Operation
This page describes operation of the PowerTroll with the steer10
operational software installed and configured as described elsewhere.
Calibration
Before you start using your PowerTroll in earnest you need to
calibrate the compass(s). This is necessary because the geomagnetic
characteristics at your location are different from those at mine. The procedure
to calibrate the compasses depends on what compass arrangement you installed.
There are three choices:
- You installed only a Devantech horizontal compass (or wish
to calibrate that compass independent of your installed vertical compass).
- With the PowerTroll installed in your boat and connected
to the Electro-Steer switches but not powered on or connected to the
Electro-Steer relays, move switches #3 and #4 to the on position (toward the
large blue connecters). These switches are called 'JustCalibrate' and
'Just2D' respectively. Leave the PowerTroll case open so you can observe the LED's.
- Plug the PowerTroll into the 12v source. You should
observe the red led blink 5 times.
- Start the boat in slow circles (either direction). The
boat should take at least 30 seconds to go all the way around.
- Observing a real compass, each time you reach N, S, E, or
W press one Electro-Steer button (either) for a moment. Go around at least
twice, so that you have pressed a button at least twice for each of N, S, E, and W. When
this is complete press both Electro-Steer buttons at the same time for a
moment. You should observe the green led blink 5 times.
- Unplug the PowerTroll from the 12v source. Move switches #3 and #4 back to the off position (away from the large blue connecters).
- You installed only a Mindsensor horizontal compass (or wish
to calibrate that compass independent of your installed vertical compass).
- With the PowerTroll installed in your boat and connected
to the Electro-Steer switches but not powered on or connected to the
Electro-Steer relays, move switches #3 and #4 to the on position (toward the
large blue connecters). Leave the PowerTroll case open so you can
observe the LED's.
- Plug the PowerTroll into the 12v source. You should
observe the red led blink 5 times.
- Start the boat in slow circles (either direction). The
boat should take at least 30 seconds to go all the way around.
- Unlike the Devantech compass, the Mindsensor does not
require you to indicate direction. Simply do a few slow circles. When this
is complete press both Electro-Steer buttons at the same time for a moment.
You should observe the green led blink 5 times.
- Unplug the PowerTroll from the 12v source. Move switches #3 and #4 back
to the off position (away from the large blue connecters).
- You installed both a horizontal and vertical compass with
associated FPU and accelerometer. Note that if desired you may perform one of
the above procedures to standalone calibrate your horizontal compass but that is
not necessary for this tilt compensated calibration to be effective.
- With the PowerTroll installed in your boat and connected
to the Electro-Steer switches but not powered on or connected to the
Electro-Steer relays, move switch #4 to the off position (away from the
large blue connecters) and move switch #3 to the on position (toward the large
blue connecters). Leave the PowerTroll case open so you can observe
the LED's.
- Plug the PowerTroll into the 12v source. You should
observe the red led blink 5 times.
- Start the boat in slow circles (either direction). The
boat should take at least 30 seconds to go all the way around.
- Simply do a few slow circles. When this is complete press
both Electro-Steer buttons at the same time for a moment. You should observe
the green led blink 5 times.
- Unplug the PowerTroll from the 12v source. Move switch #3
to the off position (away from the large blue connecters).
How to Use it
When the Controller is off it is effectively out of the
circuit so the Electro-Steer switches work exactly like they would if the
autopilot was not installed. To wit: Press one of the wired remote control
buttons and the outboard is steered one direction (while the button is down); Press the other button and it
is steered the other way. With both switches unpressed the outboard stays in
it's last position. Operation with both switches depressed is undefined.
When the Controller is on the Controller reads
the Electro-Steer switches and controls the Electro-Steer relays.
A manual control mode is provided (default at power on) that
simulates power off control, in this mode the switches directly change the
positioning of the outboard. To wit: Press one of the wired remote control
buttons and the outboard is steered one direction; Press the other button and it
is steered the other way. With both switches unpressed the outboard stays in
it's last position. Depressing both switches at once causes the controller to
switch from manual mode to automatic mode with the current heading the desired
heading. The controller acknowledges this mode change by a double 'rattle' of
the Electro-Steer Relays - sounds like 'ticka-ticka, ticka-ticka'.
The automatic control mode enables the Controller to use the
compass to control the Electro-Steer to maintain the desired heading; in this
mode the switches change the desired heading and the Controller steers to that
new heading and then holds that heading. Switch operation is as follows: Press
one of the wired remote control buttons and the desired heading is changed to
port by 10 degrees per second; Press the other button and the desired heading is
changed to starboard by 10 degrees per second. With both switches unpressed the
desired heading stays the same. Depressing both switches at once causes the
controller to switch from automatic mode back to manual mode. The controller
acknowledges this mode change by a single 'rattle' of the Electro-Steer Relays -
sounds like 'ticka-ticka'.
Tuning PID constants
Boats vary enormously in how they respond to
the helm. A long deep-V hull with little canvas to catch the wind probably has
so much directional stability that something like PowerTroll is unnecessary.
Contrast that with an inflatable, round, flat bottom life raft - can you imagine trying to
make that go any particular direction? Most boats fall between these extremes,
often because their cabins or canvas acts like a sail and let the wind push them
every which way.
PowerTroll uses a PID algorithm to keep on heading, and this
algorithm is effected by tuning constants you can change to improve how
PowerTroll works with your boat. PID is short for "proportional", "integral",
and "derivative".
Some pre-tuning is done when you assemble your PowerTroll. That will probably result in a condition I'd call 'barely
tuned'. As over time you observe the way your PowerTroll steers your
boat you will probably want to make further adjustments. That is done using the
wireless remote or the p2test9 and p2test10 programs as described on the EEProm
page.
Before
getting into that let's think about how you try to manually hold a heading with
respect to wind direction:
Going
downwind, or on a downwind quarter, is easy. On many boats you can find a 'sweet
spot' that will hold a heading for long periods. You can run the trolling motor
as slow as you like.
A crosswind
or somewhat upwind quarter is harder. You must have enough power to turn that
far up into the wind. But sometimes you can still find a sweet spot, balancing
the wind with the trolling motor power and the helm turning up into it. If you
need to troll more slowly than engine power allows you can use a
sea anchor to reduce you speed through
the water without reducing steering efficiency.
Going more or
less straight into the wind is much more difficult. There is no sweet spot to
find. You must have enough power to not only turn directly into the wind, but to
do so briskly. Holding the heading involves achieving the heading then having
the wind blow you across it the other way, so you have to turn back, achieve the
heading from that direction, and then have the wind blow you across it the other
way. And so on. A sea anchor is very useful in this case not only because it
reduces what would be too fast a troll, but because it will tend to stabilize
the heading swings.
A 'barely
tuned' PowerTroll [one using the default settings] can usually handle the
downwind quarter pretty acceptably. It should find the sweet spot within a few
minutes. It will work on a crosswind heading but may swing quite a bit, and may
not ever find a sweet spot. It may not work going straight into the wind,
especially without a sea anchor
A 'well
tuned' PowerTroll can handle both the downwind quarter and crosswind situation
well. It should find the sweet spot within a few minutes and subsequently make
only occasional minor corrections. It will work straight into the wind but some
swings may be large if no sea anchor is used - but even with those large swings
heading maintenance should be sufficient to keep you lines from getting tangled.
Realistically you would want a sea anchor if only to control your speed!
How do you
get the PowerTroll tuned?
First you
need to establish the power level you are tuning to - how effective will the
helm be. On a day with the wind as brisk as you think you'd like to fish in,
find a trolling motor power level that is able to briskly turn the boat all the
way up into the wind when the electro-steer is fully deflected to port, and to
starboard. If this power level results in an unacceptably fast trolling speed
you should experiment with a sea anchor to ensure you can get the speed you seek
with the power setting.
Use this
speed for all further tuning. If you decided you would use a sea anchor while
fishing you should use it while tuning.
Start with
PID_I at 100, PID_D at 0, and PID_P at 5.
Begin by
tuning PID_P. PID_P influences how much helm to apply based on how far off
heading. PID_P dominates when you are far off heading.
In manual
mode establish a heading straight into the wind, then go to autosteer. The boat
should start swinging back and forth over you heading. Use a compass to observe
and record the size and duration of the swings. Your recorded data may look
something like this:
Increase the
value of PID_P by 5 and repeat the above procedure. This time you data might
look like
Continue
increasing the value of PID_P and recording what happens. Each time the size of
the swings should decrease, and the time between swings should also decrease.
But at some point the change will no longer decrease the swings (or it might
even make them bigger). When that happens back off the the prior value..
Now tune
PID_D. PID_D works counter to PID_P to apply helm slowing down swing. PID_D
dominates when you are nearly on heading, so as you are swinging back to heading
and getting close to it PID_D applies helm the other way to slow the swing so
you stop at the right place instead of overshooting.
Start with
PID_D at 1 As before in manual mode establish a heading straight into the wind,
then go to autosteer. The boat should start swinging back and forth over you
heading. Use a compass to observe and record the size and duration of the
swings. Your recorded data may look something like this:
Increase the
value of PID_D by 1 (a little goes a long way!) and repeat the above procedure.
Continue
increasing the value of PID_D and recording what happens. At some point you will
stop seeing symmetric swings back and forth over the desired heading and instead
see small swings before you get to the heading or after. That's the time to
stop. Your final result might look like
Or, enhancing the
chart a bit
Your
controller should now be well tuned to these conditions. When the wind dies down
you would reduce power to keep trolling speed and this is exactly the change the
would be necessary to keep the powertroll tuned. And the same applies going
crosswind or downwind.
If you want
to troll a little faster you could decrease PID_P slightly; to troll a little
slower you could increase PID_P slightly. Usually this is not necessary as the
powertroll still works even if not completely tuned.
Are these
optimal settings? Probably not. But I'm interested in fishing - not messing with
the controller - and this simple technique results in settings that keep the
boat going reasonably straight most of the time.
Sea Anchor for Trolling
Sea anchor's don't have to be real involved. I use an extra 5 gallon paint
bucket on a rope attached to the stern. Cheap, easy to deploy, easy to retrieve,
extra storage when I'm not using it as a sea anchor!
What can go wrong?
- Goes Around in Circles instead of Holding course
Cross your
fingers the first time you switch PowerTroll to automatic mode! Once your boat
starts to go off heading PowerTroll will either steer to bring it back on
heading - or steer the wrong way to get you even further off heading! Of
course the latter very quickly turns into you just going in circles. Fix
- Don't worry, this is a one time thing. Turn off PowerTroll, change the
setting of switch #1, turn PowerTroll back on and try again. What's
going on? Because of the variety of ways an Electro-Steer can be installed
there is no way to know which of the two Electro-Steer switches will make your
boat go to port and visa-versa. So you have a 50-50 chance of getting it right
the first time; if that doesn't work out just flip the switch!
- Desired heading changes some as people move around on the Boat
Very small changes in the way the boat sits in the water can have surprisingly
large effects on a compass. This is not usually a big problem (I commonly see
15-20 degree changes on my boat) and is easy to handle by moving people around
and/or changing desired heading as necessary. But if it's to annoying - Fix
- upgrade to tilt compensated version of PowerTroll.
- Too Rough
If the boat is rocking around too much the single compass PowerTroll can't get
a good direction reading and so does not steer any particular direction - it
may even start going in circles!
Fix - make sure switch #1 is set properly (see 'Going in Circles' above).
Fix - turn off PowerTroll and run the motor yourself. Fix
- upgrade to tilt compensated version of PowerTroll.
- Too much wind (current)
When factors other than outboard helm strongly effect steering the PowerTroll
may not be able to overcome those factors quickly enough to steer effectively.
One clue is to go to manual mode and use the Electro-Steer to steer the boat
yourself. If you have a hard time keeping the boat on your desired heading
there is no way the PowerTroll will be able to do so! The issue is that while
it would take a person holding the outboard handle much less than a second to
steer the outboard lock to lock, it takes the Electro-Steer about 4 seconds to
do that! Fix - sometime increasing power (speeding up a little)
helps. Fix - change heading to reduce wind/current effect.
- Trolling too slow
If you are trolling too slowly there will not be sufficient helm control to
maintain a heading. Fix - increase power (speed up a little). Fix
- it may be possible to tune PowerTroll's PID constants to obtain better
results if you intend to regularly troll at this speed.
- Trolling too fast
If you are trolling too fast small helm changes will cause heading changes
more quickly than PowerTroll can compensate for the changes. Fix -
decrease power (slow down a little). Fix - it may be possible to
tune PowerTroll's PID constants to obtain better results if you intend to regularly
troll at this speed.
- Power Failure
The most frequent total failure I see is an electric 'power failure', usually
meaning the PowerTroll got unplugged or the boat's battery switch got turned
off. Fix - restore power!
- Electro-Steer Failure
I have seen the Electro-Steer seize up, see
reliability issues. Fix - discontinue
use of PowerTroll and Electro-Steer until seize fixed.
- PowerTroll Failure
Building and testing new PowerTroll hardware and software I see this all the
time, but you should not (except maybe your first time out if the controller
was not build or installed correctly). However I've no idea what PowerTroll's
long term reliability might be, so of course this failure could happen
anytime. Fix - disconnect
PowerTroll and discontinue use until fixed.
Copyright © Mike Noel, 2005, 2006; 2007
last updated 5/20/2007