## 3 Proposed Credibility Evaluation Methodology
### Definitions of Scenarios and Parameters  
To evaluate the credibility of XILS platforms, the test scenarios and key test parameters must be systematically defined. This section outlines the scenario selection criteria and the key parameters used in the proposed evaluation framework. We constructed six test scenarios based on driving conditions and maneuver types. Based on the control characteristics, these scenarios are categorized into lateral (A and B), longitudinal (C and D), and integrated (E and F) evaluation. Figure 3 illustrates each scenario. The lateral evaluation scenarios were designed to verify the steering performance and lateral stability of the subject vehicle. Scenario A represents a situation where the subject vehicle changes lanes on a straight road without any external environmental influence, while driving at speeds of 30 km/h, 50 km/h, and 70 km/h. Scenario B evaluates the vehicle's ability to stably follow a trajectory created based on information provided by the global positioning system (GPS) sensor on an S-shaped road, while driving at speeds of 20 km/h, 40 km/h, and 60 km/h. The longitudinal evaluation scenarios were intended to verify the subject vehicle's speed control and its interaction with a target vehicle. Scenario C involves a cut-in maneuver on a straight road, designed to evaluate the effectiveness of the adaptive cruise control function in maintaining a safe distance from the vehicle ahead. Scenario D focuses on testing the subject vehicle's ability to maintain a constant distance behind a slower target vehi  
Figure 3: Test scenarios created based on maneuver types. cle on a straight road. In both scenarios, the subject vehicle's speeds are 60 km/h, 80 km/h, and 100 km/h, while the target vehicle's speeds are 40 km/h, 60 km/h, and 80 km/h. The integrated evaluation scenarios were designed to analyze complex situations requiring simultaneous lateral and longitudinal control. Scenario E evaluates the subject vehicle's ability to perform steering and speed control while maintaining a stable distance from the vehicle ahead when both vehicles simultaneously change lanes on a straight road. In this scenario, the subject vehicle's speeds are set at 60 km/h, 80 km/h, and 100 km/h, while the target vehicle's speeds are set at 40 km/h, 50 km/h, and 80 km/h. Scenario F comprehensively assesses the subject vehicle's lateral stability and longitudinal following control while it drives behind the target vehicle on a curved road. In this scenario, the subject vehicle's speeds are 40 km/h, 60 km/h, and 80 km/h, while the target vehicle's speeds are 30 km/h, 40 km/h, and 50 km/h. In all six scenarios, the target vehicle utilizes a speed control method to maintain the specified target speeds; however, it may or may not reach the target speeds depending on the situation. By conducting experiments under these diverse scenarios, the performance of the ADS and the credibility of the XILS platform can be comprehensively evaluated. Table 1 lists the main test parameters used in this study, which are defined as internal signals reflecting the core operations of the ADS and consist of vehicle status information, object data based on perception sensors, and control commands. For the lateral evaluation scenarios (A and B), lateral acceleration (\(a_{y}\)), yaw rate (\(\gamma\)), and target steering angle (\(\delta_{des}\)) were selected as the primary metrics. These parameters are instrumental for a precise quantitative assessment of lateral control performance during lane-change maneuvers and curved-road navigation. For the longitudinal evaluation scenarios (C and D), we employed longitudinal acceleration (\(a_{x}\)), vehicle speed (\(V_{e}\)), target longitudinal acceleration (\(a_{x,des}\)), relative longitudinal distance (\(RD_{x}\)), relative lateral distance (\(RD_{y}\)), and relative speed (\(RV\)) as the core evaluation metrics. These measures are paramount for robust evaluation of whether a safe following distance is maintained and if speed is suitably regulated relative to a lead vehicle.