Robot grasping and in-hand manipulation are nowadays very active
research fields. Their study has been carried out since many years ago. A
very important topic is object-level impedance controllers. While many
different articles have been published during the last two decades, it
seems not clear that most of the newer methods have taken the advantage
over some older ones. Main reasons are related to the problem of
validating such approaches due both to the limited number of existing
robotic hands and to the high limitations of the simulation technology.
It is the aim of this work to review one of this powerful approaches,
with some extensions, and demonstrate that they still represent a strong
basis for developing robust and efficient state-of-the-art object-level
grasp and in-hand manipulation controllers. A review on the concept of
the Virtual Linkage null-space parametrization, and its application to
the implementation of object-level manipulation controllers will be
given. Furthermore, a validation using the Openrave simulator configured
with the ODE physical dynamics engine has been performed. The DLR-Hand
II has been used in these experiments.