Abstract
This study deals with an evaluation method for mental workload using the heart rate variability, especially for the RSA. RSA as an index of mental workload has to be considered to the effect of both frequency and volume of the respiration. In this study, as we need to remove the effects to improve the precision of evaluation, we consider the relationship between RSA and respiratory volume in one cycle of natural respiration. At the result, it is found that the effect of these factors is canceled. Finally, it is shown that there is a possibility to evaluate the mental work load by using of this method.
