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

Abstract

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.

Using locally adjustable hand-eye calibrations to reduce robot localization error

“…A similar error reduction was reported in [20,27,28], but it was achieved by using real-time feedback from external sensors. Other techniques based on interpolation do not need dynamic tracking of robot movement (similar to our approach), but they reduced only position error [31,32]. Equally important is to note that the reduction in both types of errors shown in Fig.…”

“…(4a). The concept that similar arm configurations should yield similar robot localization errors is at the core of the kriging procedure used in [31,32]. For arbitrary pairs of rotations (i, j) , both arm configurations are usually very different.…”

“…A spherically mounted retro-reflector (SMR) was installed on the end effector and its position was measured with a Leica AT-901 laser tracker. The average position error was reduced to 0.106 mm (robot repeatability was ± 0.06 mm) [31]. A similar procedure was applied to reduce the position error of a drilling and riveting system implemented on a KUKA KR 500-3 robot arm, which has a repeatability of ± 0.08 mm.…”

Comparative Study of Two Pose Measuring Systems Used to Reduce Robot Localization Error

“…For example, trilinear, cubic, and fuzzy interpolation were tested in computer simulations [32]. The kriging interpolation, frequently used in geostatistics [33], was applied to reduce position error of a drilling end effector using a SMR and a laser tracker, resulting in an average position error reduction to 0.106 mm [34]. A similar procedure was applied to reduce the position error of a drilling and riveting end effector mounted on a robot arm; the reported maximum absolute position error was reduced to 0.32 mm [35].…”

Self-compensation method for error of positioning accuracy of intelligent synchronous manipulator

“…Because the value of α is between 0° and 90°, the co-ordinate transformation can be realized, and then kinematics analysis is performed on the manipulator and its joints after the co-ordinate transformation [6].…”