## 3 Methodology
### User Study  
The aim of the user study is to determine the relationship between the objective variables in the maneuver and the subjective perception of the test persons. A clear correlation between subjective perception and objective variables validates the functionality of the maneuver. In the first step, a valid database must be generated to achieve this goal. In order to achieve the same meaningful boundary conditions for all test persons, they are instructed by the test supervisor. Each maneuver is completed six times, according to the following procedure. Test Drive 1 is used to instruct the test persons. Test Drives 2 to 6 take place with the recording of measurement data and they serve to generate a database. For each test drive, the test driver simulates a driving style (Table 2) in randomized order, whereby the \"maximum comfort\" driving style is the only one that is driven two times. The reason for this is that the \"maximum comfort\" driving style is the most difficult to approach for a human test driver since small driving errors can affect the comfort rating of the entire test drive. Performing this driving style twice increases the probability of an error-free test drive, and thus, the number of usable results. \begin{table}
\begin{tabular}{c c} \hline \hline
**Driving Style** & **Description** \\ \hline Maximum comfort & Acceleration and braking as smooth as possible \\  & low lateral forces \\  & Low-jerk driving \\ \hline Neutral comfort & Compromise between speedy and comfortable driving \\ \hline Low comfort & Moderate speed driving \\  & Jerky steering, braking, and acceleration \\  & Accentuated late cornering \\ \hline Minimum travel time & Swift completion of the maneuver \\  & Distance to the limit of the vehicle \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Driving styles used for the user study. After each test drive, there is a break of about two minutes during which the test persons evaluate the driving style used in the maneuver on the basis of the questionnaire. A rating of the driving comfort must be given. Selecting a word from the semantic differential and filling in the comments field are optional. The test vehicle is at a standstill during the evaluation phase. After completion of the measurement drives of each driving maneuver, the test persons have the opportunity to give general feedback regarding the test execution and the different driving styles. The acquisition of acceleration data using the inertial platform mounted in the trunk requires postprocessing of the measured data. The different positions of the platform and the test person give rise to a measurement error resulting from the angular acceleration of the vehicle. A correction for the yaw acceleration is calculated using a single-track model. Corrections for roll and pitch acceleration are neglected due to the unpredictable head movement of the test persons. Furthermore, all recorded subjective data from the questionnaire are corrected with the average of the respective test person. The reasoning behind this is that predetermined evaluation references were deliberately avoided when carrying out the experiment. Therefore, each respondent uses the evaluation scale differently. An average correction increases the comparability of the subjective evaluations. The later application of a modified version of [PERSON] power law as a regression model further requires the use of a continuous scale [47]. The application of a mean-value correction converts the stepped absolute evaluation scale to a relatively continuous scale. A connection between the objectively measured values and the subjective perception of the test persons is achieved by nonlinear regression analysis. The regression model is a modified version of [PERSON] power law of the formula:  
\[\text{Y}=1+\text{k}\;(|\text{X}-\text{X}_{0}|)^{\text{n}} \tag{1}\]  
Y is the subjective grade of the test drive by the test person on a six-level Likert scale for driving comfort and X, the maximum of the measured variable.