Hello Ayman Thanks for your answer, but I check my mot. file through txt. I found that my mot file columns only contain these: time ground_force_1_vx ground_force_1_vy ground_force_1_vz ground_force_1_px ground_force_1_py ground_force_1_pz ground_moment_1_mx ground_moment_1_my ground_moment_1_mz unl...