The Code Bender

Well, I know this is a bit late but it's been hard to find the time to sit down and acutally finish a post about what went on.  Firstly I just want to say it's been a pleasure being a member of the team this year.  From start to finish we've had 10 months to design a water tight robot that can see, hear, and is aware of it's surroudings.  Too all who have finished major projects this year, congratuations, namely, Baird Hendrix with his work on our acoustics system, Micheal and Jeffery with their work on vision, and Chris with his work on SeaSQL and libSeaWolf.  Thanks also to Tim Capo for the time put into creating the hardware that allowed us to get this far, the time and materials spent on our dropper, camera cases, torpedo launcher and movable brackets have been invaluable to us.  Finally, to our sponsors, thank you, we're hoping to grow your ranks in the next year with our vastly improved position and brand new robot!

So lets start with the practice run, which was largely an impressive success, due to tether length issues we were only able to complete the gate mission but after looking back over the logs we were able to see that Seawolf indentified both the bouy and orange marker pointing to the bouy.  After seeing Seawolf do something totally intelligent, we headed back to our tent with high hopes and ready for our next chance at qualifying.  In large we decided to leave Seawolf as she was, fixing a few funky bugs that Chris found but nothing major.  When he time came we quickly headed to the pool, ready to make the most of our last chance.  Once she was on the crane we all crossed our fingers and hoped for the best as a culmination of ten very short months and four very long days was about to hit the water for the final run.  We instructed the diver, blue RFID card to blue tape to start and kill in the event of a restart, red magnet to red tape in the event of a system failure.  Once in the water, the diver swept blue, and Seawolf sprung to life, but with no forward motion, she aligned to the gate, sank to depth, but refused to go for it.  After sitting for a few seconds she began to drift backwards and attempted to pin our poor diver under the dock, and we signaled to kill. After being dragged out from beneath the dock we quicky grabbed a hold of the crane operator Kirk, and hoisted SeaWolf onto the dock.  Throwing our teather down to Brooks, Chris plugged in and started debugging.  After 10 long minutes of bug hunting he stumbled on a bug he had corrected early which was adding an offset to the yaw directional thrusters and pushing Seawolf forward!  After a quick fix we dropped her back in the water and hoped for the best, the driver once again swiped blue and once again she saw the gate, aligned herself, sunk to depth and with only a minute to spare took off toward the gate. B-lining directly through the gate she make a small course correction to align with the orange plank sending us to the bouy, and headed for it.  Sadly, we shortly detoured and missed our target and after some debugging work later we found that a single line of code had left us stuck in the "search for path" mission.  After all we had accomplished this year, that was the least of our worries, we have a working platform from which to build on last year, and we had sucessfully qualified this year, placing us somewhere in the middle of the pack for this years competiton.

More to come.. but I'm too tired right now.  Hope you've enjoyed following us and I look forward to blogging our design process and competition again in the following year!  Thanks to everyone who's shown an interest in SeaWolf and please continue to, we're only going up from here!

Well, we didn't quite make it under the gate to qualify yesterday sadly but we've got another shot today which we're much better prepared for.  We've currently got a practice run scheduled for 10:20 and we're expecting good results.  We spent a late night last night outside the pool at the Kona Kai getting things ready and we're confident going forward that we've at least got a shot of breaking the top 10.

I'll start with yesterday thought, kind of a frustrating day for us.  Seawolf was having bugs creep up that were about as off the wall as they come.  During our qualification run Seawolf was having trouble doing anything but spinning in circles and trying to attack our poor diver.  It's quickly become apparent that when Seawolf goes into a spin the extruded aluminum coming off the rear of our craft acts as a rather scary weapon in addition to the handles they were intended.  The divers are nimble though and averted any injury but after trying to take him out a few times, we pulled our ornery bot out of the water and set to debugging.  While we're not 100% sure what was causing the problem it appears it was related to attempting to use our magnetic kill switch as a mission start.  Surprise, surprise, electronics + magnets = problems.

We quickly scheduled a practice run and sadly... we found similar results.  Seawolf was in a mood to fight and little else.  After a bit of messing around and some debugging at TRANSDEC we headed out in somewhat low spirits.  On our way out of Point Loma we happned to see another van, and it was on.  After the necessary egging on back and forth, we found that it was virginia tech, both in our 15 person rental vans.  We took off and they followed suit.  With engines roaring (a rather impressive sound, not that that translated to much in terms of speed) we barreled through San Diego.  We have the superior craft when it comes to vans though and we were eventually forced off the road as our destination approached, but there's nothing like a roaring engine (regardless of speed.. and with loaded vans there wasn't much of that) to introduce a little injection of some much needed fun into the evening. 

After grabbing a bite a Baha Fresh we headed back to the Kona Kai only to discover a full scale Luau taking place right outside our door. We took in some sights and sounds for a few minutes before packing up Seawolf and heading to the pool to correct our rather disabled craft.  After returning to our RFID card mission start system we found some improvement, at least now all of our motots were staying on, we still had some issues to debug with our yaw PID (control code).  Chris started correcting problems one by one and pretty soon, SeaWolf knew what straight was again.  With our problems solved we moved onto testing our vision bouy bumping code.

Because of the lighting in the pool, the orange bouys were showing up white, not something we were prepared to deal with, however due to Micheal and Jeffery's hard work on vision and interesintg "find the closest thing to what color we're looking for" code the red on my swim trunks quickly became a suitable target.  Torro, torro, torro!.  After some minor corrections we were quickly heading the right direction and with good time.

After all of Chris's contributions for the day he took the chance to grab some sleep while our vision guys were hard at work, but once they were done it was time to mix our "go straight" and "find the gate" code.  After waking Chris we attempted to re-test the "go straight" code with scary results, again seawolf was lost, and going in circles.  Frustrated, cold from being in the water and beat Kevin and I hopped into the hot tub to relax for a few minutes.  I was quickly requested back in the pool, and in no time, seawolf was once again on the right track.

So here we are, back at transdec, with our practice run coming in less than an hour.  We're currently mixing the vision and go straight code hoping for the best results.  Wish us luck, and we'll be back shortly!

Today kicks off our qualifying attempts at 11AM, our first of two.  If we qualify today it's on to bigger and better and time to start sleeping less than the average 5-6 hours of sleep per day we've currently been finding.  Luckily as sleep deprived as we may be, the energy around TRANSDEC is great and the club moral is as good as we could ask for.

So with that, lets move on to the slightly more humorous.  For one, we've discovered why crafts seem to like to break here... magnetic rocks. (see pictures)  We dropped our magnetic kill switch and upon picking it up discovered there were some little friends hanging on. They weren't metal shavings, but rocks.  And we wonder why the magnetic compasses go nuts here.  Yeesh.

On another note, we have apparently been doing some chemistry experiments with SeaWolf without knowing.  Yesterday we noticed one of our Fischer connectors was eroding and that the aluminum underneath was growing some interesting designs.  We assumed that something in the sharpie we had used to color code the connectors was eroding the material, we were wrong.... very, very wrong.  Last night during a late night pool test there was a mass exodus of tiny bubbles from the acoustics Fischer connector, scaring the hell out of me.  (first thought being, oh god, Seawolf is sinking)  Because of the earlier corrosion we ripped SeaWolf out of the water as quickly as possible only to discover a miniscule amount water had actually leaked in... Not at all matching what had sparked the panic.  Brooks was quick to the conclusion that based on the "corrosion" taking place on our frame that what was probably actually happening was that SeaWolf was performing electrolysis and electroplating her frame with the Fischer connector's aluminum.  After some testing we concluded that the connector was indeed powered (9V and god only knows how many amps) and our pretty little (haha... little...) lady was acting as a ground.  Since then the connectors been removed and Kevin has been working on getting the connector redone this morning.

Last night we also completed work on some basic acoustics code which will allow us to locate the pinger in a yaw direction and head towards it until vision can take over.  Vision also pool tested our path detector and follower so that we can hopefully do a bit more than make it under the gate when we qualify today!

We made pre-qualifications!  I hope to update this a bit more once I can find some stable source of an internet connection, for the time being though, we're pre-qualified and moving on.  Our true qualification round comes tomorrow at 11AM so wish us luck!  We're currently hard at work on acoustics, vision and getting the IMU to work.

It's interesting how the little things can bite you.  A new problem has arisen; SeaWolf likes going left, he's sticking to his southern heritage and apparently wants to drive a racecar.  This has the side effect of him missing our gate, at keeping us from qualifying. Hrm.  Well after discussing a few things about hydrodynamics and other possible reasons this could be, we've decided first we'll tackled a potential thruster imbalance.

So what are we doing to fix it? We're currently swapping out the thrusters to gives us the two "new" thrusters we just received from SeaBotix a few weeks ago on the port and starboard directional motors.  These motors have been recorded and should have basically the same characteristics when it comes to thrust.  The craft is naturally fairly stable when it comes to pitch and roll and we also have PIDs that will correct any errors that occur there so unbalanced thrusters aren't as big of an issue.  For our forward direction we currently rely on vision or acoustics pretty much solely, no magnetic compass or any other form of sensors rely.  This wouldn't be such a big issue except that once we're within about 10 ft of the gate we lose site of it and go into dead reckoning mode.

Assuming that the unbalanced thrusters aren't the issue we're currently dealing with, we are also doing what we can to get our IMU's magnetic compass working.  It's got quite some drift when we pole constantly but we're hoping that maybe by using a technique in which the engines are turned off, the IMU is polled and then the motor is kicked back on.  This gives us a brief period where the lightening storm of magnetic interference of the motors doesn't affect the compass values.

Update on Wednesday, July 29, 2009 at 11:05PM by Matthias

More info: After talking to a few more teams and some people from SeaBotix we are planning to try to implement a gyro for heading detection and some form of impeller for velocity tracking.  I'd like to tackle this as an Arduino project as between the two we should have functionality that resemlbes the holy grail of this kind of competiton, the Dopler Velocity Log.  A DVL basically allows for a craft to determine it's position in relation to a start point.  This kind of mapping would be extremely useful but they usually run in the area of 10+ grand.  I think we can manage to keep the cost a couple of orders of magnitude below what a real DVL would cost so it's our best bet at bang for the buck and leaves us without the drift problems our compass has.  So wish us luck, looks like we getting to hack something together in just a few short days!

Update on Thursday, July 30, 2009 at 2:49AM by Matthias

Our current IMU is responding at least semi correctly now, between the IMU yaw heading and the compas we should be able to come up with something to keep us going straight.  Simpler and more timely, but hopefully we can tackle the other project coming into the next year!