Evaluation of the relationship between masseter muscle electromyography and occlusal force in a head operated pointing device

Recently, the demand for nursing care services has been increasing in Japan due to the aging of the population. Addressing this increase in demand is an urgent issue, necessitating a qualitative shift in nursing care services. Proposals for new caregiving support measures utilizing welfare equipment are deemed effective in addressing such an issue. Thus, a Human Interface-type pointing device (Face-input Pointing Device: FPD) has been developed to promote the self-support of individuals requiring caregiving. The FPD can be controlled only by head movement, utilizing the head posture angle and masseter muscle electromyography (EMG) as control signals. However, aging may affect the operation of FPD due to a decrease in occlusal force and masseter muscle EMG potentials. Namely, investigations targeting a wide age range are necessary. In this study, the reliability of FPD operation by age group was evaluated. Test subjects were males in their 10’s to 30’s and 40’s to 50’s. In the experiment, masticatory ability (Occlusal force, occlusal pressure, occlusal contact area, etc.) measurement, masseter muscle EMG measurement and FPD operational test were conducted. The effect of aging was analyzed based on the relationship between EMG potentials and masticatory ability. In the operation test, the operational reliability of the FPD was evaluated based on the task success rate. As a result, 96.6 % of test subjects did not fall into the low occlusal force category, and task success rates were high (> 90 %), indicating that people in 10’s to 50’s are suitable candidates for FPD adaptation. On the other hand, when targeting older individuals with reduced masseter muscle EMG signals, distinguishing between EMG signals and noise may become challenging using current electromyographs. Therefore, further noise reduction measures in electromyographs for the elderly are necessary.