[SOLVED] UMBMark calibration help

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mj31382

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Hi, i tried calibrate my differential drive base using UMBMark but the error worsen. at first i did trial and error to make it go straight line and turn reasonably well. then i tried using UMBMark to fine-tune the error.

B = wheelbase, 70.37cm
C.left = 73.28 clicks per cm
C.right = 70.45 clicks per cm
L = 350cm (UMBMark square side)

i made it run 350cm for 1 round only. Otherwise it will hit the wall.
i wonder if i did anything wrong here. how should i include the number of round inside the formula?

and after i get the center of gravity coordinates, which value should i plug to the Xcgcw and Xccgw?
i assumed average Xcw and Xccw.

alpha = (Xcgcw+Xcgccw)/(-4L)*180/pi
beta = (Xcgcw-Xcgccw)/(-4L)*180/pi
R = (L/2)/sin(beta/2)

Eb = 90/(90-alpha)
Ed = (R+B/2)/(R-B/2)

C.left.error = 2/(1+Ed)
C.right.error = 2/(1/Ed+1)

Bnominal = Bactual*Eb

C.left.nominal = C.left*C.left.error
C.right.nominal = C.right*C.right.error

i attached my calculation in excel. any help is appreciated. thank you.
 

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  • Odometry Position Calculation.zip
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