A calibration apparatus includes a processor, an alignment device, and an arm. The alignment device captures images in a three-dimensional space, and a tool is arranged on a flange of the arm. The processor records a first matrix of transformation between an end-effector coordinate-system and a robot coordinate-system, and performs a tool calibration procedure according to the images captured by the alignment device for obtaining a second matrix of transformation between a tool coordinate-system and the end-effector coordinate-system. The processor calculates relative position of a tool center point of the tool in the robot coordinate-system based on the first and second matrixes, and controls the TCP to move in the three-dimensional space for performing a positioning procedure so as to regard points in an alignment device coordinate-system as points of the TCP, and calculates the relative positions of points in the alignment device coordinate-system and in the robot coordinate-system.

A method is disclosed for calibrating a tool center point of tool for an industrial robot system. The method can include moving a first part of said tool and a cross beam sensor by said industrial robot; recording a first posture and a second posture of said industrial robot during the interruptions of a first beam and a second beam of a cross beam sensor; moving a second part of said tool and said cross beam sensor by said industrial robot; recording a third posture and a fourth posture of said industrial robot; calculating the tool orientation in consideration of said first posture, second posture, third posture and fourth posture of said industrial robot; and moving said tool and said cross beam sensor by said industrial robot so that said tool center point of said tool interrupts said crossing point of said cross beam sensor.

A tool center point calibration device includes a laser light source and a semi-transparent mirror configured to split a light beam of the laser light source into the first light beam and the second light beam. The second light beam is at of about a 90 angle to the first light beam. A first light detector at the first light beam generates a first signal when the first light beam is interrupted, and a second light detector at the second light beam generates a second signal when the second light beam is interrupted.