My First ROV Project

Words of wisdom lol. Yes one day for sure.

Well I took about a 6 month break from working on this due to other responsibilities but have finally produced something that at least moves around in the water. I am currently getting a good analog video feed from the BR analog camera. The temperature sensor seems to be working well at first but after a while I get some erratic readings (Almost certainly due to bugs in my code.) There is definitely room for inprovement in the controlling of the thruster motors and I intend on working on that in the future. I am also using a standard CAT5 ethernet cable as a tether and the lack on neutral buoyancy means that it drags on the bottom and pulls down on the rear of the ROV. All said however, I am pleased with the crude results so far since this is a rough prototype. Links to video footage from an externally mounted GoPro are posted below. (No integrted video storage capabilities yet.)

https://bitdrivencircuits.com/ROV/diveLogs.html

Its always fun to read projects like this. Well done.

Awesome project! Cool that you stuck with it and got it working too.
This all takes me back to my first ROV. I also use 8 bit PIC’s for many of my projects, but stay as far away from C programming as possible. I am not so good with assembly either, so programming in BASIC is my speed, and I found “PIC Basic Pro” (http://pbp3.com/) from ME Labs to be a very powerful tool for making these types of projects and prototypes come to life very quick and easy. Its worth a look for anyone going down this road who is not an experienced programmer and does not need to learn a more complex programming language.
Thanks again for sharing!

Nathan

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Thanks guys. I appreciate the advice Nathan. I guess you can say that I have being using this project as a way to learn some fundamental skills and while 8-bit assembly may not be the most practical way to quickly get a usable ROV, it does teach you quite a lot. On the plus side, there is tons of room for improvement so this project should provide me with entertainment for years to come!

Etienne, I really enjoy reading all of your posts surrounding your controller projects! Mine is far from as advanced or professional looking as yours so it is good motivation to keep working!

A couple more videos of some fish I saw and basic maneuvering with the ROV.

https://vimeo.com/345266681

https://vimeo.com/345593198

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Someone on here ‘wound’ cat5 into cheap twisted poly rope, 1/2" i believe, to give it bouyancy and some protection. Just ‘twist’ it into the 3 strands of the rope.

That’s a nifty idea Darrell. I’ll have to consider that in the future.

Another video from the other week after I added the ability to control the gain of the thrusters. I feel like there is a definite increase in fine control over the vehicle now.

https://vimeo.com/355773629

In the video it looks like your thrusters are torqueing and vibrating on the frame…perhaps mount them more firmly, with clamps at multiple points on the frame?

Put thin foam sheet (flexible white foam used to protect electronics in manilla envelopes, can be found at WalMart) between the thruster mounts and the frame to reduce vibration. I’d imbed your cameras in it, or perhaps in soft carpet foam, as well, to reduce vibrations and sound transmitted through the frame. If using a remote microphone imbed that in soft foam as well.

This cheap ($16) recorder can be used to record analog video onboard. Eachine EV100 Micro AV Recorder 1280*480 Mini DVR Support 32G TF For Goggles Sale - Banggood USA-arrival notice-arrival notice

Consider putting bigger bouyancy chambers on top, and more ballast weights centered below. Air pulling up and concrete ingots pulling down will help to stabilize the ROV. Mine has Alot. Heavier to transport but smoother control/ better experience. Retain the lead weight boxes for fine-tuning.
I suggest having a switch to drop the concrete ballast in case of emergency. Use a winch servo to pull a thin bicycle cable, retracting the pin that supports the ballast weights. Fill the servo with mineral oil to allow it to work underwater. A thin coat of epoxy resin on the control board inside will help too.
Hang the weights by a permanent pin hooked at one end, so the retraction pin at the other end only bears half the weight. If you splice multiple cables of different lengths into the main one, multiple pins can drop the center concrete weight first, then the two either side of it, and so on as the winch servo winds up cable.

Just thinkering.

Excellent suggestions Darrell. You are right, the thrusters do vibrate and torque a decent amount. They are mounted pretty firmly but the pieces of metal I cut up to use as mounts are quite thin and allow for flexing. Some sort of dampening layer (like you mentioned) would be a good idea as well. I somewhat underestimated how much force even these smaller T100s put out! (Please don’t discontinue them BR lol). I was borderline shocked by how easily they moved what I thought was a fairly heavy ROV, and I feel that the T200’s might be overkill.

There is also some drag that pulls the vehicle to one side that needs to be addressed and the buoyancy is something I am always trying to fine-tune. I’ve had the ROV on about 4 dives so far and the list of desired improvements is long to say the least.

Thanks for the link to the video recorder! That is a future capability I would like to include for sure. The mineral oil servo trick is also something I was hoping to try for a DIY gripper arm.

At some point I will probably scrap this frame and redesign a new one from scratch to better integrate some of these improvements. The current design is larger (and heavier) than it needs to be and the layout is sub-optimal. I intended it to be more of a “proof of concept” that would give me some leeway and working space to figure out what the heck I was doing. While it has been a “workable” design, it could be done better for sure.

Thanks again for the wealth of helpful suggestions.