Problem with tracking wheels

Hello everyone,

My team has been testing the odometry with a mecanum drive. The odometry is fairly accurate when driving forward. But, it is 1-2 inches off (in y-axis) when strafing horizontally (or x-axis). The problem seems to be the random movement of the left and right tracking wheels when strafing sideways. The tracking wheels are built with omni-wheels. Is this an inherent weakness of tracking wheels when moving sideways? Has anyone experienced this problem with mecanum drive or X-drive?
Thanks.

How many tracking wheels are you using? If your drive base has the ablity to go sideways, you should try to add 3 tracking wheels, two facing fowards, and a third perpendicular to the others, shown in the picture.
image

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We have 3 tracking wheels. Attached image shows approximately the placement of the tracking wheels in the chassis.
chassis

We thought the tracking wheels were skipping, so we tightened the rubber bands, but it did not help.

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This sounds like a friction issue, I would try to rebuild the tracking wheels using the straightest axles you have, and make sure you pay attention to the spacing. Idealy they should be able to free spin for over 10seconds

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@Amanda Thanks for the suggestion. The tracking wheels are free-spinning for 1-2 seconds, we thought it was good enough. :rofl: We will rebuild them.
The challenge is with the encoder shifting slightly, possibly causing some friction. It is mounted with a single screw.

yeah I had a very similar problem before, just make sure the encoder is as straight as possible and it should work fine

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