# Route Optimization for UGVs: A Systematic Analysis of Applications, Algorithms and Challenges
## 2 Research Methodology
### Review Protocol  
Before starting a bibliographic analysis, a structured review protocol was created to methodically uncover, assess and interpret pertinent findings pertaining to the study subject (see Table 1). In order to investigate the subject from several angles, the procedure started with the creation of focused research questions. In order to create efficient search strings and conduct thorough searches throughout the four main databases--Scopus, ScienceDirect, IEEE Xplore, Springer and Google Scholar--suitable keywords were then chosen. As a first filter for the metadata sources, inclusion and exclusion criteria were established to guarantee the caliber and applicability of the findings. These standards improved the overall efficacy of the literature search and helped to narrow the research's focus. Additionally, it should be made clear that the inclusion and exclusion criteria were only applied to research that specifically examined UGVs. To keep the scope of the analysis limited to autonomous UGVs, any reference to embedded systems or mobile robotics in this assessment only relates to their use in UGVs. \begin{table}
\begin{tabular}{l p{284.5 pt}} \hline \hline Review Questions & RQ1: How is agricultural path planning optimization carried out? \\  & RQ2: What tools, techniques and technologies are employed for the best possible path planning? \\  & RQ3: What are real-time path planning’s primary obstacles? \\ \hline Selection Criteria & Articles required for inclusion criteria: \\  & - Research that was released between 2019 and 2024. \\  & - The research questions are addressed by the studies. \\  & - The use of ground mobile robotics in trajectory planning was the main topic of the literature. \\  & - The literature focused on the application of ground mobile robotics in trajectory planning. \\  & Articles with early access. \\  & Research that includes efficiency metrics. \\  & Research that has at least 10 citations. \\  & Research from indexed journals. \\  & Articles among the exclusion criteria: \\  & The use of airborne or cooperative mobile robotics in trajectory planning was the subject of the study. \\  & The complete texts of several publications were unavailable. \\  & Articles written in languages other English. \\  & Aerial (UAV) or maritime (USV) systems not hybridized with UGVs. \\  & Applications that do not use UGVs. \\ \hline \hline Literature Search & Sources: ScienceDirect, Scopus, Web of Science, IEEE Xplore and Google Scholar. \\  & The following search strings were used: \\  & - \"Route Optimization\" AND (\"Agricultural Robots\" OR \\  & \"Warehouse Robots\") AND \"Heuristic Algorithm\". \\  & - \"Path Planning\" AND \"UGV\" AND \"Heuristic Optimization\". \\  & - \"Path Optimization\" AND \"UGV\" AND \\  & \"Multi-Objective Optimization\". \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Examination of the SLR protocol. Following a systematic review of the literature (SLR), an initial pool of 61 research articles addressing the proposed topic were identified. Subsequently,rigorous selection and eligibility assessments were performed, following the PRISMA guidelines. [PERSON], a bibliographic reference manager, was used to streamline this process and identify duplicate entries. After the removal of redundant publications, a final set of 56 research articles was retained for further analysis. These selected articles formed the basis for the subsequent stages of this research (see Figure 1). The thematic distribution analysis of the studies reviewed reveals a predominance of the agricultural sector with 32 studies (57%), followed by logistics with 18 studies (32%) and surveillance with six studies (11%). This agricultural predominance is explained by the urgent need to optimize routes in sowing/harvesting operations, where algorithms such as the WOA and GA reduce ground coverage time by up to 40%. In logistics, the PSO and ACO approaches stand out for improving throughput in automated warehouses, although they present scalability limitations for networks of more than 1000 nodes.