Raspberry Pi inspired autopilot • Hacker News Board

Re: Raspberry Pi inspired autopilot

#31

Post by Alupis » Mon, Jan 12, 2015, 5:01 PM UTC

gadders wrote: post #28

When I read things like this, it always reminds me of the Kiwi chap that was trying to build a cruise missile in his garage [1]. Although this is smaller than what he had planned, I would imagine you could add a "release" functionality to the Pi Autopilot so it could drop something when at a certain position. [1] http://aardvark.co.nz/pjet/cruise.shtml

That's called a "Drop Box"[1] and they're fairly common. You just need a spare servo to operate the bay door.

[1] http://www.hobbyexpress.com/senior_telemater_plus_drop_box_1...

Re: Raspberry Pi inspired autopilot

#32

Post by zo1 » Mon, Jan 12, 2015, 5:05 PM UTC

shoggs wrote: post #23

ivereninov wrote: post #11

Earlier quoted context omitted.

Exactly! We are working on this and will include a very easy to use LTE streaming configuration for HD FPV experience.

Is it actually possible to fly FPV with that much of a delay?

Why would there be large delay? Am I missing something that you'd care to fill us in on?

Re: Raspberry Pi inspired autopilot

#33

Post by MegaDeKay » Mon, Jan 12, 2015, 5:06 PM UTC

Jeandon wrote: post #2

Looks very nice. Is Linux actually real-time enough to run autopilot code?

The second PDF in the link below compares the Raspberry Pi with the Beaglebone Black for a next gen APM. The nod went the the Beaglebone because of more GPIO, PWM support, and the two PRUs for realtime operation. The Pi B+ helps the first point, but not the other two. There is also a really interesting page in here on the latencies that are required.

BTW, this was written by Andrew Tridgell of Samba fame.

http://diydrones.com/profiles/blogs/a-peek-into-the-future-o...

Re: Raspberry Pi inspired autopilot

#34

Post by zo1 » Mon, Jan 12, 2015, 5:21 PM UTC

How much hacking and/or electronics knowledge is required to set this up and get it running?

#Edit. Another question, will the Reach (when it comes out) integrate easily with the boards coming out in Februaray, and be supported as part of Navio+?

Re: Raspberry Pi inspired autopilot

#35

Post by simpsond » Mon, Jan 12, 2015, 5:31 PM UTC

I'm somewhat intrigued by the HAT spec and how the daughter card provides the OS a device tree fragment. Can you comment on the pains/gains from conforming to it?

Re: Raspberry Pi inspired autopilot

#36

Post by igorvereninov » Mon, Jan 12, 2015, 5:45 PM UTC

simpsond wrote: post #35

I'm somewhat intrigued by the HAT spec and how the daughter card provides the OS a device tree fragment. Can you comment on the pains/gains from conforming to it?

Did not help us much(since we are working with spidev and i2cdev), but did not cause much trouble either.

Re: Raspberry Pi inspired autopilot

#37

Post by igorvereninov » Mon, Jan 12, 2015, 5:51 PM UTC

Phlarp wrote: post #29

igorvereninov wrote: post #16

Earlier quoted context omitted.

This is completely different. Autopilot runs under Linux and that gives incredible flexibility. You can send HD video over LTE, run scripts in flight. SSH to drone in the air, how cool is that?

How is running scripts (locally?) or SSHing into it over a serial modem any different from the scripting functions or telemetry information available with APM or GCS (CC3D) based systems? What advantages would the raspi have in streaming HD video over LTE that strapping last years android phone to the drone wouldn't give me?

It is very different.You have a full Linux environment with multiple libraries. It is great for education research and development.

When LTE is not available you can use long range wifi.

Re: Raspberry Pi inspired autopilot

#38

Post by lovelearning » Mon, Jan 12, 2015, 5:58 PM UTC

Phlarp wrote: post #29

igorvereninov wrote: post #16

Earlier quoted context omitted.

This is completely different. Autopilot runs under Linux and that gives incredible flexibility. You can send HD video over LTE, run scripts in flight. SSH to drone in the air, how cool is that?

How is running scripts (locally?) or SSHing into it over a serial modem any different from the scripting functions or telemetry information available with APM or GCS (CC3D) based systems? What advantages would the raspi have in streaming HD video over LTE that strapping last years android phone to the drone wouldn't give me?

700 MHz CPU, 512 MB of RAM, a competent GPU - that's good enough for things like real time terrain image processing on the copter itself.

Re: Raspberry Pi inspired autopilot

#39

Post by nacnud » Mon, Jan 12, 2015, 5:59 PM UTC

How do the power requirements for the autopilot compare to that of the rest of the flight hardware?

Re: Raspberry Pi inspired autopilot

#40

Post by lsaferite » Mon, Jan 12, 2015, 6:00 PM UTC

valarauca1 wrote: post #25

Jeandon wrote: post #2

Looks very nice. Is Linux actually real-time enough to run autopilot code?

A true real time system is likely over kill. General time-sharing systems generally are accuracy to +/- 4ms. Which is acceptable for most applications, as 60fps is ~16ms per frame. If you (ab)use Linux properly you can get most your threads to only halt on blocking for IO. So they'll get scheduled practically (not always) once that IO state is satisfied. This requires heavy multi-threading not horrible, just isn't am…

I would guess the PID loop benefits greatly from real-time execution. So much so that really the base control system should be on a dedicated controller with AP functionality as a secondary system driving the inputs to the PID controller.