A new ultrasonic urine sensor is developed for measuring the urine accumulation in the human bladder. Intensive observations are made on the bladder expansion process under the gradual accumulation of urine by using a magnetic resonance imager. It is observed that the primary changes in shape take place at the top and very small changes occur at the bottom. These findings help to establish a simple and yet reasonable mechanism for the bladder measurement because the variations in the height of the bladder can be easily ascertained with a proposed PD index in terms of the application of ultrasound beams. The principle of measurement is evaluated in a clinical test and a strong monotonic tendency is identified between the urine accumulation and the proposed PD index. Design of the new ultrasonic urine sensor is then conducted and further experimental tests are carried out with the apparatus developed. It is found that the new ultrasonic urine sensor can really display a very good indication of the urine accumulation in the bladder. The new ultrasonic urine sensor is already commercialized and has received high appraisal from a great number of users. It is characterized by non-invasive measurement, small volume, low weight and affordable price, thereby permitting easy access by various patients including older adults.

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Many reports indicated that children with developmental dyslexia have distinctive disorder in reading ability, however, there are no studies to investigate such ability based upon the characteristics of quantitative measurement in reading single character. Purpose of this study is to develop an effective method to evaluate the reading ability quantitatively. Specifically, we built a system to precisely measure the voice onset time (VOT) for hiragana characters. Here we report the results of VOT measurements in both normal and dyslexic populations. A total of eight children with dyslexia, eight healthy children and 15 healthy adults participated in the study on informed consent basis. Characters independently composed of syllabic sounds (non-contracted and contracted sounds, 106 characters in total) were chosen as the target data sets. The system automatically detected each pause and VOT and determined the time length of pronunciation in milliseconds. As a result, the time to pronounce a single character by the children with dyslexia was significantly longer than that by the healthy children and adults. The difference in VOT between non-contracted and contracted sounds suggested that the phonetic difference may affect the VOT. In conclusion, our proposed system can evaluate the reading ability for dyslexic children and it also demonstrated the effectiveness to organize the optimal strategy for improving their reading ability.

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In Japan, a research project was carried out with blind subjects from 1996 and 2000 in order to standardize Tactile Walking Surface Indicators (TWSI's) patterns. As a result of the project, JIS T 9251 “Dimensions and patterns of raised parts of tactile walking surface indicators for blind persons” instituted in 2001. However, the JIS T 9251 concerns only Foot-sole for many reasons, and does not take into consideration the usage of white canes. Detection and recognition of TWSI's by white cane are important for safe movement of blind persons, and ensuring of these is required.
This research has been conducted to measure the ease of detection and recognition of TWSI's by white cane, based on the systematic research from 1996 to 2000. Our results proved that the white cane can easily detect 5 mmhigh JIS blocks and this analysis system has the scientific grounds.

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This paper presents a user-friendly hand haptic interface to recognize surrounding obstacles around the user such as elderly or visually impaired for one's safe walk. The system is implemented on a joystick with force feedback mounted on a walker. The user is able to recognize the surrounding information by perceiving repulsive force with hand, generated in a feedback while manipulating the joystick. To build up the system, a virtual potential field corresponding to the distance and direction to the obstacle is employed. Through the experimental results, it is found that the practice time of the user who learns basic operation of the system is sufficiently short. Furthermore, the user feels the sense of security while recognizing the surrounding information through the hand haptic interface.

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We think practicing walking pattern over and over makes walk-handicapped people break plateau. For practicing walking pattern easily, a Locomotion Interface (LI, for short) can be used. LI is a piece of equipment that can give a user the sense of walking while his/her actual position remains localized in the real world. An LI system named GaitMaster3 (GM3) is developed that has two footpads, which can move to present a virtual terrain for each foot. A new gait-rehabilitation program is developed in which the footpads on the GM3 follow a motion sequence to move the user's foot, the user mounts on the GM3 and iteratively experiences the motion for each foot. We conducted a 2-month experiment with the assistance of a handicapped person. The effectiveness of our system was verified through EMG, video analysis, average walking velocities and ADL.

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This paper describes a novel method to estimate varying periods from noise corrupted quasi- periodic bio- signals. Here an observer based on the biological mathematical model named Lotka- Volterra prey- predator equations is presented. The equation can express oscillations with different periods under constant coefficients in the equations. Mathematical properties of the model are summarized and a guideline of how to build a biological model for estimating the periods is shown. Simulations to estimate the periods for the heart- beat signals corrupted by noises were carried out and the accurate periods of the signals were estimated. The periods estimated by the proposed observer from the noisy heart- beat measured by the pneumatic method showed better results than those by the conventional method.

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This paper deals with an on-line design method of compensation law for constrained linear systems. By employing a generalized singular value decomposition of linear systems, an on-line compensation law is derived. The feature of resulting compensation law is illustrated with numerical examples.

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Static friction is a typical nonsmooth phenomenon, and the input deadzone is a specific nonlinearity in an actuator. Both static friction and the input deadzone degrade the performance of control system. In this research, we discuss a controller design for compensating static friction with a backstepping method and an unknown deadzone with an adaptive method. Moreover, the stability proof based on the nonsmooth system analysis is given. The key idea is to compensate the nonsmooth term with the smooth controller and to treat the deadzone as an input-dependent disturbance. The simulation results show the effectiveness of the designed controller for unknown deadzone.

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In this paper, we consider a class of uncertain dynamic systems with unknown input nonlinearities. It is assumed that the input nonlinearities can be divided into unknown parameters part and bounded disturbance part. A robust adaptive control method which based on notion of H∞ optimality is shown. As a result, proposed control strategy does not include the discontinuous function, therefore, it can overcome the problems that the discontinuous function may cause a high-frequency fluctuation or a chattering phenomena. For the practical applications, projection algorithms method is also applied to the proposed strategy. Experimental results are shown to illustrate the effectiveness of our proposed method.

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In this paper, we present an optimal dynamic quantizer in terms of the output approximation, i. e., a difference equation based quantizer which gives an optimal output property in a given feedback control system. The quantizer allows us to design controllers of the discrete-valued input systems by the conventional methods for the usual linear systems. First, we derive an optimal dynamic quantizer and a closed form expression for the performance limitation. Then, the effectiveness of the proposed dynamic quantizer is demonstrated by a numerical example.

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In steel manufacturing processes, it is extremely important to control the temperature of products for acquiring required quality. In order to precisely control the temperature of steel plates at water-cooling process after hotrolling, it is necessary to know correct values for heat transfer coefficients. Those coefficients, however, are functions of cooling conditions such as plate temperature and cooling water flux, and it is usually difficult to calculate them directly from operational data observable on site. In this paper, a new approach is presented to estimate heat transfer coefficients at water-cooling process of steel plates, by combining parameter search with simulated annealing method and heat transfer calculation. Basic evaluation of this approach is conducted by using actual operational data.

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Some literature asserts that uncontrollable linear periodic systems can be decomposed into controllable and uncontrollable parts through appropriate state-space transformations and that the transformation matrices can be chosen to be a periodic function with the period of the systems. This paper points out that the assertion is not valid. A simple counterexample for the assertion is exhibited.

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