May 27th Long Pond Test

Today we took our 4th time field test in the long pond.

In the test, the actuators (winches and rudders) were working perfectly.
RC mode are well performed.
In the autonomous aspect, the boat responsed, but still needs to be implemented.
The hull is totally dry inside after the test. The boat is perfectly sealed.


Need to be done:

The jib winch need to be investigated, the motor perform weird after the boat is back.

Cheers,
MUN Sailbot.

May 13th Long Pond Test

First water test succeed!!!!!!!!!!!!
We are so excited to launch our 2012 boat, F' Arctica.
Compared to the last year's boat, the performance of this boat is significantly improved. The boat is lighter, faster, and easier to control.

Top speed: 3.4 knots.

Shorts! and not because its summer.

So it's finally may in St. John's and to say hello it snowed all day.  Lovely slushy stuff. So no wearing shorts.

However, we have other shorts.  The electrical kind.  Luckily our power supply is smart and decides to not turn on when there is a dead short. So for future reference, all you board designers who think you are clever and add power and ground planes on the top and bottom of your boards.  Use nylon stand-offs or at least leave enough room that the aluminum doesn't cut through the solder mask and make your board think it should be summer time.

Crunch Time

We're getting close to our in water deadline of April 28th and here is another update.  Our motors have finally arrived after bouncing around Florida, Texas, Quebec, Texas again, Nova Scotia and finally to us!

Motors Arrive

They are shiny aren't they.  They will go into our new actuator design which is completely waterproof, capable of up to 3 Nm and around 60 RPM.  Our test actuator has just finished being assembled and tested and the rest are being machined right now by Engineering Techinical Services, which has generously donated the machining time.  Thanks Tech Services!

In other news, the spreaders, shrouds and other rigging are nearing completion.  All of the pieces being attached to the mast this year are being placed on sleeves which fit over the mast.  This allows us to remove them for shipping, replace them if needed and keeps the structural aspects in tact.  The last pieces are being bagged right now.

Spreaders

Yes, that is a garbage bag and no that is not what we have been bagging with.  We use much more sophisticated milk bags from Tim Hortons. EconoBag from and mastic tape helps too.

Thuggin

Electronics Box

One of our problems last year was our power connections from the batteries to the everything else got wet and shorted.  There was lots of green corrosion and needless to say a complete lack of power to do other things, like drive motors.

This year we are moving our batteries inside a waterproof (IP67+) box along with the electronics.  All of the connections are made through circular connectors which have sealing glands around the wires and face seals.  They're also made of plastic and quite light.

Electrical box with circular connectors installed and motor driver board in place

We had a setback a few weeks ago when after working on getting the wiring set up all of the connectors were left in a box along with the heat gun and heat shrink.  Unfortunately, the resident lab thief decided the heat gun would be lovely in his personal collection (no joke).  All of our connectors were stolen.  A quick call to Tyco Electronics, however, and they agreed to send us replacements.  Thanks TE!

Another change this year has been to change the communication from the main controller to the motor controllers to I2C.  This change allows for easy expansion.  If we ever needed more motors we just add another board to the stack.  Right now we can control 4 motors using PID loops with quadrature feedback.  The motor drivers are rated to 12A without heatsinks and can operate up to 16V (we run at 12V).  There are two Arduino pro minis on the board and each one is responsible for two motors. This division allows you to actually expand the system two motors at a time.  The motor controllers provide current feedback which we use to limit the torque output (so we don't break the boat when something jams).  The best part is that all the code is updated too and it works.  Check out the repo here.

Stay tuned for more updates as we ramp up this week getting ready for first sea trials as the ice is off the lakes now!

Yeah, It's a tight fit

Electronics Rev2

We've recently put together our new electronics package.  It is essentially a breakout board for all of the different off the shelf boards we use. Check it out!  It has a Seeedstudio Arduino Mega as the master controller, a 3.5A 5V switching regulator from Pololu, SD Card data logging, 4x 12A motor controllers.  The motor controllers are controlled by two Arduino Pro Mini's (2 motor controllers to each mini) which take quadrature encoder signals as feedback for motor position and current feedback for torque limiting and control.  Big improvement over our previous protoboard ratsnest.

Our second generation wind sensor is almost put together as well.  It uses a AS5040 magnetic encoder chip.  So far the whole thing weighs less than 15g. (ignore the mastic tape I needed something to hold the vane on temporarily)  It outputs a pulse at 1kHz equal with the width equal to the orientation of the magnet attached to the wind vane shaft.

Actuator test

Development of new actuators is underway. An implementation of our shaft using aluminum resulted in some shearing and sad team members. So we remade it with stainless steel and new grub screws. Here's a test of the build that used a rapid-prototyped casing and a shaft which did not fail:

(Note: Musical tastes are those of the fabrication team and are not necessarily those expressed or endorsed by this blog.)