Apparatus for detecting axial misalignment

A diagnostic apparatus of a beam sensor installed in a vehicle, the beam sensor transmitting a probing beam and receiving a reflected beam based on the probing beam to detect a target, the diagnostic apparatus comprising:

• a diagnostic means for:
• diagnosing whether there is vertical misalignment of the probing beam in a vertical direction, the vertical direction corresponding to a height direction of the vehicle;
• and
• obtaining a quantity of the vertical misalignment in response to the diagnosing means diagnosing that there is the vertical misalignment;
• an obtaining means for obtaining detection performance information indicating a possibility that detection performance of a target by the beam sensor is lower than a predetermined detection performance, the detection performance information being determined based on an input indicating weather;
• and
• a correcting means for correcting the quantity of the vertical misalignment obtained by the diagnostic means such that:
• a value of the quantity of the vertical misalignment, when the detection performance information representing that there is a possibility that the detection performance of the target by the beam sensor being lower than the predetermined detection performance, is less than a value of the quantity of the vertical misalignment when the detection performance information represents that there is no possibility that the detection performance of the target by the beam sensor is lower than the predetermined detection performance.