It is assumed that the turningpoint for the belts is the center of the belts.

cl = 0.00348377
cr = 0.003193242
w = 1.68336

UMB test (168 KB) Data and calculation showed in this page

Where am I? Sensors and Methods for Mobile Robot Positioning:
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Chapter 5 is used as the base for these calculation. The two following articles describe the process in greater detail.

Measurement and Correction of Systematic, Odometry Errors in Mobile Robots:
Download Paper 58 (803 KB)

Correction of Systematic Odometry Errors in Mobile Robots:
Download Paper 59 (177 KB)

$r_{c.g.,cw}=\sqrt{(X_{c.g.,cw})^2+(Y_{c.g.,cw})^2}$

$r_{c.g.cw} = 83.43 cm $
$r_{c.g.ccw} = 128.67 cm$
$L = 2 m $

$$\alpha = \frac{x_{c.g.,cw}+x_{c.g.,ccw}}{-4L}\cdot \frac{(180^{\circ})}{\pi}$$

$$ \beta = \frac{x_{c.g.,cw}-x_{c.g.,ccw}}{-4L}\cdot \frac{(180^{\circ})}{\pi} $$

$$R = \frac{L/2}{sin(\beta /2)} $$

$$E_d = \frac{D_R}{D_L} = \frac{R+b/2}{R-b/2} $$

$$b_{actual} = \frac{90^{\circ}}{90^{\circ}-\alpha}\cdot b_{nominal} $$

$$c_l = \frac{2}{E_d+1} $$

$$c_r = \frac{2}{(1/E_d)+1} $$

$r_{c.g.,cw}=\sqrt{(X_{c.g.,cw})^2+(Y_{c.g.,cw})^2}$

$r_{c.g.cw} = 4.12 cm$
$r_{c.g.ccw} = 29.35 cm$