Participatory Action Design and Engineering of Powered Personal Transfer System for Wheelchair Users: Initial Design and Assessment.

Caregivers that assist with wheelchair transfers are susceptible to back pain and occupational injuries. The study describes a prototype of the powered personal transfer system (PPTS) consisting of a novel powered hospital bed and a customized Medicare Group 2 electric powered wheelchair (EPW) working together to provide a no-lift solution for transfers. The study follows a participatory action design and engineering (PADE) process and describes the design, kinematics, and control system of the PPTS and end-users' perception to provide qualitative guidance and feedback about the PPTS. Thirty-six participants (wheelchair users (n = 18) and caregivers (n = 18)) included in the focus groups reported an overall positive impression of the system. Caregivers reported that the PPTS would reduce the risk of injuries and make transfers easier. Feedback revealed limitations and unmet needs of mobility device users, including a lack of power seat functions in the Group-2 wheelchair, a need for no-caregiver assistance/capability for independent transfers, and a need for a more ergonomic touchscreen. These limitations may be mitigated with design modifications in future prototypes. The PPTS is a promising robotic transfer system that may aid in the higher independence of powered wheelchair users and provide a safer solution for transfers.

FingerSight: A Vibrotactile Wearable Ring for Assistance With Locating and Reaching Objects in Peripersonal Space.

This paper describes a prototype guidance system, "FingerSight," to help people without vision locate and reach to objects in peripersonal space. It consists of four evenly spaced tactors embedded into a ring worn on the index finger, with a small camera mounted on top. Computer-vision analysis of the camera image controls vibrotactile feedback, leading users to move their hand to near targets. Two experiments tested the functionality of the prototype system. The first found that participants could discriminate between five different vibrotactile sites (four individual tactors and all simultaneously) with a mean accuracy of 88.8% after initial training. In the second experiment, participants were blindfolded and instructed to move their hand wearing the device to one of four locations within arm's reach, while hand trajectories were tracked. The tactors were controlled using two different strategies: (1) repeatedly signal axis with largest error, and (2) signal both axes in alternation. Participants demonstrated essentially straight-line trajectories toward the target under both instructions, but the temporal parameters (rate of approach, duration) showed an advantage for correction on both axes in sequence.