Grasp acquisition using liftability regions

The author studies the mechanics of lifting a slippery two-dimensional object initially at rest on a supporting surface. The equilibrium relationships are solved to define five liftability regions, and a graphical technique for their construction is given. One of the liftability regions provides a simple way to lift the object away from its support by dexterous manipulation (moving only the fingers, not the palm). The same region can also be used to plan stable manipulation after the object loses contact with the support. The analysis can be applied to any three-dimensional object which can be modeled as a generalized cylinder, by considering a suitable cross section of the cylinder. Friction effects are easily taken into account using the graphical technique