[lammps-users] How to controll the motion of a rigid group?

I’m sorry I omit the follows in last mail:

The command “fix nve/noforce” is not suitable to this issue because the rigid group in my model should be kept free in one dimension and be set a constant velocity in another dimension, in another word, maybe I need apply “fix nve/noforce” on this rigid group of atoms in a specific dimension, but not all three dimensions.

Thanks in advance!