In this paper, a dynamic model of the hand of a power-assistive machinery is derived in pursuit of deriving a full-body model. The viscous friction coefficient and the coulomb friction force are identified from experimental data, and it is confirmed that the dynamic model is appropriate via simulation.

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This study presents several measures aimed at mathematically quantifying characteristics associated with human performance and wearable robot platform; there will be trials for improving the kinematic performance of the proposed wearable robot system through the optimization methodology. Within constrained conditions, optimal link lengths will be defined for its objectives and purposes. In particular, parameters from these studies and experiments, is one way of improving its performance of function-orient human robot corporative system; they are used for quantifying the feeling of putting on platform and flexibility, too.

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The objective of this research is to develop a wearable power assist device which helps a person to lift up a heavy object. The device is designed to support him by holding his upper body weight and reducing his inner force. It turns to the reduction of a compression force of his lower back discs, which is a major factor of a lower back injury. In a lifting-up motion, he twists and bends his body, which means three-dimensional motion analysis is necessary for the compression force analysis. However, most of related works on the compression force analysis have been carried out in a vertical plane. For understanding the characteristics of a lifting-up motion better, this paper presents three-dimensional analysis of it. Using a motion capture system, we measured a sequence of body positions with and without the power assist device in different object location and mass, as well as surface EMG (electro-myogram) signals. The compression force of the lower back discs is estimated by a three-dimensional biomechanical human body model utilizing the position data. The results show that the range of the twist angle of his body is about 30 degree in maximum and the compression force increases about 10% due to the twist angle. With respect to the effect of the power assist device, the magnitude of the surface EMG signals of spine muscles is decreased when wearing the power assist device. It means the proposed power assist device gives a good support to him.

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SUBAR (Sogang Universitypsilas biomedical assistive robot), an advanced version of the EXPOS, is a wearable robot developed for assisting physically impaired people. It provides a human with assistive forces controlled by the human intention. Since it applies geared DC motors, however, the control efforts are used mainly to overcome the resistive forces caused by the friction, the damping and the inertia in the actuator. In this paper, such undesired properties are rejected by applying a flexible transmission. With the proposed method, it is intended that an actuator exhibits zero impedance without friction and generates the desired torques precisely. Since the actuation system of SUBAR has a large model variation due to human-robot interaction, a control algorithm for the flexible transmission is designed based on robust control theory. In this paper, the mechanical design of SUBAR including the flexible transmission and its associated control algorithm are discussed. They are also verified by experiments.

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Mobility options for persons suffering from paraplegia or paraparesis are limited to mainly wheeled devices. There are significant health, psychological, and social consequences related to being confined to a wheelchair. We present the Mina, a robotic orthosis for assisting mobility, which offers a legged mobility option for these persons. Mina is an overground robotic device that is worn on the back and around the legs to provide mobility assistance for people suffering from paraplegia or paraparesis. Mina uses compliant actuation to power the hip and knee joints. For paralyzed users, balance is provided with the assistance of forearm crutches. This paper presents the evaluation of Mina with two paraplegics (SCI ASIA-A). We confirmed that with a few hours of training and practice, Mina is currently able to provide paraplegics walking mobility at speeds of up to 0.20 m/s. We further confirmed that using Mina is not physically taxing and requires little cognitive effort, allowing the user to converse and maintain eye contact while walking.

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