Hikaru Inooka

Non-restricted measurement of walking distance

Vertical walking distance is discussed. The horizontal distance is estimated by using the three dimensional acceleration of the subjects toe. Considering the movement of the foot, it is assumed that only the pitch angle of the foot changes and that the velocity of the foot is never negative. A three dimensional accelerometer is fixed to the subjects toe and measures the acceleration during the swing phase of the foot. A piezoelectric gyro is used to estimate the angle of the foot and to calculate its horizontal acceleration. The horizontal distance is obtained by integrating the horizontal acceleration twice each step. The vertical distance is calculated by integrating the change of atmospheric pressure during ascent or descent. A band pass filter is applied to reject natural changes of the atmospheric pressure and sensor noise. The integration of the output of the filter produces a value corresponding to the vertical distance. Experiments were performed in a horizontal corridor and on some stairs. The results show that the error of the horizontal distance estimated is less than 5.3% and 0.0% on average, and the vertical distance is less than 11.1%.

Characteristics of human fingertips in the shearing direction.

Abstract. The shearing strain of the human fingertip plays an important role in the determination of the optimal grasping force and in the perception of texture. Most research concerned with the mechanical impedance of the human fingertips has treated the orthogonal direction to the tip surface, and little attention has been paid to the tangential direction. This paper describes impedance characteristics of the human fingertips in the tangential directions to the tip surface. In the experiment, step and ramp shearing forces were individually applied to the tips of the thumb, middle finger, and little finger. Dynamics of the fingertips were represented by the Kelvin model. Experimental results show that each fingertip had different properties with respect to the shearing strain versus the applied force, and that the thumb had the strongest shearing stiffness among these three digits. Moreover, the shearing stiffness depended on the direction of the applied force, and the stiffness in the pointing direction was stronger than that in the perpendicular direction. As the contact force in the orthogonal direction to the fingertip surface was increased, the shearing stiffness and viscosity increased without regard to the load speed of the shearing force. Furthermore, it is shown that the average strain rate of the fingertip in the tangential direction to the fingertip surface became slower and converged to a constant value with higher contact forces.

Classification of human moving patterns using air pressure and acceleration

A new method to classify human moving behavior using one acceleration sensor and one air pressure sensor is discussed. Foot-to-head acceleration frequently varies during walking, and is used to classify the moving behavior into stepping action and rest. Walking patterns such as normal walking and jogging are estimated from variances of foot-to-head acceleration. Slight change of air pressure which results from vertical movement is used to detect the moving styles of going up/down the stairs or in an elevator. A combination of these features gives several kinds of moving patterns. The proposed method enables simple and reliable estimation of human moving pattern at the rate of 95% accuracy.

Brief Incorporation of experience in iterative learning controllers using locally weighted learning

A method of incorporating experience in iterative learning controllers is proposed in this paper. Importance of the selection of initial control input in the convergence of error is highlighted. It is proposed that if previous experience of the controller can be incorporated in the selection of the initial control input for a new desired trajectory tracking task, the convergence of error can be improved without modifying the structure of the controller. Therefore, the proposed method is very general and is applicable to most of the iterative learning control algorithms.

Stability of control system in handling of a flexible object by rigid arm robots

In this paper, we deal with the handling of a flexible object by rigid arm robots. We consider three main tasks: 1) to propose a mathematical model for a variety of flexible objects of our daily life; 2) to design a controller to achieve cooperative handling of the flexible object by the robots; and 3) to analyze the stability and robustness of the control system. In particular, demands for manipulating a large-scale structure by a space robot will be increasing. Therefore, it is important to constitute the cooperative control problem of several robots handling a flexible object, and to analyze the proposed control system.

Motion planning for hand-over between human and robot

In the future, robots may perform cooperative tasks with humans in daily life. In this paper, the authors focus on a hand-over motion as an example of cooperative work between a human and a robot, and propose an algorithm which enables a robot to perform a human-like motion. First the authors analyze trajectories and velocity patterns of a hand-over motion performed by two humans. The experimental results show that a receivers motion during hand-over has some typical characteristics. The authors then confirm that a human-like motion can be generated using these characteristics. Finally, the authors plan the robots motion considering these results. Initially, two kinds of potential fields are used to generate a motion command which leads the robot along a trajectory similar to that followed by the human. In addition, more precise motion is considered at the end of the hand-over operation to guarantee accurate positioning and to soften the shock of contact. Simulation results show the validity of the proposed method.

Dynamics of the Head-Neck Complex in Response to the Trunk Horizontal Vibration: Modeling and Identification

Although many studies exist concerning the influence of seat vibration on the head in the seated human body, the dynamic response of the head-neck complex (HNC) to the trunk vibration has not been well investigated. Little quantitative knowledge exists about viscoelastic parameters of the neck. In this study, the dynamics of the HNC is identified when it is exposed to the trunk horizontal (fore-and-aft) vibration. The frequency response functions between the HNC angular velocity and the trunk horizontal acceleration, corresponding to four volunteers, are obtained in the frequency range of 0.5 Hz to 10 Hz. A fourth-order mathematical model, derived by considering a double-inverted-pendulum model for the HNC, is designed to simulate the dynamic response of the HNC to the trunk horizontal vibration. The frequency domain identification method is used to determine the coefficients of the mathematical model of the HNC. Good agreement has been obtained between experimental and simulation results. This indicates that the system, similar to the designed fourth-order model, has mainly two resonance frequencies. The viscoelastic parameters of the neck, including the spring and damping coefficients, are then obtained by use of the optimization method.

Psychological evaluations of robot motions

Abstract Human arm motions were simulated using both computer graphics and an industrial robot under various velocity patterns, and evaluated to examine which factors are essential for human-likeness. The results are summarized as follows. First, the velocity peak position in the normalized movement time of the motion is important for the emotion of human-likeness. Second, the maximum value of the velocity affects the human impression of the motion. There exists an appropriate maximum value which best gives a subject the impression of human-likeness. Finally, the emotion of human-likeness is related to that of agreeableness. These results are almost the same for both a simulated motion on CRT and a robot motion. Relevance to industry In the future, robots will play important roles by assisting or cooperating with humans in various industrial fields. In such cases, a robots motion must be well designed taking into account human perception. The results of the research will become an important guide for the design of a robots motion.

Control of a robot hand emulating human's hand-over motion

In medical and household applications, it is necessary to consider the hand-over of an object between a human and a robot. In this paper, a physiological method motivated by the study of human hands is discussed for a robot to grasp an object or release a grasped object stably without using an object model as a man does. A humans grasping behavior is analyzed by measuring the grasp and friction forces simultaneously as a man grasps an experimental device which is designed for grasping or hand-over. The human controls the grasp force by sensing the friction force, that is, the weight of the object which is felt on his hand, but when the slip is detected by sensing skin acceleration, the grasp force becomes much greater than the minimum force required for grasping by adding the force which is proportional to the acceleration. And two methods that can predict when and how fingers will slip upon a grasped object are discussed. The experimental results show the smooth hand-over of an object between a man and a robot hand.

Evaluating the maneuverability of a control stick using electromyography

This paper proposes maneuverability indexes for a control stick that are based on consierations of muscle characteristics. The indexes are defined on the basis of muscle forces: stiffness of the musculoskeletal system and torque for accelerating the stick. Measuring muscle forces with electromyography, we examine the effectiveness of the proposed indexes experimentally. In a slow tracking operation, the index based on stiffness conforms to the subjective evaluation, but the index based on the torque is inadequate as an index of maneuverability; we therefore use the index based on stiffness as the maneuverability index. In experiments on a step operation, we divided the operation into two phases: moving and holding. The index in the holding operation is in good agreement with the subjective evaluation. In both tracking and step operations the characteristics of the index are appropriate whether or not the controlled object has a first-order lag element. As a result, it is shown that the index can indicate the maneuverability in the low-frequency tracking operation of the stick.