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Biomedical subjects

Hideyuki Takagi

Publications and source records attributed to Hideyuki Takagi.

4 recordsLinked to original sources
PubMed2005

Proposal for a framework for optimizing artificial environments based on physiological feedback.

We propose and then evaluate a new framework for finding the physical parameters of an artificial environment which give rise to given target physiological characteristics. We assume that a human is a system that takes as inputs the physical parameters of an artificial environment and outputs physiological parameters in response. We define our task as the inverse problem; we must find the best inputs from given target outputs. Our proposed framework solves the inverse problem using evolutionary computation techniques to optimize an artificial environment. We evaluate this framework using a simulation with a vibration environment and verify that it works.

Environment, Controlled↗
PubMed2005

Improving the performance of predicting users' subjective evaluation characteristics to reduce their fatigue in IEC.

Users' fatigue is the biggest technological hurdle facing Interactive Evolutionary Computation (IEC). This paper introduces the idea of "absolute scale" and "neighbour scale" to improve the performance of predicting users' subjective evaluation characteristics in IEC, and thus it will accelerate EC convergence and reduce users' fatigue. We experimentally evaluate the effect of the proposed method using two benchmark functions. The experimental results show that the convergence speed of IEC using the proposed predictor, which learns from absolute evaluation data, is much faster than the conventional one, which learns from relative data, especially in early generations. Also, IEC with predictors that use recent data are more effective than those which use all past data.

Fatigue↗
PubMed2004

Virtual reality environment design of managing both presence and virtual reality sickness.

It is difficult to design the Virtual Reality (VR) Environment which controls VR sickness and promotes presence. This is because the relationship between the user's susceptibility to VR sickness and a sense of presence, determined by velocity and visual angle of the visual information, involves a trade-off between the two. Then we propose the optimal value search system which computes efficiently the velocity and visual angle which control VR sickness and do not impair presence by taking account of a subject's characteristic. Under certain experimental conditions, some subjects showed serious VR sickness whose simulator sickness questionnaire total score was more than 60 and needed more than 30 minutes to recover from VR sickness. However, on the condition of angular velocity and visual angle computed by our proposed method, all subjects felt their vection, which was our index for the sense of presence, over 70 percent of their experiment time; no subject needed more than 5 minutes to recover from VR sickness.

Adult↗