Evaluation of power output through masseter muscle potential measurement in low temperature environments

Due to a decline in the productive-age population in Japan, the shortage of human resources in the field of nursing-care have been severe. As a measure for this problem, it is necessary to maintain the quality of nursing-care services by utilizing welfare equipments. Analysing this background, the authors developed a pointing device that controlled by voluntary head movement. However, this device malfunctions in low temperature environments. The factor is the increase in electrical noise due to the decrease in environmental temperature. Therefore, in order to improve the noise resistance of electromyography sampling, bipolar induction was adopted as the method of detecting electromyography. Furthermore, in order to accurately judge the occlusion even with electromyography containing noise, the function to detect multiple clicks was equipped with the pointing device. In this study, first, the operation was tested in low temperature environments (1-5 ℃), middle temperature environments (9-13 ℃) and warm temperature environments (23-24 ℃). Next, the operation reliability influenced by environmental temperature was evaluated based on task success rate and required times. As a result, the task success rate was 95% or more regardless of the environmental temperature, and the required times was about 0.5 sec. In addition, the superimposition of electrical noise or malfunction was not confirmed. On the other hand, some participants commented that their jaws were tired and that they were not suitable for long-term operation, regardless of the environmental temperature. The reason is that the operation of the FPD required more force than the occlusion used in daily life. For this reason, it is indispensable to verify the relationship between the occlusal force and the fatigue of jaw and improve the usability of this device.