Quote:
Originally Posted by vrcprogrammer
I have been looking around the web and couldn't find anything. I am trying to do localization, which is finding the location of a robot, on an omni-directional, such as an X-Drive or Mechanum Drive. I have encoders on all four wheels. If anyone can point me towards the formulas or the code that I can use to figure it out.
Thanks for all your help.
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Finding the correct speed for each of four mecanum (notice there's no h in mecanum) wheels, given the desired instantaneous vehicle motion (rotatation and XY translation), is called inverse kinematics.
The opposite problem -- finding the vehicle motion given the speeds of each of the four mecanum wheels -- is called forward kinematics. I discuss this briefly starting at the bottom of page7 of
this document.
But even if all four mec wheels are always turning at kinematically correct speeds (which is a non-trivial problem), in the real world there will be factors such as roller axis free play, roller friction, carpet compliance, weight distribution, acceleration forces, etc etc which cause the actual vehicle motion to differ (perhaps substantially) from the predicted motion.
Then, on top of that, you would have to integrate the vehicle motion over time to get vehicle location and orientation... and the errors would accumulate.
So the question needs to be asked: how accurate do you need the vehicle location and orientation to be, and what distances and times do you have in mind? Depending on the answers to those questions, there may be a better solution than what you currently have in mind.