Raspberry Pi
There is two RPi in this project. One is in the suitcase, and one in the ROV.
Password: send email: williha@stud.ntnu.no
ROV
Model: Raspberry Pi 4B rev 1.4 4GB
Suitcase
Model: Raspberry Pi 3B+
Docs
Fathom-X Tether Interface rev2
FathomX is an Ethernet bridge between the ROV and the suitcase. This enables communication through the tether cable.
The FathomX is connected to each side of the tether. It requires only two wires for communication.
Reference
SwitchBlox Nano
This is a miniature ethernet switch.
It is used inside the ROV for communication between different ethernet devices. (RPi, Fathom-X, and Side-scan sonar)
Reference
Teensy 4.0
Two teesny 4.0 is used in the ROV. Both are connected to RPi with USB.
Teensy is used instead of Arduino because it has a faster processor.
Teensy for stepper control
This teensy is for controlling both stepper motors drivers. (wings)
Stepper Teensy is running this code. NOTE. update link after merge
Teensy for sensors
This teensy is gathering data from various sensors and sending data to RPi.
Sensor Teensy is running this code. NOTE. update link after merge
Sensors connected:
- Echo sounder
- Pressure sensor
- Leak sensor
- IMU
Reference
Leak Sensor
Leak sensor detects water leak in the electronics tube.
Reference
Blue Robotics Guide and Docs - Chip
IMU
Inertial measurement unit is gathering positional data of roll, yaw and pitch.
Is connected to Seensor Teensy with 3.3V i2c.
Model: Adafuit 9-DOF BNO055
Reference
Depth Sensor
Depth sensor is measuring pressure. It is used to calculate the depth of the ROV. (Length from water surface to ROV)
It communicates with Sensor Teensy with I2C.
The sensor also has built in temperature sensor.
NOTE: Sensor looses accuracy if its wet for more than a day.
Model: Bar30 High-Resolution 300m Depth/Pressure Sensor
Reference
Blue Robotics Depth Sensor Guide and Docs
I2C Level Converter
For i2c devices with different voltages.
Not used. Old system used arduino with 5V I2C logic. Teensy used 3.3V logic.
All i2c sensor in ROV uses 3.3V.
Reference
https://bluerobotics.com/store/comm-control-power/tether-interface/level-converter-r1/
Stepper Motor
Stepper motors controls the two wings on the ROV. It has a gearbox to increase torque.
Model number: 17hs19-1684s-pg100
Electrical Connection
Electrical Drawing -> Stepper Diagram
Datasheet
Torque Curve
Stepper Driver Polulu DRV8825 (md20b)
A stepper driver is used to control a stepper motor. Teensy is controlling the Driver.
There is one driver for each stepper motors. (2 in total)
VREF is configured to 0.8V which corresponds to 1A/stepper phase.
Electrical Connection
Electrical Drawing -> Stepper Diagram