Questions on Using the OpenROV 2.8 platform for a hybrid build


#1

Hello, I recently contacted OpenROV support and after a few emails back and forth, Nicole recommended that I post this up out here to get others involved in the conversation. As I have studied further some of the questions I originally had have been answered fully, or partially. I am reaching that knowledge “tipping point” where I am starting to get a pretty solid big picture.

None of the existing ROV packages out there fit my needs, or they cost as much as my house (so again, not fitting my needs lol). The Trident comes very close, but not available yet, and still not “perfect.”

I want to go with the OpenROV platform though for the most important thing appears to be covered. I need the ability to build my own basestation, or use just about any available platform. So I am thinking to put together my own kit using the 2.8 developers kit. When I priced everything out individually, you basically get a free tether! I will likely go with a neutrally buoyant tether, but the dev kit one will at least get me online.

I have a handful of questions though!

I need a wireless buoy. (At least I think I do!) I will be using an HD camera setup, either the Pro Upgrade and chassis, or the Blue Robotics camera. I won’t go into more details on the BR stuff, but have seen that I am not alone in a hybrid build. Simply put for my needs, their enclosures are more configurable. Otherwise, I am preferring the simpler nature of the OpenROV stuff, and the MUCH better documentation. Anyways, the first question:

  1. Can a 2.4g wireless connection even reliably support the higher HD video data stream? Obviously we are out of the water at this point.

  2. Is there a Tenda wireless adapter that can be used on the topside?

I read the wireless buoy tutorial, but it seems that there has to be a cleaner way to build it… I can’t fully wrap my head around this. Now if I could power the topside buoy through the tether from the ROV main battery, using a setup otherwise like the tutorial would make a little more sense.

I need a different main chassis configuration. I tempt fate here as I am sure it will take me some effort to get my design balanced. The sides will have a tie fighter like look, like the Shark Marine’s Stealth 2 visible here:

My main concern is that ideally I (think I) want 2 vertical thrusters and the 2 horizontal thrusters. It appears the controller board has outputs for 6 various servo or esc based devices. I am just unsure how one goes about applying those. Is the interface similar to say Open Pilot (well actually now Libre Pilot), or Betaflight for air based UAV’s?

  1. How does the controller function, would a fourth ESC be added in parallel to the vertical thruster esc?

  2. Can I order additional ESCs from you guys? Or better yet, can I order the controller board without esc’s and use my own?

  3. Would the software image need to be changed to function with a 4th thruster? Or again, is this handled via a interface like Open Pilot…. ??? Also how does it handle more thrusters, say 6 like some other platforms use? Documentation claims control up to six thrusters, but a glance at the pictures only showed obvious spots for the 3…

  4. Can I order the scaling laser diodes separately? Or get a digikey part number? I may not be using the OpenROV camera module as I really want the ability to upgrade the camera, and possibly record video onboard.

Final question, for now!

  1. Can I use “any” USB joystick or gamepad controller? If so, how and where do I program the functions?

I have a Saitek Cyborg 3 that i purchased as soon as I saw it the other day, just for this project! Hopefully it can be utilized…

My apologies as I am SURE lots of these questions are covered in various places in the different guides. I have seen a few of my questions kinda touched on as I research them (and in fact did find and answer a few I deleted).

I will try to wait patiently for answers lol! I am waiting on some of these to decide on final parts to order. It would be cheaper to buy a full kit, but I want the flexibility of a slightly different configuration, as mentioned first thing above.

I do have an extensive background in arial drones and electronics. But this is new territory and as such the information out there (in general) is pretty scarce. Thank you guys in advance for your help!


#2

Hi @Biggs_Darklighter:

Here are some answers to your questions:

1.) You can use WiFi, but typical WiFi implementations are not optimized for sending low-latency, interruption-free video. The results you get will depend upon the amount of intereference in your area. In general, prepare to be very disappointed with the performance of WiFi when used as communication to a buoy.

For OpenROV Trident we’ve spent a huge amount of time tweaking the code in the video pathway to achieve good, low-latency performance.

2.) A couple of years ago we expermented with a Tenda WiFi homeplug unit for a topside. We ended up not releasing a product at the time, as we were busy with other stuff. But it would certainly be easy to experiment with at home. The Tenda model number was PW201 and it is still in production, and seems to be available on E-bay, though it doesn’t seem to be available on Amazon or major retailers.

3.) It is pretty easy to add a fourth ESC to the current controller board. If you search the forum archives you’ll find a post that I did a couple years ago outlining the procedure. If you are driving the two vertical ESCs with the same signal, you can do that without modifying code by just buying a “Y-cable” for the two vertical servos.

4.) I don’t believe we sell individual ESCs in the store, but the ESCs used on the controller board are available from HobbyKing. You’ll need to reprogram it from forwards-only (helicopter mode) to forward-reverse (car mode). This has been discussed before on the forum.

I don’t think we sell controller boards without the ESCs. There are just too few customers for such a product.

5.) If you’re not trying to do vertrans control (if you’re running both vertical ESCs at the same speed), then you don’t need any software changes for the 4th thruster- just use a Y-cable instead. There was an experimental build a while ago for a 4-thruster vertrans configuration, but it hasn’t been maintained in a while.

6.) According to the OROV 2.8 bill-of-materials, here are the scaling lasers we use. I don’t know whether they’re in the store. Have you looked?

7.) Don’t know.

Hope this helps. Keep us posted on how your build goes.

-W


#3

Thank you Walt!

The scaling lasers aren’t in the store. But those are cheap enough and easily obtained with that link, along with some other options too.

I have ordered my developer’s kit! It seems that the wifi option isn’t really worth bothering with for now. I went with the full dev kit as there are some things I just don’t know how to work with yet and it will get me everything to get connected and check out stuff like my joystick. I think once I have the software and interface running, most of the remaining questions will quickly become clear.


#4

I used the dev kit with my first attempt at a build also. I wanted a different configuration than the standard 2.8 design. I did have a leak issue with my end caps and am modifying the design to take a stepped end cap that will fit inside and over the end of the PVC housing. Here is a link to my initial design Rover 1 - OpenROV in a recycled body


#5

Very creative! I have thought of doing similar myself, but since photography is my first intent here, I decided to go with some more purpose made components to protect my gear. If I put one of my proper cameras in this rig, that camera will easily eclipse the cost of the actual ROV build, by double or more.

I was also a little leery of trusting the OpenROV DIY housing to pressure, waterproofness, and building mistakes. Plus one drawback to the OpenROV style setup, shooting through a curved tube causes light refraction issues. These are solved in the HD Camera setup with a special lense. But I can’t apply that lens to a M4/3rds format camera. I go with this setup and I am limited to just using the OpenROV camera, no chance for upgrades.

A domed end though solves this problem. Blue Robotics sells (for a substantial price increase) tube, dome, and other components needed to make bodies like this. The way they are made, already adds several layers of protection to the “onion” and are similar techniques and construction used for camera dive cases. And suddenly I can put any camera that I want (and can fit) into the tube. An inexpensive option like a GoPro Hero Session becomes possible.

Originally I planned to use the Pro-Upgrade. But the more I looked at it, the smarter a custom setup became because of my primary focus. I am putting a camera platform into the water.