Wednesday, August 19, 2015

Island Boys of Island Harbor

My boy's Grandpa Smitty gave them some land next to the beach at Island Harbor.  Thanks Grandpa!   This is a wonderful development environment for boys and boats.

We are going to make an old Laser sailboat hull into a solar robot boat big enough to ride on or pull Kayaks.  This is 12.5 feet at the waterline.  We ordered 2 trolling motors.  We will use the same phone software we wrote for the small solar robot boat.   We also ordered some solid state relays big enough for the trolling motors.  We already had a bluetooth motor controller that we will use to control the solid state relays.   Our phone software uses internal GPS and compass to decide what commands to send to the motor controller over bluetooth.  Since the phone and motor controller are already working we should be able to make a big robot without too much more work.  More about our plans after the pictures below.

We had too many times where the 4 foot boat would have trouble with the wind.  On the days were there was not wind there was usually clouds, so the solar did not work and the small battery could not last long.  Then there was an amazing amount of seaweed in the Caribbean these last 9 months and the little boat propellers get tangled up easily in even a small amount.  I am hoping the trolling motors have a prop design that does not get tangled so easy.  Being bigger, more powerful, and deeper in the water should mean small bits of seaweed don't bother it.    Making computer vision software to let the robot avoid big patches of seaweed seems possible but avoiding tiny pieces probably would not have been.   Spinning backward or alternating back and forth may be a way to get seaweed off if it does tangle.  With the acceleration sensors and GPS we may be able to tell when we run into a thick bunch of seaweed and backup.    If this seaweed keeps coming we will have plenty to experiment on.

The next size Quadmaran will use 4 of these same trolling motors, so working out how to control them is a step toward that goal.  The computer vision will work for that as well.

We should be able to make the trolling motors go forward and backward using 4 relays for each motor to make an H-bridge but to do that we probably have to open up the trolling motor.   We might start with forward only.

If we can make the motors go forward and back then even when one fails we can still control which way the boat is pointing.  With a daggerboard and control of direction we can get the boat to drift back to home port if it is upwind when there is a failure (there is almost always a strong trade wind around here).   So our testing will be done upwind from home base.  From Island Harbor we can send the boat along the coast and be able to drift back.   This would also work if we are sending it across the Atlantic to Africa as that is an upwind trip from Anguilla.  Fault tolerance is something we want in future designs as well.

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