I’ve done some research on creating a simple ROV (Remotely-Operated Vehicle) for underwater operations. So far I’ve been considering what to build and how to build it.
I started by identifying the requirements:
– Have a camera to see what is going on
– Be able to go up and down, and to turn around it’s own axis
– Connect to a laptop to show live images
Some other features would be cool to have:
– A gripper to pick up objects
– Pan/tilt on the camera to look around
– Ability to do simple image processing either on the ROV or on the control station
– A powerful light to see more at greater depths (Cree LEDs perhaps?)
Sources for research
Browsing hackaday and instructables for existing projects is always a good start. Here is what I found:
Instructables ROV – A build log describing a ROV with a camera, an electronic compass and lights. Uses a RC-car remote control and speed controller, using an ethernet cable as antenna.
Homemade ROV – A long description of a ROV. It uses arduino, a fiber optic cable and bilge pumps. Some good tips about buoyancy and reasons not to go for wireless transmission.
navyauv – A blog for competitors of the AUVSI competition.
Thruster for ROV – An instructale for making a thruster from a bilge pump.
ROV submersible – Instructable for gluing PVC pipes and making ROV. Uses a webcam with an usb-cable.
Another very good page was homebuiltrovs, with detailed descriptions of ROVs that are not too difficult to make.
From the research, it seems that submersible bilge pumps are the cheapest way to make thrusters. One can either use the pump as it is, running like a jet system, or open it and add a propeller.
It seems that most of the ROVs I’ve found are made using PVC pipes. That was not my plan, but maybe there is something to it.
For control of the ROV, it seems an ethernet cable is the way to go. They are made for data transmission over a long distance, are not too heavy and not too expensive.
I want to use a normal webcam for camera. I could use a single board computer with an ethernet interface and an usb plug. Then I could connect this board to a driver circuit for the motors.
The Control Board
As I happen to have the Fox Board LX832 lying around, I’ll use it for controlling the ROV. I did some research on the card, and found these links useful:
Acmesystems – The page of the producer have all important specs, a pinout drawing and everything needed to get a quick start. The documentation page covers everything from hardware to WEB programming.
Animal Robots Blog – Covers everything done until compiling a “Hello World”-application in C on the LX, using Ubuntu. Lots of other interesting stuff here as well.
Setting up FoxBoard – Instructions for flashing the FoxBoard.
Parts list (provosional)
Motors (bilge pumps)
The mechanical work requires a workshop that I don’t have at the moment. The plan is to make a 3d sketch of the existing parts and the desired product, and then start working on the most basic electronics. The lead batteries provide 12v, and a power-card is neccessary to give the FoxLx board and webcam a clean 5v supply. A set of H-bridge motor drivers or transistors will be needed to control the motors from the FoxLx board, and these will also need some form of cooling.
After this, I’ll write software for the PWM-motor control, set up a webserver and compile the camera driver, all running in separate threads.