Encoder-assisted Mecanum drive?

[IraGlass]

I'm having trouble with the programming for a Mecanum drive that runs straight. I can see how to use encoders to straighten out a tank/arcade drive, and my straightening code works fine forwards and backwards, but moving side-to-side or spinning messes up the code and just makes the robot twitch around. Is there some default code or other method to run an encoded Mecanum drive? Any advice is greatly appreciated!

[dtengineering]

We had two very talented programmers who figured out how to do this using interrupts on an IFI controller three or four years ago. I believe they calculated a desired speed for each wheel, then ran a PID loop to set the wheel speed. Aside from that, I don't actually know what they did, and am afraid to touch the code for that robot lest we send it skittling across the floor out of control. It took a while to tune it.

Have you tried using the gyro to keep it traking straight?

Jason

[Ether]

Originally Posted by IraGlass

I'm having trouble with the programming for a Mecanum drive that runs straight. I can see how to use encoders to straighten out a tank/arcade drive, and my straightening code works fine forwards and backwards, but moving side-to-side or spinning messes up the code and just makes the robot twitch around. Is there some default code or other method to run an encoded Mecanum drive? Any advice is greatly appreciated!

Just curious, how badly does your bot behave with just open-loop voltage commands given to the 4 motors?

If it's ill-behaved open-loop, it's possible there's a weak motor or a friction problem with the drivetrain or mecanum rollers. Have you checked all the rollers to make sure they spin freely?


~

[samir13k]

this is probably already considered: but just make sure your wheels are in the correct setup. i believe mechanums go in an "X" configuration? not positive though... also, maybe you would like to mention what language you are using. I cant help much, but it may be beneficial to the next guy reading this post