Joint::SetForce documentation states that:
Force is additive (multiple calls to SetForce to the same joint in the same time step will accumulate forces on that Joint).
However, it seems that this is not true for the
DART physics engine, where instead every call to SetForce is overwriting the previous one, even if no update to the physics happened in the meanwhile.
Downstream issue: https://github.com/robotology/gazebo-fmi/pull/28 Similar issue, but related to Simbody: https://bitbucket.org/osrf/gazebo/issues/2507/joint-setforce-is-not-additive-in-simbody .