logoalt Hacker News

andnedtoday at 9:01 AM1 replyview on HN

I had a very similar setup. Really happy with the xarm 6 lite. I played around with the diffusion policy paper experiments and was thinking to buy a webcam as a top camera as well but I ended up buying two intel realsense ones because of the timestamp drift issues. How did you solve that? Or is camera feed syncing not necessary for your intended projects?


Replies

mplapperttoday at 9:16 AM

I timestamp everything twice: once with the hardware clock (if available, like for the realsense camera) and once within my robot stack once it gets read from the device (using `time.monotonic_ns()`). Both are stored and alignment can happen with either timestamp. I think the 2nd timestamp is actually more meaningful since ultimately I want to reconstruct the state that the policy would've seen; so if one modality is delayed I should actually include that effect during training.

That being said, I might switch to a realsense for the static tabletop camera as well; the realsense wrist is clearly much more reliable than the cheap Logitech C920 that I currently use.

show 1 reply