DIY autopilot, under £150! - i particularly like the case!

Ive posted a couple of times asking for thoughts about diy a/helms, so as to use old mechanics/cases when the electronics give up (as they seem to like doing). I wondered if a software solution could be based on the developing tech in phones and tablets, GPS, compass, accelerometers are all there if suitable code could be written. If a quad copter can be kept level, surely a yacht could point in variable conditions for a reasonable period? There'd need to be an interface to the motor, wifi/usb-serial/BT?
Unfortunately, nobody 'bit'!
 
It's something I find interesting, due to a few unsatisfactory experiences with off the shelf autopilots.
It is a long way down the list of things to play with at the moment as the boat I mostly sail on seems OK with its Raymarine pilot.
And I'm one of those people who would rather be steering 98% of the time and I rarely sail singlehanded.

I think having direct control over parameters like error band, ram speed, averaging time etc would be nice.
Sometimes all I want is remote control of the wheel, so I could steer from under the sprayhood.
Other times I would like a full-on system that will keep the boat under the spinnaker in a breeze.....
 
On the face of it, the electronics are not complex. My old analogue autopilot used inputs from the compass unit and ruddder angle sensor to derive an error signal. Plus or minus depending in course drift, centered about 5v. Controls were provided to allow for standing rudder as well as sensitivity and rudder response. There were some subtleties incorporated into the circuitry to damp out boat movements in cross seas but it worked almost as well as a Raymarine SPX30.

I did try modify it to use nmea data (heading from a compass sensor) and even managed generate an analogue error signal by comparing the required heading with the current heading.
My hydraulic steering pump requires a 40amp H bridge to drive it, and these are more of a challenge to get working reliably. I blew a few mosfets trying but got there in the end using a single chip micro to drive them.
 
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Skyflyer... Thank you for bringing this up.. Looks like a great next project.

I have a spare Arduino mega on board and was looking into a backup for the current Raymarine course computer anyway... It looks like it would be an interesting first project just to program the Arduino with compass/heading and rudder feedback and at least have a backup autopilot that would hold a course..

Once I have the Seatalk, NMEA0183 and NMEA2000 integration on board all complete (hopefully by the weekend) I'll be seriously looking at this..
 
Very interestting.Unfortunately not all of us are electronics geeks so I'll take the Monitor approach. It also uses precious little power...
 
GHA... A lot to trawl through there and it seems like there are multiple versions of the code all with more functionality than I'd like to start with... and only a couple of schematics.. I'll have to take a better look when I have a little more time :)

As to the 'Monitor'.. Well I have a spare Arduino and a spare Linear Drive on board.. So I'm hoping for the cost of a compass sensor, a rotary feedback sensor and some DC motor control bits (less than £100 in total) then I'll have a reasonable backup... or something as a long term solution if the Raymarine should ever fail :)
 
Martin_J said:
GHA... A lot to trawl through there and it seems like there are multiple versions of the code all with more functionality than I'd like to start with... and only a couple of schematics.. I'll have to take a better look when I have a little more time :)

As to the 'Monitor'.. Well I have a spare Arduino and a spare Linear Drive on board.. So I'm hoping for the cost of a compass sensor, a rotary feedback sensor and some DC motor control bits (less than £100 in total) then I'll have a reasonable backup... or something as a long term solution if the Raymarine should ever fail :)
Click to expand...
Ive got a B&G auto pilot, a simple motor driving a hydraulic pump controlled by a big box and a Network Pilot instrument. It works brilliantly. Bzz bzz is all that we hear and the wheel twitches! Question, how does the hydraulics work? Does it just switch the flow at the motor?
S
 
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