How can i improve gmapping result for this simulation?

edit

I want to improve this simulation -> https://github.com/TDR-SDC/fsd_simulator (mainly the loop closure part)

A small gist of the simulation:

1. eufs_description contains urdf and mesh files
2. eufs_gazebo has the launch file small_track.launch whose output i want to enhance
3. robot_control has the controllers for the simulation
4. gmapping package has params.yaml which contains all the parameters

Its fine if you cant improve other aspects but i definitely want to improve consistancy of loop closure It would be great if you could even suggest some changes in parameters. I would be more than happy to test them myself.