This study evaluates the mental fatigue induced during VDT tasks using event-related potential (P 300). Since the waveform peak is not clear in the measurement of P 300, there exists a case when it is difficult to detect the amplitude and the latency. The removal of the noisy waveform based on the cross correlation between the grand average and each waveform was found to be effective for peak detection. Mental fatigue was evaluated by parameter extraction methods using a principal component analysis or temporal changes of cross correlation between the grand average and each waveform. As a result, the P 300 b component and the standard deviation of the time lag between the grand average and each waveform obtained using cross correlations were found to be effective indices that reflect mental fatigue (decrease in the cognitive information processing function).

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The purpose of this research is to show the chaotic features of rhythmic joint movement using a reconstructed phase portrait, fractal dimension, and first Lyapunov exponent. The subjects were ten male students who were right-handed. Right elbow angle during rhythmic joint movement was measured by a goniometer. Pacing was provided for ten periodic intervals (ranged from 0.5 to 1.4s in steps of 0.1s) and preferred tempo (personal tempo). All trials were recorded for 20s. When the frequency of the pace increased, both fractal dimension and first Lyapunov exponent tended to increase. The first Lyapunov exponents were positive for all values of the observed data. These results indicate that there is chaos in rhythmic joint movement and that the larger the frequency, the more chaotic the joint movement becomes. Moreover, five right-handed and five left-handed subjects conducted single-forearm movements for the left arm and the right arm separately. As a result, fractal dimension and first Lyapunov exponent for the data of elbow joint angle in dominant hand were higher than that in non-dominant hand.

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Learning process of manual assembly task is ever becoming a serious problem under the situation where a small lot size, various types of products and short product life is becoming common in assembly processing industry. The objective of this paper is to propose a conceptual guideline for work design to promote acquiring operational information. By taking the operational task of “pick and place simple objects from shelf bins” as operational model, an experiment is conducted to consider the combination of three essential operational information as experimental factor. From the results of analysis, three findings proposed for the guideline are as follows; (1) It is rather effective to devise three operational information presenting method compared with introducing partial automation of information presenting method or equipment. (2) In case of devising two operational information presenting method, the combination of supply position information and assembly point information should be avoided. (3) In case of devising only one operational information presenting method, supply position information should be selected.

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In daily personal communication, nonverbal expression plays an important role. It is crucial to build nonverbal human interface systems for realizing a friendly information environment. In the future, computer will understand real human motions, and create human mimetic motions in CG, ie., Virtual mannequin, for interactive conversations. A structural model for understanding nonverbal expression in communication was proposed. This model is composed of a functional combination of real motions, measuring data of the motions, physical motion features, linguistic motion features and feelings of player's motions. Focusing on head motions in human communication, experiments of motion capturing were conducted in a laboratory, and motion feature indices were extracted from the sequential motion capture data. The video images of human body motions were used for questionnaire surveys. From the results of questionnaire surveys, the linguistic motion features and the feelings of player's motions were extracted. Relationships among the motion feature indices, the linguistic motion features and the feelings of player's motions were analyzed by multivariate analyses. From all of the obtained results, validity of the mathematical approach was verified according to the proposed structure model and the analyzing methods. Then this result shows the potential of developing nonverbal human interface technology by this framework.

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