Re: [Gumstix-users] gumstix info

[Lawrence H. <gumstix@HariTech.com>]

Don't know if this is a possibility but a Robostix and two 3d
Accelerometers like these and some software based on this info from the
Open Moko project might make this work quite inexpensively. I have been
thinking for some time that it should be possible using inexpensive
accelerometers and without expensive gyro's but have not had time to
investigate the math. This paper seems to lay it all out. The
accelerometers are ~$20 each so 2 of them is less than the cost of most
single axis gyro's. I think it bears some study and if you should go
this route keep please us informed.

What can be done with 2 3d accelerometers:
http://wiki.openmoko.org/wiki/Technical:Accelerometer_Fundamentals
3D Accelerometers:
http://www.sparkfun.com/commerce/product_info.php?products_id=252

Otherwise the traditional route is to use 3 axis gyro's and 3 axis
accelerometer. Sparkfun sells boards to do this as well.

The Robostix does PPM output for servo control. If you want to have a
switch look for an r/c switch to allow you to use a radio channel to
swap between the radio and the robosix for server control. Something
like this:

http://www.acroname.com/robotics/parts/R306-RXMUX.html

The Robositx can decode a PPM signal from the radio
(http://docwiki.gumstix.org/Robostix_RC_input) and do the switch in
software but an outboard solution is probably the most reliable way to
do it. The circuit is quite simple and if you wanted to integrate the
accelerometers and the switch on a single circuit board that would be
easy. A 74HC157 quad 2 input mux for each 4 channels and 4013 to time
the R/C signal from the control channel works well.

Basic R/C switch using 4013 is here.
http://www.uoguelph.ca/~antoon/gadgets/rc-sw.htm
Here's an interesting project that does the same thing with some extras:
http://www.rc-cam.com/bitsw.htm

Some thought for you, hope they help.

Lawrence Harris

František Horí­nek wrote:
> Hi
>
> I chose to create stabilization system to RC heli as my bachelor work
> and currently I am searching hardware for this task.
>
> I need input ports for RC receiver and sensors (accelerometers,
> gyroscope), PWM output for servo motors and wireless connectivity (WiFi,
> Bluetooth).
>
> Can you tell me what board should I use?
> Do I need some expansion board to develop application(flashing, debuging)?
> What operating system (if any) is supported?
>
> Thank you
> Frantisek Horinek
>
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