[Autosail] Ardupilot and sensors

[Emma Bluemke]

Slack is an awesome platform for team project management, not sure if
everyone's tried it before?
It really streamlines everything and allows really convenient document
retrieval from older messages, as well as convenient categorization.

Emma

On Thu, Jul 7, 2016 at 11:34 AM, Trevor McKee <trevordmckee at gmail.com>
wrote:

> Sorry I missed the meeting.
>
> ...do we have any plans for any sort of project management system
> thingey?  I use trello at work, may be useful in theory?  or a portion of
> hacklab wiki?
>
>
>
> On Thu, Jul 7, 2016 at 11:32 AM, Alan Majer <alanmajer at hotmail.com> wrote:
>
>> Just a quick update on some of my To-Dos. Forgive me if I repeat info
>> that others have already shared.
>>
>> *Ardupilot*:
>> This thing has gone through a lot of iterations since I last looked at
>> it. Seems like it's a choice between the newer but expensive Pixhawk, and
>> the older arduino mega version that's cheaper but gets good reviews.
>>
>> The newest version, the Pixhawk, looks awesome (400Hz updates or
>> something), but it's kinda expensive too at $200. It's also out of Stock:
>> <https://store.3dr.com/products/3dr-pixhawk>
>> <https://store.3dr.com/products/3dr-pixhawk>
>> https://store.3dr.com/products/3dr-pixhawk
>> Robotshop does have in stock (and I usually get their stuff in a week or
>> so after an order):
>> http://www.robotshop.com/ca/en/3dr-px4-pixhawk-advanced-autopilot.html
>> There are much cheaper knockoffs on ebay (if we order now, probably take
>> 4-5 weeks):
>>
>> http://www.ebay.com/itm/Pixhawk-PX4-V2-4-8-32Bit-Flight-Controller-NEO-M8N-GPS-Power-Module-Multicopter-/272240662408
>> <http://www.ebay.com/itm/Pixhawk-PX4-V2-4-8-32Bit-Flight-Controller-NEO-M8N-GPS-Power-Module-Multicopter-/272240662408?hash=item3f62ced788:g:NjAAAOSw-4BXYQhc>
>>
>>
>> Seems to be some discussion about 3DR signing their units in a way that
>> locks you into their ecosystem causing interoperability issues. I haven't
>> looked at this enough to know what's going on, just seems like a minor red
>> flag to check out before we commit to Pixhawk.
>>
>> On the other hand, the slightly older version Ardupilot Mega (APM 2.8)
>> still seems to be an interesting option (rated very highly but slower at
>> 100hz... though this is a sailboat mind you). Although it's tougher to
>> source, it seems that a lot of the most likely sources don't sell it, so
>> hard to get a local copy. These guys are supposed to be makers of the
>> official board but show out of stock:
>> <https://www.unmannedtechshop.co.uk/ardupilot-mega-autopilot-kit-apm-2-8/>
>> https://www.unmannedtechshop.co.uk/ardupilot-mega-autopilot-kit-apm-2-8/
>> Hobby King looks like it has one though:
>>
>> <http://www.hobbyking.com/hobbyking/store/__56052__HKPilot_Mega_2_7_Flight_Controller_USB_GYRO_ACC_MAG_BARO.html>
>> http://www.hobbyking.com/hobbyking/store/__56052__HKPilot_Mega_2_7_Flight_Controller_USB_GYRO_ACC_MAG_BARO.html
>>
>> As can be expected, the clone market is alive and well (some of these can
>> ship via DHL to get it in a week):
>>
>> <http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20160707063654&origin=y&SearchText=ardupilot+mega>
>> http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20160707063654&origin=y&SearchText=ardupilot+mega
>>
>> Also, sadly, I cannot find my old ardupilot (nor the GPS) that I had with
>> it. It may have got consumed in another project or lent out to one. So look
>> like we will need to purchase one either way.
>>
>>
>>
>> *Sensors:*Wind speed sensor. Yes, most of the weather monitoring stuff
>> is pretty big, and around $100. But works well in very low wind speeds.
>>
>> Some options:
>>  - weather vane atop of a cheap *rotation encoder* or *Potentiometer*.
>> Not super accurate and probably has a bit of friction, but dirt cheap.
>> Might be good enough, might be worth a test considering the price is right.
>>  - Quality *encoder *with absolute position:
>> http://www.usdigital.com/products/ma3   This one gives great accuracy.
>> Not cheap at $60, but might be worth it.
>>  - Then there's a bunch of traditional weather stuff.. both ultrasonic
>> and weather vanes. This kit from sparkfun might be interesting (if a little
>> big):
>> <https://www.sparkfun.com/products/8942>
>> https://www.sparkfun.com/products/8942
>>
>> Also, in watching some RC sailing videos, I think a normal weather vane
>> may act weird at some of the sharper angles. We might want to consider some
>> kind of weighted pendulum to keep it level.
>>
>> I also have a lot of other sensors kicking around... accelerometer,
>> barometric, compass etc. We can figure out what we need. Stress sensor on
>> the mast might be interesting. I've played with strain gauges a little
>> (ones inside the wii) and they are pretty cool, but I seem to remember them
>> drifting and calibration being an issue.
>>
>>
>>
>> *Weights:*
>> Yes, I found the lead diving weights we could use if we want to melt down
>> and cast exactly how we want it. Or if we don't care about the shape and
>> need a quick and dirty solution i have lots of other heavy brass and steel
>> pieces too (some are cylinders that'd be easy to put a nose on). If we are
>> even less picky (or want to test specific weights before casting) I have
>> some iron barbell weights that we could pretty much use as is if we
>> attached them to some kind of steel/aluminum flat.
>>
>>
>>
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>>
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