“This Instuctable shows how to make a sensor based vehicle. The sensors used are the ultrasonic sensor, microphone sound sensor and IR sensor receiver.
The vehicle is aware of his surroundings so he will try not to hit obstacles but if he does he will detect the sound of impact and back up. He can be controlled with a remote.
More detailed explanation of Alfred:
By using the arrows on the remote and the middle button, the remote can tell Alfred where to go. When pressed forward he will go until he cant go further or told to stop. When told to go left or right, he will turn in the desired direction for a couple of seconds on his axis and will continue from where ever he left off.
If there is a wall or another obstacle at a certain distance in front of him, Alfred will stop. After he stops, he looks to his left and right to see where it is best to go next. If there is another obstacle on his right, he chooses to go left. He backs up for a second and turns to the chosen direction and continues to drive until he encounters the next obstacle or is told to stop by the remote control.
In case Alfred does not see an obstacle in front of him and hits it, he will hear the sound of impact and will back up and look around where to go next, just like before.
Alfred will go on until told to stop or gets in trouble.”