Hi Eric
of cause I`m interested.
I think a platform like a forum incl. possibility to upload drw and
files, would be great. I have one in spare, but unfortunately something
is going wrong, because permanent new users are generated, think by a
bot, and for time being, I closed the doors. Perhaps on the WE I will
find some time to try to update this forum, but if you have an other
idea, pleased to hear ;-)
Peter
Am 21.01.2014 19:31, schrieb Eric Frank:
Hi Peter and David,
This is very interesting for me. Ultimately, my project with these things is
for building a model sailboat that is semi-autonmous. Give it a list of
waypoints, and it will navigate to them. This is already implemented
commercially for model planes, and there are various attempts at trans-atlantic
crossings with model sailboats (so far unsuccessful).
To begin the learning process, I am using arduino and a wind direction
instrument to automatically adjust the sheet for the apparent wind. And to get
more realtime practice with the arduino, I am adding to the NEMA-based system
on Cats Paw to derive tilt-compensated true heading info. A tilt-compensated
Hall effect compass module from Sparkfun generates the NEMA code for magnetic
heading, and the RMC sentence from a little GPS unit provides the local
magnetic variation. So that allows construction of HDG (magnetic heading +
deviation and variation), which standard nav programs like MacENC or iNavX can
use to get true headings.
I have not even started putting together an autopilot for the model (on Cats Paw I use
a Raymarine wheel pilot), but would love to learn more about how you implement the
"learning" steps in having the autopilot make the appropriate rudder
corrections for a certain course error.
My guess is these projects will not be of interest to lots of the Stus-list,
so perhaps we should start communicating offline. Interested?
Eric Frank
Cat's Paw
C&C 35 Mk II
Mattapoisett, MA
From: David Paine <paineda...@gmail.com>
To: cnc-list@cnc-list.com
Subject: Re: Stus-List Homebrew autopilot
Message-ID:
<cantme359m12gxtortu3jrnd7qgbjh+5g03wyp-amz1txfov...@mail.gmail.com>
Content-Type: text/plain; charset="windows-1252"
Hi Peter,
I built a homebrew below deck autopilot for my C&C33 a couple of years ago
using a linear actuator, a mechanical clutch, a H-bridge-like serial power
controller from Pololu, an arduino, a transreflective serial LCD display,
four buttons, and most important of all, a digital compass with serial
communication (NMEA 0183) operating at 10Hz which, along with a sparkfun
gyro (15 degrees/sec) provides heading information. I bout everything from
ebay and probably have $250 and untold hours invested) The programming is
fairly easy with arduino since there is a PID controller library available
(use two, one for the positioning of the actuator, the other for correcting
for the course error (the difference between the intended course and the
present heading.
I've used my autopilot on many long solo trips including one 80 m mile
offshore run with 20 kn wind directly astern and a large swell off the
quarter (during which I was able to sleep for four hours as the system was
so stable.
Hints: Forget using GPS (or wind) alone to set the course you need much
faster response time and that is why you need a 10 Hz heading signal. I
thought about using a Kalman filter but soon learned that Kalman filter
math is serious juju and was very glad to have stuck with PID control -- we
only have two degrees of freedom its not like it's a quadracopter! The
worst part of my system as it stands now is the mechanical clutch to engage
and disengage the actuator -- one day I will find a hydraulic actuator
which will allow a solenoid to disengage the actuator. Raymarine actuators
have an electromechanical clutch which is also nice but consumes more
current than I like. Also, try to use components with serial
communications protocols -- these will have on board filtering and make the
whole exercise much easier.
Best,
David
On Tue, Jan 21, 2014 at 2:24 AM, Colomba <colo...@peter-gottwald.de> wrote:
Good day
I`m wondering if there is anybody who want to build a DIY autopilot? If
so, it would be interesting to discuss/combine ideas.
In the moment my idea ... and what I`ve done so far is following:
- Controll unit with a raspberry pi
- language Python (because I really do not know C to handle this properly)
The idea in the moment is to use this year the old wheel pilot (Navico) as
steering unit. If the controll unit will work fine, I will change the
steering unit next winter and will mount a linear drive under deck.
What I`ve done up to now ...
I took the code of FishPi autopilot as basic to change to the things which
I think are usefull.
For time being I integrated a compass/magnetrometer/accelerometer module,
called cmps10. It`s cheap and doing it`s job.
For GPS signal I`m using a simple USB GPS mouse to figure out
Lon/Lat/speed/course
... not done yet ... integrate a reader for wind direction. On board I
have the NASA clipper instruments and will read this datas via Atmel
microchip, connected to the controll system via I2Cbus. Atmel Afinity 1327
Chip is programmed and working, but up to now no test if it`s working with
the NASA clipper instrument, due to the fact, mast is down for winter... so
I have to play arround first to test it on board, but ... it`s cold
outside, so I`m still waiting.
Rudderangle, just working, with a potentiometer and signals collected by
GPIO pins of raspberry pi.
Route planing .... FishPi provide the idea of integrating routes in gpx
format. I think that idea is ok for an autonomus vehicle, but I do not like
that idea. I`ve tested to run opencpn and FishPi parallel on the raspberry
.... and it works, so I take the signal from opencpn for heading to next
waypoint via UDP and can use opencpn.
For output, Ive integrated a motor controll via SDA network, which should
work with a PA with the wheel unit. Not tested yet.
There are a lot of things to do to get everything working nicely.
- define sailing situation with no go areas (i.e. downwind or app +-38?
head wind)
- define a "learning tool" to define rudder gain vs heeling and
acceleration, my idea is to create a simple database and to store real life
datas.
- implement a kalman filter or a complementary filter (which I prefere for
time being)
- of cause ... to find a nice housing and screen to have the stuff mounted
at wheel also to sea seamap at wheel
One may say, hey, you can by this stuff, exactly what you want ...
correct. But first of all, the hardware will cost me as DIY project about
100 ? instead of min 1000 ? ... the other thing is, it makes fun to create
the own platform.
So, if anybody is interesting to join this project, he/she is wellcome ;-)
best regards
Peter
C&C34 Colomba
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