The arm posture changes all the time, when following the fixed ArUco marker

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I am using Ubuntu 18.04.6 and ROS melodic.

I use Dobot CR5, a robotic arm simulated by Gazebo. ArUco detect uses the fiducials package.

I made a python file, which will let the end of the arm continue to move to the front of the marker through the moveit commander.

The marker position remains fixed, and when the arm moves to the front, the arm will shake slightly. I think it should be related to the accuracy of ArUco detection.

But sometimes the arm will suddenly rotate and come back in front of the marker. Regarding this question, what part should I adjust?

Attach a link to the video at the time of execution: https://sendvid.com/q3stg8sg