## 3 Method
### Procedures of AOQPIO
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Algorithm**} & \multicolumn{3}{c}{**Path Length(km)**} & \multicolumn{3}{c}{**Cost**} & \multicolumn{3}{c}{**Searching Time (ms)**} \\ \cline{2-9}  & **Map1** & **Map2** & **Map3** & **Map1** & **Map2** & **Map3** & **Map1** & **Map2** & **Map3** \\ \hline AOQPIO & 155.4329 & 154.3672 & 152.2775 & 78.8326 & 58.2366 & 63.1964 & 2755 & 2632 & 2553 \\ PIO & 177.4352 & 171.2873 & 165.4109 & 79.9846 & 61.3127 & 65.3127 & 3127 & 2607 & 2515 \\ QPIO & 165.2263 & 160.4521 & 169.5543 & 79.1623 & 63.0571 & 65.4218 & 2743 & 2613 & 2538 \\ PSO & 170.5448 & 168.6482 & 170.3458 & 79.5647 & 63.8452 & 68.8647 & 2716 & 2596 & 2491 \\ \hline \end{tabular}
\end{table} 
Table 2: The statistical results of path length, cost, and running time of the algorithms in the three maps. Figure 8: The comparative curves of iteration of the algorithms of the experiment carried out in map 3.

pigeon, which can accelerate overall convergence rate. Further, the adaptive map and compass factor is allowed to vary in each iteration during the process of AOQPIO algorithm, which ensures a balanced global and local search ability. To prevent the fast decrease and algorithm premature convergence at some local optimum, a new population updating strategy was presented regarding these issues. Simulation and comparison results showed that our algorithm has a better convergence rate, and the UAV path obtained by our algorithm has the lowest cost among all existing algorithms. Project administration, J.Z. ; software, Y.X. ; supervision, C.H. ; writing--original draft, Y.X. ; writing--review & editing, C.H. This work was funded by Fundamental Research Funds for the Central Universities (Grant No. BLX201605, No. 2016 ZCQ08), and National Natural Science Foundation of China (Grant No. 61703047). The authors would like to thank the editors and reviewers for their helpful suggestions and comments, which indeed improved the manuscript. The authors declare no conflict of interest. ## References

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