Exercise 12: Butler


The „Butler“ turns the buggy (model 10) into an autonomous driving robot: it learns to recognize black lines as boundaries, drive around obstacles and play a sound when it has reached its destination.


How can a vehicle recognize dark lines with a photo transistor? How can the vehicle recognize and avoid obstacles?

Learning objective

  • Programming a (partially) autonomous vehicle
  • Detection of lines by means of a phototransistor
  • Programming obstacle detection and avoidance

Time required

If the painting robot or buggy only needs to be rebuilt, the butler only takes a few minutes to assemble. If the model is assembled from the start, a construction time of 35 minutes can be expected.

The solution to the „Destination control“ task requires a few practical tests, but is simple. The „Reach target“ task uses a solution from model 3 (alarm system) by playing a sound. The „Line detection“ task is also easy to solve by making a small adjustment to the light barrier from model 3 (alarm system). Either the self-created program or the example program in the app can be used for this.

Students should be able to solve all three tasks in one lesson. The experimental task „Avoiding obstacles“ is a little trickier and requires several tests. An additional lesson should be set aside for solving it.