# Accelerometer-Based Pavement Classification for Vehicle Dynamics Analysis Using Neural Networks
## 3 Results
This may indicate that the vehicle gradually contacts the surface or starts to traverse the cubes, albeit the impact is not yet as pronounced. Acceleration jumps become increasingly evident after 0.3 s, with several peaks exceeding \(\pm\)100 m/s\({}^{2}\), suggesting that the wheels are traversing gaps in tiles or cubes. Each apex in Figure 5 represents the contact of the wheels with the interstices between the tiles. These oscillations produce discernible although relatively weak vibrations that persist, owing to the uniform configuration of the concrete cubes. In contrast to traversing uneven terrains like potholes or ruts, this pavement type lacks significant, abrupt acceleration variations; yet, consistent vibrations do impact the vehicle's unsprung mass. Figure 4: The impact of potholes on vehicle vertical acceleration and dynamics: (**a**) the acceleration graph; (**b**) an example of the surface. Beginning at around 0.75 s in Figure 5, there is a reduction in the peaks, and the variations in acceleration become less significant. This may suggest that the vehicle has decelerated or transitioned into a smoother area where the tile gaps are less perceptible. Ultimately, from the 1 s mark onwards, the line approaches linearity, signifying a reduction in vibrations and maybe signaling that the car has departed off the concrete cube pavement. This surface, although not as coarse as a pit or grate, generates persistent, low-intensity vibrations that aggregate over an extended duration. The vehicle's suspension is perpetually exposed to stresses from the wheels traversing the gaps between the concrete cubes, perhaps resulting in a little but enduring loss of stability and discomfort for the occupants. The dynamics shown in Figure 5 indicate that each tile gap produces minor acceleration fluctuations; yet, owing to the uniform configuration of the tiles, the accelerometer captures rather stable data instead of erratic spikes typical of other surfaces. The coating of the concrete cubes, although producing reduced amplitude vibrations, provides a distinctly recognizable signal that can be detected by the accelerometer, owing to the consistent interstices between the cubes. This signal has a greater frequency and lower amplitude relative to rougher surfaces, although it still yields distinctive data beneficial for surface categorization algorithms. Figure 6 illustrates the acceleration of a vertically suspended mass traversing a cobble-stone surface. The pavement has an irregular structure, with stones varying in size and form, resulting in pronounced disparities in surface relief due to the spaces between them. These qualities result in the generation of frequent but uneven vibrations while traversing stones, as plainly seen in Figure 6.  
Between 0 and 0.2 s in Figure 6, a very subdued acceleration pattern is seen, characterized by minor and consistent vertical variations, suggesting that the vehicle has not yet encountered a significant rocky terrain or is operating at low velocities. However, from 0.25 s onwards, there are clearly more significant oscillations, indicating that the car has passed over a rougher section of stone pavement. The acceleration measurements exhibit significant fluctuations of \(\pm\)100 m/s\({}^{2}\), indicating that the vehicle's wheels encounter unevenly placed stones. The most significant increases in acceleration occur between 0.25 and 0.5 s, characterized by strong and irregular vertical acceleration, accompanied by a high frequency of leaps. The variation in stone pavement features may contribute to this phenomenon; in some areas, bigger stones induce more shocks to the vehicle's suspension, whilst in other regions, narrower gaps between stones result in milder but nevertheless frequent oscillations. At the conclusion of Figure 6, at about 0.6 s, the increments in acceleration progressively diminish, and from 0.75 s onwards, the variations stabilize almost completely.