Position Calibration For Laser Displacement Sensor With Its Application In Robot Polishing

The robot technology has been gradually applied to the grinding and polishing processes of complex components to realize the automatic production.In the production,the off-line programming needs to be conducted first based on the theory model of workpiece.Then the machining path is to be planed after the workpiece coordinate system being calibrated,The quality of grinding and polishing is affected by the practical position of the workpiece.With the complex components in large size,the common contact calibration method of workpiece is not applicable.The technologies of non-contact points-cloud collection and registration can be employed to accurately calibrate the workpiece coordinate system.The point cloud data is obtained by measuring tools and it affects the subsequent application directly,so the position calibration of measuring tools is of great importance.In this paper,the laser displacement sensor has been employed to be the measuring tool and solution has been developed for the efficiency,operability and accuracy of its position calibration.With the solution employed,researches has been conducted in the workpiece coordinate calibration application in the grinding and polishing processes of large complex components.The main research contents are given as followings:Firstly,the calibration system has been designed with the laser displacement sensor to be the target,and the position sensitive sensor to be the core.The nine-points calibration method has been proposed based on the fixed theoretical points with variable poses to calculate direction vector and origin coordinate respectively.The error has been analyzed qualitatively,and the error estimation method has been employed based on the least squares fitting sphere.The experiment platform has been established,and the results indicate the validity and practicality of the method.Secondly,the error sources have been analyzed,and the positioning method has been established based on position sensitive device.The position of the laser displacement sensor has been calibrated accurately.The calibration error and the harm to human eye have been reduced.According to the coordinate on the sensitive sensor,an automatic point localization method has been developed,by calculating the actual offset of the actual points,to achieve the automatic calibration of robots.The experiment results indicate that the calibration accuracy and automation has been improved.Thirdly,in the grinding and polishing processes of the large complex component of wind turbine blade,the study of workpiece coordinate system calibration has been conducted.After the de-noising of scanning sample points,and the reduction of pretreatment,the workpiece coordinate system and the analysis error has been obtained by combining the theoretical initial position with the iterative closest point algorithm.The difficulties and low accuracy in large complex component calibration has been solved.And the workpiece coordinate system calibration method employing measuring tools has been proved to be valid.