Differential Drive Odometry in LabVIEW

[brianrumburg]

I wasn't able to find the original Odometry.pdf anywhere in my source code repository (ack!). I did find this page which seems pretty close to what I remember reading. I haven't looked at the code in a couple of years, so I may be way off. (c:

I did find a couple of updated versions of the CalculateOdometry.vi in my repository. I assume I fixed something, but who knows what. I have attached them in hopes that they may be of help.

I don't have LabVIEW installed at the moment so I have no idea what I'm posting here. It might be a good idea to shield your eyes when opening these...

Best of luck!

-Brian

[Wamp]

Thank you all for the info.

Yesterday I found 2 interesting links:

http://rossum.sourceforge.net/papers/DiffSteer/#d6

(Same aproximation as brian used)

http://www-personal.umich.edu/~johannb/position.htm

(There is a PDF, page 20, same aproximation but more "in depth")

With everything I got and your replies, I think I understand the whole process, except the very beginning... brian calculated:

Left Wheel = Speed + Turn Rate
Right Wheel = Speed – Turn Rate

What exactly is "Turn Rate"? Obviously thats not an angle, I think it´s a transformation of some data input from the wheel encoders, but Im not sure where it comes from. I didn´t found anything about that...

(Well, I know it´s only a "simulation" and you actually set it manually from the instrument panel, Im talking about how it applies in a real situation).

Sorry if I ask something stupid, I´m a noob in robotics, this is my third month studying this field Which I have to say, I found it pretty hard, time-consuming, but also fascinanting!

BTW, I have to check better and compare the last VIs brian posted.

Oh, and maybe you can find this interesting, is a simulation comparing real trace VS Dead Reckoning aproximation: http://rossum.sourceforge.net/tools/...ionApplet.html

[Ether]

Originally Posted by Wamp

I think I understand the whole process, except the very beginning... brian calculated:

Left Wheel = Speed + Turn Rate
Right Wheel = Speed – Turn Rate

What exactly is "Turn Rate"?

If "speed" is the vehicle forward speed command in feet/sec, then the "turn rate" is equal to (L/2)*omega, where omega is the vehicle rotation rate command in radians per second and L is the vehicle trackwidth measured in feet. The above formulas will then give the required tangential velocity (in feet per second) for the left and right wheels (which can be converted to wheel rpm by multiplying by 360/pi and dividing by the wheel radius in inches).

[Wamp]

Thank you very much, Ether Finally I understand the whole process.