By L. Paul Verhage
Now that I have a small robot, it’s
time to make it do something.
So this month, you can read
about its line follower, proximity
detector, and some future designs
in the works.
remains between the IRED/phototransistor pairs, the
CheapBot-08 drives merrily along its way. However, the
detection of no reflection by either of the phototransistors
puts the little robot into a turn to correct the situation.
You will need the following parts to the make the line
What’s a robot without a line follower? Like line
followers for larger robots, this one emits two infrared
beams: one on the right side of the PCB and the other on
the left side. However, because of the small size of the
robot controller, the IR LEDs (IREDS) are separated by only
1-1/2 inches. And — like other line followers — next to each
IRED is a phototransistor to detect the reflection (or nonreflection) from its IRED neighbor. As long as the black line
58 SERVO 12.2009
•CheapBot-08 line follower PCB
•Two 330 ohm resistors
•Two 4.7K ohm resistors
•Two right angle receptacles
•Four 7/32-inch diameter aluminum tubes cut
3/8 inches long
•Two 3/8-inch diameter heat shrink tubing
Since the line follower PCB is single-sided, one jumper
wire is needed to unite the PCB’s two ground planes. The
best wire for this purpose is a cut resistor lead. If you don’t
have one handy, then solder a resistor to the PCB first.
Then, after trimming its soldered leads, you’ll have a spare
resistor lead for the jumper wire. Next, bend the leads of
the rest of the resistors and solder them to the PCB. The
interconnect between the line follower and the robot
controller is a pair of right angle receptacles (like Jameco
I designed a PCB for the standard line follower that fits the small CheapBot-08 robot controller to a tee! That’s because the printed circuit board plugs directly into the forward expansion ports of the CheapBot-08 robot controller, so there’s no need to attach the line follower to the robot body.