I can’t believe that the Fit-4-Purpose project has been going now for almost two years! Straight after my PhD with the Salford team, I joined the project in February 2018 as a Postdoctoral Researcher, with a background in Medical Engineering and Upper-limb prosthetics and I have been involved with various parts of the project ever since. In recent months I have been feeding into aspects of WP5 (led by the team at UCL) by analysing some upper-limb activity data recorded in Jordan and Uganda. But my main project has related to WP2 (led by our team here at Salford) and involves the development of methods to help us to understand the restrictions imposed by a harness on the reachable workspace of a body-powered prosthesis user, as well as where within that workspace they have control over the aperture of the prehensor.
To understand this problem, we needed a suitable experimental method. In common with other researchers we used a prosthesis simulator which can be worn by anatomically intact adults to develop and test our new approach. For this study, we have developed the techniques using the TRS body-powered simulator, which is connected to a voluntary closing prehensor (when you pull the cable the prehensor closes, and when you release it opens), and a P-loop/figure-9 harness (this is a harness used only for control, not suspension, where a loop is passed around the opposite shoulder).
We collected data within a motion capture lab using a system developed by Qualisys. By collecting 3D motion data on the participant themselves and the location of the prehensor, we were able to recreate the volume reachable by the participant, both with and without the harness attached. All participants have shown a reduced reachable volume when wearing the harness, particularly when reaching across the body or up above the shoulders. We then asked the participants to open and close the hand as far as they were able in different positions within the workspace and recorded the hand aperture using an electric goniometer. I’ve found the results of this work really interesting and they have shown some of the trade-off’s needed to operate the hand at different positions. We are currently in the process of writing up the results of this study for publication and are hoping to submit it to a journal early in the new year.
After Christmas the focus for my work will be moving away from harness evaluation (we hope that some undergraduate P&O students may be keen to take this forward as smaller projects as part of their course), and I will be moving on to another topic. More to come on this down the line.