Our work continued on the ROV viewer module for use in our Sea Perch designs for this summer. Last week, our workshop participants started testing designs based on inexpensive car backup cameras which are built with wide-angle lenses and display a series of graphic zones in the feed, meant to illustrate the car’s path when backing up and the proximity to objects along that path.
Some were unhappy with this, although others want to use that overlay to try and estimate distances to nearby submerged obstacles from their ROVs. Another type of camera arrived last week, so we began testing designs that will use small security cameras normally used for area surveillance.
This camera is smaller than the car backup cameras because it lacks built-in environmental shielding or external wide-angle lenses. It provides a single-aperture image similar to old “pinhole” style cameras, which do not depend on optics for image focus. The same provider supplied longer A/V+Power cables normally used to place these cameras in concealed locations around a property.
To simulate the ROV control panel’s power supply, I was able to repurpose 12V rechargeable battery packs from our R/C tank robots last year.
These are small but store a good amount of power, in comparison to the two of the larger 6V lantern batteries we use in the Electronics Merit Badge classes.
Finally, we used LCD displays that can accept RCA video feeds, with options allowing rotation and image reversal to match each camera’s orientation.
Each group is building a pressure vessel module to house the camera and pass the power+video wire through a water-sealed opening. Most are building PVC-based designs with acrylic or glass windows, while one group is building a much heavier metal model they hope will survive to great depths. This is way over-engineered for our Sea Perch designs but that team hopes to test their module with the OpenROV design we are crowdfunding in the #SciFund Challenge starting this Wednesday.
To avoid impacting the performance of the ROVs, each video feed module must be:
- Reasonably hydro-dynamically fashioned to reduce the force needed to move through the water
- Neutrally buoyant in fresh water (with an optional adapter allowing salt-water neutral buoyancy)
- Able to be connected to the ROV via a 3/4″-gap clamp with 1″ clearance from the vehicle itself
We will test the resulting designs after our workshops as each is completed, selecting at least one design to share on the Instructables site to aid others building their own inexpensive ROV designs.