Evaluating the task effectiveness and user satisfaction with different operation modes of an assistive bathing robot in older adults.

Bathing robots have the potential to foster the independence of older adults who require assistance with bathing. Making human-robot interaction (HRI) for older persons as easy, effective, and user-satisfying as possible is, however, a major challenge in the development of such robots. The study aimed to evaluate the effectiveness (coverage, step effectiveness) and user satisfaction (After-Scenario Questionnaire, ASQ) with three operation modes (autonomous operation, shared control, tele-manipulation) for the HRI with a bathing robot in potential users. Twenty-five older adults who require bathing assistance tested these operation modes in a water rinsing task for the upper back. Autonomous operation led to maximum effectiveness (100%), which was significantly worse in the shared control (51.6-79.4%, p ≤ 0.001) and tele-manipulation mode (43.9-64.4%, p < .001). In the user-controlled modes, effectiveness decreased with decreasing robot assistance (shared control: 51.6-79.4% vs. tele-manipulation: 43.9-64.4%, p = 0.009-0.016). User satisfaction with the autonomous operation (ASQ: 2.0 ± 1.0pt.) was higher than with the tele-manipulation mode (ASQ: 3.0 ± 1.4pt., p = 0.003) and in trend also than with the shared control mode (ASQ: 2.5 ± 1.5pt., p = 0.071). Our study suggests that for an effective and highly satisfying HRI with a bathing robot in older users, operation modes with high robot autonomy requiring a minimum of user input seem to be necessary.