Correction And Compensation For Positioning- Orientation Error Of Robot In Automatic Drilling

With the development of digital manufacturing technology, quite numbers of advanced automatic drilling technology are applied to the area of aircraft digital assembly. And robot automatic drilling technology is an important component of automatic drilling technology. Due to the strengthen of high drilling quality, well flexible integration and strong environment adaptability, robot automatic drilling technology is widely used in the product line of aircraft digital assembly.In order to improve the accuracy of verticality and position of connecting holes, this article researched the positioning orientation error of robot automatic drilling system. And details can be summarized as two parts, one is about the research of the orientation error correction, and the other is about the study of positioning error compensation.Orientation error correction is the approach to fit the feed direction of spindle of the robot end-effector with the normal direction of surface, and then to ensure the accuracy of verticality of connecting holes. With the spring up of optical measuring technique, the non-contacting measuring technique based on the laser displacement sensor is widely used in robot orientation error correction technology. Firstly, this paper introduced some background of the non-contacting measuring technique and researched the calibration method of the laser displacement sensor. Secondly, in order to dismiss the phenomenon of measured value nonlinear change of the laser displacement sensor and the error of reference pole when correcting orientation error, two measurements were proposed to improve the principle of orientation error correction. One is recording the nonlinear error of measured value and then compensating the error to in-time measured value, the other is adjusting the reference pole to surface by using accommodation technique. Statics indicate that the angle between the feed direction of spindle and the normal direction of surface is controlled under 0.2 degrees and the deep consistency of dimples is 0.03mm after compensating the nonlinear error. As a result, the validity of the correction method is verified. The problem of orientation error correction in robot automatic drilling is solved and the accuracy of verticality of connecting holes is ensured.Positioning error compensation is a way to realize accurate positioning and ensure position accuracy of connecting holes. Due to the relatively low positioning accuracy of robot, the required accuracy of drilled holes could not be directly met without compensation during robot automatic drilling. In order to improve the accuracy, the positioning error of robot is researched. Firstly, this article discussed the error sources and generating processes. And through theoretical analysis and relevant experiment, we found that the absolute positioning error would have different influences on translation component and rotation component of calibration result of robot base coordinate system. Secondly, in order to compensate for the coordinate converted error caused by calibration inaccuracy of base coordinate system, a new method based on constructing error Coons surface function is proposed from the standpoint of aircraft surface construction principle. And the validity of the new method is experimentally verified through robot automatic drilling. Results show that the average error of holes is 0.205 mm and the maximum error is less than 0.343 mm, which must be controlled under 0.5 mm. The required accuracy of robot automatic drilling is realized.