# Remote Control Device to Drive the Arm Gestures of an Assistant Humanoid Robot
## 6 Discussion and Conclusions  
This work presents a remote control device designed to drive the arm gestures of an assistant humanoid robot. The remote control is a master device that has been implemented with two passive arms replicating the four degrees of freedom of each arm of the humanoid robot. The electronic control board of the master device is based on a microcontroller that senses the position of passive each joint by using potentiometers and then sends this information to the humanoid robot for direct arm gesture replication. The remote control device also includes two gamepads instead of hands in order to control the motion and head of the mobile robot without releasing the arms of the device during telecontrol. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Gesture** & **Movement** & **Structural Delay** & **Total Telecontrol Delay** \\ \hline Upwards & Neutral (Table 2, (a))—Up (Table 2, (g)) & 0.274 s & 0.68 s \\  & Neutral (Table 3, (a))—Diagonal left (Table 3, (d)) & 0.274 s & 0.45 s \\ Upwards and lateral & Left (Table 3, (d))—Right (Table 3, (g)) & 0.274 s & 0.44 s \\  & Right (Table 3, (g))—Left & 0.274 s & 0.50 s \\ Downwards & Up (Table 2, (g))—Neutral & 0.274 s & 0.50 s \\ Circular (inwards) & Neutral—Neutral (both arms inwards, 4 turns) & 0.274 s & 0.90 s \\ Circular (clockwise) & Neutral—Neutral (both arms clockwise, 4 turns) & 0.274 s & 0.34 s \\ Wave & Neutral—up—wave (right arm, 4 waves) & 0.274 s & 0.60 s \\ Clap & Neutral—clap (4 claps) & 0.274 s & 0.53 s \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Telecontrol performances of the imitation model. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**(a) t = 0.00 s**} & \multicolumn{1}{c}{(b) t = 0.42 s} & \multicolumn{1}{c}{(c) t = 0.83 s} & \multicolumn{1}{c}{(d) t = 1.25 s} & \multicolumn{1}{c}{(e) t = 1.67 s} & \multicolumn{1}{c}{(f) t = 2.08 s} & \multicolumn{1}{c}{(g) t = 2.50 s} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Sequence of movements obtained when the operator performs an upwards and lateral gesture, moving the arms from the neutral position to upwards-left and then horizontally to the right. The imitation model implemented includes four stages: joint position measurement, mapping, data transmission and execution by the robot. The positions of the joints of each arm in the remote control device are measured and submitted at a frame rate of 20 ms as a direct reference for the imitation process. The advantage of a remote control replicating the joints of a humanoid robot is that there is no need to compute the inverse kinematics of the arms to properly map the position of the arms of the robot. This exact joint replication avoids the inverse kinematic problems reported by [PERSON] et al. [48] when controlling the position of the end effector of a humanoid robot using a complete human model as a reference. The imitation model is compatible with a half-duplex or full-duplex videoconference call to fully develop a telepresence application. To this end, the robot includes a high-resolution panoramic camera on its top and three RGB-D cameras placed at different heights. The experimental evaluation of the remote control device has been performed by comparing the time-evolution of the joints' angles of the arms of the device and of the APR-02 humanoid robot. A first experiment was conducted to monitor the joint information registered by the remote control device before submitting it to the mobile robot. This monitoring showed no jumps or irregularities in the remote control device sampling and submitting the position of the joints and other information at a general frame rate of 20 ms.  
A second experiment was conducted to measure the average structural delay of the mobile robot to replicate the position of the joints received from the remote controller device. This structural delay only depends on the current closed-loop control applied to drive the arms of the mobile robot and does not depend on the communication network.