The electrical architecture of BBAUV 4.5 is a complete revamp of the subsystem from its predecessor. The previous subsystem had reached its maturity and was fast approaching its limits in terms of what features it can support.
The subteam has taken key lessons learnt from developing the BBASV 4.0 and undertook a major redesign to lay the foundations for future improvements.
The Ethernet and CAN Bus remain as our two primary methods of communication for high- and low-level components respectively.
Next-Gen Control with STM32
We decided to change all our microcontrollers (MCUs) from Atmel AVR chips to STM32 chips. Not only does this reduce our BOM cost, but the STM32 chips also boast better performance and have better support for a wide range of firmware improvements that we can implement in the future. We also leveraged on the robust development environments that STM32 supports, such as STM32CubeMX to better streamline our firmware development.
Backplane Reimagined
Similar to AUV 4.1, BBAUV 4.5’s electrical subsystem is also based off a backplane design, where up to four daughter boards can be plugged on top of the Power Switching Board (PSB). This overhaul enables the PSB to support even more boards, allowing us to further compartmentalize key functionalities and further modularize the stack. We also took advantage of this opportunity to better redesign the daughter board mounting and improve wire management.
We have also redesigned our base backplane which supports plug-and-play of our Electronic Speed Controllers via an adapter board, making it more compact and easier to maintain.
Better Power, Smarter Control
Similar to the BBASV 4.0, BBAUV 4.5 facilitates power control via selective toggling of power channels for key components, as well as better power monitoring to debug electrical faults. This feature is also integrated over CAN, enabling the software side to access key telemetry and control as well.
BBAUV 4.5 also features better power filtering, which improves overall system reliability.
Eyes on Everything
We have also expanded our telemetry reporting to use a Telegram channel as well, which increases visibility and allows for more members to monitor vehicle stats remotely. This allows for better coordination for battery swaps with members in lab when conducting pool tests.
We have ported this idea over for battery charging, where we redesigned our battery monitoring board to be compatible with an external monitoring board fitted to the battery charger. This reports telemetry to another Telegram channel which publishes the current state of charge as well as battery statistics, allowing us to track the battery degradation over time.