5.1 How to Assemble Robot

These assembly instructions are only applicable to the AUV operating on Power Board Revision 4

Important Notice

Before proceeding, ensure the following:

• All tests apply only to Power Board Revision 4.
• Unplug everything and clear the AUV internals before starting.
• USB isolators are required for certain connections. For explanations, consult electrical leads.

1. Testing for Shorts

Using a Multimeter (Ohmmeter Beep Mode)

Battery Test Points

• Locate the two pairs of 4 test pads.
• The left 4 test points are labeled BATT and correspond to:
  1. batt1-
  2. batt1+
  3. batt2-
  4. batt2+
• Expected behavior:
  • batt1- and batt2- must be shorted to each other (pins 1 and 3).
  • No other pin combinations should be shorted.
• If pins 1 and 3 are not shorted or any other short is found, DO NOT proceed without consulting a lead.

Kill Switch Test Points

• The left set of 4 pins correspond to:
  • GND
  • Pre-System Kill Switch
  • System Kill Switch
  • Thruster Kill Switch
• Expected behavior:
  • No combination of these should be shorted.

2. Connecting Components

Thrusters

• Attach all thrusters to the thruster Molex connectors at the bottom of the board.
  • Two connectors per thruster:
    • Power connector
    • PWM connector
• Orientation:
  • Ground (black wire) should always point downwards.
• Insert 15A fuses for all thrusters.

Retest for Shorts

• Verify no shorts exist between:
  • Thruster Kill Switch Net and GND Net

Other Components

1. Attach Jetson connector to the board and plug it into the Jetson.
2. Add a 10A fuse for the Jetson.
3. Attach DVL Power Wire to the Power Board.
4. Connect DVL GND to the Power Board.
5. Connect DVL signal wires to a USB-UART converter.
6. If a Teensy 4.0 is missing from the board, attach a "cut" Teensy 4.0.
7. Attach Kill Switches:
   • System Kill Switch → Left Connector
   • Thruster Kill Switch → Right Connector

3. Power-Up Procedure (Using Power Supplies)

Initial Steps

• Open both kill switches before powering on.
• If using power supplies for the first time (or batteries are uncharged/unused for a long time), follow this method:
  • Use two identical power supplies.
  • Use alligator clips to connect them to the Molex connectors for:
    • batt1-, batt1+
    • batt2-, batt2+
  • Set voltage between 14.8V - 16.8V (recommended: 16V).
  • If thrusters, DVL, or other components are attached, allow the power supply to provide as much current as possible.
    • Recommended limit: 10A (high startup current for thrusters may trigger over-current protection and shut down power supply if limit is too low).

Powering On

1. Power on both power supplies sequentially.
   • Ensure no smoke or burning smell is detected.
2. Close the System Kill Switch.
   • The Jetson should power on.
   • Connect via DisplayPort.
   • To SSH, connect the Ethernet port.
3. Close the Thruster Kill Switch.
   • Expected Behavior:
     • 3 Beeps → Power detected
     • 2 More Beeps (if Teensy is plugged in) → ESCs and thrusters are armed (Total: 5 beeps)
4. DVL LED should flash green (indicating proper communication).

USB Connections (With Isolation)

• Teensy 4.0 on Power Board → MUST use a USB Isolator.
• Recommended Setup:
  • Teensy 4.0 → USB Isolator → USB-C Hub → Jetson
  • Avoid direct connection to PCIe extender.
  • USB-C provides built-in power management, preventing ESD spikes.
• Actuator Board → Pass through a USB Isolator → USB-C Hub.
• Other Devices:
  • Display Board, Hydrophone Board, SBG IMU, Movella IMU, Front Camera, Down Camera
  • Can connect to either PCIe or USB-C Hub (PCIe usage requires electrical lead approval).

Note: DVL may require an isolator (still under evaluation).

4. Power-Up Procedure (Using Batteries)

Safety Precautions

• Working with batteries is hazardous.
• The Power Board does not have a Battery Management System (BMS), only a Battery Monitoring System.
  • It can shut down the system, but not the batteries themselves.
  • Even when shut down, the Teensy 4.0 and kill switch circuitry remain powered, consuming ~250mA.
  • At full charge, the system can last ~80 hours in shutdown mode.

Battery Charging

1. Batteries must be fully charged before use.
2. Use Blue Robotics Charger:
   • First, connect the balance port.
   • Then, connect the power port.
   • The charger will enter monitoring mode (displaying individual cell voltages).
   • Select 4-cell (4S) mode, 14.8V rated voltage.
   • Charger will beep when fully charged but remains safe to leave plugged in.
   • Batteries must always be charged in LiPo bags and under supervision.

Battery Connection Procedure

1. Ensure both batteries are from the same batch (old/new batches must not be mixed).
2. Final Short Test Before Plugging In Batteries:
   • Battery connectors (not the battery itself!) must be tested.
   • Each receptacle has 125A fuses; test for shorts individually.
   • NEVER short test when ANY power is present on the board.
   • If one battery is plugged in, do not perform further short tests.
   • To check battery status, use the battery charger (via balance port).
3. After verifying no issues, proceed as with power supply startup.

5. Important Notes

• Short on Mains → Entire system failure
• Short on ESC → ESC burns out, requires replacement
• Powering off Jetson improperly → Jetson corruption
• Short on System Net → Jetson, DVL, Actuator Board, Display Board, and possibly thrusters may fail