This paper discusses human weight perception using a haptic device. The objective of this study is to reveal the characteristics in human force sensations, which are difficult to examine in a real environment. Further, we aim to apply the perceptual mechanisms to multimedia applications as the final target. In this study, we particularly examine the weight discriminative powers for various weight changes. Expanding our previous study, we compare the difference thresholds for the weight addition and removal during a goal-directed lifting. A statistical analysis implies that our weight discriminative power for the weight addition tends to improve in the deceleration process. As for the weight removal, the weight discriminative power declines in the deceleration process due to the inertia effect in the vicinity of the target height. In addition, this study tries to reveal the weight perception when the load force is gradually changed. The result implies that the time variation in the load force holds the tremendous potential to enable us to experience attractive force sensations and haptic illusions.

The main purpose of this study is to apply the mechanism of human weight perception to multimedia applications. When a start and the goal points are given in the human motion, the velocity profile has a unimodal profile including the acceleration and deceleration zones. In such case, it is widely said that the motion control becomes more accurate in the deceleration zone for the final approach. Hence, it is assumed that the sensing ability also improves. This study challenges to confirm the hypothesis with weight stimuli generated by a force display device. As a preliminary experiment, this study confirms that our device enables the evaluation of human perception by tracing Weber's experiment in virtual reality; the obtained difference threshold (DL: Differenz Limen) almost agrees with the previous results. The difference threshold is a very important factor, which means perceptual threshold for weight changes. We further attempt to clarify the mechanism of the human weight perception for sudden weight changes during the lifting process. Based on individual lifting profiles, this study suddenly changes the load force in the two zones, and examines the difference thresholds of each subject. The results demonstrate that the human weight perception tends to become more sensitive in the deceleration zone during the lifting process. These results also imply the effectiveness of force display devices for physical experiments.