Atlantis II - VENT7 - Unmanned Robots

VENT 7 - UNCHAT

UnChat with John Kreider, started Friday 26, 8:30 AM

Hello to Vent7 -- John Kreider speak

Hello sir. -- v7Adam Cornelius Moderator comment:

Good morning, John. -- V7Christen Gray Moderator comment:

-- v7Tawanda Sibanda speak

We have afew questions... -- v7Tawanda Sibanda speak

I will be happy to try to help -- John Kreider speak

As you well know, we are designing auv's/rov's, and we have some questions concerning there designs -- v7Adam Cornelius Moderator comment:

We are having a problem wtith tethers operating over such alonmg distance for the rovs. the cable will be too long and there will be too much drag. One solution posed to us is that we ahve many little rovs connected in a chain to reduce tether length. What do you think? -- v7Tawanda Sibanda speak

I -- v7Tawanda Sibanda speak

I understand the problem - it is legitimate. We have built and operated ROV'swith tethers up to about 25,000 ft. I know that others have built some with longer tethers for the purpose of penetrations in dam inspections. -- John Kreider speak

I will now address the idea of a chain -- John Kreider speak

You might consider the idea of a permanently instaqlled tether (carrying power and signal) to a remote station. The ROV can dock/undock from the station. The ROV could be attached to the station by a simple F/O tether (signal only, getting its batteries re-charged when it docks), or you could have the tether be larger and also carry power continuously. -- John Kreider speak

Our problems with the tether is that the vents are fragile, and the geology team would be VERY MAD at us, and we don't want to knock them over. Also, this tether must be very long, spanning 2-3 Km ideally, which brings up problems with storage -- v7Adam Cornelius -- v7Adam Cornelius Moderator comment: No Comment

Would we need a very large room to store the tether, or a very powerful motor to pull the rov back? -- v7Armando Valdes -- V7Christen Gray speak

We had that idea, but we were uncertain about the way to set a connection with the remote station. Other problem we have with that idea is that the ocean floor in a vent region is not very uniform, and there are a lot of features and or fauna down there that could be easily destroyed. -- v7Armando Valdes -- V7Christen Gray speak

The 2-3 km is not too long for existing tethers. They are typically stored on winches, which don't take up too much space. The problem with the fragile vents means you must have a neutrally buoyant tether, which is not easy to achieve in practice. You might consider a simple tether with optical fiber only (provides comms link, but not power). That way you can maintain vehicle control/oversight without a bulky tether. -- John Kreider -- V7Christen Gray speak

Storing the tether - the power and space required for a winch is not too excessive for most applications. Remember you must consdider the fact that the ROV might go "dead", so your design must accommodate recovery of a dead vehicle. -- John Kreider -- V7Christen Gray speak

Connection witht the remote station - is the entire area fragile, or can you survey a route and lay a permanent cable on the seafloor over your selected route. ONce it is in place, it has the advantage of not being dragged around. -- John Kreider -- V7Christen Gray speak

We are operating out tethers from a laboratory underwater near this vent system. Being able to operate the tether on a horizontal, without damaging any vents our rov has passed in its twists and turns is of concern to us. -- v7Adam Cornelius -- V7Christen Gray speak

Another question I have is a concerning AUV communication. Are acoustic modems sufficient in your opinion for data transfer? -- v7Adam Cornelius -- v7Adam Cornelius Moderator comment: No Comment

The Idea of the remote cable is a good one. -- v7Adam Cornelius -- V7Christen Gray speak

I'm not sure I understand what is meant by remote cable, could you clarify John? -- V7Christen Gray speak

Adam, Christen - think about different ways of getting the tether out of the way - e.g., make it buoyant so it floats up out of the way, make it small and light, or think about getting rid of it all together and go to an acoustic comms link and battery power onboard. -- John Kreider -- V7Christen Gray speak

How would we lay the cable as well? We cannot have divers this deep, so would we have to bring this up with the manned research systems team. -- v7Adam Cornelius -- V7Christen Gray speak

What is the range of the acoustic comms. We need to go sevral kilometres -- v7Tawanda Sibanda -- V7Christen Gray speak

Is the connection with a remote station easily set up, or should it be a permanent one? -- v7Armando Valdes -- V7Christen Gray speak

acousitc modems - current technology only allows minimal comms for vehicle control and occasional burst of data to verify the data collection system is working properly. The best source I can reccomend for state-of-the-art acoustic modem technology is Benthos in Falmouth, MA. They are the leaders in my opinion. -- John Kreider -- V7Christen Gray speak

On the subject of power, is lithium ion technology still experimental. Research tells me it would be the best source of power for the auvs, btu an engineer told us thast curent batteries are explosive. -- v7Tawanda Sibanda -- V7Christen Gray speak

go here: http://www.link-quest.com/html/m_models.htm ...for good specs on acoustic modems. I'll look into Benthos. -- v7Adam Cornelius -- V7Christen Gray speak

What does "SHOUT" do? -- v7Adam Cornelius shout

connection with remote station - would require some planning as to how to set it up, but you could do something like make a tether neutrally buoyant and put it on a winch at the main station. Use an ROV to pull it our along your surveyed path, then change the density or anchor it to the seafloor. You can accomplish alot with today's ROV's. Once the cable is in place, you can install the remote station using an ROV and connect the cable to the remote station with an underwater-mateable connector. This type of technology is readily available in the oilfield and used frequently for subsea installations in deep water. -- John Kreider -- V7Christen Gray speak

At the moment, how advanced is AUV technology. Are they intellgient enough to do complex tasks, like search for certain living creatures and take photos, etc -- v7Tawanda Sibanda -- V7Christen Gray speak

how important is power to complex tasks? Does the benefits of power outweigh the disadvantages of dragging a bulky tether? I guess I'm also asking how much more capable ROVs are than AUVs. -- v7Heather-Marie Knight -- V7Christen Gray speak

power- I am not personally familiar with lithium ion technology. It wouldn't surprise me that the batteries are explosive and/or difficult to handle. Many of the new power sources have problems like being explosive, difficult to re-charge, etc. When you make your selection, do an overall systems analysis - list the all the design considerations, and rate the different power sources for each of the design considerations. There is a formal design process for this type of evaluation called Kemper Trego - it is useful for many applications of evaluating system components. -- John Kreider -- V7Christen Gray speak

AUV technology - technology is fairly advanced. However, I am still of the school that it is very difficult to completely take the human out of the loop. Trying to write software to handle every conceivable decision that could come up is very difficult. In general, I would look to use AUV's for tasks that can be well-defined. Don't expect them to carry out complex tasks that require alot of on-the-spot adaptation. You can always use an acoustic modem to provide human oversight. -- John Kreider Moderator comment:

we are also trying to decide whether to use a 3d acoustic cameras -- v7Armando Valdes Moderator comment:

power for complex tasks - it all depends what you want to accomplish. Tasks such as heavy lifting, placing cables or equipment on the seafloor, manipulator work are usually accomplished by an ROV vs and AUV. If you want to do something simple, like drop a bunch of instruments at specified positions, an AUV may be ideally suited for this type of task. AUV's are also good for survey work (pre-programmed to survey an area by "mowing the lawn"). -- John Kreider Moderator comment:

3d acoustic cameras - depends what your obejctives are. Again, I recommend a systemmatic evaluation approach - -- John Kreider -- V7Christen Gray speak

1. Set your design requirements. -- John Kreider -- V7Christen Gray speak

2. Allocate the requiremetns to different systems -- John Kreider -- V7Christen Gray speak

3. Evaluate alternative design options - do this through a matrix or a formal ranking system of alternative designs -- John Kreider Moderator comment:

what are the most important elements we should think about in the structure of our ROV's.... AUVs? -- v7Heather-Marie Knight -- v7Heather-Marie Knight Moderator comment: No Comment

For example, in trying to decide about the 3d acoustic camera - why are you considering it? What are you trying to accomplish? What are alternative solutions? what are proc and cons of each? When you do the eevaluation, remember to consider not only performance issues (such as resolution, range, etc), but also consider things like power requirements, reliability, maintainability, maturity of technology, vendor support (is there only one company in the world who you must rely on - if they go out of business you are out of luck - or is it a widely supported technology that you can go to several options), flexibility fo r future growth ( if this is long term installtion, you will want to change it over the years and build in new technology as it becomes available). A few examples - hope it gives you the general idea. -- John Kreider Moderator comment:

Well, thank you John for meeting with us. Various members of our team need to head off to class now. We will keep in touch via email if/when we have further questions. -- V7Christen Gray Moderator comment:

most important elements - there is not one answer to this question. You must think about the application you are trying to do. For example, if the task is simple, you don't require a sophisticated vehicle. Things like reliability, simplicity, mature technology may be most important. On the otehr hand, if you are trying to do a complex task, you may have to go to more advanced technology, which is inherently less realible and proven. In general, I would think flexibility would be an extremely important design consideration for you. -- John Kreider Moderator comment:

By flexibility, I mean that as well as you plan and design your equipment, you are going to find things you want to change when you actually get there. In addition, since it is long term, you will want to be able to accomodate new technology. Design your systems to be as flexible as possible in being able to incoroporate new technology after the initial installation. -- John Kreider Moderator comment:

Another factor that is frequently forgotten or not given enough importance is maintainability. Your systems will break. You need ot be able to recover them and repair them in order to continue working. -- John Kreider Moderator comment:

Thanks - please feel free to send me e-mails or call. -- John Kreider Moderator comment: