Introduction
After experiencing numerous complications with our power system in 2022, I decided to undertake in a complete redesign of the power system for 2023. The goal was to create a PCB that would significantly reduce the manual wiring required in previous years. Before I started the design process, I first had to choose a software for the club to use moving forward. After some deliberation, I landed on Kicad. Kicad is an open-source EDA software that is free to use and available on all platforms. Because of its open-source nature, it also has a ton of great online learning resources available. For version control, I decided the club should use Git and GitHub. Although Git is not typically used for physical projects, the file sizes in Kicad are small enough where we can use it. Using the same version control system as the software team greatly streamlined the onboarding process for new club members.
Motivation
Managing multiple ESCs in robotics projects can be challenging due to the complexity, and sheer amount of wiring needed. Hardwiring can also be unreliable as it is easy to mess up. The primary motivations for developing this PCB include:
- Simplified Wiring: A consolidated PCB design reduces the clutter and complexity associated with multiple wires, resulting in a more organized and efficient setup.
- Enhanced Reliability: Soldered connections on a PCB are more dependable than numerous connectors and wires, minimizing potential points of failure and enhancing overall system stability.
- Ease of Maintenance: The PCB design allows for straightforward replacement of faulty ESCs, eliminating the need for complex rewiring.
- Compactness: The PCB design takes up much less space than our previous system.
- Integrated Power Management: The inclusion of an LDO for power regulation and a voltage divider for battery monitoring ensures stable operation and provides valuable insights into system power levels.
Components and Features
The key components and features of the PCB include:
- ESCs: Blue Robotics ESCs
- Microcontroller: Teensy 4.1
- Voltage Regulator: Low Dropout Regulator (LDO) to provide a stable 3.3V power supply to the Teensy
- Voltage Divider: For battery voltage measurement
- Power Source: Blue robotics 4S Lipo Battery
PCB Design
The design of this PCB focused on efficient power distribution and reliable signal connections. Important design considerations included:
- Power Distribution: The PCB was designed to handle high current loads from multiple ESCs. To accommodate a maximum power draw of 80A, a 2oz copper PCB was used, with a 10mm bus for power to traces to handle the current without overheating.
- Signal Connections: Signal lines from each ESC are routed to the Teensy 4.1 microcontroller, with careful attention to minimizing crosstalk and ensuring reliable signal integrity.
- Onboard Voltage Regulation: An LDO provides a stable 3.3V supply for the Teensy 4.1, ensuring it operates within its required voltage range.
- Voltage Monitoring: A voltage divider circuit allows the Teensy to monitor the battery voltage, providing critical information for power management and system safety.
Photos and Schematics
Conclusion
The development of this power distribution PCB has significantly improved the management of our AUVs by simplifying the wiring process, enhancing system robustness, and facilitating easier maintenance. However, this PCB is incredibly simplistic as I designed it early on in my degree. In the future I would like to remake this board with custom ESCs, bulk capacitance, decoupling capacitors, a buck regulator instead of an LDO, and a low voltage cutoff/battery protection circuit.
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