The paper presents an exoskeleton system designed for elbow joint motion rehabilitation. The proposed system is supposed to be directly attached to the lateral side of a patient’s arm and assist the elbow flexion-extension motion of the patient for rehabilitation. In the proposed system, the amount of electromyogram (EMG) signals of biceps and triceps of the patient are monitored and used to control the motion of the system. The assist level (the support level) of the system can be decided for each patient based on his/her physical and physiological condition or rehabilitation phase. The effectiveness of the proposed support system was evaluated by experiment.

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In recent years, robotic technologies have been applied to build assistive robots, such as robotic exoskeletons and rehabilitation robots. Based on the clinical considerations, new trends of rehabilitation, like over-ground rehabilitation robots and home-based mobile rehabilitation robots, have emerged by combining both the knowledge from the exoskeleton and the rehabilitation robots. In this article, we review some of the important assistive and rehabilitation robots, in terms of their hardware, actuation, sensory and controls systems. The paper ends with a discussion on the future trends of the rehabilitation robots, especially on clinical-based considerations.

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Robotic gait rehabilitation faces many challenges regarding ankle assistance, body weight support and physical human-robot interaction. This paper reports on the development of a gait rehabilitation exoskeleton prototype intended as a platform for the evaluation of design and control concepts in view of improved physical human-robot interaction. The performance of proxy-based sliding mode control as a ldquorobot-in-chargerdquo control strategy is evaluated both in simulation and in experiments on a test setup. Compared to PID control, test results indicate good tracking performance and in particular safe system behavior.

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Our new Limpact exoskeleton is mechanically based on the design of the passive Dampace and will be powered by rotational hydro-elastic actuators (rHEAs), using impedance control. In this paper we describe the design of the rHEA, which is a novel, custom-designed combination of a rotational hydraulic actuator and a symmetric torsion spring. The rHEA can also be used as a springless hydraulic actuator for stiffer admittance control, or for isometric large-torque measurements of up to 100 Nm, by locking specific components in the design. Our implementation of HEA required alterations to the existing theoretical models to account for (1) our long flexible tubes between the valve and cylinder, and (2) the influence of the pressure feedback on the valve flow. These newly adapted models gave the best fits on the frequency response functions from our open- and closed-loop identification experiments, and might even provide a better fit for the data in the original publication of the theoretical models. Multi-sine identification showed the torque-tracking bandwidth restricted to 18 Hz for a constant spectral-density reference signal of 20 nm, mostly due the transport delays in the long flexible tubes. The measured torque resolution was better then 0.01 Nm. The delivered torque resolution was below 1 Nm, although at those small amplitudes, the output signal was accompanied by significant phase lead indicating some unaccounted for non-linearities in the actuator. When manipulated manually by forefinger and thumb, almost no distortion torques were felt during minimal-impedance and virtual-spring control. The symmetric torsion spring proved difficult to model correctly, and finding the best design became an iterative process. The spring in the prototype, used for the measurements as reported in this study, had a stiffness and maximum torque below those theoretically calculated, limiting the desired output to 22 Nm. With our latest spring design for the actuators in the Limpact, t- — he maximum output torque is increased to 50 Nm.

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Robotic rehabilitation has gained significant traction in recent years, due to the clinical demonstration of its efficacy in restoring function for upper extremity movements and locomotor skills, demonstrated primarily in stroke populations. In this paper, we present the design of MAHI Exo II, a robotic exoskeleton for the rehabilitation of upper extremity after stroke, spinal cord injury, or other brain injuries. The five degree-of-freedom robot enables elbow flexion-extension, forearm pronation-supination, wrist flexion-extension, and radial-ulnar deviation. The device offers several significant design improvements compared to its predecessor, MAHI Exo I. Specifically, issues with backlash and singularities in the wrist mechanism have been resolved, torque output has been increased in the forearm and elbow joints, a passive degree of freedom has been added to allow shoulder abduction thereby improving alignment especially for users who are wheelchair-bound, and the hardware now enables simplified and fast swapping of treatment side. These modifications are discussed in the paper, and results for the range of motion and maximum torque output capabilities of the new design and its predecessor are presented. The efficacy of the MAHI Exo II will soon be validated in a series of clinical evaluations with both stroke and spinal cord injury patients.

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