Table 2.
Summary of qualitative results of the user study. The ID indicates the corresponding participant
| Category | Generalized statement | ID |
|---|---|---|
| General | ||
| Functionality | Reactions of the system were predictable | 1, 2, 3 |
| Automatic stopping of the robot was very good | 6, 8 | |
| Modality | HoloLens is comfortable to wear | 3, 7 |
| It takes some time getting used to HoloLens | 6, 7 | |
| Phantom | Fixed points of orientation are missing | 4, 5, 6 |
| Feedback | LED ring is helpful | 3, 4, 8 |
| LED ring is out of field of view when looking at monitor | 3, 5, 6, 7 | |
| Lack of haptic feedback | 1, 2, 8 | |
| Difficult to estimate the applied pressure | 1, 4, 5 | |
| Additional functions | More accurate feedback on applied pressure | 1, 6, 8 |
| Additional feedback if applied pressure too high | 3, 5, 6, 8 | |
| Additional support for orientation | 3, 6, 8 | |
| Discrete interaction | ||
| Voice command | Voice recognition worked well | 3, 4, 5, 7 |
| Voice commands are intuitive | 1, 3, 7 | |
| Move To command is not intuitive | 1, 3 | |
| Voice interaction takes too long to select navigation modes | 3, 5 | |
| Saving and moving to | Saving and moving to poses worked well | 1, 2, 3 |
| Saving and moving to poses is practical | 3, 5 | |
| Activation gestures | Activation gestures are too similar | 2, 3, 5 |
| Alternative interaction to activate navigation modes would be helpful | 3, 5 | |
| Additional functions | Command to perform large rotations | 5, 6 |
| Commands to operate US functions | 5, 7, 8 | |
| Navigation interaction | ||
| General | Gestures for interaction are intuitive | 1, 2, 4, 6, 7, 8 |
| Interaction can be learned quickly | 2, 7 | |
| Robot motions are comprehensible | 4, 8 | |
| Robot motions are very precise | 4, 8 | |
| Very fast transfer of gestures to robot motions | 6, 7, 8 | |
| Current probe pose difficult to assess when looking at monitor | 2, 3, 4, 8 | |
| Translation | Motion on one level difficult | 1, 2, 7 |
| Rotation | Rotation challenging due to anatomical limitations of arm | 3, 4, 5 |
| Practice needed to learn that start orientation of the arm can be adjusted for rotation | 3, 4, 8 | |
| Helpful that during rotation the position is kept constant | 5, 8 | |
| Interaction space | Necessary to consciously remember field of view of the camera | 1,3 |
| Camera field of view for gesture recognition too small | 3, 4, 5 | |
| Physically demanding that hand must be held up due to the interaction space | 3, 4 | |
| Hand position would be more stable if the hand did not have to be held freely | 1, 8 | |
| Additional functions | Possibility to lock axes to allow motions on one level | 2, 7 |
| Automatic maintenance of constant surface pressure | 3, 7 | |