# Determination and Evaluation of a Three-Wheeled Tilting Vehicle Prototype's Dynamic Characteristics
## 2 Three-Wheeled Vehicle Description
### Experimental Determination of Acceleration  
An aircraft runway was chosen to conduct the experimental field tests. To determine the acceleration, two different accelerometers (Dragy GP Meter and Vernier Wireless Dynamic Sensor), which were mounted on a three-wheeled vehicle center part were used. Measurements were performed while the vehicle was accelerating with two acceleration measurement devices; one of them was used for filming and measuring (Dragy GP Meter), and the Vernier Wireless Dynamic Sensor was used for measuring and using data for analysis. Obtained acceleration data are presented in Figures 5 and 6, which presents a test drive for acceleration measurements. Filtered data were obtained using the Butterworth second-order low-pass filter, which is usually used for the filtering of electric signals. The noise in the obtained data is related to the sensitivity of the measuring equipment, which was used for the determination of the three-wheeled vehicle acceleration (Figures 5 and 6). Test drive took 9.5-10 s, because the main goal was to determine the acceleration values of the three-wheeled tilting vehicle and use them for verification of the theoretical calculation. The obtained acceleration data (Figures 5 and 6) show similar results in both tests: the maximum accelerations are in the time period from 1.4 s to 4.5 s, after which it varies from 2.18 m/s\({}^{2}\) to 2.4 m/s\({}^{2}\). To precisely analyze these accelerations, we need to eliminate the 1.3 s (beginning) and 1.4 s (end) time periods, which were when the three-wheeled tilting vehicle started and ended acceleration process, because measuring devices are very sensitive and since it takes 1.3 s at the beginning to reaching the acceleration. The same is true at the end, when the three-wheeled vehicle is not accelerating. Another aspect is that when acceleration measurements were filtered, we also eliminated the maximum values at 4.2 s, when it reached more than 7 m/s\({}^{2}\) (Figure 5) and more than \(-\)2 m/s\({}^{2}\). These discrepancies were found in both experimental results and were possibly caused by the accelerometer being too sensitive, which in the same place gave values of acceleration that were different and too big. Comparing the experimental and calculated acceleration results shows that the maximum range of accelerations at the beginning, from 1.3 s to approximately 4.5 s, were similar (Figures 7 and 8). The calculated accelerations values (Table 3) were synchronized with driving speed data obtained from the Dragy GP Meter accelerometer. In this synchronizing stage, the time periods were converted from the driving speed range presented in Table 3 and the data obtained from the Dragy GP Meter accelerometer. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameter** & & & & **Values** & & & \\ \hline \(v_{a}\), m/s & 3.55 & 7.09 & 10.64 & 14.19 & 17.74 & 21.28 & 24.83 \\ \(F_{r}\), N & 1142.66 & 1142.66 & 1142.66 & 1142.66 & 1127.625 & 962.24 & 902.1 \\ \(F_{o}\), N & 1.22 & 4.88 & 10.98 & 19.50 & 30.48 & 43.90 & 59.73 \\ \(D\) & 0.2394 & 0.2386 & 0.2374 & 0.2356 & 0.2301 & 0.1926 & 0.1767 \\ \(j\), m/s\({}^{2}\) & 2.19 & 2.18 & 2.17 & 2.15 & 2.10 & 1.73 & 1.58 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Calculated three-wheeled tilting vehicle theoretical dynamic characteristics. Figure 5: First test acceleration results with and without the filter. Figure 6: Second test acceleration results with and without the filter. Figure 7: First test’s acceleration results compared with calculated results. The calculated accelerations, presented in Figures 7 and 8, were converted similarly for these time periods as those mentioned above according to the synchronized data: 1.31-2.34 s--2.19 m/s\({}^{2}\); 2.35-3.38 s--2.18 m/s\({}^{2}\); 3.39-4.42 s--2.17 m/s\({}^{2}\); 4.43-5.46 s--2.15 m/s\({}^{2}\); 5.47-6.50 s--2.1 m/s\({}^{2}\); 6.51-7.54 s--1.73 m/s\({}^{2}\); 7.55-8.58 s--1.58 m/s\({}^{2}\).