Patent ID: 7635831

Claim:
A method of detecting an inclination in a library apparatus, comprising: setting a jig on a grasping unit of a robot hand; calculating a first ratio between a first number of pixels and a second number of pixels on an image sensor mounted on the robot hand, the first number of pixels being counted between two points projected on the image sensor from a first section of a first plane, the second number of pixels being counted between two points projected on the image sensor from a second section, adjacent to the first section, of the first plane, the first plane being defined on the jig; determining a first inclination of the image sensor relative to the grasping unit based on the first ratio and a reference ratio specifying a predetermined attitude of the image sensor; directing the grasping unit to a sign immobilized relative to a storage cabinet; calculating a second ratio between a third number of pixels and a fourth number of pixels on the image sensor, the third number of pixels being counted between two points projected on the image sensor from a third section of a second plane, the fourth number of pixels being counted between two points projected on the image sensor from a fourth section, adjacent to the third section, of the second plane, the second plane being defined on the sign; determining a second inclination of the image sensor relative to the sign based on the second ratio and the reference ratio specifying the predetermined attitude of the image sensor; and canceling an angular deviation based on the first inclination so as to determine the second inclination.