## 3 JET Design  
As detailed in Table 2, the height, weight, and wingspan of the developed robot are 1.63 m, 48 kg, and 2.12 m, respectively. Other robots, including TALOS, HRP-5P, and former THORMANG platforms, and human characteristics are also shown in Table 2. Similar to the THORMANG platforms, TALOS is a commercial off-the-shelf research platform which is developed by PAL-Robotics [18]. HRP-5P is an adult-sized humanoid developed to realize the use of humanoids in large-scale assembly industries. Compared with the THORMANG of Team SNU, JET is taller and lighter. However, JET is heavier than THORMANG3, the latest released version from ROBOTIS because THORMANG3 is the shortest platform among all of the THORMANG platforms. Both THORMANG3 and JET are developed on the basis of THORMANG, but THORMANG3 is designed to focus on increasing speed by reducing size. On the other hand, JET is designed to focus on the workspace to conduct difficult tasks, such as egress from the vehicle and climbing stairs in the DRC Finals, for THORMANG due to its small size. With a similar leg length to JET, TALOS is taller but much heavier due to stronger actuators and torque sensors. Developed to perform a variety of industrial tasks with a wide joint range, HRP-5P has 23 mm longer legs, and it is taller than JET. However, HRP-5P is much heavier due to its larger degrees of freedom (DOF) and stronger actuators. Notably, the JET height, weight, and leg length are similar to the averages for Korean young women aged 20-24 [19]. Due to the torque  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mission** & **Team SNU** & **Team ROBOTIS** & **Team THOR** & **Team HECTOR** \\ \hline Driving & **O** & **O** & **O** & **O** \\ Egress & **X** & **X** & **X** & **X** \\ Door & **O** & **O** & **O** & **X** \\ Valve & **O** & **O** & **O** & **X** \\ Wall & **O** & **X** & **X** & **X** \\ Surprise & **X** & **X** & **X** & **X** \\ Rubble & **X** & **X** & **X** & **X** \\ Stairs & **X** & **X** & **X** & **X** \\ \hline Score & 4 & 3 & 3 & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Scores of THORMANG-based teams in DRC Finals. Team SNU successfully performed 4 missions (**O**), but failed 4 missions (**X**), including the egress task.  
capacity of the hip pitch joint, the length of each link in the shin and thigh was adjusted. Therefore, the JET hardware specifications are suitable for performance of various complex tasks in a human-centered environment.  
Figure 3 shows the JET joint configuration, which consists of a total of 32 DOF, excluding the LiDAR actuator. There are eight joints in each arm with the end-effectors, six in each leg, two in the waist, and two in the head. In the waist, we used two DOF joints in the yaw and roll directions to increase not only the bipedal walking stability but also the robot workspace [22].  
The following subsections present details of the proposed hardware, i.e., the electrical system and lower and upper body designs.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **JET** & **THORMANG** & **THORMANG3** & **TALOS** & **HRP-5P** & **Korean** \\  & & **(Team SNU)** & & [20] & [21] & **Young Female** \\ \hline Height (m) & 1.63 & 1.47 & 1.38 & 1.75 & 1.83 & 1.61 \\ Weight (kg) & 48 & 60 & 42 & 95 & 101 & 55 \\ Wingspan (m) & 2.12 & 1.95 & 1.69 & 2.1 & - & 1.62 \\ Leg length & & & & & & \\ (mm) & 839 & 696 & 716 & 837 & 862 & 799 \\ \
\begin{tabular}{c} Thigh length \\ (mm) \\ \end{tabular} & 370 & 300 & 300 & 380 & 380 & 384 \\ Shin length & & & & & & \\ (mm) & 373 & 300 & 300 & 325 & 380 & 352 \\ Foot height & 96 & 96 & 116 & 132 & 102 & 63 \\
\begin{tabular}{c} Degree of \\ freedom \\ \end{tabular} & 32 & 32 & 32 & 31 & 37 & - \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison of JET, THORMANG (Team SNU), THORMANG3, TALOS, HRP-5P, and average Korean young female (aged 20–24) characteristics.  
Figure 3: Kinematic structure of JET.