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The Parasitic Humanoid (PH) is a wearable robotic human interface for sampling, modeling, and assisting nonverbal human behavior. This anthropomorphic robot senses the behavior of the wearer and has the internal models to learn the process of human sensory motor integration, thereafter it begins to predict the next behavior of the wearer using the learned models. When the reliability of the prediction is sufficient, the PH outputs the difference from the actual behavior as a request for motion to the wearer by motion induction using sensory illusion. Through the symbiotic interaction, the internal model and the process of human sensory motor integration approximate each other asymptotically. This process is available to transmit modalities such as senses of sight, hearing, touch, force and balance with human embodiment. This synergistic multimodal communication between distant people wearing PH can realize experience-sharing, skill transmission, and human behavior supports.

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Due to the advantages of more intensiveness, long duration, repeatability, and task-orientation, robot-assistant training has become a promising technology in stroke rehabilitation. Regarding the upper extremity, the natural coordination called shoulder rhythm is the most challenge to the design of ergonomic shoulder exoskeleton. Based on kinematic analysis of movement of shoulder complex, a 10-degree-of-freedom (DoF) exoskeleton rehabilitation robot with six-DoF shoulder actuation mechanism driven by pneumatic muscle through Bowden cable transmitting force is proposed. The kinematic relationship between shoulder girdle motion and the humerus flexion/retroflexion and abduction/adduction was described. The compact mechanisms for cable tension and cable disconnect/connect respectively were proposed to realize the cable automatic tension and drive-unit/manipulating-unit detachment. In order to verify the manipulability of the proposed robot during assisting patient with performing activities of daily living (ADLs), the performance criteria, i.e., normalized dexterity measure and manipulability ellipsoid, are used to evaluate and compare with human upper extremity. The evaluated results confirm the ergonomic design of shoulder mechanism of the rehabilitation robot that can provide approximate dexterity of human upper extremity in ADLs.

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In the research field of robot-assisted gait rehabilitation there is increased focus on the improvement of physical human-robot interaction by means of high-performance actuator technologies and dedicated control strategies. In this context we propose a combination of lightweight, intrinsically compliant, high-torque actuators (pleated pneumatic artificial muscles) with safe and adaptable guidance along a target trajectory by means of proxy-based sliding mode control. We developed a powered knee exoskeleton (KNEXO) to evaluate these concepts. In addition to the trajectory-based controller a torque controller was implemented with a view to minimizing the interaction during unassisted walking. First, various treadmill walking experiments were performed with unimpaired subjects wearing KNEXO to evaluate the performance of the proposed controllers. Test results confirm the ability of KNEXO to display low actuator torques in unassisted mode and to provide safe, adaptable guidance in assisted mode. Subsequently, a multiple sclerosis patient participated in a series of pilot experiments. Provided there was some patient-specific controller tuning KNEXO was found to effectively support and compliantly guide the subject’s knee.

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Within the context of impedance controlled exoskeletons, common actuators have important drawbacks. Either the actuators are heavy, have a complex structure or are poor torque sources, due to gearing or heavy nonlinearity. Considering our application, an impedance controlled gait rehabilitation robot for treadmill-training, we designed an actuation system that might avoid these drawbacks. It combines a lightweight joint and a simple structure with adequate torque source quality. It consists of a servomotor, a flexible Bowden cable transmission, and a force feedback loop based on a series elastic element. A basic model was developed that is shown to describe the basic dynamics of the actuator well enough for design purpose.

Further measurements show that performance is sufficient for use in a gait rehabilitation robot. The demanded force tracking bandwidths were met: 11 Hz bandwidth for the full force range (demanded 4 Hz) and 20 Hz bandwidth for smaller force range (demanded 12 Hz). The mechanical output impedance of the actuator could be reduced to hardly perceptible level. Maxima of about 0.7 Nm peaks for 4 Hz imposed motions appeared, corresponding to less than 2.5% of the maximal force output. These peaks were caused by the stick friction in the Bowden cables.

Spring stiffness variation showed that both a too stiff and a too compliant spring can worsen performance. A stiff spring reduces the maximum allowable controller gain. The relatively low control gain then causes a larger effect of stick in the force output, resulting in a less smooth output in general. Low spring stiffness, on the other side, decreases the performance of the system, because saturation will occur sooner.

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