Understanding the Preferences for Lower-Limb Prosthesis: A Think-Aloud Study during User-Guided Auto-Tuning

Abstract

Prostheses help amputees to maintain physical health and quality of life. Prosthesis wearers’ satisfaction and adherence to the prosthesis are closely related to the preferences for prosthesis tuning settings. However, the underlying factors that contribute to the preferences were under-explored. In this study, two able-bodied participants were asked to change the robotic prosthesis settings to their preferred state and the think-aloud technique with a mixed-method approach was used to reveal the contributing factors of preferences. We found that physical perception (e.g., positions of the prosthetic foot, balance, and stability) and subjective feelings (e.g., comfortableness, satisfaction, confidence, and worries) were two major factors. Experiences with the intact leg and other profiles were used as anchors for their preference levels. Preferences may also differ with situational context such as walking speed. The saturation points were reached with no strong approach motivation. The implications for prosthesis design and research were discussed.

Finding a Natural Fit: A Thematic Analysis of Amputees’ Prosthesis Setting Preferences during User-Guided Auto-Tuning

“…Consistent with previous studies that found large inter- individual differences in preferences for degrees of ankle stiffness (e.g., Shepherd et al, 2020), we also found high variability in their preferences for not only the magnitude, direction, and pattern of the changes but also the underlying reasoning or factors related to naturalness (Schaffalitzky et al, 2009). Among the factors, the workload sub-theme was not mentioned in the non-disabled participants (Yuan et al, 2022a), surprisingly, nor in two amputee participants. Although it was only mentioned by one amputee participant, it doesn’t mean that the other participants did not have the experience or the need.…”

“…Similar to Yuan et al (2022a), we employed a mixed method approach, with the qualitative method (i.e., the think- aloud technique) as the main focus, supplemented with quantitative ratings on preference levels and other experiences. The main goal was to follow the amputees’ natural preferences and reveal the underlying reasons as they make changes to the prosthesis pretending that this is the device they would use in daily life.…”

“…In all, to provide insights into the mechanism of preferences in amputees and to contribute to the development of powered prosthesis, the current study investigated the preferences for multiple prosthesis settings in a powered robotic knee prosthesis using think aloud technique during user-guided auto-tuning and explored the differences of preferences between amputee vs non-disabled users while comparing with results in Yuan et al (2022a).…”

“…Based on this system, our previous study chose the think- aloud technique and successfully revealed the features of preferences for four control points in a powered robotic knee prosthesis in non-disabled participants (Yuan et al, 2022a). The success of this study not only suggests the potential of allowing users to lead the tuning with the assistance of the system of auto-tuning and the User Controlled Interface but also demonstrates the feasibility of using think aloud technique to unravel the reasoning behind the prosthesis users’ preferences.…”

A Novel Framework to Facilitate User Preferred Tuning for a Robotic Knee Prosthesis

“…In addition, the profile exploration trials for this study have been performed sequentially and there was no way for participants to assess how changing one control point changes their perception of the others. Thus, our ongoing study aims to analyze the psychological aspects that can drive prosthesis users' choices during the extensive exploration of their preferences while also considering the interdependent relationships between control points that could affect profile perception [43].…”