Direction of Ground Reaction Force

[Eric Hu]

Hi Dr. Geijtenbeek,

I hope you are having a wonderful day. I attached a picture of the H0914 model that I am working on and I realized that the direction of my arrows at the beginning of the gait cycle seem to be in the opposite direction. I was wondering if you happen to know how to redirect these arrows in the correct direction without sacrificing velocity or altering the initial position. For context, I set my pelvis_tx to 1 for a 1m/s COM movement in the x direction. I understand that this is the reason why the arrow is in the opposite direction, but I'm lost as to what the alternatives are.

Screenshot 2024-05-22 093521.png (133.39 KiB) Viewed 487 times

Thank you so much,

Eric

[Thomas Geijtenbeek]

The direction of the ground reaction force is the result of friction, which is based on the relative velocity of the contact and the floor. The only way to change that is by changing the velocity of the contact sphere, which can only be done by changing the coordinates.

[Eric Hu]

Dr. Geijtenbeek,

Thank you so much for the explanation. Could you explain how to do what you suggested? I'm not too familiar with how to change the velocity of the contact sphere within SCONE.

Thank you,

Eric

[Thomas Geijtenbeek]

You can only do this indirectly by changing the coordinates and the coordinate velocities.