筋肉の活動度に基づく力感覚量推定法の提案とアシスト技術への応用

広島大学(Hiroshima University)博士(工学)Doctor of Engineeringdoctora

Force perceptual bias caused by muscle activity in unimanual steering.

This study sought to investigate whether force perceptual bias was affected by differences in posture while steering an automobile using a psychophysical experiment to examine the relationship with muscle activity. The human perceptual characteristics of weight and force are known to be nonlinear, and a perceptual bias can occur, that is, bias that causes a perception of something that is larger or smaller than the actual scale. This is considered to be caused by physical and/or psychological conditions. Sense of effort is believed to be one influential factor. It is known to correlate with muscle activity intensity, and bias may be caused by muscle activity changes. In the current study, we hypothesized that force perceptual bias would depend on posture due to the intensity of muscle activity changes caused by changing postures during steering operation. By investigating this hypothesis, we can clarify the relationship between sense of effort and muscle activity. To investigate this issue, we conducted a psychophysical experiment to confirm postural dependence, and estimated muscle activity using a three-dimensional musculoskeletal model simulation with postural and arm force data during the experiment. In addition, prediction of bias was conducted based on a simulation in the psychophysical experiment using these data. The results revealed that bias existed, as measured by differences in postures. Additionally, a significant moderate correlation was found between the predicted bias and the actual bias, indicating the existence of a relationship between muscle activity and bias

Development of New Soft Wearable Balance Exercise Device Using Pneumatic Gel Muscles

Decreased ability to control posture is correlated with the risk of falls among older individuals. In particular, reactive postural control ability response to even small perturbations is important for fall prevention of older individuals. The current study sought to design a new wearable assistive device for improving balance function by generating small perturbations using pneumatic gel muscle (PGM). Furthermore, we investigated the effects of using the proposed device for balance training. The proposed wearable balance exercise device utilized PGMs possessing various features, such as a lightweight design and the ability to generate small perturbations with a small power source. We investigated the effects of the device on reactive postural control exercises. Seven healthy participants participated in this study. Three-dimensional acceleration data (Ax, Ay, and Az) were measured from participants during a single leg stance in each session. The peak Ax value generated by perturbations and responses significantly differed from baseline peak acceleration. The peak Ay value caused by perturbations was significantly decreased compared with baseline peak acceleration. In addition, the root mean square Ax value of the post-test significantly decreased compared with the pre-test value. Our results revealed that the proposed wearable balance exercise device was able to create small perturbations for assessing reactive postural balance control. Furthermore, the device was able to improve users’ stability