Electronics
Raspberry Pi
The robot uses two Raspberry Pi 5 units, referred to as the "Main" and "Aux" Raspberry Pi.
The "Main Raspi" is responsible for core robot functionality and launches the odometry, lifecycle management, and bridge-related ROS nodes.
The "Aux Raspi" handles the majority of the remaining ROS launch packages, including the computationally intensive perception and support nodes.
Hardware Specifications
Main Raspberry Pi
- Raspberry Pi 5
- 16 GB RAM
- 60 GB storage (SD card)
Aux Raspberry Pi
- Raspberry Pi 5
- 8 GB RAM
- 512 GB external SSD storage
System Architecture
During testing, it was observed that the Main Raspi could not reliably handle all ROS launch packages simultaneously. To improve stability and performance, most workloads were therefore moved to the Aux Raspberry Pi.
One likely reason for this difference is the storage medium. The Main Raspberry Pi uses an SD card, while the Aux Raspberry Pi uses an external SSD, which provides significantly faster read/write performance and better handling of high I/O workloads generated by ROS 2 nodes, logging, and vision processing.
This split architecture allows the robot to distribute computational load more effectively and improves overall system responsiveness and reliability.
Ethernet Router
Teensy Configuration
Figure: The main hardware blocks. Two Teensy processors are the interface to the hardware. The drive processor controls the drive motors, safety and battery system. The front processor controls the brush and the front wheel to lift the brush. A main PC integrates the functionality with additional sensors to allow autonomous operation.
Teensy firmware
Fejemis Teensy software is build using standard Arduino library configurations. The interface to the main PC is organized as text-lines.
Electrical
Fejemis electrical wiring etc.
Battery control
The Fejemis battery control is a 24V system (2x3cell LiPo 5Ah) with power on-off and measurement electronics. There is on-board chargers for all batteries.
