A compensation method based on error similarity and error correlation to enhance the position accuracy of an aviation drilling robot

The position accuracy of an aviation drilling robot has detrimental effects on the assembly quality, mechanical strength and life of an aircraft in aircraft manufacturing. To enhance the position accuracy of the robot, a compensation method based on error similarity and error correlation is proposed. Firstly, the positional error similarity in joint space based on the kinematic model of the robot and error correlation are presented to illustrate that co-kriging can be used to estimate the positional error of the robot. Then, a cross-variogram of positional errors is introduced. Co-kriging based on the cross-variogram is applied to estimate the estimated positional errors along the x, y, and z axes and the absolute positional error. The estimated values are filtered by using a median filter method to further enhance the estimation accuracy. The estimated positional errors after filtering are sent to the robot controller for compensation. Finally, simulations and experiments are respectively performed with a simulated robot and an aviation drilling robot to verify the correctness and effectiveness of the proposed method. The experimental results show that the average absolute positional error is reduced to 0.106 mm from 1.393 mm, and the maximum absolute positional error is reduced to 0.294 mm from 1.795 mm. The simulation and experimental results indicate that the proposed method can enhance the position accuracy of an aviation drilling robot and meet the tolerance requirements in aircraft assembly.