Tomoaki Hayasaka

Gait Analysis for Detecting a Leg Accident with an Accelerometer

We analyzed an acceleration pattern during natural walking and walking hampered by wearing weights to predict falls. These two types of walking could be distinguished with a peak at the half of the principal frequency of the gait in anterior movement. We measured walking while wearing each individual hampering weight and then analyzed. The peak was bigger when a subject wore the hampering weight that was restrictive and made the body unbalanced. As leg accidents are considered to occur with a change of the body balance, our system may be used to detect a leg accident by checking the peak at the half of the principal frequency of the gait in anterior movement

Development of a wearable surveillance system using gait analysis

An aging society is a reality in developed countries. An aging population requires more healthcare workers and facilities. To reduce this social problem, it is worthwhile to develop a wearable computer for elders or patients to watch over them. In this study, we developed a wearable computer, in which accelerometers were installed to detect variations of posture, falls, and gait disability. The advantages of this system include a designated database server in each patients home, scalability and flexibility to adapt to patients needs, and full patient access to their own information. As a first step, we adopted this system for healthy young volunteers with or without impediments to validate the system. The results show that this system can successfully detect variations in posture and falls. We also succeeded in real-time automatic gait analysis by using the Hampering Index. The present study gives useful knowledge for the development of a wearable computer to support the care of elders or other patients.

Development of hands-free operation interface for wearable computer-Hyper Hospital at home

We have been developing a network-based care supporting system called the Hyper Hospital. The Hyper Hospital is constructed on the computer based network whose interface is the virtual reality dedicated to the patients. As a part of the progress, we have been developing a wearable computer which enables a care-givers to operate various support devices connected to the network. In the process of study, we found that hands-free operation of the wearable computer is important for the care workers to keep continuous physical care works while accessing to the computer. In this paper, we proposed a method of the hands-free interface to utilize the ocular potential generated by dipolar potential of eyeball and carried out fundamental experiments to assure a usability of this method.

Virtual Chameleon - A System to Provide Different Views to Both Eyes

Some species of reptile, herbivore and fish are capable to independently control both eyes and perceive images of surrounding environment for watching predatory behaviors or avoiding dangers. Among them, chameleons can locate the prey with large and independent saccades of the highly mobile eyes. In contrast, Human cannot control both eyes independently except for convergences or divergences, and cannot perceive independent view fields for both eyes because motor system and cognitive functions of the human differ from those of chameleons. It is not clear, however, whether this is due to just the control mechanism of the eyes or due to total vision processing system. Then we assumed that the human becomes able to perceive the images for both eyes and control visual axes with an appropriate support. In this paper, we describe a system to provide two independent view fields to both eyes of human by combining two CCD cameras independently controlled and a head-mounted display. This system was composed of a camera positioning system, a 3D tracking system, and a display system. The camera positioning system controls views of two platforms equipped with CCD cameras independently. Desired angles were computed from coordinates of three-dimensional positions sampled by 3D tracking system. Position sensors of the tracking system were set on the fingers of both hands of the user. Visions taken by CCD cameras were projected onto the head-mounted display, which was equipped with two independent monocular display modules ahead of right and left eye. The system was examined by twelve volunteers. Eleven users became able to control two different view fields independently after some practice. Through the trial use, it was thought that the system has the capability to be used for the study of visual perception and to have some practical applications.

Development of automatic respiration monitoring for home-care patients of respiratory diseases with therapeutic aids

A number of patients are suffering from respiratory diseases, such as dyspnea, sleep apnea syndrome (SAS), asthma and chronic obstructive pulmonary disease (COPD). These patients can be supported by early detection of symptom and administration of mild treatment. However, it is a serious burden for them and their family to care for their respiratory conditions in daily life. In this context, we have proposed a new home-care system for such patients. The system is an automatic nebulizer control system based on continuous respiration monitoring. We employ a mask-type unit to install a measurement sensor for respiration together with a nebulizer. Respiration is monitored using a thermocouple in the mask. Respiratory rate is measured by counting peaks of temperature change due to expiration and inspiration. In addition, a capacitance microphone is positioned into the same mask to detect the sound of cough. We confirmed that the proposed system could measure respiratory rate accurately and detect the change of respiratory condition and the cough. We also confirmed that nebulizer was controlled based on the obtained respiratory information and the respiratory information could be shared with medical doctors and family through a computer network.

A Fundamental Evaluation of Human Performance with Use of a Device to Present Different Two-Eyesight Both Eyes

To investigate the flexible adaptation of the human visual system, we developed a system, “Virtual Chameleon”, that provides a human user with the artificial oculomotor ability to control their eyes independently. Virtual Chameleon consists of two independently controlled CCD cameras and a head-mounted display. We performed fundamental experiments to evaluate adaptation to the use of Virtual Chameleon and its effects on the user’s visual capabilities. Eleven healthy volunteers (18-44 years old) with normal or corrected-to-normal vision participated in the study. We obtained accuracy rates and response times while using Virtual Chameleon, as well as without it. The results showed that all volunteers were able to actively control independent visual axes and correctly understand two different fields of view while using Virtual Chameleon. However, providing two independent fields of view led to binocular rivalry in volunteers, which reduced performance compared to the control case. These results raise interesting questions on adaption to two independent fields of view.

A portable device to represent different views to both eyes

To investigate the flexible adaptation of human visual system, we developed a system to provide different view fields to both eyes of a user respectively. The system named “Virtual Chameleon” consists of two CCD cameras independently controlled and a head-mounted display was used by twelve healthy volunteers. Eleven of them became able to independently control visual axes and understood two different views. The successful users of the system were able to actively control visual axes by manipulating 3D sensors held by their both hands, to watch independent view fields presented to the left and right eyes, and to look around as chameleons do. The results raise interesting question on adaption to provided two independent view fields.

Towards Computational Biomechanics Based Cardiovascular Medical Practice

Some of our recent fundamental computational biomechanical studies of the cardiovascular system, from modeling aortic flow to the microscale dynamics of the platelet, are discussed. It is emphasized that a living system inherently needs multi-scale, multi-physics analysis, and the rapid advancement of the biological sciences must also be incorporated in computational biomechanics studies. Based on these efforts, it is now expected that a computational biomechanics-based software system that can be applied to real clinical situations will be developed for the cardiovascular system. This will help medical practitioners to accumulate the fundamental data and clinical experience that they obtain from real patients, and use it to make quantitative predictions.

Development of a system to provide different fields of view to eyes with a function to generate rapid movements

We developed a system that provides a human user with the artificial oculomotor ability to control their eyes independently, which was named Virtual Chameleon after Chameleons. Virtual Chameleon consists of two independently controlled CCD cameras, a 3D tracking sensor system and a head-mounted display. The Virtual Chameleon control independently postures of two cameras to follow the sensors of the 3D tracking system smoothly. The successful users of the system were able to actively control visual axes by manipulating 3D sensors held by their both hands, to watch independent view fields presented to the left and right eyes, and to look around as chameleons do. Although it is thought that those independent fields of view the user of Virtual Chameleon corresponds to smooth movements on human eye movements, the system did not have functions to control angles of cameras rapidly in way corresponding to saccadic eye movements and compensatory movements as numerous animals including human do. In this paper, we implemented functions to control angles camera rapidly corresponding to saccadic eye movements in Virtual Chameleon, and we performed fundamental experiments to evaluate effects on the users visual capabilities.

Sustainable patient information network (SPaIN) for primary care health center in Indonesia

Sustainable patient information network for primary care health center is needed for Indonesia. There are many of remote, isolated or urban area, which causes transportation problems and telecommunication problems, for example: necessity of wireless infrastructure. The Internet and its free software is the main agent for this system combining with information and communication technology. We develop low speed communication system to access the Internet using Internet radio packet and used PostgreSQL data base server on Linux machines. Our development is based on a data base managing system called automatic distributed synchronizing data base system. This system connects every health center to each other and avoid central data storage which common use in this day. It is a good opportunity for developing country such as Indonesia to use open free software. And radio packet communication uses radio media is no connection charge like telephone line for data communication. A general practitioner in remote and isolated area can get assistance from a specialist in one urban area using email. The study opens perspective for a further data storage, distribution, synchronizing, maintenance and security.