Hi,
I'm trying to get a list of basic ROV design decisions together to make sure I've covered the important basics.
As I see it, it goes something like:
Control - is it going to be radio (or IR/light) controlled, or use a wired controller? RF/IR/Light will not penetrate very far underwater, especially in sea water
Power - will the power come from topside or onboard the ROV? Topside power means that you need to compensate for voltage drop, onboard means bouyancy to balance the extra weight of the battery, waterproofing the battery and making sure that you've not accidentally created an underwater bomb if the battery is venting gas
Thrusters
Materials - metal, PVC or other? The right metal will allow deeper dives due to being stronger, but PVC may be easier to obtain and work with
Bouyancy - positive, negative or neutral?
Gizmos - what cameras, lights, manipulators, navigational aids, logic etc do you need onboard and how much space will they take up when mounted
Planned maximum runtime - by working out your total current draw in Amps (for motors and gizmos which would all be running at the same time) and multiplying by the runtime in hours you can calculate what size battery you would need in Amp hours (Ah)
Structure - how big will the ROV need to be to accommodate everything?
Waterproofing - how will electricals and electronics be waterproofed?
Is there anything major that's been missed off that list?
This is just my two cents, (I'm still new at this).
Forget about your Rov being radio controlled, it would only be good for about 15 feet and then it would loose your signal. It can be made to go further down but It will cost you thousands of dollars to get the extra feet, which is why just about every Professional Rov has a tether also. Plus if all else fails you will be able to pull the rov back to your boat by the tether.
As far a bouyancy is concerned I say make it slightly POSITIVE, because if it is negative you will need to always have a thruster going to keep the rov floating and when you get close to the bottom you will kick up the settled sediment and then you wont be able to see anymore.
Last edited by soulreaper on May 27th, 2011, 4:20 am, edited 1 time in total.
I agree about the bouyancy (I originally thought neutral would be best, until I read the same argument as yours on this site.)
It should be possible to control the boat using low frequency RF - in the 0-10kHz range - but there would be no way to get live camera signals back to the surface. I will do some playing to see what options there are, but it will be tethered control to start with.
I was at my regional MATE competition last Saturday, and I sat in on several of the team presentations. One team had a floating "pod" on the surface, which was attached to there vehicle via a tether. They had there battery in the pod, and the pod comunicated to the controller via radio control, so that the pod could float around on the surface above where the ROV was working. Probably not something I would ever do, but since we are talking about radio control...
I would probably say that a straight tether is your best bet, unless you have a lot of experience with radio control. My personal preference on bouyancy is pretty much neutrally boyant, but you'll be able to find your preference with a little playing around. I'd say read as much as you possibly can, ask questions, and go and build it.
You should also take into account control systems. Maybe this is a sub-category, but how the user interfaces with the ROV is VERY VERY important. A well designed control box can make or break a ROV.
Control - is it going to be radio (or IR/light) controlled, or use a wired controller? RF/IR/Light will not penetrate very far underwater, especially in sea water
Power - will the power come from topside or onboard the ROV? Topside power means that you need to compensate for voltage drop, onboard means bouyancy to balance the extra weight of the battery, waterproofing the battery and making sure that you've not accidentally created an underwater bomb if the battery is venting gas
Thrusters
Materials - metal, PVC or other? The right metal will allow deeper dives due to being stronger, but PVC may be easier to obtain and work with
Bouyancy - positive, negative or neutral?
Gizmos - what cameras, lights, manipulators, navigational aids, logic etc do you need onboard and how much space will they take up when mounted
Planned maximum runtime - by working out your total current draw in Amps (for motors and gizmos which would all be running at the same time) and multiplying by the runtime in hours you can calculate what size battery you would need in Amp hours (Ah)
Structure - how big will the ROV need to be to accommodate everything?
Waterproofing - how will electricals and electronics be waterproofed?
Dan, what a great list! I have actually dedicated one page to each of these headings in my project book just to give me a reference! Helps make the seemingly overwhelming task ahead of me seem much more manageable!
soulreaper wrote:This is just my two cents, (I'm still new at this).
Forget about your Rov being radio controlled, it would only be good for about 15 feet and then it would loose your signal. It can be made to go further down but It will cost you thousands of dollars to get the extra feet, which is why just about every Professional Rov has a tether also. Plus if all else fails you will be able to pull the rov back to your boat by the tether.
As far a bouyancy is concerned I say make it slightly POSITIVE, because if it is negative you will need to always have a thruster going to keep the rov floating and when you get close to the bottom you will kick up the settled sediment and then you wont be able to see anymore.
You can still use RC gear just not via RF transmission. I am using the data signal from my TX "PPM (Pulse Position Modulation)" to run everything on board, camera tilt, 4 ESC's for motor controls, lighting relay etc. Recently tested the tethered limits of the PPM data on a single pair to over 900 feet. How much farther it will send data is anyones guess I ran out of cable.
Im still under construction of my rov im planing to control mine via r.c. i dont plan on going anywhere past say 50 to 100ft. but what uour saying is i can run out of the trainer port on the back of my rc 2 stick remote?
