Hi guys
Tim has nailed the answer. speargun it is but I would like to use the same mechanism but with different attachments as a DNA collector, shark tagger or lionfish hunter. I have a couple of other versions nearing completion I will share in the near future.
Regarding ‘Speargunbot’, Newton’s Third Law comes to mind!
I am hoping that the roller tip neutralises the recoil to some extent at least but it may be the case I have to apply forward throttle when I fire to offset that. obviously a lot of trial and error required to get in functional so very much a work in progress.
You could maybe look at some kind of sea anchor design, some kind of collapsable ‘umbrella’ perhaps? This would help to maintain the spear’s kinetic energy. My only other worry would be the thruster fixings, although it would be pretty easy to make some silicon rubber mounts for them.
I’ll be interested to see how it develops though.
Im also doing a project in wich I intend to use the M200 motors for a 2 dof arm. I see that some of you are interested in using Volz servos. They are good but quite expensive. They sent me this email:
“Attached please find our price list detailing all options for the DA 26 and DA 30. For the oil-filling-modification we charge an additional 620€ (including pressure proof connector as shown in DA 26 datasheet).
Being a research institute we can offer you a research discount of 30% on the servo prices.
Please let us know if you have any questions, we will be happy to assist.
Best regards,
Phillipp”
If you have any advances on your project please share it here.
I’m having trouble in finding a way for the motor to produce torque at zero speed. Can you help me?
I concur with @paul-unterweiser, I’d like the same with a topside control mechanism like this:
Mechanical prototype is ready. We have done a couple of design upgrades. Let me know what you think.
Electronics development is underway. With the new updates to Ardusub and QGC, I expect we can be using the same gameplay controller for both the ROV and the ARM.
I like it! Looks a bit big, but otherwise looks good. I’m guessing the jaws are made of plastic? Where is the center of gravity of the manipulator? Unless it’s neutrally buoyant, with it extended that far it will probably pitch the ROV nose down a fair bit. Will you be offering these for sale? If so what’s the target price?
Current material is plastic, because that is what we can cut on our laser cutter. Final material might be aluminum, or we might offer it as option.
We will try to make it netrally buoyant, it’s being designed with the BlueROV2 in mind.
I don’t have a price yet. We are still in prototyping phase, so there are several things still to consider and test, material wise. For sure it will be significantly cheaper than ANYTHING currently on the market, and priced so that it’s a reasonable add-on for your BlueROV2.
We will also be accepting beta testers.
You might consider using aluminum for the jaws so you can reduce their thickness, which might allow them to pick up items from the floor. I’d love to be a beta tester! 
One other suggestion is to add mounting holes in the jaws so razor blades can be mounted. That way the jaws can be used to cut rope, etc.
That’s a good idea, we’ll try an implement it. We have also been thinking of making it such that you can remove the jaws and replace them with a screwdriver head or similar. What do you reckon?
That is cool Kevin. Or plan is to build the arm so that we can extend it with more functions in the future, adding 2 more operations:
I’ll keep you guys informed.
I think a screwdriver might be difficult to use since it requires a lot of forward pressure. A circular brush might be useful, to clean an area for inspections.
Looks neat, I like it!
@roy Looks great! I like that its pretty beefy. It might be a bit large for the standard ROV because of the battery tube down the centerline, but it will probably do really well on the payload skid.
And because it looks like you are using that rotary gear drive, you’ll have quite a few opportunities for attachments. Here are the most recent ones from Outland: http://www.outlandtech.com/rov-options/optional-jaws Seabotix also had a closeable scoop for sediment sampling, but I can’t find their page anymore.
I’d be really interested in paying for and beta testing this arm or any other products you come up with. I have one of the original beta BlueROV2s and it has seen its fair share of upgrades over the past year.
In case anyone is curious, here’s how my Robot arm setup is progressing too:
Once I get it all dialed in, I’m planning to release the design as a bolt on retrofit plate too.
great stuff, we’ll have a look at your recommendations. And I’m counting on you as one of our beta testers, also for the EnviroSense, which should hopfully be ready (3rd iteration) in less than a month, hopefully before the summer season.
Once we’re ready to ship betas will publish it here.
Here’s a short video of our very first test of the ROVARM:
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