Algorithm A1 processBackward

Input:$P_{robot}$: the robot current position; $local\_path$: A local path intercepted from the global path; $global\_target$: the global target Output:${\theta }_{local\_target}$ 1:$D_{global}\leftarrow Euclidean\_distance(P_{global\_target},P_{robot})$ 2:Set the reachable distance of the global target $\to D_{global\_near}$ 3:if$D_{global}>D_{global\_near}$then 4:    Get the $local\_target(x,y,\theta )$ from the last point of $local\_path\to local\_target$ 5:    $D_{local}\leftarrow Euclidean\_distance(P_{local\_target},P_{robot})$ 6:    Calculate the direction vector between the robot and the local target $\to {\mathit{V}}_{\mathit{lt}}$ 7:    Calculate the direction vector of the robot $\to {\mathit{V}}_{\mathit{robot}}$ 8:    $dotproduct\leftarrow {\mathit{V}}_{\mathit{lt}}·{\mathit{V}}_{\mathit{robot}}$ 9:    if $dotproduct<0$ then 10:      ${\theta }_{local\_target}\leftarrow {\theta }_{local\_target}+\pi$ 11:   else 12:      ${\theta }_{local\_target}\leftarrow {\theta }_{local\_target}$ 13:   end if 14:else 15:   ${\theta }_{local\_target}\leftarrow {\theta }_{global\_target}$ 16:end if