This paper deals with force and impedance control of series elastic actuators for driving the joints of an exoskeleton for lower limbs. Series elastic actuators are devices where elastic components are introduced between the motor’s output and the load. From the deflection of these components, it is possible to measure the force applied to the load and to control it. Also, the mechanical impedance of the actuator/load interface can be regulated to the typical values of joint’s stiffness and damping presented by humans during the walking. Results of force and impedance control applied to an active ankle-foot orthosis driven by a series elastic actuator are presented. Also, a variable impedance control strategy is performed to reproduce the behavior of an actual ankle joint.

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This paper presents the development of a prototype of an active orthosis for lower limbs. The proposed orthosis is an orthopedical device with the main objective of providing walking capacity to people with partial or total loss of limbs movements. In order to design the kinematics, dynamics and the mechanical characteristics of the prototype, the biomechanics of the human body was analized. The orthosis was projected to reproduce the movements of human gait. The movements of the joints of the orthosis are controlled by DC motors equipped with mechanical reductions, whose purpose is to reduce rotational speed and increase the torque, thus generating smooth movements. An embedded electronic system for sensory data acquisition and motor control was projected. The gait movements of the orthosis will be controlled by high level commands from a human-machine interface based on processings of electroencephalogram signals, speech recognition or joystick.

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Herein, this study proposes that the exoskeleton has not full of active DOF (degree of freedom) joint, but partial active DOF joint which is so called the quasi-active joint system. It consists of 4 quasi-active joints and 2 active joints 3 passive joint and 1 active joint. So as to verify the efficiency of the quasi-active exoskeleton, muscle activation results are compared by before and after the wearing exoskeleton results.

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Robotic lower limb exoskeletons have been built for augmenting human performance, assisting with disabilities, studying human physiology, and re-training motor deficiencies. At the University of Michigan Human Neuromechanics Laboratory, we have built pneumatically-powered lower limb exoskeletons for the last two purposes. Most of our prior research has focused on ankle joint exoskeletons because of the large contribution from plantar flexors to the mechanical work performed during gait. One way we control the exoskeletons is with proportional myoelectric control, effectively increasing the strength of the wearer with a physiological mode of control. Healthy human subjects quickly adapt to walking with the robotic ankle exoskeletons, reducing their overall energy expenditure. Individuals with incomplete spinal cord injury have demonstrated rapid modification of muscle recruitment patterns with practice walking with the ankle exoskeletons. Evidence suggests that proportional myoelectric control may have distinct advantages over other types of control for robotic exoskeletons in basic science and rehabilitation.

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This work describes the neuro-robotics paradigm: the fusion of neuroscience and robotics. The fusion of neuroscience and robotics, called neuro-robotics, is fundamental to develop robotic systems to be used in functional support, personal assistance and neuro-rehabilitation. While usually the robotic device is considered as a ldquotoolrdquo for neuroscientific studies, a breakthrough is obtained if the two scientific competences and methodologies converge to develop innovative platforms to go beyond robotics by including novel models to design better robots. This paper describes three robotic platforms developed at the ARTS lab of Scuola Superiore Sant’Anna, implementing neuro-robotic design paradigm.

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