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Function for Custom force

Posted: Mon Jan 09, 2012 11:08 am
by hanghang500
Hi, all
I met some questions when I tried to learn the Custom force class (https://simtk.org/api_docs/opensim/api_docs20b/)
I am confused about the different between "applyForce" which said "Apply a force to a particular body which only apply a force, not a torque, which is equivalent to applying the force at the body's center of mass."and "applyForceToPoint" which said "Apply a force to a particular body.Based on what point the force is applied at, automatically determines the torque produced by the force and applies that as well".

So my question is:
1. Does "applyForce" is chosen only when the force directly apply to the body's COM? is that right? Otherwise, there will be torque produced and we should choose "applyForceToPoint"
2. Especial for ligament force, which one should be used ? "applyForce" or "applyForceToPoint"

Thanks for any help and suggestion.