EV3 Classroom How-Tos

This stack will count the degrees that motor B moves  as the robot moves forward (which, in this case should be 180), and then instructs the robot to move backward that number of degrees. 

You can use the rotation sensor to count the number of degrees the robot moves  when using the ultrasonic sensor, and then tell it to move that same number of degrees when instructing the robot to return to a starting position. 

The rotation counter will AUTOMATICALLY count the degrees the motor has turned, but it will not automatically ERASE that number, so that is why you need to reset the degrees counted at the beginning of the stack -- just to be sure that you are indeed starting from zero.