Angle measurement for balancing robot.

[uffi]

Henrik,

one question regarding your posted attachment "kalman.zip". In the source "tilt.c" a header file "parameter.h" is linked, which is not included in your file "kalman.zip". Also I could not find these files in the latest releases of the autopilot UAV command and control project (version 2.5, 2.4 or 2.3). Which project at sourceforge has developed these files?
Can you post also the file parameter.h?

Thanks in advance, uffi.

[HenrikOlsson]

Hi Uffi,
I think that the original files came from the UAV project on sourceforge. Anyway the zipped archive of the complete file-set as found on the Nuts & Volts FTP-site is 345k and the max attachement size allowed here is 200k. So I'll attach the Parameter.h only (change file extension from .txt) and if you want the rest I can e-mail it to you directly or you can get them from the N&V FTP-site. Here: http://www.nutsvolts.com/~downloads/B-Bot.zip

Are you saying that you are working on converting the routines to PBP? If you do and want to share it I will owe you big time!

I just got my two SHARP GP2D120 in today so I will have a go at using them first. Then I'll revisit the gyro/accellerometer approach.

Hope to here from you!

/Henrik Olsson.

[Archangel]

Thinking about balancing robots, a lot of energy is spent to do this, both electrical energy and your energy. I would suggest using large wheels and ballasting the robot below the axle to lower the C/G. Perhaps the batteries could go there. then install one of the gyros sold for R/C helicopters to help stabalize the bot. I think then your code for the motors would be less critical, and robot would would make you smile sooner (even if the ballast is inadequate to allow it to stand without controller operating, it should help).

[vacpress]

joe - this was my first reaction also. but then i read this N&V article... they put the batteries in the 'head'... and consider the segway... sure the batteries are in the base, but the center of gravity probably is closer to our mid section when it is being ridden...

i get the impression that a high center of gravity is important.. i also notice that most bots put the accelerometer low, near the wheel axle height...

if anyone has more info.. i am reading along.. interested in the concepts, if not actually making my own balancing robot!

i know it may sound like sacrilege, but try the parallax forums.. very helpful people there...

[mister_e]

It's 2007, resource are everywhere and mostely free... so what's the problem to look elsewhere, i don't see any. This is why divorces exist after all

In this case it's more about problem approach and/or problem analysis than anything else. Time to dig in you old school books or take a few cup of coffee to see what's happen

[Archangel]

joe - this was my first reaction also. but then i read this N&V article... they put the batteries in the 'head'

I will take the time to read that article again.
JS
Edit:
The article says they moved the batteries up to "increase the inertia", I see that as an attempt to cause the accelerometers to respond faster. Their robot chassis is made of whiteboard, probably the reason they needed to increase the inertia, as that cardboard is not very stiff, I believe they could have achieved similar results by moving the accelerometers up to the "Head"
where nature put ours. Anyway those are my thoughts on the matter, It's up to you to sort out whats good and what's useless.
Have fun,
JS

[HenrikOlsson]

Hi Joe et all,

Try this: Take a pencil (low inertia) and try to balance it on the tip of your finger. Not really that easy is it? Now take a 1m (3foot) stick (more inertia) and try again, easier...?

Even better, take a pool que, try to balance it with the "fat" end down (batteries mountes low), then turn it around (batteries mounted high), which is easiest?

/Henrik Olsson.

[Archangel]

Because you are moving the part with the lower mass