Question: as the title, open it plugin.xml It was found to be blank.

Solution: find the GitHub of PR2, download and copy it to/opt/ROS/melody/share/PR2_ moto_ diagnostic_ Tool/or create your own plugin.xml File, which will be installed on GitHub plugin.xml Copy in the code in.

[new problem] prompts that we do not have permission to create a file in this path, so we need to increase the permission to obtain the super user permission: $sudo Chmod 777/opt/ROS/melody/share/PR2_ motor_ diagnostic_ tool/。 Then create a new one plugin.xml File, copy the code in and save it.