I have started to build an APM controlled sail boat.
The hull
The hull is based on a IOM boat called Goth (Free plans here). It is built with balsa strips and then glassed on both the inside and outside. Keel blade and rudder are made with balsa cores and a carbon fiber shell. The bulb is 3.5 kg lead. It is designed to weight 4.2 kg when finished.
The wind vane
The wind vane is built around the magnetic rotation sensor chip as5045. With a magnet placed just above the sensor it can detect the absolute angle of the magnet. The magnet can be seen below the ball bearing in the image below. The sensor chip measures just 5x5 mm and is embedded in epoxy. The wind vane and the sensor is placed in the tube and voila. A wind direction sensor with almost no friction and a total weight of less than 10 g. Total length is 10 cm.
I still need to figure out where to put the wind sensor. Since i have a rotating mast it is not a good idea to put it there unless i fit another rotation sensor on the mast.
The wind vane is quite sensitive. It works at walking pace so hopefully it will work on the boat.
Mast
The mast and boom is made of a fiber glass fishing pole. the sail is made drawing film. It is made as an IOM sail and the sail area is similar to an IOM size two sail (main plus jib).
I have not decided how to control the sail. I can use a traditional sail servo or rotate the mast with an arrangement under deck.
Control
The boat will be controlled using the APM hardware and sensor libraries.
The plan is to take it step by step:
- Manual RC-control
- Manual RC-steering with automatic sail control
- Heading and/or Wind angle hold.
- ...
All comments and ideas are welcome!
/Magnus
Comments
that makes sense. now how we determine that set of rules to program the ardunio.
anemometer reading should be used for determining when to tack. it's very hard to tack when you don't have enough momentum on the sailboat.
so you would have ended up with two inputs the vane could be the master while the anemometer or tilt sensor could act as slave . like the vane will do the first set of inputs to angle the sail then depending on the wind speed the anemometer will send a second command like IF or ELSE command to overwrite the sail angle from the vane. like +/- 5%-10% to my guess on how much the boat is heeling over.
was wondering which would be appropriate anemometer or tilt sensor/gyro
mostly is trial error base on manual controlling of the boat. you have to test different wind direction and sail angle each to determine the best angle for optimize speed. I don't know if this is appropriate but I its ideal to experimented on a sailing simulator first.
http://www.hangsim.com/vs/
once you got the data its time to replicate the program on the ardunio
@CliffN
Can you develop your ideas about optimizing sail angle based on wind speed? I have thought about the need for an anemometer and adding one is on my list, but i'm not sure how to use it. The apparent wind angle (AWA) will still be my main input to decide sail angle. Other possible inputs could be heel. If a gust hits the boat and it quickly heels over i could let go of the sheet a little.
Increased wind speed at a given wind direction will give a smaller AWA if the boat continue its heading.
Is it possible to create a general rule for controlling the difference between AWA and "sheeting angle" depending on wind speed?
@novrizal
Yes I agree that the stern probably is the best place for the wind vane. It obviously works on full scale self steerings.
usefull for beginners too so not to flip the boat over in strong winds. still lack anemometer. that way you can tell the wind speed and optimize the sail angle
put the wind vane at the very stern of the boat, just like a free sailing pond sailboat.
better to start with the most simple sail design, like rc laser or weenip (free plans online)..
im following this
If you want support from Droidplanner just give me a list of control modes :)
Thank you. First step is to get it into the water...
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