A wearable action-assist device which assists or executes an action of a wearer by substituting for the wearer is provided with an action-assist tool 2 having an actuator 201 which gives power to the wearer 1, a biosignal sensor 221 which detects a wearer’s biosignal, a biosignal processing unit 3 which acquires from a biosignal “a” detected by the biosignal sensor a nerve transfer signal “b” for operating a wearer’s muscular line skeletal system, and a myoelectricity signal “c” accompanied with a wearer’s muscular line activity, an optional control unit 4 which generates a command signal “d” for causing the actuator 201 to generate power according to the wearer’s intention using the nerve transfer signal “b” and the myoelectricity signal “c” acquired by the biosignal processing unit 3, and a driving current generating unit 5 which generates a current according to the nerve transfer signal b and a current according to the myoelectricity signal “c”, respectively, based on the command signal “d” generated by the optional control unit 4, and supplies the currents to the actuator 201.

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Many patients with spinal injures are confined to wheelchairs, leading to a sedentary lifestyle with secondary pathologies and increased dependence on a carer. Increasing evidence has shown that locomotor training reduces the incidence of these secondary pathologies, but the physical effort involved in this training is such that there is poor compliance. This paper reports on the design and control of a new “human friendly” orthosis (exoskeleton), powered by high power pneumatic Muscle Actuators (pMAs). The combination of a highly compliant actuation system, with an intelligent embedded control mechanism which senses hip, knee, and ankle positions, velocity, acceleration and force, produces powerful yet inherently safe operation for paraplegic patients. This paper analyzes the motion of ankle, knee, and hip joints under zero loading, and loads which simulate human limb mass, showing that the use of “soft” actuators can provide a smooth user friendly motion. The application of this technology will greatly improve the rehabilitative protocols for paraplegic patients.

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An important goal in rehabilitation engineering is to develop technology that allows individuals with severe motor impairment to practice arm movement without continuous supervision from a rehabilitation therapist. This paper describes the development of such a system, called Therapy WREX or («T-WREX»). The system consists of an orthosis that assists in arm movement across a large workspace, a grip sensor that detects hand grip pressure, and software that simulates functional activities. The arm orthosis is an instrumented, adult-sized version of the Wilmington Robotic Exoskeleton (WREX), which is a five degrees-of-freedom mechanism that passively counterbalances the weight of the arm using elastic bands. After providing a detailed design description of T-WREX, this paper describes two pilot studies of the system’s capabilities. The first study demonstrated that individuals with chronic stroke whose arm function is compromised in a normal gravity environment can perform reaching and drawing movements while using T-WREX. The second study demonstrated that exercising the affected arm of five people with chronic stroke with T-WREX over an eight week period improved unassisted movement ability (mean change in Fugl-Meyer score was 5 points plusmn2 SD; mean change in range of motion of reaching was 10%, p<0.001). These results demonstrate the feasibility of automating upper-extremity rehabilitation therapy for people with severe stroke using passive gravity assistance, a grip sensor, and simple virtual reality software.

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Joints are failure points for deployable systems and moving devices. Their reliability is therefore of great concern for space applications. Efficiency is also critical as the power budgets are limited in space and energy dissipation must therefore be avoided. Weight and dimensions must be reduced as much as possible since they have a direct impact on launch costs and thus on space mission budgets. A new type of joint design that meets the extensive and demanding space requirements would be of great use. This study tries to retrieve interesting mechanisms in the huge pool of clever designs from nature. The number of species of insects is truly awesome, for example there are over 600,000 scientifically described species of beetles with at least twice that number remaining to be disco-vered and described. And beetles are only one type of insect. To put that number in perspective, there are probably around 10,000 species of birds, and maybe 4,000 species of mammals. The total number of interes-ting mechanisms in insect species, birds and mammals is almost beyond imagination. In this work a biomime-tic approach is used in order to assess the possibility of improving robotic joints for space applica-tions. The work concerns the identification of classes of joints in nature which could inspire the design of a feasible system in which the mechanical subsystem and the actuation subsystems are merged. This report presents a study with the overall goal of finding biological articulation concepts which, when tran-slated to a mechanical equivalent, can improve performance of articulated robot systems for space applications.

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Metabolic studies have shown that there is a metabolic cost associated with carrying load [1]. In previous work, a lightweight, underactuated exoskeleton has been described that runs in parallel to the human and supports the weight of a payload [2]. A state-machine control strategy is written based on joint angle and ground-exoskeleton force sensing to control the joint actuation at this exoskeleton hip and knee. The joint components of the exoskeleton in the sagittal plane consist of a force-controllable actuator at the hip, a variable-damper mechanism at the knee and a passive spring at the ankle. The control is motivated by examining human walking data. Positive, non-conservative power is added at the hip during the walking cycle to help propel the mass of the human and payload forward. At the knee, the damper mechanism is turned on at heel strike as the exoskeleton leg is loaded and turned off during terminal stance to allow knee flexion. The passive spring at the ankle engages in controlled dorsiflexion to store energy that is later released to assist in powered plantarflexion. Preliminary stu- dies show that the state machines for the hip and knee work robustly and that the onset of walking can be detected in less than one gait cycle. Further, it is found that an efficient, underactuated leg exoske-leton can effectively transmit payload forces to the ground during the walking cycle.

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