Introduction to Robotics/Sensors/Lecture/Students

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Introduction to Robotics
Sensors: Lecture (For Students) (For Teachers) —

Lab (For Students) (For Teachers) — Assignment (For Students) (For Teachers) — Quiz (For Students) (For Teachers)


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Name:_________________________________

Date: 12 / 1 / 2009
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
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