Robotic Normalizing Force Feedback

This paper presents a solution to correct the orientation of a drilling end-effector prior to orthogonal or normal drilling of aeronautic material using an industrial robot. Using industrial robots for drilling is a challenging and difficult operation. Industrial robots are not as stiff and rigid as conventional CNC machinery, but are far more operationally flexible and cost effective. Drilling with an industrial robot, as one component for the strive towards light-weight automation, has not yet been fully utilized in aerospace manufacturing. One reason for this is the uncertainty in using a device that requires considerable calibration to achieve the demands of accuracy stated in aerospace manufacturing. The problem with a static calibration model is that it cannot maintain a guaranteed accuracy. Once an industrial robot comes into contact with a work-piece, it deflects in 6 degrees of freedom. The solution presented in this paper ensures orthogonal drilling of the hole by using force sensing feedback to assist re-normalizing the robot manipulator after preloading the work-piece.