Algorithm 1 The proposed localization strategy.
Input:$\left\{u_m^j\right\}$ and $\left\{v_m^j\right\}$ where $j\in [1,25]$. Output:$u_m$ and $v_m$. Initialization: Left/right foot horizontal coordinates $\alpha$/$\beta$ and the feet vertical coordinate $\gamma$. $\alpha ={\displaystyle \frac{\sum \left\{u_m^{15},u_m^{20},u_m^{21},u_m^{22}\right\}}{\#\left\{u_m^{15},u_m^{20},u_m^{21},u_m^{22}\right\}}}$          $\beta ={\displaystyle \frac{\sum \left\{u_m^{12},u_m^{23},u_m^{24},u_m^{25}\right\}}{\#\left\{u_m^{12},u_m^{23},u_m^{24},u_m^{25}\right\}}}$          $\gamma =\{v_m^{12}$,$v_m^{15}$,$v_m^{20}$,$v_m^{21}$,$v_m^{22}$,$v_m^{23}$,$v_m^{24}$,$v_m^{25}\}$
1:switch true do
2:    case $\alpha \ne \varnothing \wedge \beta \ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left({\displaystyle \frac{\sum \alpha }{\#\alpha }}+{\displaystyle \frac{\sum \beta }{\#\beta }}\right)$ and ${\mathcal{F}}_m^u=1$.	▹ Both feet joints are available
3:    case $\alpha \ne \varnothing \wedge u_m^{11}\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left({\displaystyle \frac{\sum \alpha }{\#\alpha }}+u_m^{11}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Left foot and right knee joints are available
4:    case $u_m^{14}\ne \varnothing \wedge \beta \ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^{14}+{\displaystyle \frac{\sum \beta }{\#\beta }}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Left knee and right foot joints are available
5:    case $u_m^{11}\ne \varnothing \wedge u_m^{14}\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^{11}+u_m^{14}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Both knees’ joints are available
6:    case $u_m^{10}\ne \varnothing \wedge u_m^{14}\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^{10}+u_m^{14}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Right hip and left knee joints are available
7:    case $u_m^{11}\ne \varnothing \wedge u_m^{13}\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^{11}+u_m^{13}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Right knee and left hip joints are available
8:    case $u_m^{10}\ne \varnothing \wedge u_m^{13}\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^{10}+u_m^{13}\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Hip’s joints are available
9:    case $u_m^2\ne \varnothing \wedge u_m^9\ne \varnothing$    then   $u_m={\displaystyle \frac{1}{2}}\left(u_m^2+u_m^9\right)$ and ${\mathcal{F}}_m^u=2$.	▹ Torso’s joints are available
10:    case $\alpha \ne \varnothing \vee \beta \ne \varnothing$    then   $u_m={\displaystyle \frac{\sum \left\{\alpha ,\beta \right\}}{\#\left\{\alpha ,\beta \right\}}}$ and ${\mathcal{F}}_m^u=2$.	▹ Consider any available feet joints
11:    otherwise   $u_m=\varnothing$ and ${\mathcal{F}}_m^u=0$.
12: end switch
13:switch true do
14:    case $\gamma \ne \varnothing$    then   $v_m={\displaystyle \frac{\sum \gamma }{\#\gamma }}$ and ${\mathcal{F}}_m^v=1$.	▹ Consider any available feet joints
15:    case $v_m^2\ne \varnothing \wedge v_m^9\ne \varnothing$    then   $v_m=v_m^9+(0.85/0.6)\left|v_m^2-v_m^9\right|$ and ${\mathcal{F}}_m^v=2$.	▹ Torso’s joints are available
16:    otherwise   $v_m=\varnothing$ and ${\mathcal{F}}_m^v=0$.
17: end switch