Project low cost autopilot

[seandepagnier]

Thank you very much Sailoog for your sincere answer.
As you can imagine, I've analyzed Sean's pilot project with a loupe, and he did not convince me for many reasons. Is a system complicated to install, that if used with openplotter depends on the MPU-9255 or MPU9250, on the one hand and on the other hand, of the peripherals that OpenPlotter has. The MPU-9255 is a cheap IMU and for some applications it is sufficient, but it has a high noise that causes inaccuracies and, on the other hand, its sensitivity to interference, especially magnetic.

It has a power driver for drones, so it is very limited (we have foreseen that our pilot works with nominal currents of 50A and peaks of up to 290A).

I also make a hydraulic controller which is capable of 4x more power used on some large boats.   It has no problem with 20 amp continuous current.

The h bridge version can be easily changed for many voltage or currents by changing a few components.

I have no idea what kind of system needs peaks of 290A. How did you get that number?  The mosfets i use are rated for 190 amp peak but they cannot handle this for any useful period in the perspective of an autopilot.

It also lacks SeaTalk and depends on Raspi for the NMEA183 and N2K sentences. That dependence for

Seatalk and n2k are proprietary and do not really have a purpose in a free software autopilot.   They should not be supported on purpose.

What do you use them for?   Better design alternatives. I have 3d printed wind sensors as well as rudder feedback.

everything is a source of problems when working in real time. Probably for a small boat, with low speed, with calm sea and little wind is enough, but in worse conditions, with greater speed of the boat, I have my doubts about if it will know how to make it work well. Do not see this as a criticism, it's just my thoughts that motivated me to discard that autopilot.

What are your doubts based on?   Already it's working on large boats, speeds and in rough sea with plenty of wind.

larger boats are easier because everything is slower.  The smaller boats need the fastest reaction time.


I received some criticism of using multiple processes to make the program too complicated.

I did this on purpose to better separate the processing loads.   This means it has much better reaction time because it can process things in parallel.   The critical process has much less to do.  The control loop is scheduled at realtime priority so it's not getting slowed by other processes.   and is guarenteed to execute at the specified rate, either 10hz or 25hz.   Either case has easily enough cpu for rpi, and only 25hz is really needed maybe for very small boats in rough seas.  

Sean's work, I think it's a breakthrough in the world of open sailing, and I take this opportunity to congratulate Sean for his excellent work, which I believe has opened a door in the field of open autopilots. You will always be welcome in the development of the new pilot.
On the other hand, that opinion of complexity is not only mine, that opinion is also held by many more people. If you observe other forums, they almost always give up due to the complexity of the pilot.

For these reasons, I decided and convinced Tehani to build our pilot, which in the worst case will always be cheaper than the commercial. He has already developed as engineer other industrial projects controlling motors with maximum precision and with remote control (cable and radio). I can give you details of that.
One of the first concepts that we consider is that it must be simple and in only one PCB (except Gyro and GPS), in such a way that any person without knowledge can also install it. When I go to the ship I want to sail and enjoy and not worry about technical problems. On the other hand, complex installations need more time and, at times, involve big problems when passing the cables and a greater potential risk that something will fail.
We have the ability to build the pilot in such a way that you do not need OpenPlotter. After all, it has its own GPS and its own IMU of better quality and reliability than the MPU-9255, and also its own sensor management software. The advantage is that it would not overload the Raspi computer where OpenPlotter is running.

And it will be usable from Windows or with any commercial Plotter.
Plugins for OpenPlotter or OpenCPN can be left for later when we have more time. As I said in the first publication, which may not have been clear, we have offered to do the plugins with your support. The idea
was to control and configure the pilot through OpenPlotter, for example, the adjustment of the rudder stops, the response sensitivity, etc., but it can also be done with a simple smartphone, and from the remote control.
The autopilot is already very advanced. I remember how his OpenPlotter project emerged from the proposals of the people, which made OpenPlotter very powerful, modular, effective and very popular. So I thought that by sharing the project, they could come up new ideas that we can implement on autopilot.

Finally, thanks for the support of Openmarine.

It will be fun to have competition of free autopilots!
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