Motion control algorithms were proposed for a 9-DOF finger-arm robot by using the finger manipulability obtained in a previous study. However, in the previous study, only methods for achieving unconstrained movement of the finger-arm robot were discussed. In this paper, the authors propose a novel method for having a finger-arm robot complete a constrained task by integrating impedance control with manipulability control of the finger. First, methods of applying the previous heuristic method to the passive impedance control and the active impedance control were developed; and experiments were performed to demonstrate the features. Then, an impedance control combined with the steepest ascent method to modulate the manipulability of the finger was proposed. The proposed method demonstrates a strong performance even when a dynamic external force is applied to the finger. By using the proposed method, the arm actively moves along a direction to effectively maintain the moving potential of the finger during both the unconstrained and the constrained tasks.

This paper describes the effect of Muller-Lyer illusion on a reaching movement just after the visual and haptic/kinesthetic cues are simultaneously presented. First, a standard experiment on this visual illusion is conducted by means of the most typical way so as to make sure that participants can experience this illusion; the result shows that all the subjects are deceived by the illusion figure as in many previous results. As the next step, the subjects are asked to physically trace one of three lines-normal line and lines with feathers of an arrow-with the same length displayed on an LCD. After a few traces, the line suddenly vanishes, and then the subjects retrace the invisible line based on only their memory and somatic sensations. During this task, we measure the trajectory of fingertip from a start to the goal using a motion capture system. The result indicates that the Muller-Lyer illusion dominantly affects the reaching task although the haptic/kinesthetic cue was also given just before the task. Thus, this result implies that the visual illusion affects the motion planning, which partly supports a planning-motion model.

This study attempts to make a compact humanoid robot acquire a giant-swing motion without any robotic models by using reinforcement learning; only the interaction with environment is available. Generally, it is widely said that this type of learning method is not appropriated to obtain dynamic motions because Markov property is not necessarily guaranteed during the dynamic task. However, in this study, we try to avoid this problem by embedding the dynamic information in the robotic state space; the applicability of the proposed method is considered using both the real robot and dynamic simulator. This paper, in particular, discusses how the robot with 5-DOF, in which the Q-Learning algorithm is implemented, acquires a giant-swing motion. Further, we describe the reward effects on the Q-Learning. Finally, this paper demonstrates that the application of the Q-Learning enable the robot to perform a very attractive giant-swing motion.

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.

Human beings usually locate their hand at the position with a higher moving potential in order to easily deal with various situations. Inspired by the human hand-arm movement, this study proposes a motion control issue for a serial-linkage finger-arm robot according to Wf.

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.

The advancement of multimedia services including audio/visual media has been rapid. The applications of cellular phones, in particular, have increased by using these technologies. In addition, if force telecommunication were realized, force information would become a next leading factor in the multimedia service. In this field, a robotic master/slave system is a leading candidate. This system has been studied as a teleoperation system between an operator and an environment; the operator controls only the master device whereas the slave device is never controlled. For multimedia applications, such systems require flexibility and bidirectionality because force telecommunication must consider the interactions between users. This paper details the fundamental issues of force communication from a viewpoint of human perception. With regard to the control system, this study uses an integrated hybrid control master/slave system that helps to find a key factor of equal bilateral force telecommunication in the sensory aspect. The employed system has a function to change the proportion of force display to position display by varying a weight parameter. We discuss the basic control performance of a force telecommunication system and evaluate qualitative feelings of users by using a psychological evaluation method

This paper investigates the motion forms of robots generated by the Q-Learning algorithm during the learning process. We analyzed the manner in which a caterpillar robot, which performs looping motions using two actuators, acquires advance actions by focusing on the process. By observing a series of processes, we confirmed that various motion forms appeared or disappeared as a result of their interactions with the learning process and approach an optimum motion form. In most algorithms, such motion forms cannot appear in the learning process because its framework is almost predetermined by the teacher data, and the cost functions for learning cannot be usually considered as a continuous process. The characteristics of reinforcement learning are very interesting from the viewpoint of biological evolution. This paper describes the effects of the interaction between the robot kinematics and the environment as a direct result of changing the environment. In addition, this study challenged the acquisition of two-dimensional motions with a starfish robot having four actuators. The result demonstrates that the robot can obtain a reasonable motion from the complicated relationships with the environment by skillfully employing its structure. Moreover, this paper implies that the reward manipulation may give a new insight for the learning process by the investigations performed in this study. This paper examines the possibility of the reward combinations for generating arbitrary motions.

In this paper, by focusing on weight perception, we attempted to clarify a perceptual mechanism using functions of the haptic interface. We especially examined the weight perceptual mechanism when the weight of an object suddenly changed, which does not take place in our natural life. This experimental condition can only be realized by using the advantage of the haptic interface. The results show the difference in the perceptual threshold due to addition and reduction of the weight. Moreover, the results indicate that subjects can also correct the supporting force corresponding to the sudden change in the weight when they could not sense the change. Namely, it implies that subjects adjust the supporting force under an imperceptible state, which may indicate an interesting muscular motion under a state of unconsciousness.