Hi Kensaku and All:
Well, I suppose this is a good time to show you what I've been working on lately and what we've been playing with at OpenROV HQ.
The vehicle has needed a power switch for some time, as well as a general cleanup of all the wires on the back side of the electronics chassis. Thomas in Norway started the cleanup process here, while also adding current monitoring to sense the power consumption of the entire vehicle. While he was working on this, Eric and I sat down and started brainstorming about future ideas for the electronics chassis, and the #1 item was making better use of the roughly 3"x3" space on the back of the electronics chassis that is currently just filled with a jumble of wires. We wanted to eventually progress to an ROV that was powered over the tether and needed room for this circuitry. So, at that point I began a phased-approach to cleaning up the electronics, using this space.
The first step was just to lay out a simple board that cleaned up all the wiring and added a power switch. This would prove out the form-factor for the board, and be a great add-on for anyone who is currently building a vehicle. We could then add features one at a time to this board with very little risk.
The first boards rolled out the door about a month ago. I called it Power Board 2.0 as Thomas' design was first. Here's a look at the board:
And here's a picture of it in an ROV:
I've attached a schematic so that those of you who have an interest in electronics can see how it works.
The 2.0 board was designed to be as flexible as possible- there are literally dozens of ways you can hook various stuff to it to switch the ROV power on and off. It will also handle various size battery packs such as 2S, 3S, and 4S lithium batteries. It runs an I2C bus through the connector and out the vehicle to support instrumentation outside the pressure vessel, and has some features to allow testing to start on power-over-tether.
Right now I'm working on the revised 2.1 unit, which will build off of the lessons we learned from playing with the 2.0 boards a bit. It's going to have a much simpler power switch circuit, which will switch the ROV on and off based upon whether it sees a live tether connection. There will still be some external test points if Stefan still wants to use his bistable reed switch :-) And I'm adding a few new features as well. But mostly, it's to roll something out the door that we can put into the hands of lots of people, perhaps by selling the boards in the OpenROV store.
After that, we're going to start rolling out further revisions that will add lots more features to the board. More on that in a future post.