  We consider the problem of finding a door along a wall with a blind robot
that neither knows the distance to the door nor the direction towards of the
door. This problem can be solved with the well-known doubling strategy yielding
an optimal competitive factor of 9 with the assumption that the robot does not
make any errors during its movements. We study the case that the robot's
movement is erroneous. In this case the doubling strategy is no longer optimal.
We present optimal competitive strategies that take the error assumption into
account. The analysis technique can be applied to different error models.
