Crazy question, could ArduCopter hardware and firmware be used in an ROV ?

Posted by Randy More on November 7, 2011 at 12:56pm

Sorry if this question is "out there" but I was wondering of the ArduCopter pilot and IMU could be adapted without too much fuss to work with an underwater ROV.

 

The ROV in question is essentially an "upside down" copter with one  thruster pushing the positively buoyant craft down and two reversible port and starboard thrusters moving it forward, backwards, and  rotating about its vertical axis.  Obviously GPS is not available but I have a water  pressure (depth) sensor available.  All thrusters are controlled using standard RC pulses sent down a teather to a set of IFI Robotics 833 motor controllers.

 

Currently it is manually controlled but it is a real bear to make it "hover" manually and I would like to automate it.  I ran across this site and this seems like a natural extension of the excellent work that has already been done.

 

Any feedback would be gratefully received. 

 

Thanks...

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –
Follow

Replies

  • kolin August 18, 2012 at 2:50pm

    Hi,

    I can clearly see idea of ordinary almost ordinary quad copter just with smaller propellers but heavier than water. Than it should be possible to use ardupilot without changes and only change PID (probably a lot)

    For cable control i would use really simple TTL<>RS485 converter for transmitting summary PPM signal from transmitter to APM.

    With brushed motors (Permax 400 as many have them from easystars) and simple 4way brushed ESC (multiwii has port for this) it should be cheap.

  • Colin Johnston November 14, 2011 at 5:38pm

    Randy, with some modifications to the software and possibly hardware, it can be done. An IMU can certainly work underwater to provide body rates of your ROV. Again you would want to convert these body rates to something in an inertial frame. There are many modern under water vehicles that use inertial measurement units already. I have been working with a PhD candidate on a design to provide automatic control of an underwater device(patent pending) that uses similar technology. It's essentially an autopilot design. It all depends on the specifics of what you want to accomplish. I'm sure it can be done!

     

  • Moderator
    Michael Pursifull November 13, 2011 at 6:17pm

    We need more of it, and more build docs and more wiki entries and shared code.

     

    See, for example (in no particular order)

    http://diydrones.com/forum/topics/underwater-glider-uuv-with

    http://diydrones.com/profiles/blog/list?user=3um9qjnkq5rxo

    http://diydrones.com/profiles/blogs/arduino-rov-sub

    http://diydrones.com/profiles/blogs/ardurov-project-remote

    http://diydrones.com/forum/topics/autonomous-submersible

    http://diydrones.com/forum/topics/705844:Topic:30854

    http://diydrones.com/forum/categories/underwater-vehicles/listForCa...

     

    And an example of the unintentional AUV:

    http://diydrones.com/forum/topics/quad-rotor-crashes-into-swimming-... (oops!)

  • Sebastian Gralla November 8, 2011 at 7:20am

    an APM would be an overkill for this purpose, ArduIMU will do ;)

  • Ellison Chan November 7, 2011 at 1:30pm

    This is not an "out there" question at all.  But, there's a new branch of Arducopter code for ArduRover, for which the purpose is to adapt the Ardu code for use in many different vehicles.  That may be a good place to start. (it's in the main menu)

    The OilPan (IMU board) being used by Arducopter has a built in barometer, so you should be able to tell the depth by just calibrating at sea level, as long as you don't try to equalize the air pressure as you dive. If you were to use and external depth sensor, you can replace the analog input of the sonar that we use with analog input from your external depth sensor.  You'll have to also modify the code to not use the onboard barometer.

    As for driving the thrusters, the code is easily capable of driving many configurations of propellers now.  Your particular configuration seems to match closely with a TriCopter setup.  In TriCopter configuration, the two propllers in front control roll, like the starboard and port thrusters, and the back propeller+servo control pitch and yaw.  The only difference is that all three motors are mixed to provide altitude control. You can adapt and rewrite the motor code to suit your particular configuration.

    As for stabilization, I think the gyros and accelerometer should work fine under water as well. I don't think they are affected by pressure or at least maybe a re-calibration may be needed.  The magnetometer, which helps to lock heading, may work as well.  

     

    So, I don't think there are any major obstacles to using the IMU and Oilpan underwater, assuming you seal it properly.

  • Anish November 7, 2011 at 1:26pm

    Hi Randy,

    very interesting view, cool. It is crazy and cool that you came up with this. Even though i am on robotrov mailing list and do bits of experimentation, never thought of this one. In theory we are looking at fluids with difference in density, so hand wavely we should be able to do the same. But I am not sure this is going to be so easy. Just my intial impressions, would be great to hear from the big brains on the list

  • Dara Shayda November 7, 2011 at 1:03pm

    I do not think your question is crazy. I have looked at:

     

    http://seaperch.mit.edu/  

     

    It is OPEN-SOURCE design and I am sure you can do all kinds of modifications to it. Kids in high schools are building it in their homes.

     

    I think the motors, specially in salt water, will have serious issues. 

     

    D

This reply was deleted.