## 5 Field Test Configuration and Results
### Credibility Evaluation Results
#### 5.2.3 Results of Dynamics-Based Evaluation  
We comparatively analyzed each scenario using the dynamics-based fidelity assessment methodology described in Section 3.4. The similarity of the dynamic motion responses between VILS and real-vehicle tests was quantitatively analyzed based on the six DOFs that constitute the translational and rotational motions of a vehicle. Table 6 lists the dynamic consistency indices calculated by weighting the average similarity index for each DOF. Values closer to 1 indicate more consistent dynamic responses between the simulated and real vehicles. Table 7 presents the dynamic correlation index for each scenario. The dynamics consistency index and correlation values in Tables 6 and 7 exhibit a clear pattern. Across all scenarios, the consistency index and correlation displayed a consistent, gradually decreasing trend with increasing speed. This is ascribed to the increased influence of disturbances such as crosswinds and road surface irregularities, which are more pronounced at higher speeds, along with amplified nonlinearities in the tire-body dynamics and increased input-output timing differences due to controller response delays. In terms of the evaluation type, the best dynamic consistency was observed within the VILS tests, while relatively low consistency was observed between the real-world and VILS tests. This is attributed to the structural advantage of the simulation environment, which allows precise control over the initial conditions. Regarding the effect of scenario complexity, the lateral-motion scenarios (A and B) exhibited the highest consistency index, the longitudinal-motion scenarios (C and D) displayed moderate consistency, and the integrated scenarios (E and F) showed the lowest consistency. The low consistency in the integrated scenarios resulted from the complex response of the system due to the simultaneous occurrence of longitudinal and lateral inputs and the dynamic interaction between the subject and target vehicles. The foregoing observations underscore the advantages of the proposed dynamics-based fidelity assessment over traditional assessment methods. First and foremost is the ability to reflect disturbances. Our method can compare the reproducibility between real-world and simulation tests, considering various disturbance factors, such as crosswinds, road surface conditions, and tire characteristics, an important aspect that is often overlooked in traditional parameter-based evaluations. Additionally, the dynamics evaluation utilizes a multidimensional measurement mechanism: rather than depending on a single parameter or a specific input condition, it integrally measures the complex response of the overall system, thereby mitigating structural inconsistencies. This results in a balanced distribution of the dynamics correlation indices, without extremes. In terms of practical credibility, the evaluation criterion (\(\alpha_{D}\)) being satisfied in all scenarios and under all speed conditions proves that the VILS platform could adequately reproduce the real vehicle's dynamics, even in complex, integrated-behavior scenarios. The dynamics-based fidelity assessment is superior to existing methodologies as it includes vehicle dynamics characteristics. Existing evaluation metrics focus only on indi