Algorithm 2 Genetic Algorithm with Minimum Energy for Data Forwarding (GAMEDF).

Initialization: Battery capacity of the UAV is insufficient for visiting all CH robots, i.e., $B<B_{TSP}$. Algorithm: for$K=(M-1):1$do    # Comment: Choose K of M CH robots and desist from visiting remaining CH robots.    find all $\left(\genfrac{}{}{0pt}{}{M}{K}\right)$ combinations of the CH robots.    # Comment: For each of the $\left(\genfrac{}{}{0pt}{}{M}{K}\right)$ combinations of CH robots.    for $a=1:\left(\genfrac{}{}{0pt}{}{M}{K}\right)$ do       # Comment: Check whether the UAV can find a route to visit all CH robots in the combination $S_a^K$.       if ${\displaystyle \underset{\pi }{min}{E}_{UAV}^{\pi }\le B}$ for $S_a^K$ then          # Comment: $S_a^K$ is a feasible K-element combination, i.e., $S_a^K\in S^K\left(B\right)$. find the minimum energy consumption of the CH robots in $S-S_a^K$.          Use Algorithm 1 for each CH robot $i\in S-S_a^K$. find ${\displaystyle \sum _{i\in S-S_a^K}{\gamma }_i^{\pi }}$      end if   end for   # Comment: If there exists at least a feasible K-element combination, find the K-element combination $S_a^K$ by which energy consumption of CH robots in $S-S_a^K$ will be minimum.   if $S^K\left(B\right)\ne \varnothing$ then       find ${\displaystyle \underset{S_a^K\in S^K\left(B\right)}{min}\sum _{i\in S-S_a^K}{\gamma }_i^{\pi }}$   end if end for     # Comment: find the combination $S_a^K$ by which the minimum energy consumption of the CH robots in $S-S_a^K$ will be minimum (In this step, all K values are considered so this is the step to find the minimum of minimum).     find ${\displaystyle \underset{K}{min}\left[\underset{S_a^K\in S^K\left(B\right)}{min}\sum _{i\in S-S_a^K}{\gamma }_i^{\pi }\right]}$.     # Comment: As output, provide the result of K and the combination $S_a^K$ as the solution. Output:${\displaystyle (K,S_a^K)=argmin\sum _{i\in S-S_a^K}{\gamma }_i^{\pi }}$