Making Fat Shark FPV goggles work with OPENROV ($7 solution ?)

March 7, 2014

Robodox ROV team is building an OPENROV 2.5 kit for Algalita Research Foundation to take on their July 2014 Pacific Gyre expedition.    The ORV catamaran , named Alguita, will take a team of scientist to sample and analyze the effects of plastic in the ocean on marine species.    To help extend their capability to locate plastic concentrations they are utilizing a variety of sensors.   One is a Phantom quadcopter drone equipped with a Fat Shark Predator V2 FPV system.

IMG_7776The Predator V2 uses two LCD screens to display video in goggles show below.


The Predator specifications are shown here.   Pictures are sent from an aerial camera platform to the goggles in real time over a 5GHz wireless link.

openrov 2.4The underwater ROV that Robodox is building will do a similar function by transmitting HD camera video to a topside Laptop computer over a two wire tether.    It would be desirable if the Fat Shark video goggles could also display the Laptop video sent by the ROV.    Unfortunately the video formats are not compatible without a VGA to composite video converter.   I did a little research into how this could be accomplished.

Here is the plan:

1) purchase a Tmart $3  VGA to A/V RCA converter.  03m-VGA-to-SVIDEO-and-RCA-Female-Cable_320x320

2) Purchase an $3.50 Allelectronics 3.5mm  A/V  to RCA cable with 6 ft  extension to allow freedom of movement between the laptop and the goggles.

3) Plug the VGA converter into the laptop VGA output port and then plug the 3.5mm A/V cable into the Fat Shark video input port via the extension.   Turn off the Fat Shark wireless receiver.

Seems like this would work…yet to be tested.

Wireless Connection to the Fat Shark

The transmitter side of the Fat Shark FPV system involves a small 600 TVL camera that plugs into a transmitter compatible with the receiver in the goggles.

Fat Shark tranmitter

If the transmitter is available on the boat (ie a spare that is used for the Phantom drone) then the output of the converter could be used in place of the camera output that plugs into the transmitter.   This way the goggles could be free from any wires. There would be another plug adapter to mate the composite video RCA plug to the plug on the xmitter.


Algalita OPENROV ready for testing

February 25, 2014


I wanted to share what the Robodox Algalita ROV engineering team has been up to for the last two months.  See Robodox Engineering ROV for ORV blog post : Feburary Status Update .   I am happy with their progress and we expect to have the underwater robot ready for the Algalita summer voyage.

Relevant posts:

Dec 20 2013 OpenROV Berkeley Trip

Robodox 599 Algalita 2014 Youth Summit Video Submission

Use of Robotics to support Algalita research into the Pacific garbage patch

Links: (build blog)

Algalita ROV project facebook page

Proposed Towed Ocean Debris Location and Evaluation Robot (TODLER)

May 22, 2013

Algalita has an informal sensor working group to help them define requirements for a 2014 voyage to sample plastic debris in the Eastern Pacific ocean.    I had proposed using robotics to assist them in some way such as a ROV or possibly R/C boat or helicopter with cameras.     These are local aids but the general problem of mapping the ocean debris remains largely unsolved due to inadequate sensors.   I began thinking there would be a need for a coarse debris ocean plastic sampler that could be towed by any ship or research vessel in the ocean including the Liquid Robotics Wave Glider which would be cheap, reliable and easily deployed.     So I wanted to start a requirements study for a proposed Towed Ocean Debris Location and Evaluation Robot (TODLER)

Why TODLERTotal debris weight data can be useful in estimating plastic content:  The plastic in the ocean is now reaching weights that are 6 to 40 + times more than the  dry biomass floating in the ocean.   E.g.  Algalita reported in 2001 that the plastic to plankton dry weight of the  was 6.1:1.   Subsequent voyages found much larger ratios… nearer to 40:1.   The ratio is increasing every year due to the influx of plastic from the rivers, ship dumping and natural disasters such as the Japanese tsunami.    Although we are interested in the amount of plastic in the ocean… measuring the total debris weight would give a reasonably accurate assessment due to the large plastic to biomass weight ratios.    It would avoid the tedious job of carefully separating biomass and plastic in the lab and give many more opportunities to collect samples world-wide.  The samples would measure the weight of wet biomass plus the debis so the ratios would be slightly lower than those mentioned above.

A total debris sample might have one additional data point… the difference between the dry and wet weight of the sample.   This could give an indication of the amount of biomass present.    The usefulness of this would vary depending upon the ratio of plastic to biomass.   On tows that do not sample a lot of plastic one could reduce the error in the plastic weight estimate by about 16% (in 6:1 ratio sample) but this would be of little use in a 40:1 .    The wet/dry ration would require some type of air or centrifugal water extraction device.   A tradeoff study would determine the cost effectiveness of the wet-dry weighing.

Concept:  This is a small towed robotic vehicle that contains  a mini  Manta plankton trawl net capability which can collect a debris surface sample, weigh the contents , record and transmit data to the towing vessel and then clean the net for another sample.   The sample time would be programmable and be based upon a flow sensor to ensure that the ocean area covered is consistent for each sample.  The total debris weight would be used to estimate the plastic debris weight.

There would be several versions of the system each with different capabilities. The baseline version would sample only the surface at <5 knots and be towable by small craft say less than 50 ft.  Follow-on versions would be capable of  sampling at greater depths and at higher speeds.   The higher speeds would allow TODLER to operate during normal ocean cruising speeds for small yachts or research vessels.  This could allow a large  amount of data to be taken by volunteers willing to tow the robot.  Automatic data logging would be a useful feature to simplify the tasks of the volunteer.     If proven successful, it might be adapted later for large cargo ships  to take data during normal voyages.     These added capabilities would change the design significantly due to the weight and stress on the towing tether.  However, possibly adding an intermediate small craft like pontoon boat/raft which had the main tether load attached to it could mean the TODLER would have a uniform interface for all its tow boats.

Prototype design driving requirements:


I.1)Towable by a  Wave Glider which can patrol the oceans at speeds from .4 to 1.5 knots using the power of the waves.   The Wave Glider weighs about 200 lbs and displaces a maximum 300 lbs.  If we assume that the drag is proportional to the displacement and we don’t want the Wave Glider to slow down too much.. then perhaps we should keep the TODDS at 30 lb limit and require it to have an aerodynamic shape.

I.2)Portable enough to fit on the Algalita  25ft x50ft ORV .  Perhaps a volume of a large duffel bag including its tow ropes and electronics.

I.3)Max off-board sensor power  13.3v at 3 amps or 40 watts. (Wave Glider driven)


II.1) Initial tow speed capability: 5 knots

II.2)Final tow speed capability TBD knots:   near the maximum speed of the Algalita ORV. (although Manta nets are typically towed at a maximum speed of 2.5 kts we would want the capability to collect plastic on outward and inward journeys without slowing down.  This could drive biomass into the mesh possibly making the scrubbing process more complex.)

II.3)  Net area:  TBD   I would like this to be small to make cleaning easier and to keep the robot volume small.   If it was 10% of the area of a Manta Trawl (209 sqin) this would make it around 20 sqin or the area of a 5 in diameter circle.  To match the ocean area of a manta trawl the tow distance would have to be increased from  about .7 km to 7 km.  If towed by a Wave Glider there could be a series of circular tows made during a voyage that would allow the sample taken to be constrained to a 1 sqkm area.

II.4 Net samples before replacement:

Prototype 40 samples

Wave Glider improvement:  Last 6 months (180 days x 6 samples per day)    ~1000 samples

This might involve having spare nets that can be changed periodically.

II.5  Measure only the wet weight of the sample.

More later:

Is this a viable thing to do??  Your comments are welcome.

Fun short film about the journey of a plastic bag…voiced by Werner Hertzog

September 1, 2012

Click on picture to see film link:


Use of Robotics to support Algalita research into the Pacific garbage patch

September 1, 2012

More great videos here:

I finally got to meet Capt Charles Moore the captain of  the research vessel Alguita that has been used by the Algalita Marine Research Institute to collect samples from the Pacific gyre that has 6x more plastic than algae by weight.   He gave a joint talk in Seal Beach with Ed Humes the author of Garbology.  I also bought an autographed copy of  Capt Moore’s book called Plastic Ocean to help support their cause.  I have been a supporting member of the Institute for a few years now because I really like what they are doing.

It has been in the back of my mind to get our robotic students involved some way.   I spoke to Capt. Moore and Bill Francis (their president) to see if they were interested in collaborating.   They said yes and I sent them the following email which had a few positive responses.  If anyone has ideas in this area , let me know.

Email text :>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

oh yeah – the O’side talk involved Gwen and me with Fred Mertz whom we met at the ESRI convention here in SD.  He’s trying to do hyperspectral analysis of the plastic samples.  I need to ping on him to see what progress he has made.

On Wed, Aug 29, 2012 at 4:18 PM, Bill Francis, Algalita Marine Research Foundation <> wrote:

Thanks, Nikhil.  Gwen, this represents a really interesting possibility.  Charlie had suggested Nikhil speak with him because of some contacts that were made at the Oceanside event a few weeks back, regarding another possibility for automation.  If you were not in those conversations, you may want to review those with Nikhil.
My thought is that if we can utilize the robotic potential, we can analyze more samples in the same amount of time.  That would allow us to get more and more information, as you have indicated we need, several times, in order to be statistically accurate.  It also engages the very types of students that will advance our cause as they learn about the plastic pollution challenges, and perhaps choose a career in our field.  Because of this, I am also copying Katie; these students could be a wonderful addition to our POPs leadership training in October.
I’d like to give this a priority for evaluation, if we could.
Bill Francis, President, Algalita Marine Research Institute      O: 562-598-4889     C: 562-896-7416
“We will eliminate plastic waste.  Each and every one of us must change the way in which we approach packaging and single use materials.  Our resolve will overcome all obstacles as we do what is right for our oceans and the rest of our world.”
 To:  Dr Nikhil Dave’ and Gwen Latting;
Algalita Marine Research Institute
I spoke with Capt Charles Moore and Bill Francis in Seal Beach the other day at their talk .  He said that Dave’ is supporting Algalita with some work that involves visual categorization I think.  He suggested I contact you to get your ideas.  Also, I am interested in the lab protocols and needs that Gwen may help with.
I mentor two high school robotic teams (1508 Grant High School  and 599 Granada Hills Charter High School) and was looking for possible ways they could leverage their robotic skills to help Algalita and get involved with the environmental community.    The kids build a robotic composter last Spring but I want to get them involved in the plastic reduction cause.
I was thinking a robot can either help collect  samples or process the samples in the lab.
Sampling:  Perhaps  an underwater robot that samples plastic around the mouth of the LA rivers  more often than after large rains might be possible.   It could be moble or stationary.   It would need a good visual inspection sensor that could count particles suspended in the water and distinguish them from non plastic stuff.  We might not have the technology that can do this accurately yet…but I wanted to run it by you.  At Lockheed we developed a laser air data system that used reflected light off atmospheric dust particles to measure air speed.  Is there something like that available for underwater use?
Processing samples in the lab:
Bill said that this  is really where Algalita needs help because lab work is very labor intensive and you only have a few techs.   Perhaps there is something that a robot can do to presort or clean samples to assist the lab techs.
Look forward to hearing from you both,
Chris Siegert
Retired Lockheed Avionics and Control System Engineer.
Mentor for 599 and 1508 Vex/First Robotics teams.