How modify the properties of the shadow hand?

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I'm Working with the shadow hand, i'm moving it on gazebo by a glove with sensors, and that's works very nice, the little problem is that sometimes the shadow hand falls , supposed to be all the gravity and properties that are simulated in gazebo. If the gravity was desactivaded nothing works fine.

The only option i suppose have to be change is the mass of the forearm and maybe put it more heavy. Also i need the position of the hand Kind different. Obviously the pkg is restricted and changes don't very easy. and try to move it to other place is hard..

any idea?? thnks