Subconcept's New Dive Module - Looks like a winner...

[safrole]

Check it out at http://www.subconcepts.com/product_p..._ADM_Lite.html

It's my humble observation that the europeans prefer piston tanks and the Americans like their gas. Of course that's a broad generalization, and I usually don't generalize about broads. (puduh boom) But it seems true more often than not. They both have their pros and cons of course, but the precise metering of the piston tank seems a distinct advantage, even if it does consume electricity.

Subconcepts is beta testing this new dive module that keeps the depth of the boat proportional to your stick. That means that with zero forward motion the boat will hover wherever you have your stick, or more likely, your knob. Of course you have to have a piston tank to use it.

To me, it seems like a quantum leap forward and I'm excited about it. It will be neat to lurk at periscope depth, if it proves that responsive. If the gas systems have a static hovering system, clue me in because I looked around a bit and did not see one. I just saw one that works while you are moving, but I'm known to overlook things on occasion.

I also wonder if that dive module would work with the RCBS system. It seems that system could "tweak" back and forth more easily than a straight propel-based system. Someone with an RCBS system should twist Frank's arm to get on the beta tester list.

[thordesign]

Skip Asay has had a

Skip Asay has had a beautiful little unit called the ADC out for several years. It is dead reliable and bullet proof. Skip pioneered the use of depth control in R/C subs and has honed it so all of us can enjoy the precise control that his little unit provides. I remember Skip playing around with the concept way back in the early 1990's...

[JWLaRue]

While actual product evaluation will

While actual product evaluation will be necessary to verify.....

It is my understanding that the various ADC devices that are on the market have a certain level of 'tolerance' in terms of their ability to actually hold a specific depth. It would be interesting to hear what the tolerance is for this variation of an ADC.

-Jeff

[safrole]

So does the ADC work

So does the ADC work while your sitting dead still in the water? I thought it operated the planes while in motion, but maybe I was wrong.

[Guest]

Safrole
Skips SubTech ADC makes the

Safrole
Skips SubTech ADC makes the bow planes move up and down as the depth changes. If your sub is dead in the water, and starts sinking, the bow planes will go up at a predetermined depth. That won't change the depth unless your model is moving forward. That's how it is designed.
Now if we attach it to the RCABS compressor instead of, or in addition to the bow planes, how will it work? Interesting question, and not a simple answer without allowing electronics for over and under compensating. Balancing weight changes with ADC and RCABS, forward motion with varying plane angles, and forward speed at the same time could present problems. I say KISS.
Art

[Guest]

I reckon you could use

I reckon you could use an ADM with RCABS, with some modification.

Instead of using a bladder filled with air, use a piston and tube, but instead of winding the piston back and forwards with a geared motor, use a compressor to create a vacuum.

The feedback pot would be connected to the piston just the same.
However I think you would need a seprate servo to blow the valve to surface.

You could also use a water pump in a similar manner. However with a water pump you wouldn't need an extra servo, provided the water pump is bi-directional.

Andy

[safrole]

The "lag time" in a

The "lag time" in a controller circuit is sometimes called "hysterisis". Subconcept's circuitry would necessarily have to anticipate less hysterisis, since the piston tank is more precise. A gas or an RCABS system has, by definition, more hysterisis which would probably prove incompatible with the "logic" of that controller.

I guess another reason it probably wouldn't work with RCABS is that it's delivering variable voltage (ESC) to make smaller ballast adjustments, which would perhaps not set well with the air pump.

I'm just excited about it, but you're right, KISS.

[JWLaRue]

Hysterisis, as you define it,

Hysterisis, as you define it, could well be a problem....both from a systems reaction time perspective as well as a battery consumption perspective.

What I was referring to was the accuracy of the sensor mechanism itself. In other words, how much of a change in water pressure is required before the ADC commands a change? Any hard information on this would be greatly appreciated.

-Jeff

[JWLaRue]

Oh...any idea how the Subconcepts

Oh...any idea how the Subconcepts device compares/differs to the existing ADC unit offerred by Engel?

-tnx,
Jeff

[skip asay]

Safrole - While the SubConcepts

Safrole - While the SubConcepts Ballast System looks promising, especially for hovering purposes, changing depth while underway is best accomplished dynamically using the planes.

Jeff - I can only speak for the SubTech ADC-1 but it’s sensitive enough that depth can be changed by approximately 1/2” per click of the TX trim tab. Full servo travel (lock to lock) occurs in 5” of change in depth. Sensitive enough? And I can reduce that by half (2 1/2”) if necessary.

But let’s set the record straight. You can’t just add/subtract a little weight to hover at a specific depth. You can, however, hover with a piston type ballast system if a depth sensor is used to control the position of the piston. But what’s really happening is, as the sensor senses an increase in depth, the piston is moved out to expel a little water. As a decrease in depth is sensed, the piston moves in adding a little water. The net result is that the boat is constantly moving up and down although not by very much. And how much is determined by the sensitivity of the whole electronics package, not just the sensor (although that does need to be sensitive enough). The amount of water moved in or out is very small so a large piston diameter requires very little travel. If hovering is a mandatory thing, then a separate, much smaller diameter piston system would be a better option.

Technically, the RCABS system should be capable of hovering but that would depend on the pump itself more than anything else. If an ADC-1 were used to drive a speed control with zero deadband (as in a servo amplifier) which then drives the RCABS pump, it should be doable. I have no idea how well that pump works in low speed situations, though.

Skip Asay
SubTech

[JWLaRue]

Skip,

Good point about the desireability

Skip,

Good point about the desireability of a second, smaller 'trim tank' to be used for 'hovering'. That makes a load of good sense!

-Jeff

p.s. the sensitivity of the ADC sounds pretty good to me for just about all models.

[safrole]

Yes the trim tank idea

[color=#000000]Yes the trim tank idea is great. Less electrical consumption AND more precision, with a mini-tank! I will be interested to see how much average consumption takes place with this "bumping" up and down to hover. This new unit's proportional-voltage fill is surely an attempt to conserve electricity while "bumping" around neutral bouyancy, so I bet it's not bad.

I bought the cheapie BTS for my Robbe. I believe (don't quote me) that the high end BTS will either fill/empty the tank, or set it to one predetermined volume, which is intended to be neutral bouyancy. We all know there's no such thing, so you either get a slow sinker or a slow riser. I guess necessity is the mother of invention.

Are the air pumps you guys use for RCABS piston or diaphragm or something else? It would seem anything like that (with a pulsing output) would have a threshold voltage below which it would not work. This means proportional rate of fill is probably not possible, which in turn means the logic of any successful controller would have to be much more complex, using "full blast" fill rate in short bursts. It would essentially need to be a full process controller(PID). There's the tip for some genius out there]