Projects/rov

From 757Labs

757 Labs underwater ROV project

Contents

[edit] Introduction

The goal is to build an underwater ROV platform to carry a payload of sensors. The ROV will use a tethered connection to the surface. The plan is to start by building a ROV platform that can be driven around underwater with a few basic sensors and video. After this phase is complete, there is talk of designing new sensors to put on the vehicle to add capabilities. Once these are designed, the designs will be shared so that others can make use of them.

[edit] Design Overview

The current platform is constructed of PVC pipe. There is a plastic mesh in the bottom. We have bilge pump motors to act as the propulsion drive motors. Work to add propellers to the motors is underway.

Electronics wise, a microcontroller program is going to be written that takes instruction via RS485 to control movement, and can relay back information collected from sensors.


[edit] Current Project Status

[edit] Currently done

  • Dave F. built base platform
  • Dave F. bought bilge pump motors
  • Dave H. has done work to saw off the unneeded plastic from the pumps

[edit] Next to be done

  • Write command line interpreter for AVR
  • Solidify mounting and design of propellers to motors
    • Possibly need to fabricate
      • Dave H. has a possible propeller solution, waiting on parts to arrive

[edit] Driver board specifications

This will be reusable with a number of other projects

  • AVR microcontroller
  • RS485 communications
  • Ability for 8 or 16 PWM outputs
  • Ability for 8+ DIO outputs (ability to expand to 128+)
  • Ability for 8 or 16 DIO inputs
  • Ability to read and report 1 wire sensors
  • Ability for analog inputs
  •  ?? What else is needed?

[edit] Specific Notes

[edit] ROV Electronics notes - Speed Control

I'm thinking it's a good idea to look at using cheap (cheap!) R/C speed controllers to run the motors. These use PWM. One issue might be half speed reverse? I'm not sure if the radio is the limiting factor in reverse speed on R/C cars or if it's a function of the speed controller. This would give us 100+ levels of speed, and is an improvement over relays and transistor H bridge designs. I've seen these for ~$8 each on eBay.


How many amps at 12vDC can they handle? The pumps say use a 5A fuse.

[edit] ROV Electronics notes - Umbilical

Notes from the meeting regarding umbilical to the surface

  • DC power cable - 12vdc
  • Digital data cable - 3 wires (GND, TX, RX)
  • Highly flexible coax for video feed

[edit] ROV Electronics notes - MCU pins

  • 1 wire temperature sensor
  • 4 x PWM for motor control (or 8 DIO)
  • 1 x DIO for lighting control

[edit] Future sensor ideas

  • Current depth sensor
  • Sonar depth (measure from ROV to bottom)
  • Sidescan sonar
  • Gripper claw
  • Hydrophone - you're supposed to be able to hear Whale Songs from hundreds of miles away.
  • Gyroscope and/or a Solid-State Compass to know what direction we're pointed (Yaw), and Accelerometers to know if we're level (Pitch & Roll); remember, you won't be able to see this thing once it's more then a few feet below the surface
  • Photo Sensor: it would be interesting to detect how the light fades as this thing descends
  • A Higgs Boson Detector
  • Metal Detector - absolutely, positively we got'ta put a real good sensitive Metal Detector on this thing so we can find man-made artifacts buried in the sand (I have a functional Metal Detector prototyped [breadboarded] on my workbench, if this project starts to make any progress I can solder it up - see http://www.youtube.com/watch?v=mrc8aoghLs4 )
  • An Underwater Camera - There are Cameras available that have Special Filters to color correct for the Spectrum Change of light underwater (probably expensive)
  • More to come later
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