Finally working on the Pan/Tilt

[Zaibach]

Spent weeks trying to find an off the shelf pan/tilt system that would fit the ROV I'm trying to build.
Unfortunately they all come out a little too tall or have really funky turning radii. Curse you giant Micro Servos >,<

Nothing fancy and right now still planning on using a Raspi Camera module. Tho I can always change it to accept some other small CCD camera if the ribbon cable for the PiCam just refuses to workout.

Proto 2.0.jpg (36.98 KiB) Viewed 9472 times

The eventual plan is to use brass fittings. I'm just going to be taking some hobby stock and flaring the ends to keep it in place. Maybe a dab or two of marine grease at initial assembly. Still really a work in progress.

So far things seem to be fitting OK the servos for example (when I remember to add a place for the wires) fit like a glove. I have put together one of the earlier tests for the front assembly and it worked quite well all things considering. Just need more screws for a final assembly, a hacksaw to start cutting the brass fittings to length and to stop making last minute changes

[a_shorething]

Wow, there's a lot going on there.

So that all fits in your design?

[Zaibach]

Its actually looks a lot larger than it is. Its about 85mm (~3") long and 50mm (~2") tall. I'm using 11g micro servos. That said it needed to be small enough that I could center the camera in a 3" PVC pipe (of as yet undetermined length) that's going to act as the pressure vessel. It will be a bit longer since it's probably going to have a fish eye lens attached to it but that shouldn't be a problem since the dome gives it a little extra wiggle room.

The problem was the original design was it was 67mm (~2.6") tall and almost allowed the camera to be centered. By shifting the pan servo from the top to the back it freed up that half inch which was enough to get it to center the camera at the cost of being a little longer and slightly more complicated. On the plus side because this mounts from the back and extends forward, it allows me to push the camera farther out into the dome. Which should give it a little better range of vision. As for design, I'm just sorta winging it as I go along

Edit: Also my bad this would apparently be more applicable in the Camera section, wasn't sure if projects currently in the project phase were applicable until I read that "Please read before posting" sickie just now :/

[a_shorething]

Would love to see the final product on this. It's a very clever design.

Do you need to do the fisheye lens on this or can you get by with just a standard or slightly wider field of view since you do have the option of pan/tilt?

For me the most important part of my design was the camera field of view and video. So I wanted the highest resolution I could get and didn't want to record and playback video with a fisheye appearance. The pan/tilt should make it so you don't need to use a fisheye, especially with the use of a dome I would think.

Anyway, keep us posted (here or in the camera section ).

[Zaibach]

I really don't know at that point if a fish eye would still be needed. I know someone was saying that you need a fish eye for underwater navigation and I'm not sure if that was in reference to fixed cameras so the pan/tilt would make it redundant or not. The fish eye lens I picked up magnetically adheres to the camera mount great for testing the water on the subject. Its pretty strong I'd have to essentially throw an ROV at the water course if I planned to stick with it I'd probably either change the front of the mount cover (as yet not pictured) or glue it

I'll certainly try to get some pics of the working printed pan/tilt as soon as possible. Right now I have a few rejects and some partial test assemblies but now that I have an actual thing I'm getting to the coding side of the project. Didn't want to start that before I had a good solid idea on how the hardware was going to be setup. The final plan involves the Pan/Tilt being integrated over an I2C network so the RasPi can control it

[a_shorething]

I'm curious to see how you implement the whole thing.

I've read lots of different things about field of view and I kind of feel like the best option is really hard to implement in a non-OPENROV style housing because the best wide-angle cameras look like they're set up kind of wide. The OPEN ROV platform has a sideways mounted lexan cylinder that has a 120 deg. HD web cam setup. I think you need something this wide or else you need two cameras: one for navigation with a fisheye and one for mission footage. The exception being if you have pan/tilt. Then I figure you can kind of look around while navigating without having to weave the ROV back and forth. I don't think I'd want my only camera to be recording in fisheye view though.

For me at least, the camera is what I'm building the whole thing around because I want to see stuff and record it and play it back.

Keep us posted.

[thegadgetguy]

I would recommend a wide angle lens camera for navigation. In my experience, I just feel like I can't see anything with a normal field of view camera for navigation. Pan/tilt definitely helps alleviate that feeling, but do you really want to be moving the camera all of the time? Also, does your controller setup let you keep your finger on the camera controls? Having to move from the navigation to camera controls gets old real fast, especially if you are trying to move and look at something at the same time. Also, for underwater photography you want to be as close to your subject as possible, as any significant distance will cause the longer wavelength colors of light to start to disappear, as well as put more particles between you and your subject.

Just my thoughts. Your pan tilt mount looks really slick! Any pictures of the actual thing?

[ROVER3D]

I would recommend a wide angle lens camera for navigation. In my experience, I just feel like I can't see anything with a normal field of view camera for navigation.

i had the same thought...

I first try a HD-camcorder with autofocus and zoom. But you need a wide angle for navigation. Now iam using Gopro...

[Zaibach]

I would recommend a wide angle lens camera for navigation. In my experience, I just feel like I can't see anything with a normal field of view camera for navigation. Pan/tilt definitely helps alleviate that feeling, but do you really want to be moving the camera all of the time? Also, does your controller setup let you keep your finger on the camera controls? Having to move from the navigation to camera controls gets old real fast, especially if you are trying to move and look at something at the same time. Also, for underwater photography you want to be as close to your subject as possible, as any significant distance will cause the longer wavelength colors of light to start to disappear, as well as put more particles between you and your subject.

Just my thoughts. Your pan tilt mount looks really slick! Any pictures of the actual thing?

Thank you for the advice and the compliment

Sadly no pictures of the actual thing yet. Still working out a few design points like how to attach the tilt harness to the pan arm. Had initially decided to go with a set of brass hobbystock tubes but decided to nix that and go with one brass tube acting as a bearing and a screw which should end up being easier in the long run. Course that is after I waited for a week on a close quarters hacksaw thinking it would do the trick cutting the tube only to find out that it binds quite a bit if I'm not rotating the stock. So now I'm looking at a dremel with a cutoff wheel ..... but of course I have no idea where any of my cutoff wheels are :/

Assuming I stick with the PiCamera module I do have an adapter that will allow for wide angle shots, nothing fancy just re-purposing one of those little smartphone lens sets. I haven't really given the control interface any thought yet but I can certainly see how moving and adjusting the camera constantly would be annoying. Could shoot for a PS2 style controller use the one Analog for moving the ROV and the other for the camera(s) and use the bumpers on either side to switch between planes and views. Could also try a toggle able link the outputs from the sensors to have it try to automatically keep a fixed perspective within its range of motion. Right now the only thing I'm certain of is that the servo controller is interfaced over I2C to the Raspberry Pi, I'm not really looking forward to all the coding

So I think I'll dedicate part of today to printing out the newest revision of the pan/tilt since I think I have made enough small changes to warrant new parts. Hopefully I can have them assembled shortly, figure out the exact range of motion the servos have so I can plug that into a driver and get some pics of something that isn't my small but growing pile of rejects

[a_shorething]

Ha ha. That would make for an interesting thread: Post up picks of your test versions of different designs that DIDN'T work.

I've only been at this a couple of months and I already have a much bigger collection of things I know won't work than things I know will work.