# Ride Comfort Prediction on Urban Road Using Discrete
## 5 Conclusions  
This paper presents a ride comfort prediction method for urban roads, utilizing the discrete roughness index (DRI). Urban road sections differ from highways and expressways in terms of their shorter length and more uneven profiles. Moreover, vehicle speeds vary widely on urban roads. Consequently, we employ the DRI instead of the IRI because it excels at identifying local features and characterizing pavement roughness on short road sections.  
Our prediction method relies on correlations between the maximum transient vibration value (MTVV) and the DRI. These correlations were developed based on simulations conducted on 108 actual road profiles. In these simulations, we utilized an eight-degree-of-freedom (8-DOF) full-car model to analyze the vehicle's rolling and pitching motions more accurately. Before calculating the vertical seat acceleration, we preprocessed the road profile data using a wavelet-based filter designed to eliminate surface irregularities and cracks' effects.  
The correlations between the MTVV and DRI were determined through a series of power functions that considered vehicle speed and the combined effect of the left and right wheel paths. The results of the comparative study revealed that the DRI exhibits better adaptability in predicting ride comfort in short road section scenarios, mainly manifested in its superior correlation with an \(r^{2}\) value exceeding 0.7, which is higher than that of the IRI. The predictive outcomes further enable the assessment of driving comfort at different speeds, thereby providing guidance for the generation of comfortable driving strategies. Subsequently, we proposed speed-related DRI thresholds based on the comfort levels and acceleration limits outlined in ISO 2631. Using these correlations and thresholds, we can estimate ride comfort distribution on a given road section. To prevent abrupt speed changes and high jerk during vehicle deceleration, we introduce a hyperbolic-tangent-based speed control strategy.  
Although the results of this study confirm the better correlation between the DRI and the MTVV, there still exist certain limitations when applied to real-world scenarios. On the one hand, the evaluation of short-term ride comfort is highly complex and closely related to human subjective perception. The MTVV used in this study only considers vertical vibration, while localized road surface irregularities can also generate lateral and longitudinal accelerations, exacerbating discomfort. On the other hand, this study only analyzes a specific vehicle type; thus, the proposed prediction method and speed control strategy have limitations. The applicability of this approach to other vehicle types needs further validation. Addressing these two main limitations, our future works will mainly focus on considering multi-axis vibration for short road section ride comfort evaluation and its applicability to different vehicle types.  
This research was funded by the National Natural Science Foundation of China, grant number 52008309. Not applicable. Not applicable. Not applicable.  
The data presented in this study are available on request from the corresponding author. The authors would like to thank [PERSON] for her help in the technical ideas and [PERSON] for his work in the conducting the simulation and coding. The author declares no conflict of interest.