Algorithm 1 Tracking of pedestrian–object relation in a zone of control
Input: The trajectory ${\mathit{s}}^{\tau .z}$ with the latest position $\langle x_{\tau },y_{\tau }\rangle$ of a pedestrian agent $i$, the current relation $p{r}_{i,m}$ with respect to the function object $f{o}_m$, the location and the zones of the object $\langle {\mathcal{Z}}^C,{\mathcal{Z}}^N,{\mathcal{Z}}^F\rangle$, and $\omega (·)$ is the intent classifier. Output: The updated behavior class $p{r}_{i,m}{}^{new}$
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17	$\mathrm{i} \langle x_{\tau },y_{\tau }\rangle \notin ({\mathcal{Z}}_m^C{\displaystyle \cup }{\mathcal{Z}}_m^E)$:   # pedestrian left the ZOC of the object  return $None$ if $p{r}_{i,m}.phase==$ Unknown:  $p{r}_{i,m}.phase\leftarrow$ passing-by if $p{r}_{i,m}.intent==user$:  if $p{r}_{i,m}.phase==$ approaching and $\langle x_{\tau },y_{\tau }\rangle \in {\mathcal{Z}}_m^N$:  # entered engaged locations   $p{r}_{i,m}.phase\leftarrow$ engaged  $\mathrm{elif} p{r}_{i,m}.phase==$ engaged and $\langle x_{\tau },y_{\tau }\rangle \notin {\mathcal{Z}}_m^N$:  # left engaged locations   $p{r}_{i,m}.phase\leftarrow$ passing-by  else:   $p{r}_{i,m}.intent \leftarrow \omega {\left({\mathit{s}}^{\tau .z}\right)}_m$    # changed intent   $p{r}_{i,m}.phase\leftarrow$ passing-by $\mathrm{elif} p{r}_{i,m}.intent==nonuser$:  $p{r}_{i,m}.intent \leftarrow \omega {\left({\mathit{s}}^{\tau .z}\right)}_m$  if: $p{r}_{i,m}.phase==user:$   $p{r}_{i,m}.phase\leftarrow$ approaching return $p{r}_{i,m}$