Projection of the hand model active workspace in the plane orthogonal on the flexion-extension motion axis when the assembly palm_fingers is stiffened. This space corresponds to the flexion-extension motion of the assembly palm-fingers (meaning only the joint 1 is moving). It can be observed that the active areas are asymmetrical disposed with respect to the horizontal axis. By stiffening all fingers' articulations, the assembly palm-fingers has a rigid body behavior and the fingers' tips trajectories are circle arcs situated in various planes parallels with x
0. The thumb's trajectory is distinct placed with respect to the other four fingers whose trajectories are parallel. The middle finger describes a circle whose radius value is 17 cm.