# Accelerometer-Based Pavement Classification for Vehicle Dynamics Analysis Using Neural Networks
## 2 Materials and Methods  
Research experiments were conducted to quantify the unsprung mass during acceleration. A passenger automobile was used for experimental investigations. The car's weight during testing was 1350 kg, with overall dimensions of 4430 mm in length, 1814 mm in width, 1510 mm in height, and a wheelbase of 2685 mm. The tire size was 205/55 R16. To measure vehicle dynamics factors, the following sensors were installed on the vehicle. Eight acceleration sensors were used, namely Analogue Devices ADXL327, with four designated for the wheels and four for sprung masses in the vertical axis. The dSpace Autobox device was used for data collection. The collected data were processed with Matlab R2022a software. The equipment used in the experiments is presented in Figure 1.  
To precisely delineate the many surfaces used in the experiment, it was essential to provide a comprehensive study of each surface's physical attributes, its impact on vehicle dynamics, and its possible effect on the experimental outcomes. Each surface in this research had distinct characteristics that influenced the unsprung mass and vehicle acceleration data, which were essential for constructing a classifier based on accelerometer measurements. The \"grater\" surface denotes one of the most abrasive surfaces used in the experiment. It is distinguished by its irregular, gritty texture that resembles a grater, which is the origin of its name. This surface is often used on roadways as a provisional layer or in regions with severe weather when smooth asphalt is not a sustainable long-term option. The coarse, irregular grater surface generates considerable vibrations in the car, particularly in the unsprung mass (wheels and suspension components), as the tires incessantly adapt to the little irregularities. The accelerometers affixed to the wheels captured high-frequency, substantial acceleration spikes in contrast to smoother surfaces. Consequently, the greater surface provided unusual accelerometer readings owing to its prominent roughness, rendering it a unique instance for surface categorization. The \"thump\" surface, in contrast to the grater, denotes a rough surface characterized by fewer, more widely spread protrusions or elevations. These bumps are substantial and induce significant vehicle oscillations, however they occur less often than the greater surface irregularities. This sort of surface is sometimes seen on inadequately maintained regional highways or locations where the surface is not routinely leveled. In this experiment, such a surface induced sporadic but significant vibrations when the vehicle's wheels encountered bigger bumps, followed by less intense vibrations in the intervals. The accelerometers recorded abrupt acceleration peaks as the vehicle traverved these bumps, yielding smoother readings in between, thereby creating a discernible pattern for categorization. This surface indicates the existence of potholes, a prevalent problem on roadways, particularly in areas experiencing severe weather that leads to asphalt degradation. Traversing potholes exerted considerable strain on both the unsprung and sprung masses of a vehicle. The dimensions, depth, and configuration of potholes vary significantly, rendering their effect on vehicle dynamics uncertain. When the vehicle's wheels encountered a pothole, the accelerometers registered abrupt, high-magnitude increases in acceleration. This presents a perilous scenario for the car, since substantial potholes may inflict damage at elevated speeds. Incorporating potholes into the experiment enabled the accelerometers to record anomalous data relative to other surfaces, owing to the abrupt and profound motions encountered by the wheels. The concrete cube surface is a prominent urban pavement, particularly in the historic sections of European towns where it is often seen on streets. Concrete cubes possess a reasonably smooth surface; yet, the connections between the individual cubes induce minor, regular vibrations.