Just a quick update on the research platform. I launched it on its final shakedown cruise into the ocean off the Central California Coast. Once out in the ocean, it completed a 30 mile circuit (15 miles straight out to sea, 15 miles back).

One reason for the final test is the addition of AIS for keeping track of other boats in the area that also have AIS. The other reason was to test real world expectations of the battery under load.

The AIS worked great. I was getting real time telemetry from the secondary satellite transmitter on board the platform every 5 to 10 minutes. The software is designed to grab the first three AIS messages it comes across. The range averaged out to about 7nm. This is a cool addition to the platform. I decided to add AIS telemetry after I priced out getting it from the internet. Fair prices if you want AIS data received by coastal stations. But once you want to get AIS information from ships far out at sea, the prices are completely un-affordable.

This has lead to another mission parameter when the platform is launched. AIS gathering while out beyond the range of coastal stations.

The Pixhawk worked well during the time at sea.  It kept the platform on track. I need to adjust the amount of data collected. The size of the bin file crashed three separate computers (all 1 year old or less) trying to parse the data in Mission Planner

The motor obviously worked as well. However, I am dropping 25% power from the code. I thought 25% would be enough power to keep the platform moving in a circle and keep it "on station" once beyond the currents of the coast. That part of the test failed miserably. All that happened is that i wasted precious battery watching it get carried far "off station" because 25% thrust on the motor just didn't cut it. This is huge revelation because in the bay where I did all of the testing, 25% was slow, but enough.

(Waves get very big out at sea.)

Unfortunately, we are pushing up against September and a weaker sun\shorter days, so I may wind up waiting until Spring for the final launch.

I will keep my twitter feed updated

https://twitter.com/pacificbots

Finally was able to get the project back into the water after a 2 month hiatus. I have been trying out different props. One is the standard manufacturers issue and the other has more torque. I launched during a flood tide with winds out of the East at 10 to 15 mph. Max speed was around 7mph with the tide (the wind probably wasn't much of a factor since the boat has practically no profile).  The higher torque prop requires more Amps in the midrange, but gives a higher speed and also has more bite against the tide.

After launch I will begin to receive telemetry via satellite. Does anyone know of any non-profit organizations that would be interested in the data? Just post it to twitter?

• Location
• Apparent wind speed
• Wind direction
• Air Temp
• Bar pressure
• Water temp
• Water PH

Last time I posted an update someone asked for a video, here it is in action.

Finally was able to get one of the bots out onto the water. For this test, I chose an area of San Francisco Bay that is subject to strong currents during the tide changes. As the tide was going out, the current was about 3 knots. The bot did fine. There were plenty of settings to tweak and a few adjustments of the Pixhawk PID had things working smoothly.

Some takeaways from the test.

Turn radius: Once I threw the switch into autonomous mode, I notice some squirrelly behavior from the bot. Checking my list I realized that I still needed to verify the turn radius. I originally estimated the turn radius to be about 3 meters. I was waaaaay off. The radius turned out to be around 7.5 meters. Once I updated that little nugget, the bot handled the waypoints with ease. 

Weight: Getting weight distribution right can be a pain. I had to stop the bot on the water a few times to adjust battery/ballast positioning so the bot would track better.

Overall a successful mission and One step closer to launch!

More updates soon.

You can check out the twitter feed for updates between blog posts!

http://twitter.com/pacificbots

A lot of people have contacted me for more pics, so I thought I would throw up some more. I will give some minimal content with them. If you have any questions, fire away and I will answer in the comments.

The first iteration of controller and Pixhawk. At the time I thought The Pi would be too big and draw too much power. Power was ok, but definitely too big.

When I got the hull from Radtek, I originally planned to use three 50 watt solar panels since I could not find a 150 watt panel that was narrow enough to fit on top. The width of the hull is 21". The length is 92"

I also planned to use the push pull system for the rudder. I quickly found out that even a heavy duty servo could not tolerate a week pushing water back and forth in my torture test bucket.

This caused me to rethink and redesign the rudder system. I eventually went with a thru-hull rudder system. This is a typical powerboat brass rudder port mounted on top of a 1/4" carbon fiber plate. On the bottom of the hull is a 1/4" ABS plastic plate. With weight ever increasing, I went with a kayak rudder and an 1" diameter aluminum rudder shaft.

After weeks breadboarding everything and testing, the final control system looked something like this. As you can see from the picture I moved from the servo rudder control to a linear servo. This one has 135 lbs of thrust and handled the bucket challenge with no problems.

The servo installed in the hull. I was very fortunate that the servo lined up almost perfectly with the rudder aperture. This is the only pic I could find of the servo so the candy obscures part of it.

Once all the systems were figured out, the challenge became how to fit them into a small enough water tight container. This caused a lot of grief.  This is a first attempt.

Finally I found the perfect waterproof container for the electronics

At the back are the waterproof ports for most of the electronics. The exposed sma connector attaches to the Satellite antenna. In all I drilled about 15 holes in the case for cabling.

Expecting that the ocean will batter the crap out of this, I mounted a carbon fiber plate to the the hull and bolted the electronics to the hull via vibration mounts. These mounts will keep the electronics about an inch off the hull. Hopefully the vibration will be significantly reduced.

Juggling family and a full time job meant that everything was done from 8pm till the wee hours of the morning, hence this taking a year (and counting). Soldering success at 3am. I had blown through 4 boards before this one by letting the solder touch and failing to clear it properly before plugging the controller board into a power source. 

I went with a 100AH battery after figuring in the power requirements. Just running the electronics 24/7 added up quickly not to mention powering the motor and the rudder. Since this platform is designed to drift with the current and monitor the ocean/air once it reaches a certain point, there will not be a constant high load demand on the battery. Getting to its destination is another power story entirely. lol...

I wanted to be able to stay on-station for many days even in the event of a lack of sunshine. A 100ah LIFePO4 battery weighs about 26lbs. You can see the battery installed in the hull in my previous post.

Once the battery was in, I then had to wire up to the charge controller and also wire up a secondary chrage port so the battery could stay charged while inside. At one point I had wires coming out of all parts of the boat. The usb ports for talking to the pixhawk and other devices are in the shot as well

That's all for now. If you have any questions, let me know.

I should have some more photos up at 

http://twitter.com/pacificbots

The end result has turned into a research platform that is intend to be used as a self-positioning buoy to monitor the ocean environment. The buoy will move to a specific area of the ocean and then drift with the current while monitoring takes place from the on-board instrumentation packages.

What will be monitored:

• Weather (air temp, pressure, apparent wind speed and direction)
• Ocean Salinity, PH and Temp.

The platform will be powered by a 100AH LIFePO4 battery charged by a solar array.

Follow me on http://twitter.com/pacificbots for more pics and updates!