Instrument Display

[neilp1]

Hi all

Ive been thinking through the options for instrument/parameter display - depth, heading, temp- but i have zero experience using microprocessors or programming. Instead, Ive been thinking about running a second camera over the cat5/6 cable which is fixed looking at a diving computer/depth gauge and compass. Hooked up to a quad splitter along with the main camera, i can have pic-in-pic of my depth, temp and heading over top of the main nav image. Im a diver, so already have the instruments available, and a decent enough color camera can be had for $~30. Adding in the cost of the video baluns and a quad-splitter brings the cost to around $80-100. Alternatively, a second 3.5-4 inch LCD for the instrument cluster runs about $40 and might be more useful than a splitter box.

I havent been able to find OSD options that include depth for anywhere near that price, but if any of you guys running OSD using arduino boards for example have any leads that a total programming noob could understand for less than @100, id really appreciate it.

Cheers

[NCUWI]

Look for my post about the "Dragon OSD+". It's a $100 OSD board designed for RC Aircraft FPV but can also be used in a ROV. It will talk to just about any I2C instrument so can be made to work with a depth sensor. Depth sensors can be pretty pricey btw. You can contact Dragon Labs directly and they may even edit the firmware to support a sensor if you ask them nicely. Another option for depth ("altitude" actually) is to use a sonar.

[bigbadbob]

I'm working on a gy-26 digital compass and leak sensors feeding an arduino over the serial port and outputting to a max7456 osd chip.
if you search on the arduino forum for max7456 you'll find some good info. i'll post my code once i've proved it works.
it's not going to be fancy but is cheap at £30 all in and only needs the code changed to make it more fancy.

[Mareike]

Compass, good point you spoke about bbb, I am struggling myself about that one and how it will work under water in a sealed housing.. Do you have any suggestions for this one or better bin it right away?
http://www.active-robots.com/sensors/compass-gps

[NCUWI]

I'm using the "HMC6343" with my DragonOSD+. Be careful to use a "tilt compensated" compass. If it's not tilt compensated you may get erroneous readings if the ROV is not perfectly level.

[neilp1]

Thanks for the comments guys. The $30 interface certainly sounds interesting, but it would all really depend on how much a pressure sensor would cost in order to get depth information. If I dont have integrated depth sensing, it really isnt worth it to me, since id still use the original method of extra cam/monitor and depth gauge.

Cheers

[bigbadbob]

Adding depth sensing shouldnt be hard to code, the arduino has analogue inputs that can be read and converted to an integer for printing to the display. as you say the price of the depth sensor itself would be the crucial factor.
my compass isn't tilt compensated which is why it is so cheap, it's just a rough guide to which way the rov is pointing, not a precision navigation device.
Marieke- compass works fine sealed and underwater as long as you don't have a ferrous housing. using magnetic shielding round the motors helps and you calibrate the compass to compensate for any metalwork near it.
(Nothing to do with ROVs but i've used a compass for navigation in an iron mine, seems daft but it works fine cos the iron's field is alligned with the earth's field)

[Never prototype]

Couldent you attach a small rheostat to a mechanical pressure gauge ya know at the needle. Then program your chip to translate the ohms into fathoms or leages or feet or whatever. Will a rheostat have a consistent enough rate of change in resistance to be used as a instrument? I don't know. Something to try, certainly cheap even if the rheostat doesn't give you a smooth and regular change in ohms at least the numbers will mean something.