Patent ID: 7386367

Claim:
A workpiece conveying apparatus comprising: a robot having a hand to grip a workpiece and conveying the workpiece; and a visual sensor, comprising: a robot controller which detects the position of the robot; image pick-up means for capturing an image of a characteristic portion of the workpiece while the workpiece is being moved by said robot to a release position; and position detecting means for detecting, on the basis of the image of the characteristic portion obtained by said image pick-up means, a position of the characteristic portion of the workpiece observed when the image is captured, said robot controller including means for synchronizing an image pick-up instruction given to said image pick-up means with said detection of the position of the robot at the time of image capture, said visual sensor recognizing the gripped state of said workpiece while the workpiece is being moved by the robot to the release position, on the basis of the positions of the robot and the characteristic portion of the workpiece when the image is captured; means for storing in advance a predetermined gripped state established by the hand of said robot; means for comparing the predetermined gripped state with the gripped state recognized by said visual sensor when the image is captured, and determining an error; and means for stopping the robot when the error exceeds a predetermined tolerance limit or for issuing a signal indicative of a fault.