R/C sub regulator project - An university midterm project underway

[jsl]

Update]Melting the lead in the

Update]Melting the lead in the form[/url]

The raw cast lead ballast

Milling the lead ballast.

The lead ballast is intentionally a bit heavier than needed. We'll cut or drill if needed to loose some mass.

Our end caps are also undergoing more work. The piston tank vents and the pressure sensor connections are underway. Also, a special arrangments of fourteen 2mm brass pins will be mounted in each cap. Connections to the future propulsion module as well as water detectors, recharging, serial communication and programming will be done from the outside. This way we rarely have to take the WTC apart and can do reprogramming much faster. Not much left to do. Below the "deck" or rack, there is no space left at all, but apart from the regulator, the middle part of the WTC above the rack seem a little "empty". Lots of room left.

A nasty bug showed up in the part of the program taking in servo control signals from a RC reciever and managing the genration of servo control signals going out to servoes. Taking in signals and generating them worked fine apart, but combining them produced some very strange signals. The bug was located monday, and that part have to be rewritten.

Some work is still needed on the WTC, but shortly we can concentrate on getting the regulator part of the program finished.

More to come in about a week.

Jacob

[jsl]

Update on weeks 11, 12,

Update on weeks 11, 12, 13 and 14.

Sorry about beeing so quiet, but weeks 12 and 13 has been spent on exam preparation. The exam went well, by the way.

We did the last assembly work on the WTC and moved all of our stuff into a basement under the Institute of Mechanical Engineering. They have a 2000 litre test tub.

The boat was after a lot of thinking named Nemo. We somehow fear having to go finding it when it at some point in the future decides to go about it's own business at open seas.

We put the WTC into the water and testet for leaks. Nothing showed up. We had done a lot of tinkering to be able to control the piston tanks by RC remote. It didn't work all that well, but well enough. We dived it for the first time.

A truely wonderfull experience seeing it dive for the first time. It's very hard to trim a sub with two piston tanks by manual. We got a real good idea of just what a challenge the regulator is facing.

After some time we got to know it well enough to make it hover in the middle of the tank. The way it just hovered seemed a bit unreal. We just spent the rest of the day hovering, facinated.

Of course a submarine regulator project cannot be documented only from the surface. A little camera housing was build for one of our tiny wireless cameras. With the housing submerged and a receiver under the tank, we managed to transmit clear pictures out of anywhere in the tank. That mean that it will transmit from a depth of at least 25 cm. Movie clips coming up later...

Housing
In the water
Strange colours on a B&W TV, but nice resolution

The time came to get rid of the manual control and let the regulator take over. Spending serveral days, the Regulator respone seemed erratic and violent. Every type of regulator software we tried to program Nemo with, the sytem never reacted well enough. In one case, the wtc submerged well enough, but overshot the desired depth of 20 cm enough to hit the bottom 60 cm down. I another case the hull made some quite interesting "frog-leaps" across the bottom. Just managing to dive again before it breached the surface, but again slammed into the bottom.

We decided to pull the hull and regulator apart and go through it all again to make sure every subsystem performed as intended. This was about the time we discovered that the H-bridges made so much EM inteference, that the depth measurements went all over the place. 40 centimeters within 0,1 sec was not uncommon. Various noise reduction modes on the processor did only partly eliminate this problem.

Through the entire process, the Regulator circuit started to show signs of the different minor problems we had encountered and solved. That, along with the noise problem, prompted us to do a total remake of the Regulator. The design was perfected quite a bit, and Sub Regulator v1.1 was completed in a record time of three days. The first version took a month and a half.. The design also looks much more clean now.

Regulator v1.1

The last thing we did friday before the weekend, was to conclude the tests on each individual subsystem. The depth measurement is now much more dependable, and is unfettered by all three H-bridges, noising to the best of their abilities. The new data shows a single mesurement in twenty, to be less than an inch off. The rest of the measurements are right on.

This is as far as we have come until now. We move back to our test tank monday, and serveral different kinds of regulator software are ready to be tested.

More updates, pics and movies to come...

Jacob

[wingtip]

cool cool cooool

cool cool cooool