compute joint torque in forward dynamics

[binbinsu@foxmail.com su]

In inverse dynamics, we can compute the joint torques with the known motion and external force (e.g. ground reaction force (GRF)).

In forward dynamics, I can get the motion data when a successful simulation is complete. But how can I get the GRF from the environment? To be specific, how can I get the ground_force_vx ground_force_vy ground_force_vz ground_force_px ground_force_py ground_force_pz 1_ground_force_vx 1_ground_force_vy 1_ground_force_vz 1_ground_force_px 1_ground_force_py 1_ground_force_pz ground_torque_x ground_torque_y ground_torque_z 1_ground_torque_x 1_ground_torque_y 1_ground_torque_z for a grf.mot file?