Sensor diagnostic apparatus and method thereof

A sensor diagnostic apparatus for diagnosing a sensor among a plurality of sensors, each of said plurality of sensors identifying an object and outputting acquired identification data of the identified object, said sensor diagnostic apparatus comprising:

• a moving object counter counting, in accordance with identification data acquired by the plurality of sensors in a predefined time period,
• a first local number of moving objects of which the identification data are acquired by a first sensor and a second sensor near the first sensor, and
• a second local number of moving objects of which the identification data are acquired by the first sensor and a third sensor near the first sensor, the first, second and third sensors being stationary;
• a reference value storage storing
• a first preset reference value for the first sensor and the second sensor;
• and
• a second preset reference value for the first sensor and the third sensor;
• and
• a comparator comparing
• a first value derived from the first local number to the first preset reference value, and
• a second value derived from the second local number to the second preset reference value,
• to determine that the first sensor is in error when
• a first difference between the first value and the first preset reference value exceeds a first predefined threshold value, and
• a second difference between the second value and the second preset reference value exceeds a second predefined threshold value.