A robot device includes a base station and a robot. The base station transmits guiding signals. The robot receives the guiding signal by three receivers. A receiver is disposed at the robot, and the other two receivers are disposed at the right and left of the receiver at different angles. The robot bypasses toward right or left according to the guiding signal received by the receivers. When the strength of the guiding signal received by the central receiver decreases, the robot stops bypassing to spin and searches the guiding signal again till the strength of the guiding signal received by the central receiver is a maximum value. The robot has a fine tuning to return to the base station to have a charge.