The Light Finder - fischertechnik Mobile Robots II Manual De Instrucciones

Solution:
Conclusion:
The complexity of the programs is increasing. We'll try to deal with this
increased difficulty with improved programming techniques. Subprograms are
a good means for doing this. We are now familiar with logical comparisons
with subsequent program branching as a new control structure. We also now
know that an increasing number of sensors are required for new properties
or improved functioning of experiments, which we have already conducted.

4.4 The Light Finder

Till now we have let the robot react rather passively to environmental
signals. Now we want to send the robot out to find things actively. The
construction kit contains two phototransistors, which we can use as light
detectors. Each sensor acts on one motor in order for "light ray tracking" to
be possible.
The program is composed of two parts. One part contains the search for a
light source, and the other part handles the tracking or controls movement
in the direction of the light source.
Of course, we again take advantage of the possibilities of the subprogram
technique. The LIGHT SEARCH subprogram is activated after the program is
started. This subprogram is only exited after a light source has been located.
The main program tries to control the robot to move toward the light source.
Whenever the direction of the robot deviates greatly from the ideal line, one
of the light sensors is no longer receives light from the light source. Then
the corresponding motor is stopped for a brief time, so that the two sensors
can again detect the light source. This gives us our task.
Task 5:
Construct the Light Finder model with the slower gear reduction
100:1. First program the "Find light" function (preferably as a
subprogram from the start). The robot rotates in this by at least
360° in one direction. Then it rotates by at least 360° in the other
direction. If a light is found during the search, the robot stops. If no
light is found after the rotations, the search is aborted and the pro-
gram ends.
If the search for light is successful, the model should move toward
the light source. If the light source moves to the left or right, the
robot follows the movement of the light. If it loses contact to the
light source, the program starts to search for light again.
Try to attract the robot with a flashlight and see if you can guide it
through an obstacle course.
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