User Tools

Site Tools


robots:armadillo:calibration:welcome

Armadillo Calibration

Odometri constants

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-mark test

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

Where am I? Sensors and Methods for Mobile Robot Positioning:
Download book from University of Michigan (12.2 MB)
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)

BEFORE CALIBRATION

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

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

CLOCKWISE, cw
ϵx [cm] ϵy [cm]
1 -63 -63.5
2 -50.5 -59
3 -34 -65
4 -26.5 -78.5
5 -41 -91.5
Xc.g.=-43Yc.g.=-71.5

COUNTERCLOCKWISE, ccw
ϵx [cm] ϵy [cm]
1 -71 97
2 -100 112
3 -74 87
4 -69 123
5 -65.5 100.5
Xc.g.=-75.9Yc.g.=103.9

Calculations

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

α = 851.99 cm
8.5199 m

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

β = -235.7484 cm
-2.357 m

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

R = -48.7 m

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

b = 1.524 m
$E_d$ =0.969

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

$b_{actual}$ =1.6834calibrated value of wheelbase
1.524before calibration

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

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

Correction factor Before CalibrationAfter Calibration
$c_l$ =1.0156 0.003430.003484
$c_r$ =0.9844 0.00324 0.003193

AFTER CALCULATION

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

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

CLOCKWISE, cw
ϵx [cm] ϵy [cm]
1 -6 -14.5
2 -12.5 -10
3 5.5 8
4 -5.5 -7
5 2.5 10.5
Xc.g.= -3.2 Yc.g.= -2.6

COUNTERCLOCKWISE, ccw
ϵx [cm] ϵy [cm]
1 -38.5 24
2 -27 10
3 -19.5 11
4 -22.5 20
5 -22 4
Xc.g.=-25.9Yc.g.=13.8

robots/armadillo/calibration/welcome.txt · Last modified: 2012/10/26 11:47 by claes