Trouble-shooting Low Traction

[alecmuller]

Originally Posted by JamesBrown

How did you measure the tension to lift through the pulleys with a bathroom scale?

I stood on the scale, pulled the cord to raise and lower the weight a few times, and watched the scale move. The friction in the pulleys works against the direction of travel both ways, so the scale goes down a few pounds when you're lowering (i.e. friction offsets the weight), and goes up a few pounds when you're lifting (i.e. friction adds to the weight). The average should be: [weight of Alec] + [weight of the paver], and the max should be [weight of Alec] + [force needed to lift paver through pulleys].

Originally Posted by IKE

You could have them all hooked together and at a higher weight than robot can pull (say 300 lbs), then record initial weight and weight at stall and the difference would be the pull weight.

I like that - like some of the teams used with their hooks to lift totes & hold them a fixed distance apart this past year. It would also provide a "stair-stepped" resistance instead of suddenly hitting the full load all at once. Unfortunately I'd need to get lighter weights (because my ~20lb weights are very low resolution).


I realize I neglected to point directly to my calculations. This Google Sheet (specifically the "Architecture" tab) has my traction calculations (lines 220 to 410).