The required tasks in fixed-base exoskeletons demand a fast position/force controller; yet robust against unknown disturbances due to the application itself is tightly coupled with a human in a wide range of operational conditions, which give rise to human-exoskeleton interaction dynamics, high nonlinear uncertain exoskeleton dynamics, noisy sensors and other parametric uncertainties, such as environmental contacts. These factors do not allow to account on a precise dynamical model, thus model-based (regressor-based) controllers are difficult to implement. This paper deals with a regressor-free smooth PID-like fast force/position controller which guarantees finite-time convergence within second order sliding modes, thus ensuring inherent robustness. Experimental platform allows assessing its performance for rehabilitation tasks, which validates its functionality in practical implementation.

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Common actuators have important drawbacks for use in an exoskeleton type of rehabilitation (training) robot. Either the actuators are heavy, complex or poor torque sources. A new actuation system is proposed and tested that 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. Measurements show that performance is sufficient for use in a gait rehabilitation robot.

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This paper presents HANDEXOS, a novel wearable multiphalanges device for post-stroke rehabilitation. It was designed in order to allow for a functional and safe interaction with the user’s hand by means of an anthropomorphic kinematics and the minimization of the human/exoskeleton rotational axes misalignment. This paper describes the mechatronic design of the exoskeleton’s index finger module, simulation, modeling, and development of the actuation unit and sensory system. Experimental results on the validation of the dynamic model and experimental characterization of the index finger module with healthy subjects are reported, showing promising results that encourage further clinical trials.

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For supporting daily activities of elderly and physically disabled people who have lost their body functioning of motions, we have developed a 7-DOF robotic exoskeleton system. It is intended to assist the motions of shoulder and elbow by mounting this on a wheel chair since human shoulder and elbow motions are involved in a lot of activities of everyday life. The proposed mechanism can maximize workspace while escaping singularity by combining the parallel mechanism at the wrist part. Admittance based velocity control scheme enables a variety of tasks to be implemented and allows us to achieve fast enough motion with acceptable accuracy. Preliminary results for mechanism analysis, trajectory tracking experiment are shown.

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Ankle exoskeleton with an artificial pneumatic actuator, which is intended for the assistance and enhancement of muscular activity, was developed. In this study, the effectiveness of the system was investigated during plantarflexion motion of ankle joint. To find an effectiveness of the system, the subjects performed maximal voluntary isokinetic plantarflexion contraction on a Biodex-dynamometer. Plantarfexion torque of the ankle joint is assisted by subject’s soleus muscle that is generated when ankle joint do plantarflexion motion. We used the muscular stiffness signal of a soleus muscle for feed-forward control of ankle-foot orthosis as physiological signal. For measurement of this signal, we made the muscular stiffness force sensor. We compared a muscular stiffness force of a soleus muscle between with feed-forward control and without it and a maximal plantarflexion torque between not wearing a ankle-foot orthosis, without feed-forward control wearing it and with feed-forward control wearing it in each ten elderly adults. The experimental result showed that a muscular stiffness force of a soleus muscle with feed-forward control was reduced and plantarflexion torque of an ankle joint only wearing ankle-foot orthosis was reduced but a plantarflexion torque with feed-forward control was increased. The amount of a increasing with feed-forward control is higher than the amount of a decreasing only wearing it. Therefore, we confirmed the effectiveness of the developed ankle-foot orthosis with feed-forward control.

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