## 4 Operational Environment  
Special-purpose vehicles should be developed to carry out operations in a variety of environments, including rough terrain, forests, deserts, mountainous areas, and other environments [24; 25]. Mobile platforms should be adopted to operate for several important applications such as search and rescue, rural transport, and surveillance. An autonomous system that recognizes the drivable areas in off-road conditions is more challenging than a system suitable for urban areas where roads can be easily distinguished. Special-purpose vehicles need to be able to navigate narrow roads, cross rivers, and traverse steep and especially high vegetation. In this environment, vehicles may face obstacles such as rocks, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Ouster OS0-32** & **Velodyne VLP-16** \\ \hline Channels & 32 & 16 \\ Range & Up to 50 m & Up to 100 m \\ Range accuracy & \(\pm\)3 cm & \(\pm\)3 cm \\ Field of view (vertical) & 90\({}^{\circ}\) (\(-\)45\({}^{\circ}\)\(\rightarrow\)45\({}^{\circ}\)) & 30\({}^{\circ}\) (\(-\)15\({}^{\circ}\)\(\rightarrow\)15\({}^{\circ}\)) \\ Angular resolution (vertical) & 2.125\({}^{\circ}\) & 2\({}^{\circ}\) \\ Field of view (horizontal) & 360\({}^{\circ}\) & 360\({}^{\circ}\) \\ Angular resolution (horizontal) & 0.18\({}^{\circ}\)-0.7\({}^{\circ}\) (configurable) & 0.18\({}^{\circ}\)-0.7\({}^{\circ}\) (configurable) \\ Rotation rate & 10 or 20 Hz (configurable) & 5–20 Hz (configurable) \\ Points per second & 655,360 & Up to 300,000 \\ Internal IMU sensor & 3-axis gyro, 3-axis accelerometer & - \\ Operating temperature & OS0: \(-\)20 \({}^{\circ}\)C to +55 \({}^{\circ}\)C (with mount) & \(-\)10 \({}^{\circ}\)C to +60 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main parameters of Ouster OS0-32 and Velodyne VLP-16. Figure 6: View of Ouster (**a**) and Velodyne (**b**) LiDAR with the indicated field of view (FOV). trees, and other vegetation that can block the UGV's path. Additionally, the weather and light conditions may also have an impact on the vehicle's performance and ability to navigate. In Central Europe, the drivability of rough terrain is determined by vegetation. The operational environment can include trees, bushes, grass, and other types of plants [26]. The presence of vegetation can make it more difficult for autonomous vehicles to perceive the environment and make decisions about the best path (Figure 7). Dense vegetation can block the view of the vehicle's sensors, making it difficult to determine the shape of the terrain or the stability of the soil. Trees can also pose challenges for unmanned vehicles, such as low-hanging branches or dense undergrowth that can hinder the vehicle's passage or cause damage to installed sensors. Bushes and plants cast shadows that can make it difficult for the vehicle's sensors to accurately perceive the environment. Forests in Europe often include natural obstacles such as fallen trees, boulders, and streams, which off-road vehicles must navigate around to maintain their path. The height of trees and the thickness of vegetation can also impact the vehicle's perception in terms of identifying potential hazards or obstacles in the surroundings. The movement of a vehicle across a forest is influenced by various vegetation factors, including the trunk diameter and tree spacing. The trunk diameter affects the clearance of the vehicle and the width of the paths that it can take. The tree spacing determines the accessibility of the vehicle to different parts of the forest and its maneuverability. There are also seasonal factors, such as in summer, when warmer temperatures and longer days stimulate photosynthesis in trees, providing the energy they need to produce more leaves and grow taller. Additionally, in spring, constantly changing terrain conditions can lead to changes in terms of adhesion characteristics and rolling resistance, which can slow down vehicles and reduce their traction force and kinetic energy.