Comment by John_Mac on May 23, 2009 at 12:31pm

Brian

Very impressive.

I have coded something similar to your display in Visual Basic (but probably much slower), but can you tell me what application you are using to display? This is a nice test station to check things out.

Thanks
John

Comment by Brian Wolfe on May 23, 2009 at 3:24pm

Hey John,
It's developed with Python. I've heard of Python for years but never really looked into it, but when I saw the reference to it on one of Louis LeGrand's posts I decided to jump in. He was nice enough to share his script which I then modified to match my hardware configuration and display the axis.
You'll need to install Python as well as the VPython, pyserial and pywin extensions (assuming your on a windows platform).

Once you've done that you can run this scriptdemo.py

The script reads the data in via a serial port so you might need to edit it to point to the appropriate com port.

It's easy to get going, so jump in!!

Regards,
Brian

Comment by Brij on May 27, 2009 at 8:56pm

Hello Brain,

Thats great progress!!
Comming back to ground station software discussion. I have not used the Labview based Ardupilot Ground station software and not aware of Labview environment. Is labview environment good for general programming if one wants to build ground station for autonomous aircraft.

I was also leaning towards Python + mathplotlib for developing the ground station GUI and data visualization. I had also heard good things about Python and decided to check it out. Have not done any serious programming in it yet.

If you have not yet come across Paul Graham's essays on Python and programming in general, you should check them out. They are a good read. Here is an example essay.

Comment by Earl on May 27, 2009 at 10:09pm

I use Labview for my GS. Data sent via XBee radio and video on 900mhz with overlay data. Your welcome to use it as I was inspired by Chris Anderson and Jordy. They won the Sparkfun autonomous competition 4/15/90. The Sparkfun 6DOF is reasonably priced at $124 and has a simple serial output. My whole system is working good now as far as the sensord, video with overlay, and GS 2 way data to the wing. This is fun for an old retired goat like me.
Earl

Comment by Patrick on February 7, 2010 at 1:21am

Hi Brian,
I want to thank you for being so generous by sharing your knowledge with all of us. I have learned so much by reading your blog.
I have a question about the exact format that the serial data needs to be in to work with the demo.py file that you have posted. I have the demo loaded up in python and I am trying to get it to work with my new 9DOF IMU from sparkfun. What format does my serial code coming from my IMU need to be in to supply the correct values for your code to read? Right now I am just using the stock firmware that the IMU shipped with, which outputs the data like: X=180,Y=180,Z=180.
Do I output it like:
rmat:value
row1:value
row2:value
row3:value
with a carriage return after each line?

What does rmat refer to? Does the value 32767 refer to the baud rate, or something else?

Thank you very much for any help you can give me, and keep up the great work!

Comment by Brian Wolfe on February 16, 2010 at 8:07pm

Patrick,
Sorry for the delay in getting back to you, I only just noticed your post.
It's been awhile since I used the Python script so hopefully I can remember the details.

You would send

rmat:
row1: val[0][0] val[0][1] val [0][2]
row2: val[1][0] val[1][1] val [1][2]
row3: val[2][0] val[2][1] val [2][2]

with a line feed ( \n or ASCII 0x0A) after each line.

The rmat just stands for rotation matrix. It's just to let the script know what data is
coming. You could certainly streamline things and get rid of it if you wanted. On a later
version of the script I also sent some magnetic vectors, so a header on each data group
just made it a little easier to keep things organized.

As far as the 32768, since I'm using a 32 bit integer processor most of my internal variables
are represent in fixed point (18.14). The data is sent to the Python script as a 32 bit integer
and by dividing it by 32767 it is converted back to the appropriate floating point value. In the
case of the DCM, a value between +/- 1.

Let me know if that answers your questions.

Brian

Comment by Patrick on February 16, 2010 at 9:09pm

Thanks a lot for taking the time to reply...that answers all my questions perfectly.

I have created a flight center in Flash that reads the serial data from the sparkfun 9DOF imu (converted to AHRS) and displays it on an artificial horizon complete with heading, pitch, and roll. It makes it easy to connect to the aircraft over XBee and monitor data in real time. It includes battery monitoring, airspeed, altitude, etc and can also send commands (launch the parachute!!) to a microcontroller on the aircraft. I will post a link to the code for anyone who wants a copy once I get it completely debugged. Thanks again.

Comment by Jesmond Gatt on July 4, 2010 at 7:58am

Hi, do you have the pc software to make the board rotate? if yes could you please upload it.Regards
Jesmond

Comment by oliver Grant on December 9, 2010 at 3:26pm

Hi Brian,
fantastic project. By far one of the best I have seen. Will keep an eye our for you gerbers!!
I'm doing a postgraduate degree in controls engineering at the moment and I'm looking for something to tinker with on the 'rainy days'. let me know if there is something I can do to contribute. In fact, your board design would look great on my soon to be purchased heli (TREX600..)

keep us posted

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