, techniques and adaptability. This study has been done because: 1) driving a vehicle is critical and one of the most common daily tasks; 2) simulators are used for the purpose of training and researching driver behavior and characteristics; 3) the article addresses driver experience by involving new virtual reality technologies. A simulator has been used to assist novice drivers to learn how to drive in a very safe environment, and researching and collecting data for researchers has become easier due to this secure and user-friendly environment. The theoretical framework of this driving simulation has been designed by using the Unity3D game engine (5.4.f3 version) and was programmed with the C# programming language. To make the driving environment more realistic we, in addition, utilized the HTC Vive Virtual reality headset which is powered by Steamvr. We used Unity Game Engine to design our scenarios and maps because by doing this we are able to be more flexible with designing. In this study, we asked 10 people ranging from ages 19 - 37 to participate in this experiment. Four Japanese divers and six non-Japanese drivers engaged in this study, some of which do not have a driver’s license in Japan. A few Japanese drivers have a license and car, while others have a license but no car. In order to analyze the results of this experiment we are used MatlabR2016b to analyze the gathered data. The result of this research indicates that individual’s behavior and characteristics such as controlling the speed, remaining calm and relaxed when driving, driving at appropriate speeds depending on changes in road structures and etc. can affect their driving performance.
Development of a Driving Simulator with Analyzing Driver’s Characteristics Based on a Virtual Reality Head Mounted Display  [PDF]
Seyyed Meisam Taheri, Kojiro Matsushita, Minoru Sasaki
Journal of Transportation Technologies (JTTs) , 2017, DOI: 10.4236/jtts.2017.73023
Abstract: Driving a vehicle is one of the most common daily yet hazardous tasks. One of the great interests in recent research is to characterize a driver’s behaviors through the use of a driving simulation. Virtual reality technology is now a promising alternative to the conventional driving simulations since it provides a more simple, secure and user-friendly environment for data collection. The driving simulator was used to assist novice drivers in learning how to drive in a very calm environment since the driving is not taking place on an actual road. This paper provides new insights regarding a driver’s behavior, techniques and adaptability within a driving simulation using virtual reality technology. The theoretical framework of this driving simulation has been designed using the Unity3D game engine (5.4.0f3 version) and programmed by the C# programming language. To make the driving simulation environment more realistic, the HTC Vive Virtual reality headset, powered by Steamvr, was used. 10 volunteers ranging from ages 19 - 37 participated in the virtual reality driving experiment. Matlab R2016b was used to analyze the data obtained from experiment. This research results are crucial for training drivers and obtaining insight on a driver’s behavior and characteristics. We have gathered diverse results for 10 drivers with different characteristics to be discussed in this study. Driving simulations are not easy to use for some users due to motion sickness, difficulties in adopting to a virtual environment. Furthermore, results of this study clearly show the performance of drivers is closely associated with individual’s behavior and adaptability to the driving simulator. Based on our findings, it can be said that with a VR-HMD (Virtual Reality-Head Mounted Display) Driving Simulator enables us to evaluate a driver’s “performance error”, “recognition errors” and “decision error”. All of which will allow researchers and further studies to potentially establish a method to increase driver safety or alleviate “driving errors”.
Evaluating Hazard Response Behavior of a Driver Using Physiological Signals and Car-Handling Indicators in a Simulated Driving Environment  [PDF]
Joseph Kamau Muguro, Minoru Sasaki, Kojiro Matsushita
Journal of Transportation Technologies (JTTs) , 2019, DOI: 10.4236/jtts.2019.94027
Abstract: Road traffic accidents are a major cause of casualties and costly implications to all the stakeholders. Research focusing on the driver as one of the causal agent of accidents has been studied for centuries and with the advent of modernized driver assistance technologies. This paper sought to evaluate response of a driver using active-driving performance indicators like reaction time and physiological signal response (surface electromyogram), to understand hazard response behavior. Simulation of driving scenes was done using Unity3D engine and VR Head mounted display. The driver was presented with stimulus (collision objects) of different size and distance. From the results, an event scene that the driver considered hazardous was marked with increased electromyography response distinct from non-event scenes. From the results, we noted an increase in pedal misapplication during hazard response. The proposed approach is applicable in a real time driving analysis for on-road risk level classification.
Ohno's relation for finite multiple zeta values
Kojiro Oyama
Mathematics , 2015,
Abstract: Ohno's relation is a well-known relation among multiple zeta values. In this paper, we prove Ohno's relation for finite multiple zeta values, which is conjectured by Kaneko. As a corollary, we give another proof of the sum formula for finite multiple zeta values.
Visualization of High-Speed Impact of Penetrator into Icy Target  [PDF]
Kojiro Suzuki, Kazuya Namba, Yasumasa Watanabe
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2016, DOI: 10.4236/jfcmv.2016.42006
Abstract: For application to exploration under the surface of icy objects in the solar system, the penetration of an impact probe into an icy target was experimentally simulated by using the ballistic range. Slender projectiles with a cylindrical body and various nose shapes were tested at the impact velocity 130 - 420 m/s. The motion of the penetrator, fragmentation of ice and crater forming were observed by the high-speed camera. It revealed that the crown-shaped ejection was made for a short time after the impact and then the outward normal jet-like stream of ice pieces continued for much longer time. The concave shape of the crater was successfully visualized by pouring the plaster into it. The two-stage structure, the pit and the spall, was clearly confirmed. The rim was not formed around the crater. Observation of the crater surface and the ice around the trace of the penetrator shows that both crushing into smaller ice pieces and recompression into ice blocks are caused by the forward motion of the penetrator. In case of a body with a flow-through duct, ice pieces entering the inlet at the nose tip were ejected from the tail, resulting in relaxation of the impact force. The correlation of the penetration distance and the crater diameter with the impact velocity was investigated.
Visualization of High-Speed Impact of Projectile in Granular Sheet with Destructive Collision of Particles  [PDF]
Chihiro Masaki, Kojiro Suzuki, Yasumasa Watanabe
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2018, DOI: 10.4236/jfcmv.2018.63012
Abstract: The impact and penetration of a projectile in a particle-laden space, which are expected to have frequently occurred during the formation of the solar system and will occur in the case of an impact probe for future planetary exploration, were experimentally simulated by using the ballistic range. A two-dimensional sheet made from small glass beads or emery powder was formed by the free-falling device through a long slit in the test chamber evacuated down to about 35 Pa. A polycarbonate projectile of a hemi-sphere-cylinder or sphere shape with the mass and diameter about 4 g and 25 mm, respectively, was launched at the velocity up to 430 m/s, and the phenomena were observed by the high-speed camera at 20,000 fps. From a series of images, the bow-shock-wave-like laterally facing U-shaped pattern over the projectile and the absence of particles in the trail behind it were clearly seen. At the impact of the particles on the projectile surface, fine grains were formed due to the destructive collision and injected outward from the projectile. The images obtained by different lighting methods including the laser light sheet were compared. The effects of the particle diameter, its material and the impact velocity were also investigated.
Synthesis of Adaptive Gain Robust Output Feedback Controllers for a Class of Lipschitz Nonlinear Systems with Unknown Upper Bound of Uncertainty
Hidetoshi Oya,Kojiro Hagino
Journal of Control Science and Engineering , 2012, DOI: 10.1155/2012/902576
Abstract: We propose a new adaptive gain robust output feedback controller for a class of the Lipschitz nonlinear systems with unknown upper bound of uncertainty. The proposed adaptive gain robust output feedback controller is designed so as to reduce the effect of uncertainties and Lipschitz nonlinearities. In this paper, we show that sufficient conditions for the existence of the proposed adaptive gain robust output feedback controller are reduced to LMI conditions. Finally, the effectiveness of the proposed robust output feedback controller is demonstrated by numerical simulations. 1. Introduction Robustness of control systems to uncertainties has always been the central issue in feedback control, and therefore the problems of stability analysis and stabilization for uncertain systems have received much attention for a long time (e.g., [1, 2] and references therein). In particular, there are lots of existing results for state feedback robust control such as quadratic stabilizing control and control (see [3, 4] and references therein). Besides, some design methods of variable gain robust state feedback controllers for uncertain systems have been suggested (e.g., [5–8]). Yamamoto and Yamauchi [5] proposed a design method of a robust controller with the ability to adjust control performances adaptively. In [6], an adaptive robust controller with adaptation mechanism has been presented and the adaptive robust controller is tuned on-line based on the information about parameter uncertainties. Besides, we have proposed robust controllers with adaptive compensation inputs [7, 8]. These controllers consist of a fixed gain controller and a variable gain one, and the variable gain controller is tuned by updating laws. However, not all the states are measurable in practical systems because of technical, physical, and/or economic reasons. Therefore, the control strategies via observer-based robust controllers (e.g., [9, 10]) or robust output feedback one (e.g., [11–13]), which is of interest in this paper, have also been well studied. For robust output feedback controllers, Moheimani and Petersen [11] have presented a set of cross-coupled algebraic Riccati equations and algebraic Lyapunov equations. Geromel et al. [12] and Iwasaki et al. [13] adopted linear matrix inequality (LMI) approaches to design static output feedback controllers based on a set of the Lyapunov inequalities coupled by the constraint that one Lyapunov matrix is the inverse of another. Additionally the work of Matsuoka and Hagino [14] has presented an observer-based variable gain controller for a class
Administration of bisphosphonate for hypercalcemia associated with oral cancer
Kojiro Onizawa, Hiroshi Yoshida
Head & Face Medicine , 2006, DOI: 10.1186/1746-160x-2-9
Abstract: Sixteen hypercalcemic patients, most of whom had uncontrollable locoregional lesions and lung metastases, were studied. Nine patients had been given BP, and the rest had not.There were significant differences in age and serum ALT between the BP-treated and -untreated groups. The first administration of BP effectively and safely decreased the serum calcium level, but repeated administrations were less effective. Although the patients treated with BP survived significantly longer than the untreated subjects, the difference of the median was only about 2 weeks.The occurrence of hypercalcemia in oral cancer patients apparently implies an extremely poor prognosis, and long-term survival cannot be expected, even with BP treatment.Cancer-associated hypercalcemia (CAH) frequently occurs in patients with advanced oral cancer and indicates that the patients have entered the terminal stage of the disease [1]. Increased serum calcium (Ca) levels induce symptoms in the gastrointestinal, kidney, and central nervous systems [2], reducing the patients' quality of life (QOL). Although CAH cannot be adequately resolved without controlling tumor progression, the administration of bisphosphonate (BP) has been reported to effectively decrease the serum Ca level, and improve QOL [2-4]. Especially in the case of patients with a slow-growing tumor, such as breast cancer, BP can significantly control pain caused by bone metastasis [5]. Accordingly, BP administration might be useful to improve the QOL of CAH patients in whom long-term survival is anticipated. However, advanced oral cancers usually progress rapidly, and the average survival time after the occurrence of CAH is approximately 1 or 2 months [1,6]; thus, BP treatment might not be helpful for all CAH patients with advanced oral cancer. However, there have been few reports on the clinical effects of giving BP to oral cancer patients with CAH, so its potential usefulness is uncertain.Here we retrospectively investigated the clinical
Gain Performance for a Class of Lipschitz Uncertain Nonlinear Systems via Variable Gain Robust Output Feedback Controllers
Hidetoshi Oya,Kojiro Hagino
Journal of Control Science and Engineering , 2013, DOI: 10.1155/2013/432034
Abstract: We consider a design problem of a variable gain robust output feedback controller with guaranteed gain performance for a class of Lipschitz uncertain nonlinear systems. The proposed variable gain robust output feedback controller achieves not only robust stability but also a specified gain performance. In this paper, we show that sufficient conditions for the existence of the proposed variable gain robust output feedback controller with guaranteed gain performance are given in terms of linear matrix inequalities (LMIs). Finally, a simple numerical example is included. 1. Introduction In general, there exists a gap between controlled systems and their mathematical models. Therefore controller design methods dealing with the model uncertainties explicitly have been required, and, for linear dynamical systems with unknown parameters, a large number of design methods of robust state feedback controllers have been presented (e.g., [1] and references therein). In particular, there are lots of existing results for state feedback robust control such as quadratic stabilizing control, control (see [2, 3] and references therein). Besides, some design methods of variable gain robust controllers for uncertain dynamical systems have also been suggested (e.g., [4, 5]). These controllers consist of a fixed gain controller and a variable gain one, and the variable gain controller is tuned by updating laws. By the way, since not all the states are measurable in practical systems because of technical, physical, and/or economic reasons, the control scheme may be designed via observer-based robust controllers [6] or robust output feedback one [7], which is of interest in this paper, and these robust controllers have also been well studied. Geromel et al. [8] use LMI approach to design static output feedback controllers based on a set of Lyapunov inequalities coupled by the constraint that one Lyapunov matrix is the inverse of another. Additionally for a class of linear systems with uncertainties of which upper bounds are unknown, an adaptive robust output feedback stabilizing controller has been proposed [9]. On the other hand in recent years, much attention has been focusing upon global stabilization for nonlinear systems via output feedback control (e.g., [10, 11]). Mazenc et al. [10] have shown that, through counter examples, some extra growth conditions on the unmeasurable states of the plant are usually necessary for the global stabilization of nonlinear systems via output feedback. Additionally, some researchers have studied the control problem for a selective class
Thermal fluctuations of granular gas under HCS using two-point kinetic theory
Ryosuke Yano,Kojiro Suzuki
Physics , 2011,
Abstract: Thermal fluctuations of the granular gas under the homogeneous cooling state (HCS) are estimated using two-point kinetic theory by Tsuge-Sagara. Thermal fluctuations of the elastic gas are modified for the granular gas by nonequilibrium moments, which defines the distribution function under the HCS. The deviations of thermal fluctuations for the granular gas from those for the elastic gas obtained by the fluctuation-dissipation theorem are calculated as a function of the restitution coefficient.
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