CHAPTER 6 ■ ROBOT LINE-FOLLOWING
There are a number of reasons why a sensor adjustment dial is necessary. First, it would be very difficult
to find four perfectly matched brightness sensors. Second, during soldering, one sensor is inevitably placed
a little bit higher than another. Third, as the parts age or become soiled with dirt or dust, they may no longer
provide the same sensitivity that they did originally.
With the adjustment dial, you can balance the left pair of sensors against the right pair. Since
adjustments need to be made when the robot is already in place on a track, the dial must be accessible with
the robot assembled. However, the dial needs to be recessed so it isn’t nudged accidentally during handling.
An internally mounted dial with an access hole ends up being the solution.
Fine-tuning dials are wise features to have.
Brighter-Side Indicators
If the robot isn’t following a line or otherwise isn’t responding correctly, it’s important to have some
indication of what the robot thinks it is seeing. Also, it would be impossible to properly adjust the sensor
balance dial without some feedback from the robot as to which pair of sensors was seeing more light.
Three yellow LEDs light up on the right side when the right sensors see more brightness than the left
sensors. Conversely, three green LEDs light up on the left side when the left sensors see more brightness
(see Figure 6-14). When completely balanced, both sets of LEDs light up or blink off and on.
Figure 6-13. Front-mounted sensor adjustment dial