ROV Library

A custom library developed by RobEn that exactly fits our needs, be it programmatically controlling a Remote Operated Vehicle (ROV) or processing image data from the on-board cameras, it's got you covered.

Table of contents 🗒

• Installation
• Usage
  • Cameras
  • Control
• Dependency
  • User side
  • ROV side
• Future Plans
• Authors

Installing ⬇

The module is available at pypi, download with a simple

$ pip install rovlib

General Usage 🔑

Like any other 3rd party module you can easily import the desired sub-module by specifying what you want from the main rovlib module

from rovlib.cameras import RovCam
# or
from rovlib.control import RovMavlink, JoyStickControl

More about rovlib.cameras ? ➡ Cameras module
More about rovlib.control ? ➡ Control module

---

ROV-cameras 🎥

The camera module is required to receive OpenCV frames from ROV cameras being sent by the On board camera system used in conjunction with this user level module.

How to use it 🔧

Starting a camera 🟢

To start capturing frames from a specific camera you have to start an instance of RovCam similarly as starting a cv2.VideoCapture() instance from opencv.

As it might seem the interface is very similar to OpenCV's as the image data is originally captured on the ROV with OpenCV so it is required to run the script.

from rovlib.cameras import RovCam
import cv2

cam = RovCam(RovCam.FRONT)

while True:
  image = cam.read()

  cv2.imshow("ROV", image)

  if cv2.waitKey(1) & 0xFF == ord('q'):
    break

cv2.destroyAllWindows()

The RovCam instance requires the user to specify which camera to get image data from, only a supported camera would work

Camera Options 📸

As for now the camera option are:

Front main camera looking ahead

RovCam.FRONT

Arm facing camera looking exactly at the robotic arm

RovCam.ARM

Misc cameras looking wherever we need to position them (still not supported in this version)

RovCam.MISC1 RovCam.MISC2

---

ROV-control 🕹

It is a python sub-module that simplifies the use of pymavlink APIs, to ease the control of our beloved Alenda (the ROV).

How to use it 🔧

Establish communication 🤝

# create an instance of RovMavlink
# Those are the default constructor params.
rov = RovMavlink(connection_type = 'udpin', connection_ip = '0.0.0.0', connection_port = '14550', silent_mode = True)
# Binds to the port in the given address
rov.establish_connection()

To start controlling the vehicle you should Arm it first. To arm it use there following commands.

# Silent mode is used to shut off prints from the used functions for instance - > 'vehicle Armed successfully'
rov = RovMavlink(silent_mode=False).establish_connection()
rov.arm_vehicle() # you only need to arm the vehicle once, there is no need to arm it every time you want to stablize it

# to disarm vehicle
rov.disarm_vehicle()

Set vehicle mode 🎯

rov = RovMavlink().establish_connection()
rov.arm_vehicle()
rov.set_vehicle_mode(rov.Mode.STABILIZE)

Those are all the modes you would need to use. If you used set_vehicle_mode() with any thing other that Mode enum it would raise a violation ❌.

class Mode(IntEnum):
    STABILIZE = 0
    ACRO = 1
    ALT_HOLD = 2
    AUTO = 3
    GUIDED = 4
    CIRCLE = 7
    SURFACE = 9
    POSHOLD = 16
    MANUAL = 19

# use them as follows
# rov.set_vehicle_mode(Mode.STABILIZE)

sending custom control 🎮

⚠ Take care the throttle of x, y, z and rotation is a value between -1 to 1. any value out side this boundry will raise a violation. ❌🔞

rov.send_control(JoyStickControl(x_throttle = 0.5, y_throttle = 0.5, z_throttle = 0, rotation_throttle = 1))

also you can it as follows ⬇

rov = RovMavlink(silent_mode=False).establish_connection()
period = 10 # period for moving the joystick control in seconds
rov.arm_vehicle()
# my_lovely_fake_joy_stick = JoyStickControl(x_throttle=1, y_throttle=1) # name the param u want to add and give it a value between -1 to 1
my_lovely_fake_joy_stick = JoyStickControl(y_throttle=0.8)
rov.send_control(my_lovely_fake_joy_stick)

Orientation of the ROV 🧭

Authors

• Karim Kohel
• Youssef Abbas
• Mostafa Wahdan