This paper reports on the evaluation of various actuation technologies to be used in a portable exoskeleton for space applications. It is divided into four parts. The first part defines the scope of the project and gives a brief overview of the existing arm exoskeleton devices. The second part is devoted to the description of the three actuation technologies evaluated: DC motors and their combination with other mechanical systems in order to integrate them in a portable haptic device, a brake prototype developed at the ASL using magnetorheological fluid and finally ultrasonic motors. The third part is devoted to the experimental prototyping with the description of the 1 DOF setup built to compare the actuators, and the results obtained for each of them. Finally, the fourth part shows some comparisons between the technologies, related to relevant parameters for portable haptic interfaces.

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Diese Arbeit stellt ein Modell und ein System zur Steuerung von Exoske-letten mit Hilfe von elektrischen Signalen vor, die an den Muskeln des Benutzers gemessen werden. Anhand dieser Signale wird der eigene Drehmomentbeitrag des Benutzer zur gewünschten Bewegung abgeschätzt, und ein einstellbarer Faktor bestimmt das vom Exoskelett hinzugefügte Drehmoment in Bezug auf den Beitrag des Benutzers. Die Signale werden durch ein komplexes biomechanisches Modell ausgewertet.

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In this paper, the design of a hip joint of an exoskeleton is presented so as to automatically assist the hip joint motion of a physically weak person. A spherical three-degrees-of-freedom parallel mechanism is used for the purpose. The problem is framed as an optimization problem with an objective of determining the proper connection points for the links of the structure at the human body, keeping in account the aspects of self-collision, human anatomy and comfort. The design parameters are optimized for a specific pose and the workspace around this central configuration is built to develop enough mobility required for the human body to attain different postures.

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In 2003, 700,000 persons in the United States suffer-ed a cerebral vascular accident (CVA), or stroke, with the total number of survivors estimated at 5.5 mil-lion. The total cost for rehabilitation and lost revenue in 2006 was 57.9 billion (Thom, Haase et al. 2006 ). Stroke commonly causes significant residual physical, cognitive, and psychological impairment (Gre-sham 1990). As the geriatric population increases and more effective therapies for acute stroke management emerge, there will be more survivors living with disabilities. In addition to greater numbers of survi-vors, there has been an increase in the number of more moderately affected survivors (Wolf, D’Agostino et al. 1992), which has increased the demand for stroke rehabilitation in an era of health care cost contain-ment. Efforts to prevent stroke must, therefore, be balanced with pragmatic efforts to prevent disability and maximize quality of life for stroke survivors. Persons with hemiparesis following stroke constitute the largest group of patients receiving rehabilitation services in this country. The current consensus re-garding rehabilitation of patients with some voluntary control over movements of the paretic limb is that they be encouraged to use the limb in functional tasks and receive training directed toward improving strength and motor control, relearning sensorimotor relationships, and improving functional performance (Gresham, Alexander et al. 1997). Given such recommendations, the research community has responded with ef-forts to improve the effectiveness of rehabilitative treatment of motor disability resulting from stroke.

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This paper introduces a control scheme and algorithm for a powered orthosis. Recognizing the intended motion is based on real-time evaluation of EMG signals recorded from the operator’s leg muscles. The desired motion is executed with a torque controller for an electric linear actuator. In contrast to most of the previous approaches for similar applications, this is performed without pattern clas-sification and without a dynamic biomechanical model ofthe human body.

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