Research On Self-calibration Based On Geometric Constraints And The Direct Teaching For Seed Sampling Robot

The teaching method of robot and automatic localization of the operational objectives are the keys in the study of fundamental theory and the application of industrial robots,so it has important practical value and theoretical significance.According to the self-localization problem of the operational objectives and the direct teaching,an industrial robot system used to automatically cut and sample the crop seeds is designed with the support of precursory science and technology project of the Chinese Academy of Sciences.The self-localization problem of the crop seeds during the sampling process is resolved,which is proved by the experiment.This paper hereby makes the following researches on the issue.Depending on the needs of breeding experts from home and abroad on automation equipment for sampling seeds,the robot system is designed for cutting and sampling the crop seeds.The host computer procedure based on VC++ is implemented to resolve the self-localization problem and achieve the function of the direct teaching.Focusing on the self-localization problem of the robot during the operation process,this paper proposes a self-calibration method of industrial robot,after analyzing the geometrical characteristics of the seed sampling box.It is based on geometric constraints of points in the coordinate system of the seeds sampling box,which realizes the automatic acquisition of the absolute coordinates of robot target points by using the homogeneous coordinate transformation matrix of the workpiece coordinate system and base coordinate system of robot.So the self-localization problem during the operation process is solved by this method.In order to realize the function of the direct teaching of the robot in the sampling process,the direct teaching problem of robots is analyzed.The direct teaching system is developed on the ER6C60,which adopts the active compliance control method based on position adjustment of the robot.The operator's force can be detected by the force/torque sensor and the force signals obtained by the transformation of static force between coordinate systems are converted into the position adjustment of the robot end-effector,so it can realize the compliance tracking.The upper PC adopts network programming technology based on MFC dialog and realizes the function of the direct teaching of the robot.The self-calibration method based on geometric constraints and the direct teaching based on the position adjustment is verified by experiments.The test results show that the absolute value of the difference of theoretical coordinates and the actual coordinates is less than 0.8 mm,which means the method is correct and practicable and can meet the requirements of practical work.It is easy to implement and it has advantages of low cost and high accuracy,which is of referential significance to solve the self-localization of the workpiece.Meanwhile,the robot direct teaching system based on position adjustment can well realize the manipulator's compliant traction tracking.The effectiveness and reliability of the direct teaching system are validated experimentally.This method is also applicable for the closed control system of industrial robot,which means it has strong universality.