Payload Interface: Mechanical (Trident Kickstarter Update #10)

One of the core features of the OpenROV kit is modularity and extendibility. We’ve always been pleasantly surprised to see what payloads community members are adding to their devices, and wanted to make sure that Trident provided the same flexibility for users. We’ve spoken with scientists who want to add pH and dissolved oxygen sensors, salvagers who want to add gripper arms, and cinematographers who want to add additional cameras and lighting, just to name a few. This is a companion discussion topic for the original entry at


I’ve made several Payloads for my OpenROV 2.8. First I was interested to get a Profil for the light intensity, the signals for Red, Green and Blue Light, the temperature and according the depth during a dive. This informaton allows me to find where in the lake I can catch the plancton and where to look for small fishes. Therefore I made a simple sensor system with a Arduino compatibel datalogger, light sensor from Adafruit and a depth sensor. All this componente I stuffed into a battery tube from a openROV. This sensor can now be mounted on top of my ROV during dives and I can read the data nicely from the integrated SD card afterwards.
If I want to catch the plancton afterwards, I will use my pump module. This is very simple. Instead of the external lights from the ROV Shop, I just connect a simple pump to the external PWM channel (ALT-I from the cockpit). the pump is flushing the water through glas vials. in the first glas vial I have a “filter” ( I use nylon stockings) at the outlet to the second vials. the second vials has a small check valve at the outlet. With that simple device I can “concentrate” the plancton in the first vial and in the second vial I get water for physical, chemical analysis (such as O2, pH, nitrate…) afterwards.
Because I would like to get sometimes some better images of my dives, I combined the vial holder adapterplate with a camera mounting possibility (I use a Denver AC-5000 camera with a waterproof case). In this case, I just unplugg my pump module and connect the external light cubes. I use here simple waterproof plugs used in cars and it works great down to 35m (which is the depth of my little lake I am playing).
Pictures, Movies… of this project can be found on my google website (sorry it’s in German)

Holder for the paylods (3D prints)

Sensors in openROV battery tubes

Results from the sensors (profil of the lake)


Well done. Most impressive to say the least!



Fantastic work!! Having been to that lake many times, it was so exciting to see your underwater footage!! Thanks for posting.



Thanks for the encouraging feedbacks. Attached now some pictures of my simple payload interface, allowing to mount the camera “on Top” or at the bottom of the ROV. You also can see the pump module and the water proof plugs to switch easy between external lights or pump module.

To mount the external lights, I used Velcro Tape. This is really easy to adjust the “angle”–> facing downwoards or the the front.


Thanks for posting these! Very fun too, seeing your custom 3d prints.


Will the Trident be capable of adding a grabber arm to pick stuffup? I already pre-purchased the top package and would like to get some of the addons going.

Small Details Make Big Differences (Trident Kickstarter Update #16)

There is a mechanical mounting pattern and wifi for communication. It is definitely possible to design a grabber that would interface with the vehicle system.

I hope this helps to answer your questions.


Great, thanks Brian. Do you have any way of getting me the mounting pattern details so I can get started building the grabber arm? And with regards to the wifi communication, is there a specific communication standard that you are all using? Thanks, I appreciate your help!


The mounting pattern can be found on the specifications page for the vehicle.

For the wifi this forum post will give you a general overview.


Thanks Brian! That helps out perfectly. I am working on a complete undercarriage of multiple arms to grab and hold directly below the Trident in adttion to the main grabber/investigative arm for the front. Do you know if there would be any way to purchase or get my hands on the lower body only for test and design? I’ve got a great design and will likely replicate it for others in the community after I am done. Thanks again for all of the help.



That GoPro setup, is that live feed to the surface?


@jason.jenkins21 The payload you are working on sounds awesome! I can’t wait to see it in action. Unfortunately we are not able to send any parts out like you are asking for. We plan to release CAD for this section once everything is finalized 100%. The reason why we have not released anything yet is we only release files once they are finalized with all the information that a developer like yourself will need. We don’t want any mis-information about Trident floating around that people are basing their design off of.

@Ethan_Bunch More to come on that. It is a software issue interfacing with the GoPro. We have a proof of concept at this time.


@Brian_Grau Thanks for the response. I completely understand about releasing the bottom section before you are all finished. I will simply use the information that you provided to start and will look forward to the release of the CAD files when you are finished. I realize that you are busy, but one final question…Is there an absolute payload weight that will need to be under in order for the Trident to stay operational? You may not have this information but I figured I would ask just in case. Thanks again for everything. I can’t wait to get my hands on our pre-ordered Trident!!!


The assumption that we are making is that all payloads are neutrally buoyant. This is the recommendation/constraint that would be put on developers such as yourself. The center of mass and center of drag of the payload will have an effect on the vehicle performance and this might have to be tested more on a trial and error side. This can be done computationally, but does require some more specialized software.

We have had a couple pound payloads on the vehicle without major issues. This was in still water though.

Here is a picture

We are all very busy here in order to get Trident into your hands, but we will do our best to answer questions in a timely manner.


Thanks that helps. No more questions from me!!


Has anyone on the forum used a Trident to kill Lionfish?


Hi Jason
Are there any developement on your side on this issue of Payload Interface and developing tools including
multiple arms to grab and main grabber/investigative arm in the front of the Trident.
As OpenROV finally have started shipping Trident Beta units its getting more and more important to have available some useful tools. Video shooting will not be enough for many of the future users.


Good morning Kaare and yes, there has been.

Whilst I am still in the design development stage, I am almost ready
to fabricate the first two prototypes of what I would like to think
will be a range of general purpose payload modules that can be built
using mostly off the shelf parts by the rest of our community.
Please see attached sketch of what I have in mind. (Sketch
removed due to error in mailer - please send me your email address)
(Sketch now attached below)

My primary focus at the moment is on extending the mission duration of
Trident so payload capability is secondary at the moment however the
ability to carry payload comes for free with the additional structure
I have designed (until I can minaturise it) so this might be a real
feature for some. Room and structure for manipulator arms on the
leading edge can certainly be provided in my proposed design and
reasonably significant weights can be carried on the leading edge with
adequate counterbalancing. My personal/professional interest in
payloads will be in fitting ultrasonic thickness measuring devices and
laser range/distance measuring devices.

The first prototype will be a pair of side mounted external battery
modules with provisions for nominal payloads up to 100 x 75 x 50
(horizontal width x horizontal length x depth) in the leading edge and
two flexible wet or dry payload compartments within the body of the
wing. One of these compartments is for the battery and controller.

The second prototype will be similar but has a depth of 75mm for
larger and heavier attachments and with more room for additional
payloads in the two compartments.

I will finally receive delivery of sufficient shell material to
fabricate up to six of each prototype early next week and I will be
ordering the components so that I can work on and perhaps finish the
first prototypes over Christmas (I don’t expect to receive my Trident
until February at the earliest).

Naturally, I have not yet seen the new Trident and I have no
information on its hydronamics or thrust parameters so I have been
working with estimated design inputs only. These prototypes are
relatively large, they essentially double Trident’s width and add
50% more volume. I have been careful to maintain centres of
buoyancy/gravity/pressure and to minimise drag so they will either
work extremely well…or completely defeat the purpose of Trident by
reducing its speed and agility. In any case, they will make
Trident a bit slower and perhaps a little more difficult to control (I
have plans for this too however the optimist in me tells me to wait
and see).

With a 3S4P battery pack in each module the greatest risk at the
moment is a leak and subsequent electrical fault. Not a good thing
to think about considering recent events. The modules will be
mechanically attached but otherwise independent of Trident until I
trust them enough and until I (we) can develop a way to provide power
to Trident via the tether connector or other connection. Wireless
data connectivity is probably a good first step.

I will be documenting my efforts and making all information freely
available to help others in the community design and create similar
modules. I am only just now starting to make myself known to the
community after more than a year and a half in isolation down here in

I met with the openROV team last year to discuss my ideas and out of
respect for them (and to avoid distracting them from delivering my
Trident) I have been sandbagging many technical questions for the
forum. You will soon see lots of activity on battery and payload
related threads for Trident. If you have similar ideas then I look
forward to working with you and the rest of the community on these
ideas as soon as Trident starts to ship.

Thanks for being aware and interested. We and I have exciting and
ambitious plans for Trident…

Kind regardsJason


external_payload_sketch.pdf (76.0 KB)

Ahaa, I now have the ability to attach documents. Please see the attached sketch for what I have in mind.