This paper is aimed to perform optimization of a multifunctional actuator utilizing magnetorheological (MR) fluids. In the design of the MR fluid based rotary devices, the inner coils are mainly in interior and exterior forms. However, the effect of these two forms of inner coils on output torque was not discussed. In this research, models with different inner coils are built, analyzed and compared. Among them, the model with interior inner coil is the best option in terms of output torque. Based on the analysis, optimization of the multifunctional actuator is carried out. The corresponding prototype is then fabricated and each function of the developed multifunctional actuator is tested.

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Different gait patterns of stroke patients cannot be derived satisfactorily by traditional treadmill training robots. This paper presents a method to generate adaptive trajectories for controlling a lower extremity rehabilitation exoskeleton designed to help patients recover or improve walking ability. The model-based adaptation mechanism that consists of an inverse dynamic model, a trajectory generator and a fuzzy adaptation algorithm is proposed to minimize patient’s discomfort when active muscle contractions are not easily to be obtained. The effectiveness of the fuzzy adaptation algorithm, which accounts for the experience of a rehabilitation doctor, is demonstrated numerically with an illustrative example in this paper.

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This paper outlines a detailed description of the design on a 3-DOF hip robotic device for kinematically establishing animal model of avascular necrosis (AVN) of the femoral head. In order to realize the hip extension/flexion and abduction/adduction movements of rabbit subjects, a novel 2-DOF hip motion apparatus based on a pair of cardan joints is investigated. 2 electric grounded motors are used to drive rabbits passively in terms of predefined trajectories repeatedly with an additional periodical impact loading on the femoral head during motions. It is ideal to simulate usual forceful and repeated actions in sports, such as gymnastics and acrobatics, and initiated a new way to establish animal femoral head AVN models by means of kinematically simulating the real motion procedure rather than traditional medical or physiological operation method. With sets of experiments, the characterization of the exoskeleton system is discussed.

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To active rehabilitation training, Newton-Euler method is applied to build dynamic models for the powered exoskeleton and the subject. A method to extract the subject’s active force is proposed combined with the models. A mechanism for measuring the human-robot coupling force is designed on that basis. Two prototype experiments are proposed, one is an on-line experiment via different mass loadings, the other is the experiment via different forcing at rest positions in one gait cycle. The experimental results show that the mechanism is available for human-robot coupling force measuring. It also provides the feasibility and validity which will be used in subject’s on-line extracting of active forces based on the dynamic model during rehabilitation training.

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The distinguishing features of active exoskeletons are the capability of guiding arm movement at the level of the full kinematic chain of the human arm, and training full 3D spatial movements. We have specifically developed a PD sliding mode control for upper limb rehabilitation with gain scheduling for providing «assistance as needed», according to the force capability of the patient, and an automatic measurement of the impaired arm joint torques, to evaluate the hypertonia associated to the movement during the execution of the training exercise. Two different training tasks in Virtual Reality were devised, that make use of the above control, and allow to make a performance based evaluation of patient’s motor status. The PERCRO L-Exos (Light-Exoskeleton) was used to evaluate the proposed algorithms and training exercises in two clinical case studies of patients with chronic stroke, that performed 6 weeks of robotic assisted training. Clinical evaluation (Fugl-Meyer Scale, Modified Ashworth Scale, Bimanual Activity Test) was conducted before and after treatment and compared to the scores and the quantitative indices, such as task time, position/joint error and resistance torques, associated to the training exercises.

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