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Sensors in Flexible Manufacturing Systems
FIGURE 8.19 Standoff. 403
FIGURE 8.20 Large surface measurements.
Frequency, kHz Wavelength, mm Standoff Distance, mm
20 17 25
40 8 12
80 4 6
TABLE 8.1 Correlation Functions of Typical Standoff d, Wavelength λ ,
s
and Frequency f
Frequency f, kHz 20 40 80
Wavelength λ , mm 17 8 4
s
Minimum area of surface, mm 2 275 70 20
TABLE 8.2 Correlation of Minimum Size of Large Surface,
Frequency, and Wavelength
accuracy depends on the wavelength of the sound waves selected.
A “large” surface must be at least one wavelength distance on each
side (Table 8.2).
The large surface being measured should change its dimension
perpendicular to the surface, in the same direction as the sound wave
emitted from the sound source (Fig. 8.21).
