Yuzo Takahashi

Role of metacognition to promote strategy transfer in problem solving

Metacognition affects acquisition, comprehension, retention, and application of what is learned, in addition to affecting learning efficiency, critical thinking, and problem solving. The development of an instructional method to promote metacognition can be used effectively to create an environment in which computer skills are acquired by means of the interrelationship between the user and the computer. In this study, the effectiveness of metacognition in promoting strategy transfer to acquire problem cognition and problem-solving strategies is examined.

Change of equilibrium under the influence of VR experience

The effectiveness of a virtual reality (VR) system is suggested in all cases (e.g., remote manipulation using a robot at a nuclear power plant). However, there are no guidelines on the influence of a VR system on humans. In this study, we assumed that sensory conflict was a cause of VR sickness, and the influence of a VR experience on equilibrium was examined from the points of view of stabilometry and walking. The negative effects of a VR experience were examined relative to stabilometry (static equilibrium) and a walking period (dynamic equilibrium). The experimental results showed that the mean-movement distance and the mean movement velocity of the center of pressure (COP) increased during the VR experience with a head-mounted display (HMD) for 60 minutes. It was suggested that the VR experience appeared to affect the high posture control mechanism and the VR experience caused motion sickness-like symptoms.

Evaluation of display design based on human's eye movement

In this study, the effectiveness of icon interfacing and grouping was discussed from the viewpoints of both efficiency (scanning speed) and eye movement characteristics. The icon and grouping interface was effective especially when the number of displayed stimuli increased. The analysis of eye movement data revealed that the icon and grouping interface reduced the number of fixation The grouping also reduced eye movement velocity. These two characteristics must be important factors that lead to higher efficiency of the icon and grouping interfaces. In human-computer interactions, the display design mustbe evaluate using efficiency and eye movement characteristics such as number offixation and eye movement welocity.

Evaluation of static and dynamic equilibrium before and after immersion in a virtual environment

The effectiveness of VR (virtual reality) systems is well documented, but there are no guidelines for determining the influence that such systems have on humans, particularly with regard to adaptation to the VR environment. The results of an experiment are summarized as follows: 1) A VR experience using an HMD made the integration of sensory information in the equilibrium nucleus confusing. 2) Sensory conflict caused motion-sickness-like symptoms in the subjects. 3) As a result of equilibrium deterioration, movement velocity, movement distance, and sway area of the center of pressure were increased. These results suggest that the VR experience causes motion-sickness-like symptoms and worsens equilibrium.

A pneumatic arm power-assist system prototype with EMG-based muscle activity detection

Wearable robotic assist devices need to be safe for the user. Pneumatic actuators are suitable for driving those devices because they are highly safe for humans. However, the responsiveness of pneumatic actuators is lower than that of electric actuators. In this paper, we propose an approach to muscle-burst onset detection by monitoring surface electromyogram (EMG) signals, and utilize it to trigger the actuator of a pneumatic power-assist device for the human arm. Experimental verification demonstrates the validity of our approach for detecting muscle-burst onset by EMG signals online, and the applicability of the EMG trigger for the pneumatic power-assist device.

Development of Intention Inference Algorithm Based on EMG Signals at Judging Directional of Arrow Cues

Inferring a device wearer’s intention is important for supporting devices that exert force, dexterity and sustainability. In this research, we considered a simple ON and OFF function. If one can discriminate whether an order to move a specific muscle is voluntary or involuntary when the command reaches the periphery, estimating the direction in which the supporting device assists the movement is easy. Therefore, in this study, we measured voluntary biceps brachii muscle contraction in response to a visual stimulus, with various stimulus intensities. We found that the preparation start time and the lifting start time were earlier during the condition (“right directional arrow” and “left directional arrow”) where there was high confidence in the choice to execute a forearm lift, among other available stimuli. In contrast, the center frequency of the biceps brachii muscles, at the time of preparing the lifting motion, tended to be higher. Finally, by using an algorithm to infer movement intention, it was possible to identify if the next movement comprised flexion or extension, before muscle torque generation.