Algorithm 1 Collision Avoidance Algorithm

Input:${\psi }_{way}\left(t\right)$,${\psi }_{i{n}_i}\left(t\right)$,${\psi }_{j,k}\left(t\right)$,${\psi }_{j,centre}\left(t\right)$,$\varphi \left(t\right)$,${\varphi }_{i{n}_i}\left(t\right)$,$R_{i{n}_i}\left(t\right)$,$R_j\left(t\right)$.

Output:$\dot{\varphi }\left(t\right)$.

1: for each moving intruder UAV i do      12:         $[{\psi }_{j,R},{\psi }_{j,L}]$← Equation (8);

2:     if $R_{i{n}_i}\left(t\right)<R_{RC,i}$ then           13:     end if

3:         $\rho \left(t\right)$←Equation (4);           14: end for

4:         $P\left(t\right)$←Equation (3);          15: $\mathcal{I}$←Equation (10);

5:         $R_p\left(t\right)$←Equation (6);          16: if ${\psi }_{way}\left(t\right)\in \mathcal{I}$ then

6:         $[{\psi }_{i{n}_i,R}\left(t\right),{\psi }_{i{n}_i,L}\left(t\right)]\leftarrow$Equation (5);        17:     ${\psi }_d\left(t\right)$←Equation (12);

7:     end if                      18:     $\dot{\varphi }\left(t\right)$←Equation (14);

8: end for                    19: else

9: for each fixed obstacle j do         20:     $\dot{\varphi }\left(t\right)\leftarrow K({\psi }_{way}\left(t\right)-\varphi \left(t\right))$

10:     if $R_j\left(t\right)<R_{RC,j}$ then                 21: end if

11:         $[k_R,k_L]$←Equation (7);         22: return $\dot{\varphi }\left(t\right)$