Hub posture detection method and apparatus

A hub posture detection apparatus for, prior to mounting of a wheel on a hub of a vehicle conveyed along a vehicle conveyance line, detecting an inclination and center of the hub and orientations of hub bolts, comprising:

• a control device that imaginarily divides a front surface of the hub into four equal parts, by use of perpendicularly-intersecting lines, to divide a pitch circle of the hub bolts into upper and lower and left and right divided pitch circle portions and specify a first horizontally-elongated rectangular area including the upper divided pitch circle portion and a second horizontally-elongated rectangular area including the lower divided pitch circle portion;
• and
• first and second distance meters, the first distance meter measuring a distance from a predetermined reference position to the first horizontally-elongated rectangular area, the second distance meter for measuring a distance from the predetermined reference position to the second horizontally-elongated rectangular area,
• the control device being adapted to:
• calculate, on the basis of the distances measured by the first and second distance meters, coordinates of respective centers of two of the hub bolts included within the first and second horizontally-elongated rectangular areas;
• calculate center coordinates of the hub on the basis of the coordinates of the centers of the two hub bolts;
• acquire, from portions of the first and second horizontally-elongated rectangular areas where no hub bolt is included, coordinates of three points that define apexes of an imaginary triangle;
• calculate, on the basis of the coordinates of the three points, an inclination angle of the hub relative to a vertical plane extending along the vehicle conveyance line;
• and
• calculate an orientation of each of the hub bolts on the basis of the center coordinates of the hub and the coordinates of the center of the hub bolt.