CHAPTER 25
■ Chapter 25: Launching the Line-Follower
This chapter begins with last-minute checks followed by a qualifying run of your line-following robot.
I provide you with simple tests for diagnosing and solving likely problems, and data to compare your robot to
mine. The chapter concludes with line course ideas and potential robot enhancements.Correcting and Tweaking
Don’t expect your robot to run perfectly on the first try. There will be bad connections, loose screws, burrs,
and things rubbing. Because of an early collision, Wavy stalled every few feet. After days of wasted effort
concentrating on the electronics, it turned out that a cross axle hadn’t been glued properly in a coupler and
was slipping. These things should be expected.
Be prepared to spend as much time tweaking the “finished” robot as you did in other phases of the
project. Logically, a properly adjusted robot performs better than an unadjusted robot. Minor alterations are
often the difference between success and failure.Preliminary Examination
Before setting the robot onto a track, there are some important basic tests and calibrations to perform.
This ensures the robot is road-worthy.Checking the Power Supply
- Test the circuit board with a multimeter before applying power. For a list of tests
to perform, see the end of Chapter 23. - Toggle the line-following switch to the center (off ) position.
- Turn on the power switch.
If neither the headlights, brightness indicator LEDs, nor tube LEDs turn on, then something is wrong
with the power supply module. Check the voltage of the battery, battery connector, power switch, and power
switch connector. Measure the voltage at different points in the circuit to see where it may be dropping off.
The board has four deliberately-added test points (TP+, TP-, TP1, TP2) for testing battery and sensor
voltage. However, every exposed solder point, component lead, and connector pin can be considered
a test point. It is often helpful to probe the voltages of each point with a multimeter. Is pin 4 of IC1
(the comparator) around 0 V and pin 8 around 9 V?