Standing up using one leg is a challenging task for those with a transfemoral amputation, particularly for elderly users with a low activity level. Active prostheses are generally not accessible to this group and available passive prostheses do not support standing up. This article presents the design and evaluation of the “Energy Restoring Intelligent Knee” (ERiK), which stores energy during sit-down in a pneumatic cylinder and returns it during stand-up. We hypothesized that the system would reduce the time needed to perform transitions and also enable higher load sharing by the prosthetic leg. However, the results of an experimental study with seven participants with transfemoral amputation contradict these hypotheses: the participants could neither move faster nor make more use of the prosthetic leg to share their body weight during transitions. We observed that a major obstacle to the useful functionality of the leg was the absence of ankle dorsiflexion – the foot tended to slip during stand-up initiation, such that only low pre-pressures and therefore support levels could be set. The rather binary action of the pneumatics also complicated movement initiation. The lessons learned from this study may be helpful to those seeking to create better designs in the future.@en

Building upon recent advancements in linear electroadhesive clutch materials and performance, this paper examines the feasibility of a self-reinforcing electroadhesive rotational clutch using a simple model. The design aims to deliver improvements in applications where performance is limited by the torque-to-power and torque-to-mass ratios offered by conventional electromagnetic or magnetorheological clutches. The performance of the self-reinforcing design is related to the device's geometric parameters and hence the robustness of clutch configurations is examined by modeling the system parameters as having stochastic properties. A design example based on the clutch requirements of a gyroscopic balance assistance device is analyzed. The analysis predicts that substantial improvements in torque-to-power and torque-to-mass ratios are possible with the presented design compared to industry-leading rotational clutches.

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