A minus value of friction force


I have a question about the friction force of “AMMRV1.2\Application\Examples\AirlinePassenger”.

At the end of steps, nStep = 13, at the L5SupportNode, the friction force of Y direction has minus value.
Main.Model.ModelEnvironmentConnection.Support.BackrestSupport.L5Support.Push.FrictionForceVec = {23.6252, -40.92004, 2.028503e-014};
What does it mean?

In the Model View, the vector direction of L5SupportNode friction force is opposite to other friction forces vector, ex. T12SupportNode.

Does the L5SupportNode friction force reduce the total friction force of backrest in Y direction?

Please help me to get your advice.
Thank you


This is the geometric vector in the Global reference frame, so it can take positive as well as negative values. In this case it means it is pushing on the negative direction of the global Y axis.

The system is calculating the best support configuration to lower the muscle activity, so it is posible that one of the friction force goes in the opposite direction of the others if it helps relax the body.

Best regards, Sylvain.