Human friendly robots should behave as human beings as well as their appearances. This paper proposes a motion planning method that let robots' motions look like humans'. This paper deals with a very typical case that dual-arm robots execute partially restricted coordinated tasks. The proposed method derives the desired trajectories by using a cost function consists of “minimum torque change” and “degree of visibility, ” the concept, “degree of visibility” is first introduced in this paper. Several simulations and human subjects' experiences have shown that this method can derive more human like behaviors than the conventional methods. Especially, it could be recognized that the “degree of visibility” may play some important roles for human perceptions.

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It is important to realize nonverbal human interface systems using natural motions. Nonverbal human interface is useful for the improvement of friendliness in man-machine interactions. The previous research proposed a structure model for understanding nonverbal expression. The model is composed of serial relations among real motions of the players, measured data of the motions, physical motion features, linguistic motion features, and feelings and intentions of player's motions. This study focuses on computer tasks and aims at examining applicability of nonverbal expressions to human interfaces. The motion observations of experiments using subjects were conducted for three types of computer tasks. From the experimental data linguistic motion features and feelings and intentions of player's motions were extracted and relationships among them were analyzed by pattern classification and discriminant analysis. From all the obtained results in a context of computer tasks, the validity of the related structure of linguistic motion features and feelings and intentions of player's motions was confirmed. The results suggested the possibility of developing nonverbal human interface to support computer tasks.

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In the case like a cellular manufacturing which one worker attaches many parts in process of the work, there is a problem that a worker takes a long period of time till the worker memorizes the working method with using a present working instruction based on documents and OJT. The purpose of this study is an analysis about learning of the work and an acquisition of a basic knowledge of the work instruction with using characters and still pictures instead of documents and OJT. In an experiment, 12 students are examinees and they experienced an easy assembly work. At the time, characters and still pictures are shown as a direction of the work to them. The following results are obtained as to the use of characters and still pictures when these examinees need to learn the work information. (1) Time of acquisition for the work information through characters is shorter than still pictures immediately after they start to work. (2) Time of acquisition increases in proportion to growth of quantity of the work information through characters immediately after they start to work. (3) At the time on right after they start to work, accuracy of work with using still pictures is higher than characters. (4) To memorize the work information through characters is much effective than still pictures.

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The purpose of this study was to investigate the effects of dimensions of stairs and slopes on the low back load during ascending and descending. We measured the low back joint moment as one of the objective representatives of the low back load, using force plates and three-dimensional motion analysis systems. The measurements were performed on eight healthy men to create reference data for the elderly. The subjects were asked to ascend and descend six stairs and two slopes of different dimensions which were selected with references to the upper limit values of the Building Standards Act in Japan and recommended values of the Japanese Ministry of Construction. It was found that the low back joint moments during ascending and descending stairs was larger than those of slopes. Increase in riser dimensions resulted in increased low back joint moments during ascending stairs while no charge was observed with increase in tread dimensions. During descending, the low back joint moment increased only on a staircase with the upper limit values of the Building Standards Act in Japan.

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The purpose of this study was to clarify the characteristics of steering by elderly subjects and their rolling motion encountered during cycling. Ten elderly and nine younger subjects were asked to ride a bicycle along a 50m track. Experimental trials consisted of: (i) a straight run at low, medium, and high speeds; (ii) a free run on a restricted width track; and (iii) a slalom run. The steering angle, the angular acceleration of rolling, and the cycling speed were measured during the trials, and from these, the magnitude of angular acceleration during steering and rolling, the locus of cycling, and the frequency and correlation function of the angular acceleration were calculated. The angular acceleration and the width of locus of the elderly subjects were higher than those of the younger subjects in all the trials, and this was especially so at low speeds. Compared with younger subjects, elderly subjects showed poorer regularity or periodicity of steering and rolling motions. In the elderly subjects, the rolling motion was more strongly influenced by the steering motion, and no changes in steering or rolling motion were made according to the cycling conditions.

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