Hi Peter,

Thanks for your answears. Just one thing taking the exemple of the stool..The rection force, as you said, at each leg reports the amount of load each leg is carrying. However if I look at the sign of the components of the reaction force I can understand the direction towards which the leg opposes to the movement due to the load, right? Thus, if I want to know the direction towards which the leg is supposed to be moved due to the applied load I think it would be sufficient to consider the vector of reaction force with opposite direction (thus the components x y and z have an opposite sign). Does it make sense for you?