To program the robot we use the open source software Scratch.
Here is the distance sensor:
When an obstacle is close to the sensor it returns the value 0. When the obstacle is more than 6 inches the sensors returns 100. Otherwise a number between 0 and 100 is returned, corrsponding the the distance with the obstacle. You can read the value of the sensor using the following construct in scratch:
 .
To start the engine in a direction use:  . You can change the direction with  .
This gives the following code for the robot:
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