Chapter 4: Boe-Bot Navigation · Page 135
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You can also think about the distance you just recorded as your Boe-Bot’s speed, in units
per second. Let’s say that your Boe-Bot traveled 9 in (23 cm). Since it took one second
for your Boe-Bot to travel that far, it means your Boe-Bot travels at around 9 in/s (23
cm/s). Now, you can figure out how many seconds your Boe-Bot has to travel to go a
particular distance.
Inches and centimeters per second – The abbreviation for inches is in, and the
abbreviation for centimeters is cm. Likewise, inches per second is abbreviated in/s, and
centimeters per second is abbreviated cm/s. Both are convenient speed measurements for
the Boe-Bot. There are 2.54 cm in 1 in. You can convert inches to centimeters by
multiplying the number of inches by 2.54. You can convert centimeters to inches by dividing
the number of centimeters by 2.54.
Example – Time for 20 in
At 9 in/s, your Boe-Bot has to travel for
2.22 s to travel 20 in.
s22.2
in 9
s1
in 20
in/s 9
in 20
time
=
×=
=
Example – Time for 51 cm
At 23 cm/s, your Boe-Bot has to travel for
2.22 s to travel 51 cm.
s22.2
cm 23
s1
cm 15
cm/s 23
cm 51
time
=
×=
=
In Chapter 2, Activity #6, we learned that it takes 24.6 ms (0.024 s) each time the two
servo
PULSOUT and one PAUSE commands are executed in a FOR…NEXT loop. The
reciprocal of this value is the number of pulses per second that the loop transmits to each
servo. A reciprocal is when you swap a fraction's numerator and denominator. Another
way to take a reciprocal is to divide a number or fraction into the number one. In other
words, 1 ÷ 0.024 s/pulse = 40.65 pulses/s.
Since you know the amount of time you want your Boe-Bot to move forward (2.22 s) and
the number of pulses the BASIC Stamp sends to the servos each second (40.65 pulses/s),
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