Introduction to Robotics/Printouts/Sound Waves

Speed of sound

$D=Ct$

D is the distance, measured in meters.

C is the speed of sound in air, measured in meters per second.

t is the amount of time the wave travels, measured in seconds.

At 72°, sound travels at 344.8m/s.

Convert to Centimeters

We convert to centimeters because they are more useful, and it helps to remove fractions from our calculation.

$D=Ct\times \frac{100cm}{1m}=100Ct$

For the BoeBot

$D=\frac{100CT}{2}$

Because the sound wave must travel to the object and back.

The BoeBot measures t in "clock cycles", which are each 2μseconds. We must convert the equation to use seconds instead of clock cycles:

$D=\frac{100Ct}{2}\times \frac{2}{1,000,000}=\frac{Ct}{10,000}=0.03448t$

Fractional Math

The BoeBot can do some limited math with fractions.

The "**" operator is used as follows:

$A**B=A\times \frac{B}{65536}$

We calculate that:

We can use the following code to convert time to distance:

Distance = Conversion ** time

Finding the Conversion Constant

$Conversion=0.03448\times 65536=2260$