Overview Notes

7-13-2024 Notes

In the design of this stack up I am hoping to reduce the count of boards while keeping modularity. I plan to separate high risk systems out into their independent boards so if the first rev does not work out we have an isolated system to work on.

I plan to have three separate housings excluding sensors/ cameras

List of housings:

• Main electrical box → this will hold all of the main electronics and will either be created out of sheet metal or machined out of something thermally conductive like Al
• Battery Housing → this will house the battery and possibly a management/ status PCB. It will be a costume box machined out of Al
• Hydrophone Housing: This will house all hydrophone signal processing circuits and mount to the hydrophones. I expect this to take a long time to develop and there could be noise problems from it crossing with the bandwidth of the ESCs, so this system will be isolated. This will be on the low priority end of the list and will be worked on last

List of sensors

Sensor	Function	Interface With
IMU	Navigation	-
DVL	Navigation	-
Hydrophone	Navigation	-
Cameras	Navigation	-
Pressure Sensor	Navigation	-
Temperature/ Humidity	Status	-
Battery Voltage	Status	-
Leak Detection	Status	-
ESC Dshot	Status/Navigation	-

List of Boards

• Power/ Battery Management board → This board will will measure the voltage level of the battery and report it. Must also display this onto a screen that is viable to the operator. There should be status lights and possibly and alarm that is set off that indicates when the battery has been discharged past a safe level.

If we do a redundant two battery system, we would need a way of switching between the two using some high power mosfets. I do not think that this is a smart idea unless we find a good reason to do it like this.

I think that If we can spec a good OTS battery it would make the most scenes to just use on battery in a housing and have it connect to a management system in the main electrical box

• Backplane Board → This board will hold all of the electronics that directly interface with hardware. The power from the Battery Management board will be converted on the back plane and there will be routing signal wires

  • Vin → 12V Power Bus
  • Vin → 9V Power Bus
  • Vin → 5V Power Bus
  • Vin → 3.3V Power Bus
  • All power buses must have capacitor banks, fusing, zener protection and status lights
  • ESC Power Bus → This power bus must me separated from the other components. It will need to be able to disconnect via mosftes witch will be used in connection with the kill switch board for an emergency shutoff
  • Must have a plugin for the ESC boards and provide power to them. Also must rout PWM and Dshot to the hardware board.
  • Routes wires from leak detection sensor to Hardware board
  • Have Backup power connection ports on all busses (must be able to plug in jetson, ethernt switch, and other hardware external to the stack)
  • Need bench testing power in port for when we are not using the batires.

• ESC Board → This behaves as a carrier board for the 4 in 1 ESC module. This must be a plug-able module that plugs into the bottom of the backplane and connects to its power bus. Must also route signal wires to the hardware board. It would be cool to make it so this module has an RP2040 on it, but since there are two esc boards, this may add extra complexity for not good reason. I think that this would make the software architecture much more difficult and and we would be required to write a custom prototypical instead of using micro ros.

• Hardware Board →

• Kill Switch Sensor Board →

• jetson ots

• router ots

• cameras and other modules