Sawako Nakajima

A Preliminary Study of MR Sickness Evaluation Using Visual Motion Aftereffect for Advanced Driver Assistance Systems

Mixed reality (MR) technologies have recently been explored in many areas of human-machine interface (HMI) such as medicine, manufacturing, entertainment and education. However MR sickness, a kind of motion sickness is caused by sensory conflicts between the real world and virtual world. The purpose of this paper is to find out a new evaluation method of motion and MR sickness. This paper investigates a relationship between the whole-body vibration related to MR technologies and the motion aftereffect (MAE) phenomenon in the human visual system. This MR environment is modeled after advanced driver assistance systems in near-future vehicles. The seated subjects in the MR simulator were shaken in the pitch direction ranging from 0.1 to 2.0 Hz. Results show that MAE is useful for evaluation of MR sickness incidence. In addition, a method to reduce the MR sickness by auditory stimulation is proposed.

A soft metal hydride actuator using LaNi 5 alloy and a laminate film bellows

Rehabilitation systems and assistive technology devices for people with motor disabilities caused by stroke or the aging process require a human-friendly actuator that is soft, compact, slow, noiseless, and environmentally benign. In order to realize these kinds of actuators, we designed a soft metal hydride (MH) actuator using a copper-coated LaNi5 alloy and a laminate film bellows. For the purpose of this study, we selected a suitable LaNi5 alloy and developed a soft and light end-effector for the soft MH actuator. As a result of experimental tests, the LaNi5 alloy that has a low plateau pressure at room temperature performs well for the MH actuator. Moreover, the end-effector applied to the soft bellows made of an aluminum laminate film is 20 times lighter and 30 times longer than the metal bellows used in a conventional MH actuator. These findings support the efficacy of the soft MH actuator using the LaNi5 alloy with low plateau pressure and laminate film bellows for the purpose of developing a portable rehabilitation system or a wearable force feedback device in virtual reality.

Preliminary design of a simple passive toe exercise apparatus with a flexible metal hydride actuator for pressure ulcer prevention

In an aging society, social demands for home-based rehabilitation and assistive technologies by healthcare and welfare services are globally increasing. The progress of quality-of-life technologies and rehabilitation science is a very important and urgent issue for elderly and disabled individuals as well as for their caregivers. Thus, there is a substantial need to develop simple bedside apparatuses for both continuous exercise of joints and for power assistance for standing to prevent and manage disuse syndromes (e.g., pressure ulcers, joint contractures and muscular atrophy). Unfortunately, there are currently no commercially-available actuators compatible with the human requirements of flexibility, quietness, lightness and a high power-to-weight ratio. To fulfill the above demands, we have developed a novel actuation device using a metal hydride (MH) alloy and a laminate film, called the flexible MH actuator, as a human-friendly force generator for healthcare and welfare services. In this paper, we show the basic structure and characteristics of the flexible MH actuator used to create a passive exercise system for preventing disuse syndromes. To evaluate the efficiency of passive exercise for bedsore prevention, subcutaneous blood flow during passive exercise at common pressure-ulcer sites is measured by a laser blood flow meter. The force and range-of-motion angle required for a passive exercise apparatus is also examined with the help of a professional physical therapist. Based on these findings, a prototype of a passive exercise apparatus is fabricated using the flexible MH actuator technology, and its operation characteristics are preliminarily verified using a thermoelectric control system.

Proposal of reduction method of Mixed Reality sickness using auditory stimuli for advanced driver assistance systems

Mixed Reality (MR) technologies have recently been explored in many areas of Human-Machine Interface (HMI) such as medicine, manufacturing, entertainment and education. However MR sickness, a kind of motion sickness is caused by sensory conflicts between the real world and a virtual world. The purpose of this paper is to find a method to reduce MR sickness based on MR technology with a Head-Up Display (HUD). This MR environment is modeled after advanced driver assistance systems in near-future vehicles. In this paper, a relationship between auditory stimuli and equilibrium function after whole-body vibration related to MR technologies is evaluated. The seated subjects in the MR simulator are shaken in the pitch direction at 0.2 and 2.0 Hz. Consequently, it is shown that auditory modulation is useful for diminishing postural instability. Moreover, we discuss what type of auditory stimuli is most efficient to reduce MR sickness by changing the sound level and exposure timing.

Surplus heat drive actuators using MH alloys for assistive devices

A metal hydride (MH) actuator that uses the reversible reaction between the heat energy and mechanical energy of a hydrogen absorbing alloy is characterized by its small size, low weight, noiseless operation and mechanical compliance. Though the moving speed of the MH actuator is slow, this actuator is a suitable as a power source for rehabilitation or assistive devices. Prototype assistive devices using the MH actuator were reported, such as a wheelchair with a seat lifter and a robotic transfer aid to assist sit-to-stand motion. The main characteristic of the MH actuator includes a heat drive. This allows the MH actuator to be driven by surplus heat present in the surrounding environment. When only a high-temperature heat source is available, the surplus heat drive of the MH actuator requires rapid hydrogen absorbing to the MH alloy. This paper describes the means to improve the hydrogen absorption characteristics of the MH alloys. Three compositions of MH alloys were tested. One of these alloys obtained sufficient hydrogen absorption under natural cooling of the MH module. This means that the surplus heat source provides repeating absorption and release of hydrogen on the MH alloy. Maintaining this cycle forms an MH air compressor in which the air pressure is produced by converting the hydrogen pressure in the MH actuator. The advantages of this air compressor are that the small size and easily altered shape have the potential for the realization of unprecedented assistive technology devices for persons with disabilities.

A Preliminary Study of a Power Assist System for Toe Exercise using a Metal Hydride Actuator

In an aging society, there is concern that the population of bedridden elderly people will increase due to diseases and injuries such as cerebral strokes and bone fractures. From this social background, we have been developing a power assist system using a soft MH actuator for home health care to help prevent disuse syndromes. The soft MH actuator, which uses a laminate film bellows, has suitable properties for use as home-based motor rehabilitation equipment. To examine the preventive effect on bedsore formation of a passive motion exercise machine, we measured the skin blood flow of the lower limb. Results have shown a significant blood flow increase at sites frequently associated with decubitus ulcers. Thus, passive motion at toe joints may be useful for the prevention of disuse syndromes. Furthermore, we demonstrate a prototype of a power assist system using the soft MH actuators electrically controlled by Peltier devices. This system has performed moderate slow extension and flexion motion for toe joints. The soft MH actuator seems to provide a key solution to develop a human-friendly power assist system for motor rehabilitation and quality-of-life technology.

Development of a metal hydride actuator driven only by solar heat

A metal hydride (MH) actuator provides mechanical work by applying the hydrogen pressure transition that originates from the reversible reaction of the MH alloy as it absorbs and desorbs hydrogen gas. The MH actuators that have been reported employ a Peltier element or an electrical heating resistance wire as a heat source. This paper describes the design of an MH actuator that is driven by low-quality heat sources, such as solar heat. A certain composition of a LaNi5-based alloy that produces desorbing and absorbing reactions through a low-temperature difference is specified. This alloy composition can provide a large amount of hydrogen desorption using solar heat and a large amount of hydrogen absorption by natural air cooling in an adequate reaction time. To improve the moving speed and to control the performance, a reciprocating air compressor that applies this solar heat-driven MH actuator is proposed. These findings support the efficacy of an MH actuator operating without electric or fossil fuel energy consumption.

Public health information and statistics dissemination efforts for Indonesia on the Internet

Objectives To elucidate current issues related to health statistics dissemination efforts on the Internet in Indonesia and to propose a new dissemination website as a solution. Methods: A cross-sectional survey was conducted. Sources of statistics were identified using link relationship and Google™ search. Menu used to locate statistics, mode of presentation and means of access to statistics, and available statistics were assessed for each site. Assessment results were used to derive design specification; a prototype system was developed and evaluated with usability test. Results: 49 sources were identified on 18 governmental, 8 international and 5 non-government websites. Of 49 menus identified, 33% used non-intuitive titles and lead to inefficient search. 69% of them were on government websites. Of 31 websites, only 39% and 23% used graph/chart and map for presentation. Further, only 32%, 39% and 19% provided query, export and print feature. While >50% sources reported morbidity, risk factor and service provision statistics, <40% sources reported health resource and mortality statistics. Statistics portal website was developed using Joomla!™ content management system. Usability test demonstrated its potential to improve data accessibility. Discussion and conclusion: In this study, government’s efforts to disseminate statistics in Indonesia are supported by non-governmental and international organizations and existing their information may not be very useful because it is: a) not widely distributed, b) difficult to locate, and c) not effectively communicated. Actions are needed to ensure information usability, and one of such actions is the development of statistics portal website.

Evaluation of Mixed Reality Sickness by Changing the Time Lag between Real Images and Virtual Images in an Advanced Driver Assistance System

Mixed Reality (MR) technologies have recently been explored in many areas of Human-Machine Interface (HMI) such as medicine, manufacturing, entertainment and education. However, MR sickness, a kind of motion sickness, is caused by sensory conflicts between the real world and the virtual world. The purpose of this paper is to determine a method to reduce MR sickness associated with MR technology with a Head-Up Display (HUD). This MR environment is mod- eled after advanced driver assistance systems in near-future vehicles. In this paper, we evaluate the influence of the delay time between real images and virtual images derived from image processing in a MR system on equilibrium function and activity of the autonomous nervous system (respiration). The seated subjects in the MR simulator were shaken in the pitch direction at 0.1, 0.2, 0.4, 1.0 and 2.0 Hz and presented with 10- min MR simulations at three delay times: about 66 ms, 133 ms and 200 ms. We discovered that the biological effect of the MR environment increases or has peak shift as the delay time be- comes larger. This tendency is particularly strong in the range of low frequencies, under 0.4 Hz or 1.0 Hz.