Effective Compensations for Disability: Results from a Usability Evaluation of an Assistive Robot Among Spinal-Cord-Injured Users

Wheelchair-mounted robotic arms (WMRAs) are assistive manipulators designed to increase the functional independence of individuals with limitations in the upper and lower extremities. While previous research has identified several visual, cognitive, and physical abilities that facilitate optimal operation of such a device, these have yet to be accounted for when designing the human–robot interface. This study investigates whether interface-level compensations can improve usability and support more personalized control across users with different abilities. Five interface compensations were implemented and evaluated: object highlighting, move suggestions, slowing near objects, a one-click approach, and a level indicator. A user study was conducted among individuals with spinal cord injury as well as able-bodied younger and older adults serving as comparison groups. Evaluations of task performance metrics, perceived WMRA usability, and user experience were conducted. The results indicate that younger adults achieved the highest task efficiency, followed closely by participants with spinal cord injury, with both groups reporting good-to-excellent usability, whereas older adults showed lower efficiency and rated the system as having fair usability. The one-click automated object approach feature was identified as the most useful compensation among all participant groups. Overall, participant feedback indicated that spatial visualization and spatial orientation were the most important individual differences affecting the operation of the arm.