homemade autopilot

Here is a good testimony on a $3 autopilot...
(autopilot about halfway into video)

http://www.youtube.com/watch?v=ZN3MS1vYv_4&feature=mfu_in_order&list=UL

 

I think i found the best one yet! ....(lot's of new vids of self-steering systems on youtube here lately)

This man is loving life i can tell ya with his set up.

look at this right here...

http://www.youtube.com/watch?v=PY1qx3PfUS0&feature=related

 

Frosty, my setup is for a 24' powerboat. I agree that an autopilot is serious. This may be a hobby but that doesnt mean that I take it lightly. So you think only a team full of people at well known autopilot companies can make autopilots? I do not think so. I am an electrical engineer, not someone who is new to hardware/software and is doing this on a whim.

 

I was refering to the bits of string tied to the tiller of a sail boat.

I have a power boat and dont have an auto pilot. A 44foot cat at 22 knots needs constant surveillance of the water ahead and debris or fishing stakes but that a different issue.

 

Actually i had much more in mind than these $3 setups. This is cart and buggy days stuff compared to what i have in mind....but look how well the $3 cart and buggy performs....can't beat the amp draw!

 

I have a home made navigation chart plotter / autopilot that I assembled. I do industrial control engineering as my business but I love boats.. I looked at the available autopilot systems and I am not impressed. They seem very expensive and not really state of the art unless you want to pay $3000 plus which is outside of my budget. If you break it you can send it back for a flat rate repair fee which is hundreds of dollars. Not much is user serviceable. I wanted something more generic.

What I came up with is a PC running OpenCPN under Linux. The PC runs off the boats 12 volt system and can survive an engine start without rebooting or having problems. I have an industrial programmable logic controller which communicates with the PC and receives the Autopilot NMEA sequences. The PLC also receives the NMEA sequences from Fluxgate compass. The PLC controls an electric linear actuator to steer the boat. The actuator has a feedback device built in that supplies the tiller position back to the PLC. I have a remote pendant setup for this also for use in the cockpit that has a joystick on it, along with an on-off-auto switch and status light for the autopilot controls.

I believe that I can fit the PC, PLC, power supply boards etc into a 10" plastic enclosure. I'm going to use a LCD display mounted on a swingarm so it can swing into the companionway or back into the cabin.

I wanted a multifunctional system that can do a lot for not much $ and I think this is going to work very well. The PC is powerful enough to run multiple programs at the same time, ie play music into some stereo speakers, while charting the progress, while typing an email to Aunt Millie etc..

Power consumption is minimal. The PC draws about 20 watts, the PLC just a couple of watts. The actuator only draws power when correcting the tiller position. The screen power consumption depends on the size and type of screen.

Everything is working well and the first mockup is ready for testing and tuning on my 29 ft sailboat.

What I am wondering is if this system works as I believe it will, would this be something that some of you would be interested in buying whole or in some portion?

 

This is along the lines of what I'm intending to do with OP. Although I do not expect to make any money. You might like to talk to the OpenCPN guys before selling it. I'm sure they'd be happy, but you have to be clear in your sales terms. You would not be selling an autopilot, you would be reselling the hardware to run an autopilot, tested with a particular chart-plotter.

Do you have pictures?

Tim B.

 

Dav911. I used to do PLC programming as my main job for a few years. Now I mainly do HMI's. What PLC did you use? Just curious as most require 120vac or 24vdc. I would also be concerned about moisture. If I was to use a PLC I would make sure it was conformally coated. But this does drive the cost up. I planned on potting mine when I was happy with it.

 

Tim B.

>>You would not be selling an autopilot

Well, actually I would be. What runs on the PC is pretty much irrelevant. OpenCPN or SeaClear II could be included free of charge or the end user could install it themselves. SeaClear II also supports the same autopilot sentence. If Open Pilot output an autopilot sentence that could be used as well. The PLC really doesn't care or know where the data is coming from. The PLC is actually piloting the boat and directing the boat according to whatever desired heading is delivered by the PC/Chartplotter software.

I would not sell something without an intention of making a profit. If I am not going to make money, I might as well simply give it away. On the other hand saving time and effort by buying a pre-assembled and tested system is worth something. Selling and supporting equipment and software also takes effort. I already work too many hours (I have three CNC machine part programs that I still need to generate tonight and test and it is past 10pm. :-/ )

I'm just wondering if there is an interest in purchasing something like this as a assembly or ?.....



I don't have any pictures yet and there is not much to photograph at this point. The PC, power supply boards, PLC are all attached to a mockup board sufficient to keep things in order. The mockup is going on board in the next few weeks for some testing on the water. I'm sure the PLC code will undergo some changes along the way. But I think it is very close.

Tim B you sound like a busy guy. Are you still renovating a house? I've done that and while it saved a bunch of money it is hard work. Say did the Open Pilot UAV guys swipe your name or did it come about at about the same time? Or is it all somehow connected?

X7JAYX.
This PLC runs off 24 volts and I am using a 12 to 24 volt converter to get the 24 volts. They are hard to find but they are available. The one I am using now is not the best unit so I will be trying another one. Very little power is required at 24 volts. There are a few 12 volt powered PLCs available but I don't like their instruction sets. Moisture can be a problem but I am really not very concerned about it down below during the sailing season. If the boat went into storage (as mine does every winter) I would pull the control box out of the boat. Conformal coating and potting can create other issues.

 

Please explain. Potting is one of the easiest ways to waterproof electronics. There are some things you have to watch for when potting. If not done properly it can lead to issues. All new (and most old) outboard and jetski ecu's and other electronics are potted. I wouldn't want to take a box of electronics out of my boat because I am worried about them getting ruined by moisture.

 

I am wondering can your linear actuator handle the outdoor salty environment? If yes, may I ask which model?

also.... what on earth is "potting"?

regards

 

Boards (like motherboards) are designed and tested so no components on the board exceed a certain temperature range. Applying any type of coating or potting without considering the ramifications of how the chips on the board will be affected can cause problems. Also capacitance issues can arise from potting or coatings on the boards that can screw up high frequency circuits.

I've built many control panels that live outside all of the time and condensation issues are really not as bad as you might think. In fact some of the control panels are in areas that I would consider very hostile both from a temperature and humidity standpoint and we have never had any problems. Look at all of the sail and powerboats that routinely keep laptops and TVs on board. I'm sure the failure rate is greater than a laptop that lives in an air conditioned home environment, but for the most part they do quite well.

 

farjoe: I have a cheap IEI actuator right now for testing. It seems to work fine, but I'm looking for a better one with a ball screw rather than a acme screw. However the one I have was really cheap - about $90.00. If it lasts for a while I could afford to keep a spare on board. I think I will just use it and see how it holds up. There are a lot of actuators out there to chose from.

 

farjoe:
http://www.pottingsolutions.com/my site/Technology/overview_of_potting.htm

 

You have to accomadate for heat issues and other things that can lead to problems while potting. The biggest drawback to me is that once potted it cannot be repaired or altered. I have been looking and the cheapest waterproof enclosure w/waterproof connectors I could find was 3-4 times more than a potted solution but it is way more flexible. I would have to make a custom PCB for all my components as well if I went with an enclosure.

BTW, are you using a micrologix?