# Head Pose Detection for a Wearable Parrot-Inspired Robot Based on Deep Learning
## 2 Robot Architecture  
The main scope of this research study is to design and develop a wearable pet robot that can mimic the head pose orientation of the wearer. In terms of morphology, the KiliRo robot can be defined as a two-legged wearable robot, having a physical appearance that resembles a parrot. We considered a set of design constraints in deciding the dimensions of the robot during the concept generation process:  
* Height <250 mm;
* Weight <250 g;
* Head rotation 180 degrees;
* Operate between 10 \({}^{\circ}\)C and 45 \({}^{\circ}\)C  
After a series of brainstorming sessions on concept generation and selection sessions, we developed a wearable pet robot KiliRo centered on achieving 180 degrees of rotating head design. The curvature of the robot's leg design was optimized to create a wearable robot design. The dimensions and weight of the robot played a vital role in the wearable robot design, as the wearers wore them in most cases. The dimensions of KiliRo-W and the selection of commercial devices, such as servo motors, electronic boards, etc., were opted to fit the robot design constraint on size and weight. The robot has three parts: head, body, and wings. The neck part connects the head and body. A static tail is attached at the top of the head for aesthetic appeal. The feet were designed through inspiration from parrots and were modified to adapt to the wearable design, which can fix to the body part. The robot parts were designed to be hollow to minimize the weight and optimize the three-dimensional printed materials. The specifications of the mechanical properties of the wearable parrot robot are listed in Table 1.  
The robot's head was mounted with two servo motors (SG90, manufactured by TowerPro) to provide pitch and yaw motions. The robot can turn its head 90\({}^{\circ}\) left and right from the center, and move up and down. The produced design can mimic 5 head positions of the wearer, namely, straight, left, right, left intermediate, and right intermediate at angles of 0\({}^{\circ}\), 90\({}^{\circ}\), \(-\)90\({}^{\circ}\), 45\({}^{\circ}\), and \(-\)45\({}^{\circ}\), respectively. The exploded of KiliRo robot is presented in Figure 1 and its physical architecture is illustrated in Figure 2. The head rotation positions and the schematic of the robot are presented in Figures 3 and 4, respectively. Initial head position of the robot is set at 0\({}^{\circ}\) and when it detects the wearer's head position as left, it turns 90\({}^{\circ}\), and turns \(-\)90\({}^{\circ}\) when the wearer turns their head toward the right. Similarly, 45\({}^{\circ}\) and \(-\)45\({}^{\circ}\) are achieved when the robot detects left intermediate and right intermediate positions of the wearer's head. Even though the robot can achieve pitch motion on its head, it was not deployed during this study. The robot uses the camera mounted on its head to detect the wearer's head position and processes it using a Raspberry pi-3 small computer to detect and actuate its head accordingly. The list of hardware used in the robot is presented in Table 2. A TREK Ai-Ball portable Wi-Fi camera as the imaging sensor was used for the KILIRO robot. The Wi-Fi camera used can capture images at 30 Hz with a maximum resolution of 640 \(\times\) 480. The camera possesses a range of focal length form 20 cm up to infinity with a view angle of 300\({}^{\circ}\). \begin{table}
\begin{tabular}{c c} \hline \hline
**Robot Full Body Material** & **PLA (Poly Lactic Acid)** \\ \hline Dimensions W \(\times\) H (mm) & 160.36 \(\times\) 81.39 \\ Weight (g) & 140 \\ Head rotation (degrees) & 180 \\ Head tilting (degrees) & 45 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mechanical properties of wearable KiliRo robot.