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Re: [PSUBS-MAILIST] Sub launched ROV
Hi Carsten,
I'm also looking into 300V DC at 3Amps over 20 gauge wire for
power transmission. This will have a fairly big voltage drop
over 600Meteres (it's go to go there and back), but should
be able to provide usable power.
I'm not so comfortable with the idea the ROV would run
out of power to maneuver and either require time to
recharge or to be left behind.
Aside from the ROV thrusters, I think lighting will be
another big use of power. So maybe the ROV can run
the thrusters and a small navigation light from the
tethered power. The main ("Oh wow look at that") bright
lights could be ran from internal batteries. I'm
thinking that the need to use all the bright lights will
occur less than the need to use the thrusters. The
internal battery could be charged from the tether.
Yes, I'm in full agreement, small tether equals small
ROV, also smaller equipment on the submarine side.
How powerful do you think your thrusters will need to be?
Cheers,
Ian.
-----Original Message-----
>From: MerlinSub@t-online.de
>Sent: Jun 21, 2008 2:43 PM
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] Sub launched ROV
>
>Hi Ian, the problem is power via a 300 Meter cable.
>
>300 meter rules 12 and 24 V DC application out.
>Cable gets to strong and a offshore Rov with some
>strong motors to run in currents - to big for a Psub.
>So cable support must be 240 AC or better higher 380V AC.
>This voltage must be also over a seawatertight swifel..
>
>That was the main reason to go with one fiber or coaxial copper
>for both directions and have high tec batterys on board Rov
>- to get a light cable.
>
>A light cable means a light ROV.
>
>vbr Carsten
>
>
>"irox" <irox@ix.netcom.com> schrieb:
>> Hi,
>>
>> one thing to keep in mind is that we are wanting robots for different
>> purposes.
>>
>> When I'm out in my sub and I'm on-site somewhere worth exploring, I
>> do not want to be spending that time sitting around waiting for the ROV's
>> batteries to recharge. If I have a reason, I want to be able to run
>> it around the clock (for several days). So it must get power from the
>> sub. I did consider having the sub trickle charge a battery on the
>> ROV via the tether, but I see little value in this right now.
>>
>> Carsten's specs are very similar to mine. 300meters, fiber gives you
>> great bandwidth for sonar/cameras/etc.. Fiber gives great bandwidth
>> and flexibility for future gizmos/expansion. One fiber pair and one
>> copper pair for power should give a pretty light cable. Bonus if I
>> can 300meter fiber/copper cable from some other ROV.
>>
>> I want it to be as solid state as possible, so where one where it's
>> unavoidable will solenoids. I'm planning on the ROV having an on
>> board computer (embedded linux), ethernet over the fiber, talking
>> to another computer on the sub.
>>
>> I'm also considering that it might be cheaper/easier to buy at
>> used ROV. There was one ebay a couple of days a going that sold
>> for $3500, seemed nice. I've seem other small ROVs on ebay from
>> around $20,000 (I think the Sea-otter or something like that)
>> with lots of spare parts and cable.
>>
>> I spent some time looking at slip rings for eletrical/fiber use,
>> and there is quite a bit out there. Last time I looked only
>> manufacturer had slip rings which had a high enough signal
>> transmission quality to run digital protocols like USB, FireWire
>> and Ethernet over them. Now they are much more (and I hope that
>> means the price came down a little).
>>
>> Cheers,
>> Ian.
>>
>> -----Original Message-----
>> >From: ShellyDalg@aol.com
>> >Sent: Jun 20, 2008 3:19 PM
>> >To: personal_submersibles@psubs.org
>> >Subject: Re: [PSUBS-MAILIST] Sub launched ROV
>> >
>> >Hi Ian. A reel would need the connection to swivel, and would attach to the
>> >sub in a simple multi-prong electrical through-hull. A possible option would
>> >be a cone shaped cable holder, where the cable spools off, but it would still
>> >need to curl up the cable. Retrieval could be accomplished by rotating the
>> >cone shaped spool. ( simple motor drive )
>> >If the sub was say 200 feet deep, and the cable was 100 feet long, you could
>> >cover an area about 100 feet around the sub, or go deeper with the ROV ( but
>> >with less area )
>> >It seems like a fiber-optic cable would be prone to problems. Wouldn't it
>> >work to use coax cable for the video feed?
>> >As for power, I would rather see a battery on the ROV so no heavy power
>> >cables are needed from the sub to the ROV. Just low voltage wires so they could
>> >be cut if needed.
>> >The pressure proof container is the easy part. Just a stout piece of pipe
>> >with a window in the front, camera and battery inside, control panel for motor
>> >drive and dive plane positioning. Make it neutrally buoyant with a drop
>> >weight. It would be small enough so you could make the whole thing from stainless
>> >at a reasonable cost. Something about 24 inches long and 12 inch dia. for the
>> >pressure container would be enough if you packed the stuff inside right.
>> >Some fixed ballast tanks to achieve neutral buoyancy, and with a grabber arm on
>> >the sub, you could make a simple docking mechanism so the ROV could be stowed
>> >away in it's holder after retrieval.
>> >Low voltage solenoids inside the ROV for powering switches so no heavy
>> >cables are needed from the sub.
>> >Seems like an eight pair cable would be enough for the minimum, plus the
>> >coax video feed.
>> > One problem is voltage drop over a long cable, but with the right
>> >solenoids, that would be solved. I had some info on an off-the-shelf video device that
>> >was posted earlier this month here on the psub mail thing. It was pricey but
>> >was a complete system including cable, camera, and monitor. I think it was
>> >built to be deployed from the surface like from a boat or maybe ice fishing.
>> > The cost of a simple camera( about $150), a small TV monitor ( like the
>> >small TV/VCR combo made for a motorhome, 12 volt, $99 at Best Buy ) and your
>> >own pressure cylinder as a start. Then add the motors and controls, the cable
>> >and connections, spooling reel, and various mechanical things like dive
>> >planes and drop weight. Doesn't Steve Pierce have something like that he's been
>> >working on? I think you can buy an off-the-shelf tiny ROV for about $2500.
>> >There's a guy here in Santa Cruz that has one he rents out to boat owners. I
>> >remember seeing an advert on it a while back. Anyway, lots to think about. Frank
>> >D.
>> >
>> >
>> >
>> >**************Gas prices getting you down? Search AOL Autos for
>> >fuel-efficient used cars. (http://autos.aol.com/used?ncid=aolaut00050000000007)
>>
>>
>>
>>
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