Some parents of non-ambulatory children are not eager to allow their children to use powered wheelchairs because of apprehension of further deterioration of their functionality and the risk for accidents. The authors think that not all but some such children could develop their ability to operate powered wheelchairs and might expand their knowledge about the circumstances and interests in them. Thus we made a prototype cart for them eventually to experience motion by themselves. Based on a 6-wheeled chassis, the two middle wheels are driven with a traction roller drive system. We had been testing this prototype with a child with cerebral palsy for one year. Acquisition of skills in pushing switches and enjoyment of motion were confirmed. However, we encountered several problems such as difficulty in rolling on a carpet and in handling due to its weight. The ability to record moving speed and operation of input devices helps rehabilitation experts to conduct quantitative performance evaluation. To solve these problems, we manufactured another prototype. The second prototype was tested with another child with cerebral palsy for one year. The problems were solved. She acquired the operation skills necessary to operate the prototype with four switch operation.

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Attendant propelled wheelchairs are driven by people who often feel necessity for power assistance while pushing them up or going down on ramps, sideslopes or curbs. We propose a novel power-assisted wheelchair with a force sensing mechanism. A DC motor and a differential gear are employed. The power assistance is controlled as if it were always operated on a solid flat ground. The control alogrithm is based on a model reference adaptive control (MRAC). A prototype was made and initially tested. It was found effective to reduce operator's driving force.

Abstract-This study develops a power assist suit (PAS) to assist laborers in agricultural work. This device is expected to reduce the strain produced by heavy agricultural work. During grape cultivation, pruning fruits in a posture, where workers have to keep their arms raised continuously, imposes a heavy burden on the workers including elderly. The objective of the PAS is to reduce the fatigue involved in the fruit pruning task by mounting a motor and spring-assisted mechanism on the suit. Quantifying the degree of fatigue reduction during agricultural work was necessary while developing the PAS. In this study, the surface electromyography (EMG), amount of energy expended, and exercise intensity were measured for motions similar to those involved in the shelf work in grape cultivation to verify the effects of reducing labor while wearing a PAS for agricultural work. The results demonstrated that the PAS developed for agricultural work could effectively reduce labor during static motions, such as maintaining postures.Index Terms-Power assist suit, agricultural work, surface EMG, energy expenditure, heart rate reserve.

This paper describes an improved micrometer electrode system for the measurements of dielectric constant, dissipation factor, and mean thickness of sheet specimens in a wide frequency range and its appplication to a series of measuring methods. The influence of the edge capacitance and the residual impedance of this electrode system has been decreased to a negligibly small amount by the adoption of a shield ring and improvements in construction of the electrode system. The characteristics of the system are easily examined by using its electrode gap fine adjustment mechanism, which is developed for a series of measuring methods. In case the varying gap immersion method is adopted, the imperfect contact between the electrodes and the specimen and the residual impedance of the system do not affect the results, even at the highest frequency. Furthermore, the measurements are limited to only the gap variations and the resonance voltage ratio, and are freed from those of the electrode gap length, the electrode area, and the specimen thickness. Therefore, the measuring and calculating processes are so simplified that they take only a few minutes for each specimen, and in a series of methods, the best results are obtained without any correction in a wide frequency range from 1 to 200 MHz. The resolution is limited by the sensitivity and stability of the adopted apparatus such as a Q meter. The accuracy reaches ±0.2% for dielectric constant and ±2% or 3 μrad for dissipation factor, respectively, even at the highest frequency of 200 MHz.