## 4 Modeling and Experimental Validation Dynamics Characteristics of the Truck
### Dynamic Validation of the Truck Model  
For the experimental test, a scenario repeated double-lane change was chosen to verify the lateral dynamics of the truck model, where the truck follows a defined trajectory, as shown in Figure 11.  
These experiments were carried out at the Military Academy in Belgrade on a dry asphalt road. Two tests were performed. Sensors were essential for signal acquisition. Tree types of sensors were used to extract dynamic information and these were the following:  
* A Potentiometer sensor is placed on the truck's steering wheel to record the steering wheel rotation angle applied by the driver as a function of time during the maneuver. * SST 810 dynamic inclinometer (Vigor Technology, Shanghai, China) is placed in the truck's center of gravity and is used to measure the angle and acceleration. Figure 11: A repeated double-lane change scenario. Figure 10: Full truck models: (**a**) 3D model; (**b**) multi-body model. * Kistler Correvit S-350 sensors (Winterthur, Switzerland) are used for the direct, slip-free measurement of a vehicle's longitudinal and transverse dynamics, placed on the left side of the truck to measure the truck's longitudinal and lateral velocities. For data acquisition, an HBM Quantum MX840B universal amplifier was used together with HBM Catman easy 5.4.2.11 software for measurement and result analyses (HBK, Darmstadt, Germany). The entities measured by each sensor are presented in Table 6 and their positions on the truck are shown in Figure 12.  
Before the test started, it was necessary to calibrate the sensors. The truck ha to be driven in a straight line to reach the desired speed, and the driver had to maintain this speed during the test. The data from the steering sensor and the average truck's velocity were an input for the simulation. Two event files were created in the ADAMS software to control the steering wheel of the truck model, and to impose a constant truck velocity. These files included the curves of the steering wheel angle as a function of time, obtained from the experiments, as shown in Figure 13, and the imposed truck velocities, which were 47 km/h and 45 km/h for test 1 and test 2, respectively. The results obtained from the experimental test and the simulation for test 1 and test 2 are presented in Figures 14 and 15, respectively, where the truck velocity (\(v\)), lateral velocity (\(v_{y}\)), yaw acceleration (\(a_{z}\)), roll acceleration (\(a_{x}\)), roll angle (\(\theta_{x}\)), and lateral acceleration (\(a_{y}\)), are plotted. From these figures, it can be observed that the curves obtained from the experiment and the simulation are in phase. This enables better validation than the one presented in [5]. In the case of a double lane change maneuver [5], the simulation results demonstrate a phase shift in time compared to the experimental ones, which is due to the inability to control the steering wheel rotation during the simulation in order to reproduce the same maneuver performed by the driver during the experiment. On the other hand, validation of the model presented here was carried out by comparing five  
From the comparison of the Root Mean Square (RMS) of each parameter between the simulation and the experiment, as detailed in Tables 7 and 8, the deviation is within the acceptable range, and the maximum deviation does not exceed 10%. The deviation between the simulated model and experimental test due to several parameters such as the truck model is not ideal due to their structural complexity, the initial conditions during the experiment, road conditions, and the sensor errors. Based on the lateral dynamics results, the multi-body model can be considered validated. This validation allows us to proceed with the complete validation in future works focusing on the vertical dynamic and further suspension optimization to gain better off-road characteristics of the truck.