Part overview
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Raspberry Pi
There is two RPi in this project. One is in the suitcase, and one in the ROV.
Both is configured with realVNC server.
Password: send email to williha@stud.ntnu.no
ROV
Model: Raspberry Pi 4B rev 1.4 4GB
Suitcase
Model: Raspberry Pi 3B+
Docs
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Mainboard - ROV
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The ROV main mainboard connects most of the components together. It is a custom design.
The jumpers are used to disable the stepper drivers.
Connections
| External | NR | PCB | |
|---|---|---|---|
Echo ping sonar | Green (RX) White (TX) | X10 | TS_P8 (TX2) TS_P7 (RX2) |
| Red Black | X9 | 5V GND | |
Pressure sensor | White (SDA) Green (SCL) | X8 | SDA SCL |
| Red Black | X7 | 5V GND | |
Stepper starboard | Green (A-) Green/White (A+) | X6 | DRV1 A2 DRV1 A1 |
| Blue/White (B+) Blue (B-) | X5 | DRV1 B1 DRV1 B2 | |
| Sensor starboard | Orange Orange/White | X4 | 3,3V TM_P9 |
Stepper port | Green (A-) Green/White (A+) | X3 | DRV2 A2 DRV2 A1 |
| Blue/White (B+) Blue (B-) | X2 | DRV2 B1 DRV2 B2 | |
| Sensor port | Orange Orange/White | X1 | 3,3V TM_P17 |
Mainboard gets power from "Dual Voltage supply - ROV"
The connection is located on the backside of the PCB.
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.
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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
Stepper Driver Polulu DRV8825 (md20b)
A stepper driver is used to control a stepper motor. Teensy is controlling the Drivers.
There is one driver for each stepper motors. (2 in total)
VREF is configured to 0.70V which corresponds to 1A/stepper phase.
Electrical Connection
Electrical Drawing -> Stepper Diagram
Reference
Leak sensor
Leak sensor detects water leak in the electronics tube.
The sensor is connected to sensor teensy.
Reference
Blue Robotics Guide and Docs - Chip
IMU
Inertial measurement unit is gathering positional data of roll, yaw and pitch.
Is connected to sensor Teensy with 3.3V i2c.
Model: Adafruit Precision NXP
Reference
Temperature sensor
This sensor is planned to measure the internal temperature of the ROV. Two sensor is planned, one for each side.
Both PCB has ready holes for the sensor. Sensor is not currently mounted or bought.
Code is not edited to support the sensor, but should not be hard to implement.
The purpose of this sensors is to check if the tube is overheating.
Model: DS18B20
Reference
digikey DS18B20 store and docs
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Raspberry Pi
There is two RPi in this project. One is in the suitcase, and one in the ROV.
Both is configured with realVNC server.
Password: send email to williha@stud.ntnu.no
ROV
Model: Raspberry Pi 4B rev 1.4 4GB
Suitcase
Model: Raspberry Pi 3B+
Docs
Camera
Model: Low-Light HD USB Camera
This camera is not yet in use. Older unknown camera is connected to RPi, and works (poorly) through realVNC.
New cameras is bought, but not tested.
The plan was to use servo for controlling camera angle. (this is implemented in code)
Blue robotics have 3D models for mounting bracket on this website.
Reference
Blue Robotics camera Guide and Docs
LED Lights
LED lights illuminates underwater for the camera.
The lights are not currently mounted.
Previous plans was to control the lights from RPi.
Code is already implemented.
Input Voltage: 10-48V
Controlled with servo PWM.
NOTE: High power draw! up to 60W,
Reference
Fathom-X Tether Interface rev2
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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
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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
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 Sensor Teensy with 3.3V i2c.
Model: Adafruit Precision NXP
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.
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Model: Bar30 High-Resolution 300m Depth/Pressure Sensor
Reference
Blue Robotics Depth Sensor Guide and Docs
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Ping sonar measures distance to seabed.
It is connected to sensor teensy.
Reference
Docs and guide - Blue robotics Ping sonar
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Side scan sonar
Model: DeepView HM680D
The interface box is lost.
Reference
Specs - Deepvision side scan sonar
TODO: Find more docs and guides
LED Lights
LED lights illuminates underwater for the camera.
Input Voltage: 10-48V
NOTE: High power draw! max 60W,
Reference
Stepper Motor
Stepper motors controls the two wings on the ROV. It has a gearbox to increase torque.
A stepper motor is connected to a stepper driver.
Model number: 17hs19-1684s-pg100
Electrical Connection
Electrical Drawing -> Stepper DiagramSee Mainboard → Connections
Datasheet
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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.
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Electrical Drawing -> Stepper Diagram
Reference
Magnetic sensor
Magnetic sensor is a switch that closes when nearby to a magnet.
One is used in each motor house for calibration.
Output is on/off like a normal switch.
Reference
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Adafruit Ultimate GPS
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- Dc-dc converter (right): i7c-4w-008a-120v-0f1
Input: 9V to 53V DC
Output: 9,6V to 48V (adjustable with trimpot)
Max output current at 12V (input) is 2,2A
Max output current at 24V (input) is 4,5A
See datasheet for more info - Dc-dc converter (left): VMA404
Input: 4V to 40V DC
Output: 1,25V to 35V (adjustable with trimpot)
Max output current: 2,5A - Custom pcb
- 4x screw terminal 5.08mm pitch
- 2x SPDT switch
- 2x Fuse 2A and fuse holder
- Trim pot 12kohm
- Capacitors (see schematic for value)
Reference
Find drawing under towedROV -> Electrical schematics
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Dual voltage converter - ROV
This is a voltage converter located inside the ROV. It has a connector on the backside to power the mainboard.
INPUT Vin: 46V from the Tether cable.
OUTPUT: 5V and 12V with different types of connections.
Warning: 5V does not work with very small loads. ex. connecting only one microcontroller will not work.
Reference
UWE 48 -> 12V (black)
TEN 25-2411WI (pink)
Electrical schematicsdatasheets DS18B20
I2C Level Converter
For i2c devices with different voltages.
Not used. Old system used arduino with 5V I2C logic. Teensy used use I2C 3.3V logic.
All i2c sensor in ROV uses 3.3V.
Reference
https://bluerobotics.com/store/comm-control-power/tether-interface/level-converter-r1/
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