## 3 Results
### Qualitative Evaluation (Questionnaires)  
After running all tests, the participants were asked to grade every driving mode, in this particular scenario, on the following questions, from 1 (no/bad) to 10 (yes/good):  
1. Did you have the feeling that you were free to perform the secondary task?
2. Did you feel the system required your continuous monitoring of the situation?
3. Did you have the feeling that the system was too intrusive?Did you feel that your security was ensured by the system?
5. Did you feel that your interaction with the system was harmonious?
6. Provide an overall evaluation of the system.  
Figure 15 compiles participant's scores for each question and their respective averages. Questions 1, 2, and 4 relate to the perception of the system's ability to improve safety. Questions 3 and 5 address the issue of comfortable interaction through haptic feedback. Question 6 asks for an overall assessment of the different driving modes, requiring participants to express a balancing criterion.  
Questions 1, 2, and 4, correlate very well. The MANUAL mode is absolutely perceived as not providing any safety in the simulated scenario with repeated distraction events. The LK mode is perceived to provide some safety and the LC and SC are almost identically perceived to provide a high level of safety. Curiously, only one driver felt that the SC required less continuous monitoring of the situation than LC, while all others felt as compelled or more compelled to keep monitoring by the SC.  
Questions 3 and 5 also correlate well, showing that MANUAL and SC provided highly harmonious interactions and that the SC is not felt to be an intrusive system. On the other hand, the LC is perceived as the most intrusive of all tested modes, in line with the highest conflicting torque discussed above, while the LK is perceived as less intrusive, but also less harmonious, which most likely reflects the freedom to wander within small trajectory deviations that are characteristic of human drivers (low intrusiveness) combined with momentary corrections or \"notches\" that perturb the harmony of the interaction.  
Finally, after having pondered both safety and comfort parameters, the participants were asked to provide an overall score for each mode, forcing them to ponder their system evaluation under their particular criterion. A clear trend favoring SC appears in the answers. Again, a noteworthy answer is attributed to a participant that gave a perfect score to the MANUAL mode, apparently favoring driving independence in this mode, while accepting its inherent inability to provide extra protection during a distraction event. Not surprisingly, this answer came from the driver that never crossed the lane during the tests.  
From the driver's perception information, it also becomes apparent that a combination of SC with LK is worth evaluating. Not only might the anticipating torque of the LK help the already favored SC mode to improve dynamic parameters as discussed above, it could also help it to feel more harmonious and, if needed (depending on the automation capabilities), it could allow a reduction of the authority during normal driving (attentive driver) and compel the driver to keep monitoring the environment and avoid performing secondary tasks without compromising the added safety.  
Figure 15: System performance perception from questionnaires applied to the test drivers.