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The design of orthotic devices that tries to fit to the anthropomorphic structure of human limbs faces the problem of achieving the highest approximation to the anatomical kinematics. This paper studies the main characteristics and performances of orthotic devices, mainly focusing on the upper limbs, and proposes a solution to the problem of the superposition of rotation and displacement of some joints, as the shoulder, elbow or knee. A 3 DoF virtual joint is proposed to emulate a human joint, solving the isocentricity and size adaptation of most current orthosis.

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A «muscle suit» that provides muscular support for the paralyzed or those otherwise unable to move unaided is being developed as a wearable robot. The lack of a metal frame and use of McKibben artificial muscle allow the muscle suit to be lightweight, making it realistic to use in daily life. Although all motion for the upper limb by the armor-type muscle suit with the mechanical joints and hard frame is realized, shoulder joints has difficulty in smooth motion because of DOF limitation. To overcome the limitation, new link mechanism is proposed and smooth motion for shoulder is achieved.

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One of the major outcomes of the EPSRC/British Aerospace supported project “Enabling Tactile Technology Environments”, was the Reactabot, a three degree of freedom force feedback device which provides tactual/kinaesthetic feedback to an operator via a surrogate object. Systems of this nature exhibit unwanted oscillatory behaviour and eventually instability if the virtual mass is reduced to too low a value, corresponding to raising the loop gain too high. The onset of this behaviour is found to be operator dependent. This paper studies the phenomenon in detail, modelling both the open loop system and human operator in the feedback path. It is shown that the variation between operators, allied with the unwanted but inevitable phase lags in the open loop system, cause the undesirable behaviour and suggestions are made to minimise their effect

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We present a new device aimed at being used for upper limb rehabilitation. Our main focus was to design a robot capable of working in both the passive mode (i.e. the robot shall be strong enough to generate human-like movements while guiding the weak arm of a patient) and the active mode (i.e. the robot shall be able of following the arm without disturbing human natural motion). This greatly challenges the design, since the system shall be reversible and lightweight while providing human compatible strength, workspace and speed. The solution takes the form of an orthotic structure, which allows control of human arm redundancy contrarily to clinically available upper limb rehabilitation robots. It is equipped with an innovative transmission technology, which provides both high gear ratio and fine reversibility. In order to evaluate the device and its therapeutic efficacy, we compared several series of pointing movements in healthy subjects wearing and not wearing the orthotic device. In this way, we could assess any disturbing effect on normal movements. Results show that the main movement characteristics (direction, duration, bell shape profile) are preserved.

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