Homebuilt ROVs Forum

It seems like there is some interest in an inexpensive off the shelf control system for rovs but there is nothing on the market that is readily available or supported.

Ironically earlier this week I spent some time evaluating a next generation control system for our rov. I don't expect my requirements to exactly match everyone else's, but I thought by sharing my ideas with others we could develop a more flexible system that others in the community use. This has been done before in other hobbies - look at the diy drones guy's ardupilot for a similar system.

I'm a big fan of arduinos. If you are not familiar with arduinos, start here:


http://arduino.cc

Arduinos support plug on modules called shields to expand their functionality. My idea would be to design two shields (one in the rov and one topside) for rov control. The link between the two could be an ethernet tether. The reason for this is to use cheap ip cameras on the rov. For example ($50):


http://www.dealextreme.com/p/ip-400-sta ... sion-15974

You could put quite a few of these on the rov and run the video up two pairs of wires. Of course this will require a switch in the rov, but those are pretty small and cheap too. Or, with only one camera, you could use two pairs for the camera and two pairs for the controller in a single cat 5 cable.

An ethernet arduino would handle control on the rov. The only custom piece of hardware would be a rov shield that has the motor controller, light controls, water sensor, etc. It might be also possible to put a current loop interface on there (similar to another commercial rov system) for those how don't want to deal with ethernet. I'm not married to the idea of an ethernet arduino, but that is my starting point.

Topside would be another rov shield to interface with the controller or pc (your choice). You could use an off the shelf controller (like a ps3 or wii controller), build your own out of a couple of joysticks or drive it from a computer. That is up to you.

I'm just kind of thinking out loud here. Is there any interest in a community designed rov control system? Did I miss anything critical? Does anyone else want to contribute?

I have been considering the same thing for my project, what occurred to me though was since the Arduino is open source you can design your own layouts and PCB's with the circuits so why not print out 4" diameter round arduino boards and shields that can stack and fit neatly inside a 4" PVC pipe instead of trying to squeeze a square peg into a round hole.

That is certainly one option. It may even be the best option. I don't know at this point.

If we were to design a round arduino base with round add on boards, then I'm not sure we could consider them shields anymore. My motivation for sticking with the arduino shield form factor would be to provide flexibility in which arduino the end user could use. Some may want ethernet, some may not. some might want more io and therefore need a mega, and so on.

Another option might be to make the rov add on board round to fit in a 4" pipe, but put the shield connectors on it to mate to a standard arduino.

There are lots of possibilities. Let's keep the discussion going.

Another question:

How many motor controllers do people want?

I'm thinking a minimum of four independent controls. That may not be enough for a lot of configurations, though.

I think six would be ideal, but that will drive up the cost.

Well I think motor controllers for safety sake (since they could be dealing with some respectable amps) would do better as a shield. 6 motors to a shield would cover probably the majority of designs (4 directional, and 2 for trim or ballast) but 4 may be more reasonable if they are stackable since 6 may be overkill in some designs.

I would think for the main control board you would want your communication circuit, and power management, and thats about it, maybe an emergency system for leak detection or auto-surface. and everything else would be stacked as a shield for motors, ballast, sensors, and tools.

Thats just how I imagine it anyhow.

For my purposes 2 directional and 2 PWM for up and down / trim would work great. I think that it would be important to enable them to handle 12v @ at least 3 amps to run standard bilge pump motors for those of us still using them.

I am just starting out on the Arduino and if you have never written code, it can be a little challenging at first but I am catching on.

Thanks for your feedback.

I'm looking for motor control devices that can handle 28v with a 5 a continuous rating, but I'm having a hard time finding such a part. All motor outputs on this controller with allow for bi-directional, variable motor speed control. I see no point in designing a board that can only turn a motor on and off.

The motor controllers I used can run up to 9 a, but they are expensive and only operate up to 16v. 28v parts will allow for the use of 24v binge pumps. This may or may not be a worthwhile goal.

I need to contact some vendors and ask for their recommendations, but I haven't had the time yet.

Derelicte,

What motor controlers are you currently using that you mention in your post?

"The motor controllers I used can run up to 9 a, but they are expensive and only operate up to 16v."

It is all documented here:

viewtopic.php?f=18&t=444

They use a st chip.

That was VERY helpful, thanks!