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Look Mom! No
Hands!
One of the gadgets we added to Toy Boat 2 was a Simrad AP12R autopilot.
Luxury? Or irreplaceable tool?
Background
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Installation
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Commissioning
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Peformance
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Safety&Reliability
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Summary
Once we got it installed, here's what we did to make the unit operational, and
to test basic functions.
Aligning the compass
The first step is to start the system, and tell it which way the
compass is
pointing. The compass can actually point towards the front, back, left or right of the boat.
The AP12R computer can compensate for this, but obviously has to be told which
direction the compass is facing relative to the bow. In this case, the fluxgate
compass was facing 180 degrees away from the bow (straight back).
Garage test with the GPS
After setting the compass direction, we cycled power, and told the
AP12R to start navigating a straight line. We could feel the AP12R take
control of the wheel. We tested the manual override by grabbing the wheel and
forcing a turn. It was difficult, but it worked.
We tried out the "Power Steering" feature by using the left and right arrow keys
to move the motor back and forth.
We tried to test the autopilot navigation function by programming our
GPS simulator to pretend like it was in a certain position, running at 30 mph,
on a specific heading, then telling the AP to navigate to a waypoint
approximately 20 miles away on a different heading.
Imagine our surprise when nothing happened! This ultimately
lead to the discovery that when in simulator mode, the GPS prefixes all
packets with an error flag so that autopilots won't use the data accidentally
(go figure). See our article in Issue 2 "Can We Talk?" that
discusses this.
On-the-water test
Our first on-the-water test was a big success. We ran through the
normal navigation tests, and everything worked as advertised. We ran
through the compass auto-compensation mode, and after we got the
circling speed correct, it worked fine. Getting the speed
right was a bit tricky, because our tendency was to circle too
slowly.
Impact of solenoids
We also tried cycling power to the solenoids under the console,
to see what impact they would have on the fluxgate compass. We
recorded a 10 degree deviation when the solenoids were powered up. That is,
the compass appeared to swing 10 degree counter-clockwise, because the AP swung the boat
10 degrees counter-clockwise to follow it.
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