Effect of variable transmission on body-powered prosthetic grasping

Abbott, Michael E.; McPherson, Andrew; Torres, Wilson O; Adachi, Keilani; Stuart, Hannah

doi:10.1109/icorr55369.2022.9896542

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…When studied independently, participants show a clear preference, both in terms of function and perception, for low forces and low ranges of motion when operating body-powered prostheses. While not feasible with traditional fixed transmissions which inherently involve force-position tradeoffs, future work could examine the possibility of variable transmissions in body-powered prostheses, such as those detailed in [36]- [38]. Such a system has the potential to appropriately amplify output forces or positions based on user inputs and limit uncomfortable loads and postures from the user.…”

Section: B Relevance To Body-powered Device Designmentioning

confidence: 99%

Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

Abbott¹,

Stuart²

2023

Preprint

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<p>Upper-limb prosthesis users continue to reject devices despite continued research efforts. Today, the passive topology of body-powered prehensors, which physically transmits grasp force and position data between user and device, results in improved performance over myoelectric alternatives. However, the loads and postures on the user's body also result in discomfort, fatigue, and worsened grasp force control. Despite the long history and everyday adoption of body-powered prehensors in society, the measurement of how specific body loads and postures affect grasp performance and user experience has yet to be systematically studied. In this work, we present a body-powered prosthesis emulator to independently change required input forces and motions to study the positive and negative effects provided by the inherent haptic feedback. Using a simulated grasping task, we collect functional and qualitative data from 15 participants using a shoulder harness interface. Outcomes show that reducing input loads and excursions to below 24 N and 45 mm, respectively, significantly reduces negative outcomes, but further reductions beyond those thresholds produce limited benefit. Coupling load and excursion, as is the case in real passive body-powered transmissions, demonstrates the importance of the force-motion tradeoff within the tested range of transmission ratios from 0.5:1 to 2:1. The purpose of this study is to inform future prehensor designs that leverage the transparency of body-power to deliver high functionality while mitigating user discomfort.</p>

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Section: B Relevance To Body-powered Device Designmentioning

confidence: 99%

Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

Abbott¹,

Stuart²

2023

Preprint

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“…To complement these works, controlled experimentation is also needed to evaluate the extent to which such variable transmissions affect human grasping performance and haptic understanding while operating BP prostheses. Our prior work with a desktop prosthesis simulation testbed has shown that a continuously variable transmission in body-powered prostheses allows for more successful grasping of objects with a wider variety of masses and stiffnesses than alternative transmission topologies in a grasping task [19]. The present work introduces a motorized wearable testbed device, pictured in Fig.…”

Section: B Variable Transmission For Graspingmentioning

confidence: 99%

A Wearable Testbed for Studying Variable Transmission in Body-Powered Prosthetic Gripping

McPherson,

Abbott,

White

et al. 2023

2023 International Conference on Rehabilitation Robotics (ICORR)

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For those with upper limb absence, body-powered prostheses continue to be popular for many activities despite being an old technology; these devices can provide both inherent haptic feedback and mechanical robustness. Yet, they can also result in strain and fatigue. Body-powered prosthetic graspers typically consist of a simple lever providing a relatively constant transmission ratio between the input forces from the user's shoulder harness and the grip force of their prosthetic prehensor. In the field of robotic hand design, new continuously varying transmissions demonstrate particular promise in generating a wide range of grasping speeds without sacrificing grip strength. These benefits, if applied to shoulder-driven prosthetic grippers, have the potential to both reduce shoulder exertion and fatigue. This work presents the integration of a continuously variable transmission into a body-powered, voluntary close prosthetic testbed. We introduce the design and validate its performance in a benchtop experiment. We compare constant transmission conditions with a force-dependent, continually varying condition. The device is mounted on a prosthetic emulator for a preliminary wearable demonstration.

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Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

Abbott

Stuart

2023

IEEE Trans. Neural Syst. Rehabil. Eng.

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Effect of variable transmission on body-powered prosthetic grasping

Cited by 3 publications

References 15 publications

Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

A Wearable Testbed for Studying Variable Transmission in Body-Powered Prosthetic Gripping

Characterizing the Force-Motion Tradeoff in Body-Powered Transmission Design

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