In this study, we propose a SkilMate Hand for space extravehicular activity gloves which is equipped with devices of both a power assist and a tactile media. The paper focuses on development of component technologies for constructing a SkilMate Hand, which is proposed for recovering deteriorated haptic sensation in human hands. First, we manufacture a power assist device which compensates the bending moment exerted at a human nger joint utilizing a standing-wave-type ultrasonic motor. We plot the examined characteristics, propose a control policy of the actuators and show some control perforce in Bode plots. Second, we produce a tactile media device which is composed of a vibrotactile sensor element on the outer side and a vibrotactile display element on the inner side at the ngertips of the SkilMate Hand. Piezo-rubber is chosen to be used as a vibrotactile sensing transducer whose sensing performance is examined in the extremely high/low-temperature regions. We locate SkilMate in a wider framework of wearable intelligent machines which assist in affording such working surroundings that they can exhibit their skills in spite of their necessity for wearing special suits typical in hazardous environments. A proposal of a wearable intelligent machine such as that of a SkilMate with its concept has not been made before.

Patient transfer (PT) tasks are a significant cause of low back pain (LBP) in caregivers. Adopting proper motion strategies is an effective and inexpensive approach to reduce the risk of LBP. However, since the standardization of PT tasks is not specified in ISO 11228, there is an increasing need to develop a quantitative assessment method for the lumbar safety of caregivers. Therefore, we aim to determine the effect of representative factors, extracted from caregivers’ movements and of external force, on peak compressive force (CF) in patient transfer tasks using the lumbar compressive force as a criterion. The CF at the lumbar region is estimated using a biomechanical simulator, and regression analysis is performed between the estimated CF and representative factors. The results imply that peak CF occurs in the incipience of transfer and occurs after the occurrence of the peak trunk angle. The results also indicate that the peak CF can be reduced by preventing the representative factors from simultaneously reaching the maximum values. In this study, we provide a method of reducing peak CF by estimating the timing and magnitude of the peak to help caregivers assess the severity of LBP risk in actual PT, which is expected to contribute to the standardization of PT tasks.

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