I have a question about robot and camera calibration.

I have experience to calibrate btw 6DOF robot arm and hand-eye camera. But this time I should use a machine like CNC plotter. This machine can move only x and y directions and no rotation. I will set a camera under the machine. In this case, can I do calibration btw a cam and the machine? And also can I calculate transformation matrix btw them?

If anyone knows how to solve it please let me know. And if there are some papers about this, also let me know.

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    $\begingroup$ Adding a 'thanks' section to a question is not required, we all tend to be thankful for the people helping us, and expect other people to be thankful too, so saying it just adds noise to the question and distracts people from the problem posed. It may seem counter intuitive, but excessive politeness can itself be impolite, as giving people extra text to read, even if they ignore it, is disrespectful of their time. $\endgroup$
    – Mark Booth
    Commented Sep 13, 2019 at 10:51
  • $\begingroup$ Welcome to Robotics, Soonmyun Jang. I'm not sure I understand your question. You said I have experience to calibrate btw 6DOF robot arm and hand-eye camera, but then go on to ask for help with a CNC plotter. If you've got experience with the 6 DOF system, what is the trouble you're having with a 2 DOF system? The problem you're trying to solve now is a simplified version of the problem you already have experience with. What's the trouble you're having? $\endgroup$
    – Chuck
    Commented Sep 13, 2019 at 12:49
  • $\begingroup$ @MarkBooth I understand. It is just culture of my country. $\endgroup$ Commented Sep 14, 2019 at 7:50
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    – Mark Booth
    Commented Sep 14, 2019 at 11:17
  • $\begingroup$ I understand @SoonmyunJang, I'm from Britain, so I apologise when I walk in front of someone taking a photograph *8'), but Stack Exchange has it's own culture. We value peoples time and attention here highly, and expect people to be polite, just not so polite that it wastes peoples valuable time. $\endgroup$
    – Mark Booth
    Commented Sep 14, 2019 at 11:22

1 Answer 1


In this case, the Z value and rotation value are constant, so it's a 2DOF system. You can do the same calibration as with the 6DOF and you'll find a homogeneous matrix as usual.

The difference here is that instead of a direct kinematics approach from a manipulator you'll have to determine the position (0, 0) for the CNC Plotter and the constant Z and rotation. Depending on the method (if you're using a least-squares method), you can find the Z and rotation value as well, otherwise, one approach is to determine them previously and find the X and Y values for the matrix.


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