# SambotII: A New Self-Assembly Modular Robot Platform Based on Sambot
## 3 Information System of SambotII  
One noticeable improvement of SambotII, as compared with SambotI, is the information system (see Figure 5). The perception, computing, and communication abilities are enhanced by integrating a camera, a MCU (i.e., a microprocessor unit that serves as a coprocessor), a powerful x86 dual-core CPU, and some other sensors into a cell robot. Figure 6 shows the major PCBs (Printed Circuit Board) of SambotII.  
Figure 4: The schematic of docking deviation of two SambotII.  
Figure 5: Structure of the information system.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Direction**} & **Permission** & \multirow{2}{*}{**Direction**} & **Permission** \\  & **Deviation/mm** & & **Deviation/(\({}^{\circ}\))** \\ \hline Movement along X & 13 & Rotation around X & \(\pm\)5 \\ Movement along Y & \(\pm\)4.5 & Rotation around Y & 10 \\ Movement along Z & \(\pm\)19.5 & Rotation around Z & \(\pm\)5 \\ \hline \hline \end{tabular}
\end{table}
Table 3: The acceptable docking deviation between two SambotIIs.  
The information system consists of three subsystems: The actuator controlling system, the sensor system, and the central processing system.  
The actuator controlling system controls motors, which determine the movement and operations of SambottII. The PWM signals are generated by a MCU at first, and then they are transmitted into the driver chip to be amplified. Those amplified analog signals are eventually used to drive the customized  
Figure 6: The major PCBs (Printed Circuit Board) of SambottII. (**a**) Top view of main board 1, which contains motor drivers, MCU, plugs, etc.; (**b**) Top view of main board 2 with some level translation and I/O chips on its back; (**c**) Assembly of main board 1, main board 2 and Intel Edison module; (**d**) Mechanisms of the hooks and its PCB in the active docking surface; (**e**) Camera and laser tube in the active docking surface; and,(**f**) PCB of LEDs in both left and right sides of SambottII with the I/O chip on the back of PCB.  
motors. Each motor is integrated with a Hall effect rotary encoder, which converts angular velocity into pulse frequency and then feed back into MCU, forming a closed-loop control system. When combining with limit switches, the MCU can open or close the hooks and rotate the neck. By controlling the I/O chip, the MCU can change the colors of LED lights, read the states of switches and turn on or off the laser.  
The sensor system includes the encoders, switches, an IMU (Inertial Measurement Unit used to measure orientation and rotation) and a customized HD CMOS camera. Combined with laser tube and LED lights, the sensor system can measure the distance and angle between two docking robots. By identifying the combination of color-changeable LED lights, the robot can locate the specific surface it should connect with during the self-assembly procedure.  
The central processing system is a high-density integrated module [17] (see Figure 5) that contains an Intel Atom CPU, a storage, a wireless, etc. (see Table 4). It supports Linux Operation System (OS) and can run multiple softwares concurrently, capture pictures from the camera through USB, and communicate with other robots through Wi-Fi. Moreover, it is binary compatible with PC.