drift while start mapping

[Masoumeh]

dear mattieu,

I have attached two launch file that i use for my simulation environment. but i donot know when i start to do mapping, i have drift in my map:
rtabmap_minerobot_Simulation.launch
rtabmap.launch

note: i have only. velodyne, imu and odometer.
Would you please help me to find the problem?

thanks