## 2 Andruino Robots Design Criteria  
The Andruino family of low-cost educational robots, i.e., Andruino-A1 and the new Andruino-R2, is based on the following design and construction criteria:  
* Simplicity: It should contain the minimum amount of hardware components, with simple mechanical construction using easily accessible tools and simple assembly techniques, and with the simplest code. Sensors added to improve robot characteristics should be inexpensive.
* Open: Students should be able to build it from parts that are easy to find (local or popular web stores) and should be modular and extensible. Information should be distributed, so that students or others can easily repeat and improve the robot design, using open tools. The preference for open source will not imply the prohibition of the use of other tools accessible to students, in the event that there is no open alternative, so as not to limit the creativity of students. As a robotic system, the robot could be operated using a common robotic frame tool.
* Low-cost: Considering the use of student-owned smartphones, the rest of the robot components must be as cheap as possible, within a range of 35-40 euros.
* Educational: Both the construction of the robot, as well as the improvements and practical applications made by the students, must implement the knowledge of the procedure in several areas. It must provide a holistic view of product development, including hardware, communications, programming, robotics, IoT, artificial intelligence, networking, social skills, and teamwork. Its educational purpose is the motto that inspires the project: \"All doing is knowing / All knowing is doing\".
* Autonomous, cooperative and cloud robotics oriented: The robot must be designed to work autonomously but, at the same time, it must have the ability to act in cooperation with other robots or computers using communication networks, such as the Internet, and especially the resources of the public cloud. Therefore, the robot must be able to remotely use the processing and services offered by the cloud, to take advantage of the Internet of Things and advances in artificial intelligence, which are often offered in the public cloud to students.  
Respecting the design principles, the main differences and similarities between the Andruino-A1 and Andruino-R2 robots are summarized in Table 1. As can be seen, Andruino-R2 is integrated with ROS, has more onboard sensors, in addition to substantially improving processing and remote access to functions and data, as is typical of robots in the cloud.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Feature** & **Andruino-A1** & **Andruino-R2** \\ \hline Robot Chassis & Any 2 WD DC motors & Any 2 WD DC motors \\ \hline Andruino Shield & Version 1.0 & Version 2.0 \\ \hline Android-Arduino Link & Android to Arduino & Bidirectional \\ \hline Link Type & FSK Modulation, Audio & OTG, USB \\ \hline Arduino functions & Low-level Motor Control & Low-level Motor Control, Light Sensors, Ultrasonic Sensors \\ \hline On-Board Sensors & Camera, accelerometer, gyroscope, magnetometer, GPS, Bluetooth, Wi-Fi & Camera, accelerometer, gyroscope, magnetometer, GPS, Bluetooth, Wi-Fi & 3 \\  & GPS, Bluetooth, Wi-Fi & ultrasonic sensors, 3 light sensors \\ \hline High-Level Communication & Wi-Fi, pure socket (TCP/IP) & Wi-Fi, ROS (publish-subscribe architecture) \\ \hline ROS integrated & No & Yes \\ \hline
3D Model Gazebo & No & Yes \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of Andruino-A1 and new Andruino-R2.  
Figure 1: Andruino Robots: Andruino-A1 mobile robot (**left**); New Andruido-R2 mobile robot (**right**).  
The following two sections will provide details of both the hardware and the software of the new Andruino-R2 robot, as well as the relevant aspects that they contribute from an educational point of view.