Vision-based kinematic calibration of a 4-DOF pick-and-place robot

Pick-and-place robot is usually a 4 degrees-of-freedom (DOFs) apparatus and indispensable in flip chip bonder. Placement accuracy is the most important index to evaluate it. To improve placement accuracy, machine vision is generally utilized to provide the exact pose parameters of chip and pad, which two must be aligned with each other before placement. This paper proposes an effective vision-based kinematic calibration method which calibrates 3 translational DOFs and 1 rotational DOF of pick-and-place robot, respectively. For the 3 translational DOFs, a down-look vision system takes an image and obtains position of a fixed reference cross mark when it moves with pick-and-place robot and the relationship between displacement of pick-and-place robot and position parameters of the cross mark in down-look vision system is the key factor to calibrate it. For the rotational DOF, error parameters of it can be derived after the projective curve of its trajectory in the image plane of up-look vision system is fitted with an ellipse. Placement accuracy is improved to better than ±30μm in the experiment after kinematic calibration. Result shows this vision-based kinematic calibration method is valid and very suitable for 4-DOF pick-and-place robot in flip chip bonder.

[1]  Hanqi Zhuang,et al.  Simultaneous calibration of a robot and a hand-mounted camera , 1993, IEEE Trans. Robotics Autom..

[2]  Maisheng Hong ERROR MOTION DIAGNOSIS OF NC MACHINE TOOLS, COMMENT AND COUNTERMEASURE , 2002 .

[3]  S. Balamurugan,et al.  Machine vision for alignment and inspection in die bonder , 1997, Other Conferences.

[4]  Gilles Burel,et al.  Vision feedback for SMD placement using neural networks , 1995, Proceedings of 1995 IEEE International Conference on Robotics and Automation.

[5]  M. Burdekin,et al.  Calibration system based on a laser interferometer for kinematic accuracy assessment on machine tools , 2006 .

[6]  Roger Y. Tsai,et al.  A new technique for fully autonomous and efficient 3D robotics hand/eye calibration , 1988, IEEE Trans. Robotics Autom..

[7]  M. Yamada,et al.  A Kinematic Calibration Method for Industrial Robots Using Autonomous Visual Measurement , 2006 .

[8]  Wuyi Chen,et al.  A methodology for error characterization and quantification in rotary joints of multi-axis machine tools , 2010 .

[9]  Yin Zhouping,et al.  A Vision-Based Kinematic Calibration for Pick-and-Place Robot , 2011 .

[10]  Gu Fang,et al.  A low cost hand-eye calibration method for arc welding robots , 2009, 2009 IEEE International Conference on Robotics and Biomimetics (ROBIO).

[11]  Zhengchun Du,et al.  Development of a multi-step measuring method for motion accuracy of NC machine tools based on cross grid encoder , 2010 .

[12]  Tian Huang,et al.  Error modeling, sensitivity analysis and assembly process of a class of 3-DOF parallel kinematic machines with parallelogram struts , 2002 .

[13]  Zhao Xiao ERROR MODEL OF NC MACHINE TOOL , 2001 .

[14]  Anthony Chukwujekwu Okafor,et al.  Derivation of machine tool error models and error compensation procedure for three axes vertical machining center using rigid body kinematics , 2000 .

[15]  Eric R. Marsh,et al.  Experiences with the master axis method for measuring spindle error motions , 2000 .