ROV Simulators and Pressure Issues

100' RCA Video and Power cable

Our students continue work on their ROV video monitors using small automotive backup safety cameras and security video cameras protected during submergence by pressure vessels each group is creating by hand. One issue that has emerged from the depth tests is that water bypassed waterproofing efforts using a seal around the cable’s outer shroud, because both CAT-5 cable and the A/V+Power cables are formed from multiple independent internal strands wrapped by a plastic sheath. During use, minor scratches to the outer shroud will later when submerged more than a few feet, the water pressure allows water to enter the spaces between individual strands and proceed along the line of the cable into the pressure vessel itself.

ROV thruster canisters

One of our groups had injected cyanoacrylate glue from our 3D printer build sessions into their cable’s shroud and this reduced the total amount of water that later had to be drained from the housing compared to other groups that had simply applied sealant external to the cable shroud. Directly applied wax left over from preparing the three thruster canisters for each ROV added some protection in subsequent depth tests, but was too easily pushed out of position during extended submergence although the same wax remained intact in thrusters either because it fully enclosed the DC motor in each canister or because it was applied when melted to a liquid state rather than simply pressed into place around the cables. The groups are testing methods to separate individual strands and pass them through various sealing materials (Resin, Epoxy, Wax and Silicone sealants in different groups). Some consideration is being given to whether the plastic cover of each strand will have similar issues as the outer shroud at greater depths, but passing bare wires from outside the pressure vessel offers challenges in salt-water environments where free ions in solution could short the circuits.

Illuminated OpenROV Model

Although our crowd-funding effort continues having minor issues around the hosting service’s outages and other difficulties around their name transformation from “Microryza” to “Experiment”, our project to obtain an OpenROV advanced submerged robot is ongoing until early March. We have been allowing the students to test out transparent plastic filament and their AtTINY85 LED “pixels” from last Halloween, in case we have any supporters that need multi-colored illuminated OpenROV models.

While we are building Sea Perch ROV designs, only so many hands can work on each at one time, so our workshop participants have been using the OpenROV Simulator to get an idea of what controlling the robot will be like. The same principles apply to our Sea Perch ROV designs as well, although the lighter weight will make them respond to waves and currents more strongly than an OpenROV would.

We have used simulators for our LEGO- and Arduino-based terrestrial robots before, and flight simulators during our Aviation Merit Badge workshops, so our students already understand proper cooperative practices during a workshop. We find it is best to allow the primary pilot to keep the display directly in front of them, while the display is mirrored to another screen (when available) for their team to watch from one side. This way, we avoid distraction due to shouted suggestions from too close alongside. When using only a primary display at schools without additional resources, we appoint a member in each group to control overenthusiastic participants, minimize disruption, and keep everyone focused on the assigned task.

A popular example of visualization using a multi-display interface for display of maps and video games.

It is best to be flexible in your own setting to make use of available resources and spend as little as possible when setting up for a workshop, so that you can afford to move on to sharing the next workshop in turn with your students. Having multiple monitors and fancy video cards are wonderful if available, but a simple laptop with its built-in screen can also allow learning and instruction opportunities just as well.

Outdated Computer Scrap

Learning workshops and local makerspaces can be elaborate or very minimal as you build up your programs, and anything left over from one workshop may play a part in later sessions so invest in storage boxes your students can sort materials into before you worry about whether your workstations need a complete overhaul. More than anything else, remember that learning should be fun!

2 thoughts on “ROV Simulators and Pressure Issues

  1. Pingback: ROV Simulators and Pressure Issues | Maker Stuf...

  2. Pingback: February 2014 Workshops | STEMulate Learning